NISTIR 7298

Revision 2 

Glossary of Key Information 

Security Terms 

Richard Kissel, Editor
NISTIR 7298

Revision 2 

Glossary of Key Information Security 

Terms 

Richard Kissel, Editor 

Computer Security Division

Information Technology Laboratory 

May 2013

U.S. Department of Commerce 

Rebecca Blank, Acting Secretary

National Institute of Standards and Technology

Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director
ii

National Institute of Standards and Technology Interagency or Internal Report 7298r2

222 pages (May 2013)

 

 

National Institute of Standards and Technology

Attn: Computer Security Division, Information Technology Laboratory

100 Bureau Drive (Mail Stop 8930) Gaithersburg, MD 20899-8930

Email: secglossary@nist.gov

Certain commercial entities, equipment, or materials may be identified in this document in order to 

describe an experimental procedure or concept adequately. Such identification is not intended to imply 

recommendation or endorsement by NIST, nor is it intended to imply that the entities, materials, or 

equipment are necessarily the best available for the purpose. 

There may be references in this publication to other publications currently under development by NIST 

in accordance with its assigned statutory responsibilities. The information in this publication, including 

concepts and methodologies, may be used by Federal agencies even before the completion of such 

companion publications. Thus, until each publication is completed, current requirements, guidelines, 

and procedures, where they exist, remain operative. For planning and transition purposes, Federal 

agencies may wish to closely follow the development of these new publications by NIST. 

Organizations are encouraged to review all draft publications during public comment periods and 

provide feedback to NIST. All NIST Computer Security Division publications, other than the ones 

noted above, are available at http://csrc.nist.gov/publications.
iii

Reports on Computer Systems Technology

The Information Technology Laboratory (ITL) at the National Institute of Standards and Technology 

(NIST) promotes the U.S. economy and public welfare by providing technical leadership for the Nation’s 

measurement and standards infrastructure. ITL develops tests, test methods, reference data, proof of 

concept implementations, and technical analyses to advance the development and productive use of 

information technology. ITL’s responsibilities include the development of management, administrative, 

technical, and physical standards and guidelines for the cost-effective security and privacy of other than 

national security-related information in Federal information systems. 

Abstract

The National Institute of Standards and Technology (NIST) has received numerous requests to 

provide a summary glossary for our publications and other relevant sources, and to make the 

glossary available to practitioners. As a result of these requests, this glossary of common

security terms has been extracted from NIST Federal Information Processing Standards (FIPS), 

the Special Publication (SP) 800 series, NIST Interagency Reports (NISTIRs), and from the 

Committee for National Security Systems Instruction 4009 (CNSSI-4009). This glossary 

includes most of the terms in the NIST publications. It also contains nearly all of the terms and 

definitions from CNSSI-4009. This glossary provides a central resource of terms and definitions 

most commonly used in NIST information security publications and in CNSS information 

assurance publications. For a given term, we do not include all definitions in NIST documents –

especially not from the older NIST publications. Since draft documents are not stable, we do not 

refer to terms/definitions in them.

Each entry in the glossary points to one or more source NIST publications, and/or CNSSI-4009, 

and/or supplemental sources where appropriate. The NIST publications referenced are the most 

recent versions of those publications (as of the date of this document).

Keywords

Cyber Security; Definitions; Glossary; Information Assurance; Information Security; Terms
1

Introduction

We have received numerous requests to provide a summary glossary for our publications and

other relevant sources, and to make the glossary available to practitioners. As a result of these 

requests, this glossary of common security terms has been extracted from NIST Federal 

Information Processing Standards (FIPS), the Special Publication (SP) 800 series, NIST 

Interagency Reports (NISTIRs), and from the Committee for National Security Systems 

Instruction 4009 (CNSSI-4009). The glossary includes most of the terms in the NIST

publications. It also contains nearly all of the terms and definitions from CNSSI-4009. The 

glossary provides a central resource of terms and definitions most commonly used in NIST 

information security publications and in CNSS information assurance publications. For a given 

term, we do not include all definitions in NIST documents – especially not from the older NIST 

publications. Since draft documents are not stable, we do not refer to terms/definitions in them.

Each entry in the glossary points to one or more source NIST publications, and/or CNSSI-4009, 

and/or supplemental sources where appropriate. A list of the supplemental (non-NIST) sources 

may be found on pages 221-222. As we are continuously refreshing our publication suite, terms 

included in the glossary come from our more recent publications. The NIST publications 

referenced are the most recent versions of those publications (as of the date of this document).

It is our intention to keep the glossary current by providing updates online. New definitions will 

be added to the glossary as required, and updated versions will be posted on the Computer 

Security Resource Center (CSRC) Web site at http://csrc.nist.gov/.

The Editor, Richard Kissel, would like to express special thanks to Ms. Tanya Brewer for her 

outstanding work in the design of the original cover page and in the overall design and 

organization of the document. Thanks also to all who provided comments during the public 

review period of this document. The Editor also expresses special thanks to the CNSS Glossary 

Working Group for encouraging the inclusion of CNSSI-4009 terms and definitions into this 

glossary. 

Comments and suggestions on this publication should be sent to secglossary@nist.gov. 
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Access – Ability to make use of any information system (IS) resource.

SOURCE: SP 800-32

Ability and means to communicate with or otherwise interact with a 

system, to use system resources to handle information, to gain 

knowledge of the information the system contains, or to control 

system components and functions.

SOURCE: CNSSI-4009

Access Authority – An entity responsible for monitoring and granting access privileges 

for other authorized entities.

SOURCE: CNSSI-4009

Access Control – The process of granting or denying specific requests to: 1) obtain and 

use information and related information processing services; and 2) 

enter specific physical facilities (e.g., federal buildings, military 

establishments, border crossing entrances). 

SOURCE: FIPS 201; CNSSI-4009

Access Control List (ACL) – 1. A list of permissions associated with an object. The list specifies 

who or what is allowed to access the object and what operations are 

allowed to be performed on the object. 

2. A mechanism that implements access control for a system resource 

by enumerating the system entities that are permitted to access the 

resource and stating, either implicitly or explicitly, the access modes 

granted to each entity.

SOURCE: CNSSI-4009

Access Control Lists (ACLs) – A register of:

1. users (including groups, machines, processes) who have been 

given permission to use a particular system resource, and

2. the types of access they have been permitted.

SOURCE: SP 800-12

Access Control Mechanism – Security safeguards (i.e., hardware and software features, physical 

controls, operating procedures, management procedures, and various 

combinations of these) designed to detect and deny unauthorized 

access and permit authorized access to an information system.

SOURCE: CNSSI-4009

Access Level – A category within a given security classification limiting entry or 

system connectivity to only authorized persons. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Access List – Roster of individuals authorized admittance to a controlled area.

SOURCE: CNSSI-4009

Access Point – A device that logically connects wireless client devices operating in 

infrastructure to one another and provides access to a distribution 

system, if connected, which is typically an organization’s enterprise 

wired network.

SOURCE: SP 800-48; SP 800-121

Access Profile – Association of a user with a list of protected objects the user may 

access.

SOURCE: CNSSI-4009

Access Type – Privilege to perform action on an object. Read, write, execute, 

append, modify, delete, and create are examples of access types. See 

Write.

SOURCE: CNSSI-4009

Account Management, User – Involves

1) the process of requesting, establishing, issuing, and closing user 

accounts;

2) tracking users and their respective access authorizations; and 

3) managing these functions.

SOURCE: SP 800-12

Accountability – The security goal that generates the requirement for actions of an 

entity to be traced uniquely to that entity. This supports nonrepudiation, deterrence, fault isolation, intrusion detection and 

prevention, and after-action recovery and legal action.

SOURCE: SP 800-27

Principle that an individual is entrusted to safeguard and control 

equipment, keying material, and information and is answerable to 

proper authority for the loss or misuse of that equipment or 

information.

SOURCE: CNSSI-4009

Accounting Legend Code (ALC) – Numeric code used to indicate the minimum accounting controls 

required for items of accountable communications security 

(COMSEC) material within the COMSEC Material Control System.

SOURCE: CNSSI-4009

Accounting Number – Number assigned to an item of COMSEC material to facilitate its 

control.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Accreditation – See Authorization.

Accreditation Authority – See Authorizing Official.

Accreditation Boundary – See Authorization Boundary.

Accreditation Package – Product comprised of a System Security Plan (SSP) and a report 

documenting the basis for the accreditation decision.

SOURCE: CNSSI-4009

Accrediting Authority – Synonymous with Designated Accrediting Authority (DAA). See 

also Authorizing Official.

SOURCE: CNSSI-4009

Activation Data – Private data, other than keys, that are required to access 

cryptographic modules.

SOURCE: SP 800-32

Active Attack – An attack that alters a system or data.

SOURCE: CNSSI-4009

An attack on the authentication protocol where the Attacker 

transmits data to the Claimant, Credential Service Provider, 

Verifier, or Relying Party. Examples of active attacks include 

man-in-the-middle, impersonation, and session hijacking. 

SOURCE: SP 800-63

Active Content – Electronic documents that can carry out or trigger actions 

automatically on a computer platform without the intervention of a 

user.

SOURCE: SP 800-28

Software in various forms that is able to automatically carry out or 

trigger actions on a computer platform without the intervention of a 

user.

SOURCE: CNSSI-4009

Active Security Testing – Security testing that involves direct interaction with a target, such as 

sending packets to a target.

SOURCE: SP 800-115

Activities – An assessment object that includes specific protection-related

pursuits or actions supporting an information system that involve 

people (e.g., conducting system backup operations, monitoring 

network traffic).

SOURCE: SP 800-53A
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Ad Hoc Network – A wireless network that dynamically connects wireless client devices 

to each other without the use of an infrastructure device, such as an 

access point or a base station.

SOURCE: SP 800-121

Add-on Security – Incorporation of new hardware, software, or firmware safeguards in 

an operational information system.

SOURCE: CNSSI-4009

Adequate Security – Security commensurate with the risk and the magnitude of harm 

resulting from the loss, misuse, or unauthorized access to or 

modification of information.

SOURCE: SP 800-53; FIPS 200; OMB Circular A-130, App. III

Security commensurate with the risk and magnitude of harm resulting 

from the loss, misuse, or unauthorized access to or modification of 

information. 

Note: This includes assuring that information systems operate 

effectively and provide appropriate confidentiality, integrity, and 

availability, through the use of cost-effective management, personnel, 

operational, and technical controls.

SOURCE: CNSSI-4009; SP 800-37

Administrative Account – A user account with full privileges on a computer.

SOURCE: SP 800-69

Administrative Safeguards – Administrative actions, policies, and procedures to manage the 

selection, development, implementation, and maintenance of security 

measures to protect electronic health information and to manage the 

conduct of the covered entity's workforce in relation to protecting 

that information.

SOURCE: SP 800-66

Advanced Encryption Standard –

(AES)

The Advanced Encryption Standard specifies a U.S. governmentapproved cryptographic algorithm that can be used to protect 

electronic data. The AES algorithm is a symmetric block cipher that 

can encrypt (encipher) and decrypt (decipher) information. This 

standard specifies the Rijndael algorithm, a symmetric block cipher 

that can process data blocks of 128 bits, using cipher keys with 

lengths of 128, 192, and 256 bits.

SOURCE: FIPS 197
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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A U.S. government-approved cryptographic algorithm that can be 

used to protect electronic data. The AES algorithm is a symmetric 

block cipher that can encrypt (encipher) and decrypt (decipher) 

information.

SOURCE: CNSSI-4009

Advanced Key Processor (AKP) – A cryptographic device that performs all cryptographic functions for 

a management client node and contains the interfaces to 1) exchange 

information with a client platform, 2) interact with fill devices, and 3) 

connect a client platform securely to the primary services node 

(PRSN).

SOURCE: CNSSI-4009

Advanced Persistent Threats(APT) – An adversary that possesses sophisticated levels of expertise and 

significant resources which allow it to create opportunities to achieve 

its objectives by using multiple attack vectors (e.g., cyber, physical, 

and deception). These objectives typically include establishing and 

extending footholds within the information technology infrastructure 

of the targeted organizations for purposes of exfiltrating information, 

undermining or impeding critical aspects of a mission, program, or 

organization; or positioning itself to carry out these objectives in the 

future. The advanced persistent threat: (i) pursues its objectives 

repeatedly over an extended period of time; (ii) adapts to defenders’ 

efforts to resist it; and (iii) is determined to maintain the level of 

interaction needed to execute its objectives.

SOURCE: SP 800-39

Adversary – Individual, group, organization, or government that conducts or has 

the intent to conduct detrimental activities.

SOURCE: SP 800-30

Advisory – Notification of significant new trends or developments regarding the 

threat to the information systems of an organization. This 

notification may include analytical insights into trends, intentions, 

technologies, or tactics of an adversary targeting information 

systems.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Agency – Any executive department, military department, government 

corporation, government-controlled corporation, or other 

establishment in the executive branch of the government (including 

the Executive Office of the President), or any independent regulatory 

agency, but does not include: 1) the Government Accountability 

Office; 2) the Federal Election Commission; 3) the governments of 

the District of Columbia and of the territories and possessions of the 

United States, and their various subdivisions; or 4) governmentowned contractor-operated facilities, including laboratories engaged 

in national defense research and production activities.

SOURCE: FIPS 200; 44 U.S.C., Sec. 3502

ALSO See Executive Agency.

Agency Certification Authority –

(CA)

A CA that acts on behalf of an agency and is under the operational 

control of an agency.

SOURCE: SP 800-32

Agent – A program acting on behalf of a person or organization.

SOURCE: SP 800-95

Alert – Notification that a specific attack has been directed at an 

organization’s information systems.

SOURCE: CNSSI-4009

Allocation – The process an organization employs to determine whether security 

controls are defined as system-specific, hybrid, or common.

The process an organization employs to assign security controls to 

specific information system components responsible for providing a 

particular security capability (e.g., router, server, remote sensor).

SOURCE: SP 800-37

Alternate COMSEC Custodian – Individual designated by proper authority to perform the duties of the 

COMSEC custodian during the temporary absence of the COMSEC 

custodian.

SOURCE: CNSSI-4009

Alternate Work Site – Governmentwide, national program allowing federal employees to 

work at home or at geographically convenient satellite offices for part 

of the work week (e.g., telecommuting).

SOURCE: CNSSI-4009

Analysis – The examination of acquired data for its significance and probative 

value to the case.

SOURCE: SP 800-72
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Anomaly-Based Detection – The process of comparing definitions of what activity is considered 

normal against observed events to identify significant deviations.

SOURCE: SP 800-94

Anti-jam – Countermeasures ensuring that transmitted information can be 

received despite deliberate jamming attempts. 

SOURCE: CNSSI-4009

Anti-spoof – Countermeasures taken to prevent the unauthorized use of legitimate 

Identification & Authentication (I&A) data, however it was obtained, 

to mimic a subject different from the attacker.

SOURCE: CNSSI-4009

Antispyware Software – A program that specializes in detecting both malware and nonmalware forms of spyware.

SOURCE: SP 800-69

Antivirus Software – A program that monitors a computer or network to identify all major 

types of malware and prevent or contain malware incidents.

SOURCE: SP 800-83

Applicant – The subscriber is sometimes called an “applicant” after applying to a 

certification authority for a certificate, but before the certificate 

issuance procedure is completed.

SOURCE: SP 800-32

Application – A software program hosted by an information system.

SOURCE: SP 800-37

Software program that performs a specific function directly for a user 

and can be executed without access to system control, monitoring, or 

administrative privileges.

SOURCE: CNSSI-4009

Approval to Operate (ATO) – The official management decision issued by a DAA or PAA to 

authorize operation of an information system and to explicitly accept 

the residual risk to agency operations (including mission, functions, 

image, or reputation), agency assets, or individuals.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Approved – Federal Information Processing Standard (FIPS)-approved or 

National Institute of Standards and Technology (NIST)-

recommended. An algorithm or technique that is either 

1) specified in a FIPS or NIST Recommendation, or 

2) adopted in a FIPS or NIST Recommendation.

SOURCE: FIPS 201

Approved – FIPS-approved and/or NIST-recommended.

SOURCE: FIPS 140-2

FIPS-approved and/or NIST-recommended. An algorithm or 

technique that is either 1) specified in a FIPS or NIST 

Recommendation, 2) adopted in a FIPS or NIST 

Recommendation, or 3) specified in a list of NIST-approved 

security functions.

SOURCE: FIPS 186

Approved Mode of Operation – A mode of the cryptographic module that employs only Approved 

security functions (not to be confused with a specific mode of an 

Approved security function, e.g., Data Encryption Standard CipherBlock Chaining (DES CBC) mode).

SOURCE: FIPS 140-2

Approved Security Function – A security function (e.g., cryptographic algorithm, cryptographic key 

management technique, or authentication technique) that is either 

a) specified in an Approved Standard; 

b) adopted in an Approved Standard and specified either in an 

appendix of the Approved Standard or in a document 

referenced by the Approved Standard; or 

c) specified in the list of Approved security functions. 

SOURCE: FIPS 140-2

Assessment – See Security Control Assessment.

Assessment Findings – Assessment results produced by the application of an assessment 

procedure to a security control or control enhancement to achieve an 

assessment objective; the execution of a determination statement 

within an assessment procedure by an assessor that results in either

a satisfied or other than satisfied condition.

SOURCE: SP 800-53A

Assessment Method – One of three types of actions (i.e., examine, interview, test) taken by 

assessors in obtaining evidence during an assessment.

SOURCE: SP 800-53A
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Assessment Object – The item (i.e., specifications, mechanisms, activities, individuals) 

upon which an assessment method is applied during an assessment.

SOURCE: SP 800-53A

Assessment Objective – A set of determination statements that expresses the desired outcome 

for the assessment of a security control or control enhancement.

SOURCE: SP 800-53A

Assessment Procedure – A set of assessment objectives and an associated set of assessment 

methods and assessment objects.

SOURCE: SP 800-53A

Assessor – See Security Control Assessor.

Asset – A major application, general support system, high impact program, 

physical plant, mission critical system, personnel, equipment, or a 

logically related group of systems.

SOURCE: CNSSI-4009

Asset Identification – Security Content Automation Protocol (SCAP) constructs to uniquely 

identify assets (components) based on known identifiers and/or 

known information about the assets. 

SOURCE: SP 800-128

Asset Reporting Format (ARF) – SCAP data model for expressing the transport format of information 

about assets (components) and the relationships between assets and 

reports. 

SOURCE: SP 800-128

Assurance – Grounds for confidence that the other four security goals (integrity, 

availability, confidentiality, and accountability) have been adequately 

met by a specific implementation. “Adequately met” includes (1) 

functionality that performs correctly, (2) sufficient protection against 

unintentional errors (by users or software), and (3) sufficient 

resistance to intentional penetration or by-pass.

SOURCE: SP 800-27

The grounds for confidence that the set of intended security controls 

in an information system are effective in their application.

SOURCE: SP 800-37; SP 800-53A

Measure of confidence that the security features, practices, 

procedures, and architecture of an information system accurately 

mediates and enforces the security policy.

SOURCE: CNSSI-4009; SP 800-39
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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In the context of OMB M-04-04 and this document, assurance is 

defined as 1) the degree of confidence in the vetting process used 

to establish the identity of an individual to whom the credential 

was issued, and 2) the degree of confidence that the individual 

who uses the credential is the individual to whom the credential 

was issued. 

SOURCE: SP 800-63

Assurance Case – A structured set of arguments and a body of evidence showing that an 

information system satisfies specific claims with respect to a given 

quality attribute.

SOURCE: SP 800-53A; SP 800-39

Assured Information Sharing – The ability to confidently share information with those who need it, 

when and where they need it, as determined by operational need and 

an acceptable level of security risk. 

SOURCE: CNSSI-4009

Assured Software – Computer application that has been designed, developed, analyzed,

and tested using processes, tools, and techniques that establish a level 

of confidence in it.

SOURCE: CNSSI-4009

Asymmetric Cryptography – See Public Key Cryptography.

SOURCE: CNSSI-4009

Asymmetric Keys – Two related keys, a public key and a private key that are used to 

perform complementary operations, such as encryption and 

decryption or signature generation and signature verification.

SOURCE: FIPS 201

Attack – An attempt to gain unauthorized access to system services, resources, 

or information, or an attempt to compromise system integrity.

SOURCE: SP 800-32

Any kind of malicious activity that attempts to collect, disrupt, deny, 

degrade, or destroy information system resources or the information 

itself.

SOURCE: CNSSI-4009

Attack Sensing and Warning 

(AS&W) –

Detection, correlation, identification, and characterization of 

intentional unauthorized activity with notification to decision makers

so that an appropriate response can be developed.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Attack Signature – A specific sequence of events indicative of an unauthorized access 

attempt.

SOURCE: SP 800-12

A characteristic byte pattern used in malicious code or an indicator, 

or set of indicators, that allows the identification of malicious 

network activities.

SOURCE: CNSSI-4009

Attribute Authority – An entity, recognized by the Federal Public Key Infrastructure (PKI) 

Policy Authority or comparable agency body as having the authority 

to verify the association of attributes to an identity.

SOURCE: SP 800-32

Attribute-Based Access Control – Access control based on attributes associated with and about subjects, 

objects, targets, initiators, resources, or the environment. An access 

control rule set defines the combination of attributes under which an 

access may take place.

SOURCE: SP 800-53; CNSSI-4009

Attribute-Based Authorization – A structured process that determines when a user is authorized to 

access information, systems, or services based on attributes of the 

user and of the information, system, or service.

SOURCE: CNSSI-4009

Audit – Independent review and examination of records and activities to 

assess the adequacy of system controls, to ensure compliance with 

established policies and operational procedures, and to recommend 

necessary changes in controls, policies, or procedures.

SOURCE: SP 800-32

Independent review and examination of records and activities to 

assess the adequacy of system controls, to ensure compliance with 

established policies and operational procedures.

SOURCE: CNSSI-4009

Audit Data – Chronological record of system activities to enable the reconstruction 

and examination of the sequence of events and changes in an event.

SOURCE: SP 800-32

Audit Log – A chronological record of system activities. Includes records of 

system accesses and operations performed in a given period. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Audit Reduction Tools – Preprocessors designed to reduce the volume of audit records to 

facilitate manual review. Before a security review, these tools can 

remove many audit records known to have little security significance. 

These tools generally remove records generated by specified classes 

of events, such as records generated by nightly backups.

SOURCE: SP 800-12; CNSSI-4009

Audit Review – The assessment of an information system to evaluate the adequacy of 

implemented security controls, assure that they are functioning 

properly, identify vulnerabilities, and assist in implementation of new 

security controls where required. This assessment is conducted 

annually or whenever significant change has occurred and may lead 

to recertification of the information system.

SOURCE: CNSSI-4009

Audit Trail – A record showing who has accessed an Information Technology (IT) 

system and what operations the user has performed during a given 

period.

SOURCE: SP 800-47

A chronological record that reconstructs and examines the sequence 

of activities surrounding or leading to a specific operation, procedure, 

or event in a security relevant transaction from inception to final 

result.

SOURCE: CNSSI-4009

Authenticate – To confirm the identity of an entity when that identity is presented.

SOURCE: SP 800-32

To verify the identity of a user, user device, or other entity.

SOURCE: CNSSI-4009

Authentication – Verifying the identity of a user, process, or device, often as a 

prerequisite to allowing access to resources in an information system.

SOURCE: SP 800-53; SP 800-53A; SP 800-27; FIPS 200; SP 800-30

Authentication – The process of establishing confidence of authenticity.

SOURCE: FIPS 201

Authentication – Encompasses identity verification, message origin authentication, and 

message content authentication.

SOURCE: FIPS 190
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Authentication – A process that establishes the origin of information or determines an 

entity’s identity.

SOURCE: SP 800-21

The process of verifying the identity or other attributes claimed by or 

assumed of an entity (user, process, or device), or to verify the source 

and integrity of data. 

SOURCE: CNSSI-4009

The process of establishing confidence in the identity of users or 

information systems. 

SOURCE: SP 800-63

Authentication Code – A cryptographic checksum based on an Approved security function 

(also known as a Message Authentication Code [MAC]).

SOURCE: FIPS 140-2

Authentication Mechanism – Hardware-or software-based mechanisms that force users to prove 

their identity before accessing data on a device.

SOURCE: SP 800-72; SP 800-124

Hardware or software-based mechanisms that forces users, devices, 

or processes to prove their identity before accessing data on an 

information system.

SOURCE: CNSSI-4009

Authentication Mode – A block cipher mode of operation that can provide assurance of the 

authenticity and, therefore, the integrity of data.

SOURCE: SP 800-38B

Authentication Period – The maximum acceptable period between any initial authentication 

process and subsequent reauthentication processes during a single 

terminal session or during the period data is being accessed.

SOURCE: CNSSI-4009

Authentication Protocol – A defined sequence of messages between a Claimant and a Verifier 

that demonstrates that the Claimant has possession and control of a 

valid token to establish his/her identity, and optionally, demonstrates 

to the Claimant that he or she is communicating with the intended 

Verifier. 

SOURCE: SP 800-63

A well-specified message exchange process between a claimant and a 

verifier that enables the verifier to confirm the claimant’s identity.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Authentication Tag – A pair of bit strings associated to data to provide assurance of its 

authenticity.

SOURCE: SP 800-38B

Authentication Token – Authentication information conveyed during an authentication 

exchange.

SOURCE: FIPS 196

Authenticator – The means used to confirm the identity of a user, process, or device 

(e.g., user password or token).

SOURCE: SP 800-53; CNSSI-4009

Authenticity – The property of being genuine and being able to be verified and 

trusted; confidence in the validity of a transmission, a message, or 

message originator. See Authentication.

SOURCE: SP 800-53; SP 800-53A; CNSSI-4009; SP 800-39

Authority – Person(s) or established bodies with rights and responsibilities to 

exert control in an administrative sphere.

SOURCE: CNSSI-4009

Authorization – Access privileges granted to a user, program, or process or the act 

of granting those privileges. 

SOURCE: CNSSI-4009

Authorization (to operate) – The official management decision given by a senior organizational 

official to authorize operation of an information system and to 

explicitly accept the risk to organizational operations (including 

mission, functions, image, or reputation), organizational assets, 

individuals, other organizations, and the Nation based on the 

implementation of an agreed-upon set of security controls.

SOURCE: SP 800-53; SP 800-53A; CNSSI-4009; SP 800-37

Authorization Boundary – All components of an information system to be authorized for 

operation by an authorizing official and excludes separately 

authorized systems, to which the information system is connected.

SOURCE: CNSSI-4009; SP 800-53; SP 800-53A; SP 800-37

Authorize Processing – See Authorization (to operate).

Authorized Vendor – Manufacturer of information assurance equipment authorized to 

produce quantities in excess of contractual requirements for direct 

sale to eligible buyers. Eligible buyers are typically U.S. government 

organizations or U.S. government contractors.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Authorized Vendor Program(AVP) – Program in which a vendor, producing an information systems 

security (INFOSEC) product under contract to NSA, is authorized to 

produce that product in numbers exceeding the contracted 

requirements for direct marketing and sale to eligible buyers. 

Eligible buyers are typically U.S. government organizations or U.S. 

government contractors. Products approved for marketing and sale 

through the AVP are placed on the Endorsed Cryptographic Products 

List (ECPL).

SOURCE: CNSSI-4009

Authorizing Official – Official with the authority to formally assume responsibility for 

operating an information system at an acceptable level of risk to 

agency operations (including mission, functions, image, or 

reputation), agency assets, or individuals. Synonymous with 

Accreditation Authority.

SOURCE: FIPS 200

Senior federal official or executive with the authority to formally 

assume responsibility for operating an information system at an 

acceptable level of risk to organizational operations (including 

mission, functions, image, or reputation), organizational assets, 

individuals, other organizations, and the Nation.

SOURCE: CNSSI-4009

A senior (federal) official or executive with the authority to formally 

assume responsibility for operating an information system at an 

acceptable level of risk to organizational operations (including 

mission, functions, image, or reputation), organizational assets, 

individuals, other organizations, and the Nation.

SOURCE: SP 800-53; SP 800-53A; SP 800-37

Authorizing Official

Designated Representative –

An organizational official acting on behalf of an authorizing official 

in carrying out and coordinating the required activities associated 

with security authorization.

SOURCE: CNSSI-4009; SP 800-37; SP 800-53A

Automated Key Transport – The transport of cryptographic keys, usually in encrypted form, using 

electronic means such as a computer network (e.g., key 

transport/agreement protocols).

SOURCE: FIPS 140-2

Automated Password Generator – An algorithm which creates random passwords that have no 

association with a particular user.

SOURCE: FIPS 181
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

17

Automated Security Monitoring – Use of automated procedures to ensure security controls are not 

circumvented or the use of these tools to track actions taken by 

subjects suspected of misusing the information system.

SOURCE: CNSSI-4009

Automatic Remote Rekeying – Procedure to rekey a distant crypto-equipment electronically without 

specific actions by the receiving terminal operator. See Manual 

Remote Rekeying.

SOURCE: CNSSI-4009

Autonomous System (AS) – One or more routers under a single administration operating the same 

routing policy.

SOURCE: SP 800-54

Availability – Ensuring timely and reliable access to and use of information.

SOURCE: SP 800-53; SP 800-53A; SP 800-27; SP 800-60; SP 800-

37; FIPS 200; FIPS 199; 44 U.S.C., Sec. 3542

The property of being accessible and useable upon demand by an 

authorized entity.

SOURCE: CNSSI-4009

Awareness (Information Security) – Activities which seek to focus an individual’s attention on an 

(information security) issue or set of issues.

SOURCE: SP 800-50

Back Door – Typically unauthorized hidden software or hardware mechanism used 

to circumvent security controls. 

SOURCE: CNSSI-4009

Backdoor – An undocumented way of gaining access to a computer system. A 

backdoor is a potential security risk.

SOURCE: SP 800-82

Backtracking Resistance – Backtracking resistance is provided relative to time T if there is 

assurance that an adversary who has knowledge of the internal state 

of the Deterministic Random Bit Generator (DRBG) at some time 

subsequent to time T would be unable to distinguish between 

observations of ideal random bitstrings and (previously unseen) 

bitstrings that were output by the DRBG prior to time T. The 

complementary assurance is called Prediction Resistance. 

SOURCE: SP 800-90A
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

18

Backup – A copy of files and programs made to facilitate recovery, if 

necessary.

SOURCE: SP 800-34; CNSSI-4009

Banner – Display on an information system that sets parameters for system or 

data use.

SOURCE: CNSSI-4009

Banner Grabbing – The process of capturing banner information—such as application 

type and version—that is transmitted by a remote port when a 

connection is initiated.

SOURCE: SP 800-115

Baseline – Hardware, software, databases, and relevant documentation for an 

information system at a given point in time.

SOURCE: CNSSI-4009

Baseline Configuration – A set of specifications for a system, or Configuration Item (CI) 

within a system, that has been formally reviewed and agreed on at a 

given point in time, and which can be changed only through change 

control procedures. The baseline configuration is used as a basis for 

future builds, releases, and/or changes. 

SOURCE: SP 800-128

Baseline Security – The minimum security controls required for safeguarding an IT 

system based on its identified needs for confidentiality, integrity,

and/or availability protection.

SOURCE: SP 800-16

Baselining – Monitoring resources to determine typical utilization patterns so that 

significant deviations can be detected.

SOURCE: SP 800-61

Basic Testing – A test methodology that assumes no knowledge of the internal 

structure and implementation detail of the assessment object. Also 

known as black box testing.

SOURCE: SP 800-53A

Bastion Host – A special-purpose computer on a network specifically designed and 

configured to withstand attacks.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

19

Behavioral Outcome – What an individual who has completed the specific training module 

is expected to be able to accomplish in terms of IT security-related 

job performance.

SOURCE: SP 800-16

Benign Environment – A non-hostile location protected from external hostile elements by 

physical, personnel, and procedural security countermeasures.

SOURCE: CNSSI-4009

Binding – Process of associating two related elements of information.

SOURCE: SP 800-32

Binding – An acknowledgement by a trusted third party that associates an 

entity’s identity with its public key. This may take place through (1) 

a certification authority’s generation of a public key certificate, (2) a 

security officer’s verification of an entity’s credentials and placement 

of the entity’s public key and identifier in a secure database, or (3) an 

analogous method.

SOURCE: SP 800-21

Process of associating a specific communications terminal with a 

specific cryptographic key or associating two related elements of 

information.

SOURCE: CNSSI-4009

Biometric – A physical or behavioral characteristic of a human being.

SOURCE: SP 800-32

Biometric – A measurable physical characteristic or personal behavioral trait used 

to recognize the identity, or verify the claimed identity, of an 

applicant. Facial images, fingerprints, and iris scan samples are all 

examples of biometrics.

SOURCE: FIPS 201

Biometric Information – The stored electronic information pertaining to a biometric. This 

information can be in terms of raw or compressed pixels or in terms 

of some characteristic (e.g., patterns.)

SOURCE: FIPS 201
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Biometric System – An automated system capable of: 

1) capturing a biometric sample from an end user; 

2) extracting biometric data from that sample; 

3) comparing the extracted biometric data with data contained in one 

or more references; 

4) deciding how well they match; and 

5) indicating whether or not an identification or verification of 

identity has been achieved.

SOURCE: FIPS 201

Biometrics – Measurable physical characteristics or personal behavioral traits used 

to identify, or verify the claimed identity, of an individual. Facial 

images, fingerprints, and handwriting samples are all examples of 

biometrics.

SOURCE: CNSSI-4009

Bit – A contraction of the term Binary Digit. The smallest unit of 

information in a binary system of notation.

SOURCE: CNSSI-4009

A binary digit having a value of 0 or 1.

SOURCE: FIPS 180-4

Bit Error Rate – Ratio between the number of bits incorrectly received and the total 

number of bits transmitted in a telecommunications system.

SOURCE: CNSSI-4009

BLACK – Designation applied to encrypted information and the information 

systems, the associated areas, circuits, components, and equipment 

processing that information. See also RED.

SOURCE: CNSSI-4009

Black Box Testing – See Basic Testing.

Black Core – A communication network architecture in which user data traversing 

a global Internet Protocol (IP) network is end-to-end encrypted at the 

IP layer. Related to striped core.

SOURCE: CNSSI-4009

Blacklist – A list of email senders who have previously sent span to a user.

SOURCE: SP 800-114

A list of discrete entities, such as hosts or applications, that have been 

previously determined to be associated with malicious activity.

SOURCE: SP 800-94
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Blacklisting – The process of the system invalidating a user ID based on the user’s 

inappropriate actions. A blacklisted user ID cannot be used to log on 

to the system, even with the correct authenticator. Blacklisting and 

lifting of a blacklisting are both security-relevant events. 

Blacklisting also applies to blocks placed against IP addresses to 

prevent inappropriate or unauthorized use of Internet resources.

SOURCE: CNSSI-4009

Blended Attack – A hostile action to spread malicious code via multiple methods.

SOURCE: CNSSI-4009

Blinding – Generating network traffic that is likely to trigger many alerts in a 

short period of time, to conceal alerts triggered by a “real” attack 

performed simultaneously.

SOURCE: SP 800-94

Block – Sequence of binary bits that comprise the input, output, State, and 

Round Key. The length of a sequence is the number of bits it 

contains. Blocks are also interpreted as arrays of bytes.

SOURCE: FIPS 197

Block Cipher – A symmetric key cryptographic algorithm that transforms a block of 

information at a time using a cryptographic key. For a block cipher 

algorithm, the length of the input block is the same as the length of 

the output block.

SOURCE: SP 800-90

Block Cipher Algorithm – A family of functions and their inverses that is parameterized by a 

cryptographic key; the function maps bit strings of a fixed length to 

bit strings of the same length.

SOURCE: SP 800-67
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Blue Team – 1. The group responsible for defending an enterprise’s use of 

information systems by maintaining its security posture against a 

group of mock attackers (i.e., the Red Team). Typically the Blue 

Team and its supporters must defend against real or simulated 

attacks 1) over a significant period of time, 2) in a representative 

operational context (e.g., as part of an operational exercise), and 3) 

according to rules established and monitored with the help of a 

neutral group refereeing the simulation or exercise (i.e., the White 

Team). 

2. The term Blue Team is also used for defining a group of 

individuals that conduct operational network vulnerability 

evaluations and provide mitigation techniques to customers who have 

a need for an independent technical review of their network security 

posture. The Blue Team identifies security threats and risks in the 

operating environment, and in cooperation with the customer, 

analyzes the network environment and its current state of security 

readiness. Based on the Blue Team findings and expertise, 

they provide recommendations that integrate into an overall 

community security solution to increase the customer's cyber security 

readiness posture. Often times a Blue Team is employed by itself or 

prior to a Red Team employment to ensure that the customer's 

networks are as secure as possible before having the Red Team test 

the systems.

SOURCE: CNSSI-4009

Body of Evidence (BoE) – The set of data that documents the information system’s adherence 

to the security controls applied. The BoE will include a 

Requirements Verification Traceability Matrix (RVTM) delineating 

where the selected security controls are met and evidence to that 

fact can be found. The BoE content required by an Authorizing 

Official will be adjusted according to the impact levels selected.

SOURCE: CNSSI-4009

Boundary – Physical or logical perimeter of a system.

SOURCE: CNSSI-4009

Boundary Protection – Monitoring and control of communications at the external boundary 

of an information system to prevent and detect malicious and other 

unauthorized communication, through the use of boundary protection 

devices (e.g., proxies, gateways, routers, firewalls, guards, encrypted 

tunnels).

SOURCE: SP 800-53; CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Boundary Protection Device – A device with appropriate mechanisms that: (i) facilitates the 

adjudication of different interconnected system security policies (e.g., 

controlling the flow of information into or out of an interconnected 

system); and/or (ii) provides information system boundary protection.

SOURCE: SP 800-53

A device with appropriate mechanisms that facilitates the 

adjudication of different security policies for interconnected systems.

SOURCE: CNSSI-4009

Browsing – Act of searching through information system storage or active 

content to locate or acquire information, without necessarily knowing 

the existence or format of information being sought.

SOURCE: CNSSI-4009

Brute Force Password Attack – A method of accessing an obstructed device through attempting 

multiple combinations of numeric and/or alphanumeric passwords. 

SOURCE: SP 800-72

Buffer Overflow – A condition at an interface under which more input can be placed 

into a buffer or data holding area than the capacity allocated, 

overwriting other information. Attackers exploit such a condition to 

crash a system or to insert specially crafted code that allows them to 

gain control of the system.

SOURCE: SP 800-28; CNSSI-4009

Buffer Overflow Attack – A method of overloading a predefined amount of space in a buffer, 

which can potentially overwrite and corrupt data in memory.

SOURCE: SP 800-72

Bulk Encryption – Simultaneous encryption of all channels of a multichannel 

telecommunications link.

SOURCE: CNSSI-4009

Business Continuity Plan (BCP) – The documentation of a predetermined set of instructions or 

procedures that describe how an organization’s mission/business 

functions will be sustained during and after a significant disruption.

SOURCE: SP 800-34

The documentation of a predetermined set of instructions or 

procedures that describe how an organization’s business functions 

will be sustained during and after a significant disruption.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Business Impact Analysis (BIA) – An analysis of an information system’s requirements, functions, and 

interdependencies used to characterize system contingency 

requirements and priorities in the event of a significant disruption.

SOURCE: SP 800-34

An analysis of an enterprise’s requirements, processes, and 

interdependencies used to characterize information system 

contingency requirements and priorities in the event of a significant 

disruption.

SOURCE: CNSSI-4009

Call Back – Procedure for identifying and authenticating a remote information 

system terminal, whereby the host system disconnects the terminal 

and reestablishes contact. 

SOURCE: CNSSI-4009

Canister – Type of protective package used to contain and dispense keying 

material in punched or printed tape form.

SOURCE: CNSSI-4009

Capstone Policies – Those policies that are developed by governing or coordinating 

institutions of Health Information Exchanges (HIEs). They provide 

overall requirements and guidance for protecting health information 

within those HIEs. Capstone Policies must address the requirements 

imposed by: (1) all laws, regulations, and guidelines at the federal, 

state, and local levels; (2) business needs; and (3) policies at the 

institutional and HIE levels. 

SOURCE: NISTIR-7497

Capture – The method of taking a biometric sample from an end user.

Source: FIPS 201

Cardholder – An individual possessing an issued Personal Identity Verification 

(PIV) card.

Source: FIPS 201

Cascading – Downward flow of information through a range of security levels 

greater than the accreditation range of a system, network, or 

component.

SOURCE: CNSSI-4009

Category – Restrictive label applied to classified or unclassified information to 

limit access.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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CBC/MAC – See Cipher Block Chaining-Message Authentication Code.

CCM – See Counter with Cipher-Block Chaining-Message Authentication 

Code.

Central Office of Record (COR) – Office of a federal department or agency that keeps records of 

accountable COMSEC material held by elements subject to its 

oversight

SOURCE: CNSSI-4009

Central Services Node (CSN) – The Key Management Infrastructure core node that provides central 

security management and data management services.

SOURCE: CNSSI-4009

Certificate – A digital representation of information which at least

1) identifies the certification authority issuing it,

2) names or identifies its subscriber, 

3) contains the subscriber's public key,

4) identifies its operational period, and

5) is digitally signed by the certification authority issuing it. 

SOURCE: SP 800-32

Certificate – A set of data that uniquely identifies an entity, contains the entity’s 

public key and possibly other information, and is digitally signed by 

a trusted party, thereby binding the public key to the entity. 

Additional information in the certificate could specify how the key is 

used and its cryptoperiod.

SOURCE: SP 800-21
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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A digitally signed representation of information that 1) identifies 

the authority issuing it, 2) identifies the subscriber, 3) identifies its 

valid operational period (date issued / expiration date). In the 

information assurance (IA) community, certificate usually implies 

public key certificate and can have the following types:

cross certificate – a certificate issued from a CA that signs the 

public key of another CA not within its trust hierarchy that 

establishes a trust relationship between the two CAs.

encryption certificate – a certificate containing a public key that can 

encrypt or decrypt electronic messages, files, documents, or data 

transmissions, or establish or exchange a session key for these same 

purposes. Key management sometimes refers to the process of 

storing, protecting, and escrowing the private component of the key

pair associated with the encryption certificate.

identity certificate – a certificate that provides authentication of the 

identity claimed. Within the National Security Systems (NSS) PKI, 

identity certificates may be used only for authentication or may be 

used for both authentication and digital signatures.

SOURCE: CNSSI-4009

A set of data that uniquely identifies a key pair and an owner that is 

authorized to use the key pair. The certificate contains the owner’s 

public key and possibly other information, and is digitally signed by 

a Certification Authority (i.e., a trusted party), thereby binding the 

public key to the owner.

SOURCE: FIPS 186

Certificate Management – Process whereby certificates (as defined above) are generated, stored, 

protected, transferred, loaded, used, and destroyed.

SOURCE: CNSSI-4009

Certificate Management Authority –

(CMA)

A Certification Authority (CA) or a Registration Authority (RA).

SOURCE: SP 800-32

Certificate Policy (CP) – A specialized form of administrative policy tuned to electronic 

transactions performed during certificate management. A Certificate 

Policy addresses all aspects associated with the generation, 

production, distribution, accounting, compromise recovery, and 

administration of digital certificates. Indirectly, a certificate policy 

can also govern the transactions conducted using a communications 

system protected by a certificate-based security system. By 

controlling critical certificate extensions, such policies and associated 

enforcement technology can support provision of the security 

services required by particular applications.

SOURCE: CNSSI-4009; SP 800-32
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Certificate-Related Information – Information, such as a subscriber's postal address, that is not included 

in a certificate. May be used by a Certification Authority (CA) 

managing certificates.

SOURCE: SP 800-32

Data, such as a subscriber's postal address that is not included in a 

certificate. May be used by a Certification Authority (CA) managing 

certificates.

SOURCE: CNSSI-4009

Certificate Revocation List (CRL) – A list of revoked public key certificates created and digitally signed 

by a Certification Authority.

SOURCE: SP 800-63; FIPS 201

Certificate Revocation List – A list of revoked but un-expired certificates issued by a CA.

SOURCE: SP 800-21

A list of revoked public key certificates created and digitally signed 

by a Certification Authority.

SOURCE: CNSSI-4009

Certificate Status Authority – A trusted entity that provides online verification to a Relying Party of 

a subject certificate's trustworthiness, and may also provide 

additional attribute information for the subject certificate.

SOURCE: SP 800-32; CNSSI-4009

Certification – A comprehensive assessment of the management, operational, and 

technical security controls in an information system, made in support 

of security accreditation, to determine the extent to which the 

controls are implemented correctly, operating as intended, and 

producing the desired outcome with respect to meeting the security 

requirements for the system.

SOURCE: FIPS 200

Certification – The process of verifying the correctness of a statement or claim and 

issuing a certificate as to its correctness.

SOURCE: FIPS 201

Comprehensive evaluation of the technical and nontechnical security 

safeguards of an information system to support the accreditation 

process that establishes the extent to which a particular design and 

implementation meets a set of specified security requirements. See 

Security Control Assessment.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Certification Analyst – The independent technical liaison for all stakeholders involved in the 

C&A process responsible for objectively and independently 

evaluating a system as part of the risk management process. Based 

on the security requirements documented in the security plan, 

performs a technical and non-technical review of potential 

vulnerabilities in the system and determines if the security controls 

(management, operational, and technical) are correctly implemented 

and effective.

SOURCE: CNSSI-4009

Certification Authority (CA) – A trusted entity that issues and revokes public key certificates.

SOURCE: FIPS 201

Certification Authority – The entity in a public key infrastructure (PKI) that is responsible for 

issuing certificates and exacting compliance to a PKI policy.

SOURCE: SP 800-21; FIPS 186

1. For Certification and Accreditation (C&A) (C&A Assessment): 

Official responsible for performing the comprehensive evaluation 

of the security features of an information system and determining 

the degree to which it meets its security requirements

2. For Public Key Infrastructure (PKI): A trusted third party that 

issues digital certificates and verifies the identity of the holder of the 

digital certificate.

SOURCE: CNSSI-4009

Certification Authority Facility – The collection of equipment, personnel, procedures and structures 

that are used by a Certification Authority to perform certificate 

issuance and revocation.

SOURCE: SP 800-32

Certification Authority Workstation

(CAW) –

Commercial off-the-shelf (COTS) workstation with a trusted 

operating system and special-purpose application software that is 

used to issue certificates

SOURCE: CNSSI-4009

Certification Package – Product of the certification effort documenting the detailed results of 

the certification activities.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Certification Practice Statement –

(CPS)

A statement of the practices that a Certification Authority employs in 

issuing, suspending, revoking, and renewing certificates and 

providing access to them, in accordance with specific requirements 

(i.e., requirements specified in this Certificate Policy, or requirements 

specified in a contract for services).

SOURCE: SP 800-32; CNSSI-4009

Certification Test and Evaluation –

(CT&E)

Software and hardware security tests conducted during development 

of an information system.

SOURCE: CNSSI-4009

Certified TEMPEST Technical 

Authority (CTTA) –

An experienced, technically qualified U.S. government employee 

who has met established certification requirements in accordance 

with CNSS-approved criteria and has been appointed by a U.S. 

government department or agency to fulfill CTTA responsibilities.

SOURCE: CNSSI-4009

Certifier – Individual responsible for making a technical judgment of the 

system’s compliance with stated requirements, identifying and 

assessing the risks associated with operating the system, coordinating 

the certification activities, and consolidating the final certification 

and accreditation packages.

SOURCE: CNSSI-4009

Chain of Custody – A process that tracks the movement of evidence through its 

collection, safeguarding, and analysis lifecycle by documenting each 

person who handled the evidence, the date/time it was collected or 

transferred, and the purpose for the transfer.

SOURCE: SP 800-72; CNSSI-4009

Chain of Evidence – A process and record that shows who obtained the evidence; where 

and when the evidence was obtained; who secured the evidence; and 

who had control or possession of the evidence. The “sequencing” of 

the chain of evidence follows this order: collection and identification; 

analysis; storage; preservation; presentation in court; return to owner. 

SOURCE: CNSSI-4009

Challenge and Reply 

Authentication –

Prearranged procedure in which a subject requests authentication of 

another and the latter establishes validity with a correct reply.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

30

Challenge-Response Protocol – An authentication protocol where the verifier sends the claimant a 

challenge (usually a random value or a nonce) that the claimant 

combines with a secret (often by hashing the challenge and a shared 

secret together, or by applying a private key operation to the 

challenge) to generate a response that is sent to the verifier. The 

verifier can independently verify the response generated by the 

Claimant (such as by re-computing the hash of the challenge and the 

shared secret and comparing to the response, or performing a public 

key operation on the response) and establish that the Claimant 

possesses and controls the secret.

SOURCE: SP 800-63

Check Word – Cipher text generated by cryptographic logic to detect failures in 

cryptography.

SOURCE: CNSSI-4009

Checksum – Value computed on data to detect error or manipulation. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

31

Chief Information Officer (CIO) – Agency official responsible for:

1) Providing advice and other assistance to the head of the executive 

agency and other senior management personnel of the agency to 

ensure that information technology is acquired and information 

resources are managed in a manner that is consistent with laws, 

Executive Orders, directives, policies, regulations, and priorities 

established by the head of the agency;

2) Developing, maintaining, and facilitating the implementation of a 

sound and integrated information technology architecture for the 

agency; and 

3) Promoting the effective and efficient design and operation of all 

major information resources management processes for the 

agency, including improvements to work processes of the agency.

SOURCE: FIPS 200; Public Law 104-106, Sec. 5125(b)

Agency official responsible for: 1) providing advice and other 

assistance to the head of the executive agency and other senior 

management personnel of the agency to ensure that information 

systems are acquired and information resources are managed in a 

manner that is consistent with laws, Executive Orders, directives, 

policies, regulations, and priorities established by the head of the 

agency; 2) developing, maintaining, and facilitating the 

implementation of a sound and integrated information system 

architecture for the agency; and 3) promoting the effective and 

efficient design and operation of all major information resources 

management processes for the agency, including improvements to 

work processes of the agency. 

Note: Organizations subordinate to federal agencies may use the 

term Chief Information Officer to denote individuals filling positions 

with similar security responsibilities to agency-level Chief 

Information Officers.

SOURCE: CNSSI-4009; SP 800-53

Chief Information Security Officer –

(CISO)

See Senior Agency Information Security Officer.

Cipher – Series of transformations that converts plaintext to ciphertext using 

the Cipher Key.

SOURCE: FIPS 197

Any cryptographic system in which arbitrary symbols or groups of 

symbols, represent units of plain text, or in which units of plain text 

are rearranged, or both.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cipher Block Chaining-Message 

Authentication Code –

(CBC-MAC)

A secret-key block-cipher algorithm used to encrypt data and to 

generate a Message Authentication Code (MAC) to provide 

assurance that the payload and the associated data are authentic.

SOURCE: SP 800-38C

Cipher Suite – Negotiated algorithm identifiers. Cipher suites are identified in 

human-readable form using a pneumonic code. 

SOURCE: SP 800-52

Cipher Text Auto-Key (CTAK) – Cryptographic logic that uses previous cipher text to generate a key 

stream.

SOURCE: CNSSI-4009

Ciphertext – Data output from the Cipher or input to the Inverse Cipher.

SOURCE: FIPS 197

Data in its enciphered form.

SOURCE: SP 800-56B

Ciphertext/Cipher Text – Data in its encrypted form.

SOURCE: SP 800-21; CNSSI-4009

Ciphony – Process of enciphering audio information, resulting in encrypted 

speech.

SOURCE: CNSSI-4009

Claimant – A party whose identity is to be verified using an authentication 

protocol.

SOURCE: SP 800-63; FIPS 201

Claimant – An entity which is or represents a principal for the purposes of 

authentication, together with the functions involved in an 

authentication exchange on behalf of that entity. A claimant acting on 

behalf of a principal must include the functions necessary for 

engaging in an authentication exchange. (e.g., a smartcard [claimant]

can act on behalf of a human user [principal])

SOURCE: FIPS 196

An entity (user, device or process) whose assertion is to be verified 

using an authentication protocol.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Classified Information – Information that has been determined pursuant to Executive Order 

(E.O.) 13292 or any predecessor order to require protection against 

unauthorized disclosure and is marked to indicate its classified status 

when in documentary form.

SOURCE: SP 800-60; E.O. 13292

See Classified National Security Information.

SOURCE: CNSSI-4009

Information that has been determined: (i) pursuant to Executive

Order 12958 as amended by Executive Order 13292, or any

predecessor Order, to be classified national security information;

or (ii) pursuant to the Atomic Energy Act of 1954, as amended, to

be Restricted Data (RD).

SOURCE: SP 800-53

Classified Information Spillage – Security incident that occurs whenever classified data is spilled either 

onto an unclassified information system or to an information system

with a lower level of classification.

SOURCE: CNSSI-4009

Classified National Security 

Information –

Information that has been determined pursuant to Executive Order 

13526 or any predecessor order to require protection against 

unauthorized disclosure and is marked to indicate its classified status 

when in documentary form.

SOURCE: CNSSI-4009

Clear – To use software or hardware products to overwrite storage space on 

the media with nonsensitive data. This process may include 

overwriting not only the logical storage location of a file(s) (e.g., file 

allocation table) but also may include all addressable locations. See 

comments on Clear/Purge Convergence.

SOURCE: SP 800-88

Clear Text – Information that is not encrypted.

SOURCE: SP 800-82

Clearance – Formal certification of authorization to have access to classified 

information other than that protected in a special access program 

(including SCI). Clearances are of three types: confidential, secret, 

and top secret. A top secret clearance permits access to top secret, 

secret, and confidential material; a secret clearance, to secret and 

confidential material; and a confidential clearance, to confidential 

material. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Clearing – Removal of data from an information system, its storage devices, and 

other peripheral devices with storage capacity, in such a way that the 

data may not be reconstructed using common system capabilities 

(i.e., through the keyboard); however, the data may be reconstructed 

using laboratory methods. 

SOURCE: CNSSI-4009

Client – Individual or process acting on behalf of an individual who makes 

requests of a guard or dedicated server. The client’s requests to the 

guard or dedicated server can involve data transfer to, from, or 

through the guard or dedicated server.

SOURCE: CNSSI-4009

Client (Application) – A system entity, usually a computer process acting on behalf of a 

human user, that makes use of a service provided by a server.

SOURCE: SP 800-32

Clinger-Cohen Act of 1996 – Also known as Information Technology Management Reform Act. A 

statute that substantially revised the way that IT resources are 

managed and procured, including a requirement that each agency 

design and implement a process for maximizing the value and 

assessing and managing the risks of IT investments.

SOURCE: SP 800-64

Closed Security Environment – Environment providing sufficient assurance that applications and 

equipment are protected against the introduction of malicious logic 

during an information system life cycle. Closed security is based 

upon a system's developers, operators, and maintenance personnel 

having sufficient clearances, authorization, and configuration control.

SOURCE: CNSSI-4009

Closed Storage – Storage of classified information within an accredited facility, in 

General Services Administration-approved secure containers, while 

the facility is unoccupied by authorized personnel.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

35

Cloud Computing – A model for enabling on-demand network access to a shared pool of 

configurable IT capabilities/ resources (e.g., networks, servers, 

storage, applications, and services) that can be rapidly provisioned 

and released with minimal management effort or service provider 

interaction. It allows users to access technology-based services from 

the network cloud without knowledge of, expertise with, or control 

over the technology infrastructure that supports them. This cloud 

model is composed of five essential characteristics (on-demand selfservice, ubiquitous network access, location independent resource 

pooling, rapid elasticity, and measured service); three service 

delivery models (Cloud Software as a Service [SaaS], Cloud Platform 

as a Service [PaaS], and Cloud Infrastructure as a Service [IaaS]); 

and four models for enterprise access (Private cloud, Community 

cloud, Public cloud, and Hybrid cloud). 

Note: Both the user's data and essential security services may reside 

in and be managed within the network cloud.

SOURCE: CNSSI-4009

Code – System of communication in which arbitrary groups of letters, 

numbers, or symbols represent units of plain text of varying length.

SOURCE: CNSSI-4009

Code Book – Document containing plain text and code equivalents in a systematic 

arrangement, or a technique of machine encryption using a word 

substitution technique.

SOURCE: CNSSI-4009

Code Group – Group of letters, numbers, or both in a code system used to represent 

a plain text word, phrase, or sentence.

SOURCE: CNSSI-4009

Code Vocabulary – Set of plain text words, numerals, phrases, or sentences for which 

code equivalents are assigned in a code system.

SOURCE: CNSSI-4009

Cold Site – Backup site that can be up and operational in a relatively short time 

span, such as a day or two. Provision of services, such as telephone 

lines and power, is taken care of, and the basic office furniture might 

be in place, but there is unlikely to be any computer equipment, even 

though the building might well have a network infrastructure and a 

room ready to act as a server room. In most cases, cold sites provide 

the physical location and basic services.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

36

A backup facility that has the necessary electrical and physical 

components of a computer facility, but does not have the computer 

equipment in place. The site is ready to receive the necessary 

replacement computer equipment in the event that the user has to 

move from their main computing location to an alternate site. 

SOURCE: SP 800-34

Cold Start – Procedure for initially keying crypto-equipment.

SOURCE: CNSSI-4009

Collision – Two or more distinct inputs produce the same output. Also see Hash 

Function.

SOURCE: SP 800-57 Part 1

Command Authority – Individual responsible for the appointment of user representatives for 

a department, agency, or organization and their key ordering 

privileges.

SOURCE: CNSSI-4009

Commercial COMSEC Evaluation 

Program (CCEP) –

Relationship between NSA and industry in which NSA provides the 

COMSEC expertise (i.e., standards, algorithms, evaluations, and 

guidance) and industry provides design, development, and production 

capabilities to produce a type 1 or type 2 product. Products 

developed under the CCEP may include modules, subsystems, 

equipment, systems, and ancillary devices.

SOURCE: CNSSI-4009

Commodity Service – An information system service (e.g., telecommunications service) 

provided by a commercial service provider typically to a large and 

diverse set of consumers. The organization acquiring and/or 

receiving the commodity service possesses limited visibility into the 

management structure and operations of the provider, and while the 

organization may be able to negotiate service-level agreements, the 

organization is typically not in a position to require that the provider 

implement specific security controls.

SOURCE: SP 800-53

Common Access Card (CAC) – Standard identification/smart card issued by the Department of 

Defense that has an embedded integrated chip storing public key 

infrastructure (PKI) certificates.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

37

Common Carrier – In a telecommunications context, a telecommunications company that 

holds itself out to the public for hire to provide communications 

transmission services. Note: In the United States, such companies 

are usually subject to regulation by federal and state regulatory 

commissions.

SOURCE: SP 800-53

Common Configuration 

Enumeration (CCE) –

A SCAP specification that provides unique, common identifiers for 

configuration settings found in a wide variety of hardware and 

software products. 

SOURCE: SP 800-128

Common Configuration Scoring 

System (CCSS) –

A set of measures of the severity of software security configuration 

issues.

SOURCE: NISTIR 7502

A SCAP specification for measuring the severity of software security 

configuration issues. 

SOURCE: SP 800-128

Common Control – A security control that is inherited by one or more organizational 

information systems. See Security Control Inheritance.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; CNSSI-4009

Common Control Provider – An organizational official responsible for the development, 

implementation, assessment, and monitoring of common controls 

(i.e., security controls inherited by information systems).

SOURCE: SP 800-37; SP 800-53A

Common Criteria – Governing document that provides a comprehensive, rigorous 

method for specifying security function and assurance requirements 

for products and systems.

SOURCE: CNSSI-4009

Common Fill Device – One of a family of devices developed to read-in, transfer, or store 

key.

SOURCE: CNSSI-4009

Common Misuse Scoring System –

(CMSS)

A set of measures of the severity of software feature misuse 

vulnerabilities. A software feature is a functional capability provided 

by software. A software feature misuse vulnerability is a 

vulnerability in which the feature also provides an avenue to 

compromise the security of a system.

SOURCE: NISTIR 7864
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

38

Common Platform Enumeration –

(CPE)

A SCAP specification that provides a standard naming convention for 

operating systems, hardware, and applications for the purpose of 

providing consistent, easily parsed names that can be shared by 

multiple parties and solutions to refer to the same specific platform 

type.

SOURCE: SP 800-128

Common Vulnerabilities and 

Exposures (CVE) –

A dictionary of common names for publicly known information 

system vulnerabilities.

SOURCE: SP 800-51; CNSSI-4009

An SCAP specification that provides unique, common names for 

publicly known information system vulnerabilities. 

SOURCE: SP 800-128

Common Vulnerability Scoring 

System (CVSS) –

An SCAP specification for communicating the characteristics of 

vulnerabilities and measuring their relative severity. 

SOURCE: SP 800-128

Communications Cover – Concealing or altering of characteristic communications patterns to 

hide information that could be of value to an adversary.

SOURCE: CNSSI-4009

Communications Deception – Deliberate transmission, retransmission, or alteration of 

communications to mislead an adversary's interpretation of the 

communications. 

SOURCE: CNSSI-4009

Communications Profile – Analytic model of communications associated with an organization 

or activity. The model is prepared from a systematic examination of 

communications content and patterns, the functions they reflect, and 

the communications security measures applied.

SOURCE: CNSSI-4009

Communications Security –

(COMSEC)

A component of Information Assurance that deals with measures and 

controls taken to deny unauthorized persons information derived 

from telecommunications and to ensure the authenticity of such 

telecommunications. COMSEC includes crypto security, 

transmission security, emissions security, and physical security of 

COMSEC material.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Community of Interest (COI) – A collaborative group of users who exchange information in pursuit 

of their shared goals, interests, missions, or business processes, and 

who therefore must have a shared vocabulary for the information 

they exchange. The group exchanges information within and 

between systems to include security domains.

SOURCE: CNSSI-4009

Community Risk – Probability that a particular vulnerability will be exploited within an 

interacting population and adversely impact some members of that 

population.

SOURCE: CNSSI-4009

Comparison – The process of comparing a biometric with a previously stored 

reference. 

SOURCE: FIPS 201

Compartmentalization – A nonhierarchical grouping of sensitive information used to control 

access to data more finely than with hierarchical security 

classification alone.

SOURCE: CNSSI-4009

Compartmented Mode – Mode of operation wherein each user with direct or indirect access to 

a system, its peripherals, remote terminals, or remote hosts has all of 

the following: (1) valid security clearance for the most restricted 

information processed in the system; (2) formal access approval and 

signed nondisclosure agreements for that information which a user is 

to have access; and (3) valid need-to-know for information which a 

user is to have access.

SOURCE: CNSSI-4009

Compensating Security Control – A management, operational, and/or technical control (i.e., safeguard 

or countermeasure) employed by an organization in lieu of a 

recommended security control in the low, moderate, or high baselines 

that provides equivalent or comparable protection for an information 

system.

NIST SP 800-53: A management, operational, and technical control 

(i.e., safeguard or countermeasure) employed by an organization in 

lieu of the recommended control in the baselines described in NIST 

Special Publication 800-53 or in CNSS Instruction 1253, that provide 

equivalent or comparable protection for an information system. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Compensating Security Controls – The management, operational, and technical controls (i.e., safeguards

or countermeasures) employed by an organization in lieu of the 

recommended controls in the low, moderate, or high baselines 

described in NIST Special Publication 800-53, that provide 

equivalent or comparable protection for an information system.

SOURCE: SP 800-37

The management, operational, and technical controls (i.e., safeguards 

or countermeasures) employed by an organization in lieu of the 

recommended controls in the baselines described in NIST Special 

Publication 800-53 and CNSS Instruction 1253, that provide 

equivalent or comparable protection for an information system.

SOURCE: SP 800-53A; SP 800-53

Comprehensive Testing – A test methodology that assumes explicit and substantial knowledge 

of the internal structure and implementation detail of the assessment 

object. Also known as white box testing.

SOURCE: SP 800-53A

Compromise – Disclosure of information to unauthorized persons, or a violation of 

the security policy of a system in which unauthorized intentional or 

unintentional disclosure, modification, destruction, or loss of an 

object may have occurred.

SOURCE: SP 800-32

Compromise – The unauthorized disclosure, modification, substitution, or use of 

sensitive data (including plaintext cryptographic keys and other 

CSPs).

SOURCE: FIPS 140-2

Disclosure of information to unauthorized persons, or a violation of 

the security policy of a system in which unauthorized intentional or 

unintentional disclosure, modification, destruction, or loss of an 

object may have occurred. 

SOURCE: CNSSI-4009

Compromising Emanations – Unintentional signals that, if intercepted and analyzed, would 

disclose the information transmitted, received, handled, or otherwise 

processed by information systems equipment. See TEMPEST.

SOURCE: CNSSI-4009

Computer Abuse – Intentional or reckless misuse, alteration, disruption, or destruction of 

information processing resources.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Computer Cryptography – Use of a crypto-algorithm program by a computer to authenticate or 

encrypt/decrypt information.

SOURCE: CNSSI-4009

Computer Forensics – The practice of gathering, retaining, and analyzing computer-related 

data for investigative purposes in a manner that maintains the 

integrity of the data.

SOURCE: CNSSI-4009

Computer Incident Response Team –

(CIRT)

Group of individuals usually consisting of Security Analysts 

organized to develop, recommend, and coordinate immediate 

mitigation actions for containment, eradication, and recovery 

resulting from computer security incidents. Also called a Computer 

Security Incident Response Team (CSIRT) or a CIRC (Computer 

Incident Response Center, Computer Incident Response Capability,

or Cyber Incident Response Team).

SOURCE: CNSSI-4009

Computer Network Attack (CNA) – Actions taken through the use of computer networks to disrupt, deny, 

degrade, or destroy information resident in computers and computer 

networks, or the computers and networks themselves.

SOURCE: CNSSI-4009

Computer Network Defense(CND) – Actions taken to defend against unauthorized activity within 

computer networks. CND includes monitoring, detection, analysis 

(such as trend and pattern analysis), and response and restoration 

activities.

SOURCE: CNSSI-4009

Computer Network Exploitation –

(CNE)

Enabling operations and intelligence collection capabilities 

conducted through the use of computer networks to gather data from 

target or adversary information systems or networks. 

SOURCE: CNSSI-4009

Computer Network Operations –

(CNO)

Comprised of computer network attack, computer network defense, 

and related computer network exploitation enabling operations. 

SOURCE: CNSSI-4009

Computer Security (COMPUSEC) – Measures and controls that ensure confidentiality, integrity, and 

availability of information system assets including hardware, 

software, firmware, and information being processed, stored, and 

communicated.

SOURCE: CNSSI-4009

Computer Security Incident – See Incident.
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Computer Security Incident 

Response Team (CSIRT) –

A capability set up for the purpose of assisting in responding to 

computer security-related incidents; also called a Computer Incident 

Response Team (CIRT) or a CIRC (Computer Incident Response 

Center, Computer Incident Response Capability).

SOURCE: SP 800-61

Computer Security Object (CSO) – A resource, tool, or mechanism used to maintain a condition of 

security in a computerized environment. These objects are defined in 

terms of attributes they possess, operations they perform or are 

performed on them, and their relationship with other objects.

SOURCE: FIPS 188; CNSSI-4009

Computer Security Objects 

Register –

A collection of Computer Security Object names and definitions kept 

by a registration authority.

SOURCE: FIPS 188; CNSSI-4009

Computer Security Subsystem – Hardware/software designed to provide computer security features in 

a larger system environment.

SOURCE: CNSSI-4009

Computer Virus – See Virus.

Computing Environment – Workstation or server (host) and its operating system, peripherals, 

and applications.

SOURCE: CNSSI-4009

COMSEC – Communications Security.

SOURCE: CNSSI-4009

COMSEC Account – Administrative entity, identified by an account number, used to 

maintain accountability, custody, and control of COMSEC material.

SOURCE: CNSSI-4009

COMSEC Account Audit – Examination of the holdings, records, and procedures of a COMSEC 

account ensuring all accountable COMSEC material is properly 

handled and safeguarded.

SOURCE: CNSSI-4009

COMSEC Aid – COMSEC material that assists in securing telecommunications and is 

required in the production, operation, or maintenance of COMSEC 

systems and their components. COMSEC keying material, 

callsign/frequency systems, and supporting documentation, such as 

operating and maintenance manuals, are examples of COMSEC aids.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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COMSEC Assembly – Group of parts, elements, subassemblies, or circuits that are 

removable items of COMSEC equipment.

SOURCE: CNSSI-4009

COMSEC Boundary – Definable perimeter encompassing all hardware, firmware, and 

software components performing critical COMSEC functions, such 

as key generation, handling, and storage.

SOURCE: CNSSI-4009

COMSEC Chip Set – Collection of NSA-approved microchips.

SOURCE: CNSSI-4009

COMSEC Control Program – Computer instructions or routines controlling or affecting the 

externally performed functions of key generation, key distribution, 

message encryption/decryption, or authentication.

SOURCE: CNSSI-4009

COMSEC Custodian – Individual designated by proper authority to be responsible for the 

receipt, transfer, accounting, safeguarding, and destruction of 

COMSEC material assigned to a COMSEC account.

SOURCE: CNSSI-4009

COMSEC Demilitarization – Process of preparing COMSEC equipment for disposal by extracting 

all CCI, classified, or cryptographic (CRYPTO) marked components 

for their secure destruction, as well as defacing and disposing of the 

remaining equipment hulk.

SOURCE: CNSSI-4009

COMSEC Element – Removable item of COMSEC equipment, assembly, or subassembly; 

normally consisting of a single piece or group of replaceable parts.

SOURCE: CNSSI-4009

COMSEC End-item – Equipment or combination of components ready for use in a 

COMSEC application.

SOURCE: CNSSI-4009

COMSEC Equipment – Equipment designed to provide security to telecommunications by 

converting information to a form unintelligible to an unauthorized 

interceptor and, subsequently, by reconverting such information to its 

original form for authorized recipients; also, equipment designed 

specifically to aid in, or as an essential element of, the conversion 

process. COMSEC equipment includes crypto-equipment, cryptoancillary equipment, cryptographic production equipment, and 

authentication equipment.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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COMSEC Facility – Authorized and approved space used for generating, storing, 

repairing, or using COMSEC material.

SOURCE: CNSSI-4009

COMSEC Incident – Occurrence that potentially jeopardizes the security of COMSEC 

material or the secure electrical transmission of national security 

information or information governed by 10 U.S.C. Section 2315.

SOURCE: CNSSI-4009

COMSEC Insecurity – COMSEC incident that has been investigated, evaluated, and 

determined to jeopardize the security of COMSEC material or the 

secure transmission of information.

SOURCE: CNSSI-4009

COMSEC Manager – Individual who manages the COMSEC resources of an organization.

SOURCE: CNSSI-4009

COMSEC Material – Item designed to secure or authenticate telecommunications. 

COMSEC material includes, but is not limited to key, equipment, 

devices, documents, firmware, or software that embodies or describes 

cryptographic logic and other items that perform COMSEC 

functions.

SOURCE: CNSSI-4009

COMSEC Material Control System 

(CMCS) –

Logistics and accounting system through which COMSEC material 

marked "CRYPTO" is distributed, controlled, and safeguarded. 

Included are the COMSEC central offices of record, crypto logistic 

depots, and COMSEC accounts. COMSEC material other than key 

may be handled through the CMCS.

SOURCE: CNSSI-4009

COMSEC Modification – See Information Systems Security Equipment Modification.

SOURCE: CNSSI-4009

COMSEC Module – Removable component that performs COMSEC functions in a 

telecommunications equipment or system.

SOURCE: CNSSI-4009

COMSEC Monitoring – Act of listening to, copying, or recording transmissions of one's own 

official telecommunications to analyze the degree of security.

SOURCE: CNSSI-4009

COMSEC Profile – Statement of COMSEC measures and materials used to protect a 

given operation, system, or organization.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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COMSEC Survey – Organized collection of COMSEC and communications information 

relative to a given operation, system, or organization.

SOURCE: CNSSI-4009

COMSEC System Data – Information required by a COMSEC equipment or system to enable it 

to properly handle and control key.

SOURCE: CNSSI-4009

COMSEC Training – Teaching of skills relating to COMSEC accounting, use of COMSEC 

aids, or installation, use, maintenance, and repair of COMSEC 

equipment.

SOURCE: CNSSI-4009

Concept of Operations (CONOP) – See Security Concept of Operations.

SOURCE: CNSSI-4009

Confidentiality – Preserving authorized restrictions on information access and 

disclosure, including means for protecting personal privacy and 

proprietary information.

SOURCE: SP 800-53; SP 800-53A; SP 800-18; SP 800-27; SP 800-

60; SP 800-37; FIPS 200; FIPS 199; 44 U.S.C., Sec. 3542

Confidentiality – The property that sensitive information is not disclosed to 

unauthorized individuals, entities, or processes.

SOURCE: FIPS 140-2

The property that information is not disclosed to system entities 

(users, processes, devices) unless they have been authorized to access 

the information.

SOURCE: CNSSI-4009

Configuration Control – Process of controlling modifications to hardware, firmware, software, 

and documentation to protect the information system against 

improper modification prior to, during, and after system 

implementation.

SOURCE: CNSSI-4009; SP 800-37; SP 800-53

Configuration Control Board –

(CCB)

A group of qualified people with responsibility for the process of 

regulating and approving changes to hardware, firmware, software, 

and documentation throughout the development and operational life

cycle of an information system.

SOURCE: CNSSI-4009

Confinement Channel – See Covert Channel.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

46

Container – The file used by a virtual disk encryption technology to encompass 

and protect other files.

SOURCE: SP 800-111

Contamination – Type of incident involving the introduction of data of one security 

classification or security category into data of a lower security 

classification or different security category.

SOURCE: CNSSI-4009

Content Filtering – The process of monitoring communications such as email and Web 

pages, analyzing them for suspicious content, and preventing the 

delivery of suspicious content to users.

SOURCE: SP 800-114

Contingency Key – Key held for use under specific operational conditions or in support 

of specific contingency plans. See Reserve Keying Material.

SOURCE: CNSSI-4009

Contingency Plan – Management policy and procedures used to guide an enterprise 

response to a perceived loss of mission capability. The Contingency 

Plan is the first plan used by the enterprise risk managers to 

determine what happened, why, and what to do. It may point to the 

Continuity of Operations Plan (COOP) or Disaster Recovery Plan for 

major disruptions.

SOURCE: CNSSI-4009

See also Information System Contingency Plan.

Continuity of Government (COG) – A coordinated effort within the federal government's executive 

branch to ensure that national essential functions continue to be 

performed during a catastrophic emergency.

SOURCE: CNSSI-4009

Continuity of Operations Plan –

(COOP)

A predetermined set of instructions or procedures that describe how 

an organization’s mission-essential functions will be sustained within 

12 hours and for up to 30 days as a result of a disaster event before 

returning to normal operations.

SOURCE: SP 800-34
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Management policy and procedures used to guide an enterprise 

response to a major loss of enterprise capability or damage to its 

facilities. The COOP is the third plan needed by the enterprise risk 

managers and is used when the enterprise must recover (often at an 

alternate site) for a specified period of time. Defines the activities of 

individual departments and agencies and their sub-components to 

ensure that their essential functions are performed. This includes 

plans and procedures that delineate essential functions; specifies 

succession to office and the emergency delegation of authority; 

provide for the safekeeping of vital records and databases; identify 

alternate operating facilities; provide for interoperable 

communications, and validate the capability through tests, training, 

and exercises. See also Disaster Recovery Plan and Contingency 

Plan.

SOURCE: CNSSI-4009

Continuous Monitoring – The process implemented to maintain a current security status for one 

or more information systems or for the entire suite of information 

systems on which the operational mission of the enterprise depends. 

The process includes: 1) The development of a strategy to regularly 

evaluate selected IA controls/metrics, 2) Recording and evaluating IA 

relevant events and the effectiveness of the enterprise in dealing with 

those events, 3) Recording changes to IA controls, or changes that 

affect IA risks, and 4) Publishing the current security status to enable 

information-sharing decisions involving the enterprise.

SOURCE: CNSSI-4009

Maintaining ongoing awareness to support organizational risk 

decisions. 

SOURCE: SP 800-137

Control Information – Information that is entered into a cryptographic module for the 

purposes of directing the operation of the module.

SOURCE: FIPS 140-2

Controlled Access Area – Physical area (e.g., building, room, etc.) to which only authorized 

personnel are granted unrestricted access. All other personnel are 

either escorted by authorized personnel or are under continuous 

surveillance.

SOURCE: CNSSI-4009

Controlled Access Protection – Minimum set of security functionality that enforces access control on 

individual users and makes them accountable for their actions 

through login procedures, auditing of security-relevant events, and 

resource isolation.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

48

Controlled Area – Any area or space for which the organization has confidence that the 

physical and procedural protections provided are sufficient to meet 

the requirements established for protecting the information and/or 

information system.

SOURCE: SP 800-53

Controlled Cryptographic Item –

(CCI)

Secure telecommunications or information system, or associated 

cryptographic component, that is unclassified and handled through 

the COMSEC Material Control System (CMCS), an equivalent 

material control system, or a combination of the two that provides 

accountability and visibility. Such items are marked “Controlled 

Cryptographic Item,” or, where space is limited, “CCI”.

SOURCE: CNSSI-4009

Controlled Cryptographic Item 

(CCI) Assembly –

Device embodying a cryptographic logic or other COMSEC design 

that NSA has approved as a Controlled Cryptographic Item (CCI). It 

performs the entire COMSEC function, but depends upon the host 

equipment to operate.

SOURCE: CNSSI-4009

Controlled Cryptographic Item 

(CCI) Component –

Part of a Controlled Cryptographic Item (CCI) that does not perform 

the entire COMSEC function but depends upon the host equipment, 

or assembly, to complete and operate the COMSEC function.

SOURCE: CNSSI-4009

Controlled Cryptographic Item 

(CCI) Equipment –

Telecommunications or information handling equipment that 

embodies a Controlled Cryptographic Item (CCI) component or CCI 

assembly and performs the entire COMSEC function without 

dependence on host equipment to operate.

SOURCE: CNSSI-4009

Controlled Interface – A boundary with a set of mechanisms that enforces the security 

policies and controls the flow of information between interconnected 

information systems.

SOURCE: CNSSI-4009; SP 800-37

Controlled Space – Three-dimensional space surrounding information system equipment, 

within which unauthorized individuals are denied unrestricted access 

and are either escorted by authorized individuals or are under 

continuous physical or electronic surveillance.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

49

Controlled Unclassified Information 

(CUI) –

A categorical designation that refers to unclassified information that 

does not meet the standards for National Security Classification 

under Executive Order 12958, as amended, but is (i) pertinent to the 

national interests of the United States or to the important interests of 

entities outside the federal government, and (ii) under law or policy 

requires protection from unauthorized disclosure, special handling 

safeguards, or prescribed limits on exchange or dissemination. 

Henceforth, the designation CUI replaces "Sensitive But 

Unclassified" (SBU).

SOURCE: SP 800-53; SP 800-53A

Controlling Authority – Official responsible for directing the operation of a cryptonet and for 

managing the operational use and control of keying material assigned 

to the cryptonet.

SOURCE: CNSSI-4009

Cookie – A piece of state information supplied by a Web server to a browser, 

in a response for a requested resource, for the browser to store 

temporarily and return to the server on any subsequent visits or 

requests.

SOURCE: SP 800-28

Data exchanged between an HTTP server and a browser (a client of 

the server) to store state information on the client side and retrieve it 

later for server use.

SOURCE: CNSSI-4009

Cooperative Key Generation – Electronically exchanging functions of locally generated, random 

components, from which both terminals of a secure circuit construct 

traffic encryption key or key encryption key for use on that circuit. 

See Per-Call Key.

SOURCE: CNSSI-4009

Cooperative Remote Rekeying – Synonymous with manual remote rekeying.

SOURCE: CNSSI-4009

Correctness Proof – A mathematical proof of consistency between a specification and its 

implementation.

SOURCE: CNSSI-4009

Counter with Cipher Block 

Chaining-Message

Authentication Code (CCM) –

A mode of operation for a symmetric key block cipher algorithm. It 

combines the techniques of the Counter (CTR) mode and the Cipher 

Block Chaining-Message Authentication Code (CBC-MAC) 

algorithm to provide assurance of the confidentiality and the 

authenticity of computer data.

SOURCE: SP 800-38C
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

50

Countermeasure – Actions, devices, procedures, or techniques that meet or oppose (i.e., 

counters) a threat, a vulnerability, or an attack by eliminating or 

preventing it, by minimizing the harm it can cause, or by discovering 

and reporting it so that corrective action can be taken. 

SOURCE: CNSSI-4009

Countermeasures – Actions, devices, procedures, techniques, or other measures that 

reduce the vulnerability of an information system. Synonymous with 

security controls and safeguards.

SOURCE: SP 800-53; SP 800-37; FIPS 200

Cover-Coding – A technique to reduce the risks of eavesdropping by obscuring the 

information that is transmitted.

SOURCE: SP 800-98

Coverage – An attribute associated with an assessment method that addresses the 

scope or breadth of the assessment objects included in the assessment 

(e.g., types of objects to be assessed and the number of objects to be 

assessed by type). The values for the coverage attribute, 

hierarchically from less coverage to more coverage, are basic, 

focused, and comprehensive.

SOURCE: SP 800-53A

Covert Channel – An unauthorized communication path that manipulates a 

communications medium in an unexpected, unconventional, or 

unforeseen way in order to transmit information without detection by 

anyone other than the entities operating the covert channel.

SOURCE: CNSSI-4009

Covert Channel Analysis – Determination of the extent to which the security policy model and 

subsequent lower-level program descriptions may allow unauthorized 

access to information.

SOURCE: CNSSI-4009

Covert Storage Channel – Covert channel involving the direct or indirect writing to a storage 

location by one process and the direct or indirect reading of the 

storage location by another process. Covert storage channels 

typically involve a finite resource (e.g., sectors on a disk) that is 

shared by two subjects at different security levels.

SOURCE: CNSSI-4009

Covert Testing – Testing performed using covert methods and without the knowledge 

of the organization’s IT staff, but with the full knowledge and 

permission of upper management.

SOURCE: SP 800-115
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Covert Timing Channel – Covert channel in which one process signals information to another 

process by modulating its own use of system resources (e.g., central 

processing unit time) in such a way that this manipulation affects the 

real response time observed by the second process.

SOURCE: CNSSI-4009

Credential – An object or data structure that authoritatively binds an identity (and 

optionally, additional attributes) to a token possessed and controlled 

by a Subscriber.

SOURCE: SP 800-63

Credential – Evidence attesting to one’s right to credit or authority.

SOURCE: FIPS 201

Evidence or testimonials that support a claim of identity or assertion 

of an attribute and usually are intended to be used more than once.

SOURCE: CNSSI-4009

Credential Service Provider –

(CSP)

A trusted entity that issues or registers Subscriber tokens and issues 

electronic credentials to Subscribers. The CSP may encompass 

Registration Authorities (RAs) and Verifiers that it operates. A CSP 

may be an independent third party, or may issue credentials for its 

own use.

SOURCE: SP 800-63

Critical Infrastructure – System and assets, whether physical or virtual, so vital to the U.S. 

that the incapacity or destruction of such systems and assets would 

have a debilitating impact on security, national economic security, 

national public health or safety, or any combination of those matters. 

[Critical Infrastructures Protection Act of 2001, 42 U.S.C. 5195c(e)]

SOURCE: CNSSI-4009

Critical Security Parameter (CSP) – Security-related information (e.g., secret and private cryptographic 

keys, and authentication data such as passwords and Personal 

Identification Numbers [PINs]) whose disclosure or modification can 

compromise the security of a cryptographic module.

SOURCE: FIPS 140-2; CNSSI-4009

Criticality – A measure of the degree to which an organization depends on the 

information or information system for the success of a mission or

of a business function.

SOURCE: SP 800-60
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Criticality Level – Refers to the (consequences of) incorrect behavior of a system. The 

more serious the expected direct and indirect effects of incorrect 

behavior, the higher the criticality level. 

SOURCE: CNSSI-4009

Cross Site Scripting (XSS) – A vulnerability that allows attackers to inject malicious code into an 

otherwise benign website. These scripts acquire the permissions of 

scripts generated by the target website and can therefore compromise 

the confidentiality and integrity of data transfers between the website 

and client. Websites are vulnerable if they display user supplied data 

from requests or forms without sanitizing the data so that it is not 

executable. 

SOURCE: SP 800-63

Cross-Certificate – A certificate used to establish a trust relationship between two 

Certification Authorities.

SOURCE: SP 800-32; CNSSI-4009

Cross-Domain Capabilities – The set of functions that enable the transfer of information between 

security domains in accordance with the policies of the security 

domains involved.

SOURCE: CNSSI-4009

Cross-Domain Solution (CDS) – A form of controlled interface that provides the ability to manually 

and/or automatically access and/or transfer information between 

different security domains.

SOURCE: CNSSI-4009; SP 800-37

Cryptanalysis – 1) Operations performed in defeating cryptographic protection 

without an initial knowledge of the key employed in providing the 

protection.

2) The study of mathematical techniques for attempting to defeat 

cryptographic techniques and information system security. This 

includes the process of looking for errors or weaknesses in the 

implementation of an algorithm or of the algorithm itself.

SOURCE: SP 800-57 Part 1; CNSSI-4009

Crypto Officer – An operator or process (subject), acting on behalf of the operator, 

performing cryptographic initialization or management functions.

SOURCE: FIPS 140-2

Cryptographic – Pertaining to, or concerned with, cryptography.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cryptographic Alarm – Circuit or device that detects failures or aberrations in the logic or 

operation of crypto-equipment. Crypto-alarm may inhibit 

transmission or may provide a visible and/or audible alarm.

SOURCE: CNSSI-4009

Cryptographic Algorithm – A well-defined computational procedure that takes variable inputs, 

including a cryptographic key, and produces an output.

SOURCE: SP 800-21; CNSSI-4009

Cryptographic Ancillary 

Equipment –

Equipment designed specifically to facilitate efficient or reliable 

operation of cryptographic equipment, without performing 

cryptographic functions itself.

SOURCE: CNSSI-4009

Cryptographic Binding – Associating two or more related elements of information using 

cryptographic techniques. 

SOURCE: CNSSI-4009

Cryptographic Boundary – An explicitly defined continuous perimeter that establishes the 

physical bounds of a cryptographic module and contains all the 

hardware, software, and/or firmware components of a cryptographic 

module.

SOURCE: FIPS 140-2

Cryptographic Component – Hardware or firmware embodiment of the cryptographic logic. A 

cryptographic component may be a modular assembly, a printed 

wiring assembly, a microcircuit, or a combination of these items.

SOURCE: CNSSI-4009

Cryptographic Equipment – Equipment that embodies a cryptographic logic.

SOURCE: CNSSI-4009

Cryptographic Hash Function – A function that maps a bit string of arbitrary length to a fixed length 

bit string. Approved hash functions satisfy the following properties:

1) (One-way) It is computationally infeasible to find any input which 

maps to any pre-specified output, and

2) (Collision resistant) It is computationally infeasible to find any 

two distinct inputs that map to the same output.

SOURCE: SP 800-21

Cryptographic Ignition Key (CIK) – Device or electronic key used to unlock the secure mode of cryptoequipment.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cryptographic Initialization – Function used to set the state of a cryptographic logic prior to key 

generation, encryption, or other operating mode.

SOURCE: CNSSI-4009

Cryptographic Key – A value used to control cryptographic operations, such as decryption, 

encryption, signature generation, or signature verification. 

SOURCE: SP 800-63

A binary string used as a secret parameter by a cryptographic 

algorithm.

SOURCE: SP 800-108

Cryptographic Key – A parameter used in conjunction with a cryptographic algorithm that 

determines the specific operation of that algorithm.

SOURCE: FIPS 201; FIPS 198

Cryptographic Key – A parameter used in conjunction with a cryptographic algorithm that 

determines 

 the transformation of plaintext data into ciphertext data, 

 the transformation of ciphertext data into plaintext data, 

 a digital signature computed from data,

 the verification of a digital signature computed from data, 

 an authentication code computed from data, or 

 an exchange agreement of a shared secret.

SOURCE: FIPS 140-2

Cryptographic Logic – The embodiment of one (or more) cryptographic algorithm(s) along 

with alarms, checks, and other processes essential to effective and 

secure performance of the cryptographic process(es).

SOURCE: CNSSI-4009

Cryptographic Material –

(slang CRYPTO)

COMSEC material used to secure or authenticate information.

SOURCE: CNSSI-4009

Cryptographic Module – The set of hardware, software, firmware, or some combination 

thereof that implements cryptographic logic or processes, including 

cryptographic algorithms, and is contained within the cryptographic 

boundary of the module.

SOURCE: SP 800-32; FIPS 196

Cryptographic Module – The set of hardware, software, and/or firmware that implements 

Approved security functions (including cryptographic algorithms and 

key generation) and is contained within the cryptographic boundary.

SOURCE: FIPS 140-2
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cryptographic Module Security 

Policy –

A precise specification of the security rules under which a 

cryptographic module will operate, including the rules derived from 

the requirements of this standard (FIPS 140-2) and additional rules 

imposed by the vendor.

SOURCE: FIPS 140-2

Cryptographic Module Validation 

Program (CMVP) –

Validates cryptographic modules to Federal Information Processing 

Standard (FIPS) 140-2 and other cryptography-based standards. The 

CMVP is a joint effort between National Institute of Standards and 

Technology (NIST) and the Communications Security Establishment 

(CSE) of the government of Canada. Products validated as 

conforming to FIPS 140-2 are accepted by the federal agencies of 

both countries for the protection of sensitive information (United 

States) or Designated Information (Canada). The goal of the CMVP 

is to promote the use of validated cryptographic modules and provide 

federal agencies with a security metric to use in procuring equipment 

containing validated cryptographic modules.

SOURCE: FIPS 140-2

Cryptographic Net – Stations holding a common key.

SOURCE: CNSSI-4009

Cryptographic Period – Time span during which each key setting remains in effect.

SOURCE: CNSSI-4009

Cryptographic Product – A cryptographic key (public, private, or shared) or public key 

certificate, used for encryption, decryption, digital signature, or 

signature verification; and other items, such as compromised key lists 

(CKL) and certificate revocation lists (CRL), obtained by trusted 

means from the same source which validate the authenticity of keys 

or certificates. Protected software which generates or regenerates 

keys or certificates may also be considered a cryptographic product.

SOURCE: CNSSI-4009

Cryptographic Randomization – Function that randomly determines the transmit state of a 

cryptographic logic.

SOURCE: CNSSI-4009

Cryptographic Security – Component of COMSEC resulting from the provision of technically 

sound cryptographic systems and their proper use.

SOURCE: CNSSI-4009

Cryptographic Strength – A measure of the expected number of operations required to defeat a 

cryptographic mechanism. 

SOURCE: SP 800-63
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cryptographic Synchronization – Process by which a receiving decrypting cryptographic logic attains 

the same internal state as the transmitting encrypting logic.

SOURCE: CNSSI-4009

Cryptographic System – Associated information assurance items interacting to provide a 

single means of encryption or decryption.

SOURCE: CNSSI-4009

Cryptographic System Analysis – Process of establishing the exploitability of a cryptographic system, 

normally by reviewing transmitted traffic protected or secured by the 

system under study.

SOURCE: CNSSI-4009

Cryptographic System Evaluation – Process of determining vulnerabilities of a cryptographic system and 

recommending countermeasures.

SOURCE: CNSSI-4009

Cryptographic System Review – Examination of a cryptographic system by the controlling authority 

ensuring its adequacy of design and content, continued need, and 

proper distribution.

SOURCE: CNSSI-4009

Cryptographic System Survey – Management technique in which actual holders of a cryptographic 

system express opinions on the system's suitability and provide usage 

information for technical evaluations.

SOURCE: CNSSI-4009

Cryptographic Token – A token where the secret is a cryptographic key.

SOURCE: SP 800-63

A portable, user-controlled physical device (e.g., smart card or 

PCMCIA card) used to store cryptographic information and possibly 

also perform cryptographic functions.

SOURCE: CNSSI-4009

Cryptography – The discipline that embodies the principles, means, and methods for 

the transformation of data in order to hide their semantic content, 

prevent their unauthorized use, or prevent their undetected 

modification.

SOURCE: SP 800-59

Cryptography – The discipline that embodies principles, means, and methods for 

providing information security, including confidentiality, data 

integrity, non-repudiation, and authenticity.

SOURCE: SP 800-21
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cryptography – Is categorized as either secret key or public key. Secret key 

cryptography is based on the use of a single cryptographic key shared 

between two parties. The same key is used to encrypt and decrypt 

data. This key is kept secret by the two parties. Public key 

cryptography is a form of cryptography which makes use of two 

keys: a public key and a private key. The two keys are related but 

have the property that, given the public key, it is computationally 

infeasible to derive the private key [FIPS 140-1]. In a public key 

cryptosystem, each party has its own public/private key pair. The 

public key can be known by anyone; the private key is kept secret.

SOURCE: FIPS 191

Art or science concerning the principles, means, and methods for 

rendering plain information unintelligible and for restoring encrypted 

information to intelligible form.

SOURCE: CNSSI-4009

Cryptology – The science that deals with hidden, disguised, or encrypted 

communications. It includes communications security and 

communications intelligence.

SOURCE: SP 800-60

The mathematical science that deals with cryptanalysis and 

cryptography.

SOURCE: CNSSI-4009

CVE – See Common Vulnerabilities and Exposures.

Cyber Attack – An attack, via cyberspace, targeting an enterprise’s use of cyberspace 

for the purpose of disrupting, disabling, destroying, or maliciously 

controlling a computing environment/infrastructure; or destroying the 

integrity of the data or stealing controlled information.

SOURCE: CNSSI-4009

Cyber Incident – Actions taken through the use of computer networks that result in an 

actual or potentially adverse effect on an information system and/or 

the information residing therein. See Incident.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Cyber Infrastructure – Includes electronic information and communications systems and 

services and the information contained in these systems and services. 

Information and communications systems and services are composed 

of all hardware and software that process, store, and communicate 

information, or any combination of all of these elements. Processing 

includes the creation, access, modification, and destruction of 

information. Storage includes paper, magnetic, electronic, and all 

other media types. Communications include sharing and distribution 

of information. For example: computer systems; control systems 

(e.g., supervisory control and data acquisition–SCADA); networks, 

such as the Internet; and cyber services (e.g., managed security 

services) are part of cyber infrastructure.

SOURCE: NISTIR 7628

Cybersecurity – The ability to protect or defend the use of cyberspace from cyber 

attacks.

SOURCE: CNSSI-4009

Cyberspace – A global domain within the information environment consisting of 

the interdependent network of information systems infrastructures 

including the Internet, telecommunications networks, computer 

systems, and embedded processors and controllers.

SOURCE: CNSSI-4009

Cyclical Redundancy Check –

(CRC)

A method to ensure data has not been altered after being sent through 

a communication channel.

SOURCE: SP 800-72

Error checking mechanism that verifies data integrity by computing a 

polynomial algorithm based checksum.

SOURCE: CNSSI-4009

Data – A subset of information in an electronic format that allows it to be 

retrieved or transmitted.

SOURCE: CNSSI-4009

Data Aggregation – Compilation of individual data systems and data that could result in 

the totality of the information being classified, or classified at a 

higher level, or of beneficial use to an adversary.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Data Asset – 1. Any entity that is comprised of data. For example, a database is 

a data asset that is comprised of data records. A data asset may be a 

system or application output file, database, document, or Web page. 

A data asset also includes a service that may be provided to access 

data from an application. For example, a service that returns 

individual records from a database would be a data asset. Similarly, 

a Web site that returns data in response to specific queries (e.g., 

www.weather.com) would be a data asset. 

2. An information-based resource.

SOURCE: CNSSI-4009

Data Element – A basic unit of information that has a unique meaning and 

subcategories (data items) of distinct value. Examples of data 

elements include gender, race, and geographic location.

SOURCE: SP 800-47; CNSSI-4009

Data Encryption Algorithm (DEA) – The DEA cryptographic engine that is used by the Triple Data 

Encryption Algorithm (TDEA).

SOURCE: SP 800-67

Data Encryption Standard (DES) – Cryptographic algorithm designed for the protection of unclassified 

data and published by the National Institute of Standards and 

Technology (NIST) in Federal Information Processing Standard 

(FIPS) Publication 46. (FIPS 46-3 withdrawn 19 May 2005) See 

Triple DES.

SOURCE: CNSSI-4009

Data Flow Control – Synonymous with information flow control.

SOURCE: CNSSI-4009

Data Integrity – The property that data has not been altered in an unauthorized 

manner. Data integrity covers data in storage, during processing, and 

while in transit.

SOURCE: SP 800-27

The property that data has not been changed, destroyed, or lost in an 

unauthorized or accidental manner. 

SOURCE: CNSSI-4009

Data Loss – The exposure of proprietary, sensitive, or classified information 

through either data theft or data leakage.

SOURCE: SP 800-137
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Data Origin Authentication – The process of verifying that the source of the data is as claimed and 

that the data has not been modified. 

SOURCE: CNSSI-4009

Data Security – Protection of data from unauthorized (accidental or intentional) 

modification, destruction, or disclosure.

SOURCE: CNSSI-4009

Data Transfer Device (DTD) – Fill device designed to securely store, transport, and transfer 

electronically both COMSEC and TRANSEC key, designed to be 

backward compatible with the previous generation of COMSEC 

common fill devices, and programmable to support modern mission 

systems.

SOURCE: CNSSI-4009

Decertification – Revocation of the certification of an information system item or 

equipment for cause.

SOURCE: CNSSI-4009

Decipher – Convert enciphered text to plain text by means of a cryptographic 

system.

SOURCE: CNSSI-4009

Decode – Convert encoded text to plain text by means of a code.

SOURCE: CNSSI-4009

Decrypt – Generic term encompassing decode and decipher.

SOURCE: CNSSI-4009

Decryption – The process of transforming ciphertext into plaintext.

SOURCE: SP 800-67

Decryption – The process of changing ciphertext into plaintext using a 

cryptographic algorithm and key.

SOURCE: SP 800-21

Decryption – Conversion of ciphertext to plaintext through the use

of a cryptographic algorithm.

SOURCE: FIPS 185
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Dedicated Mode – Information systems security mode of operation wherein each user, 

with direct or indirect access to the system, its peripherals, remote 

terminals, or remote hosts, has all of the following: 1. valid security 

clearance for all information within the system, 2. formal access 

approval and signed nondisclosure agreements for all the information 

stored and/or processed (including all compartments, 

subcompartments, and/or special access programs), and 3. valid needto-know for all information contained within the information system. 

When in the dedicated security mode, a system is specifically and 

exclusively dedicated to and controlled for the processing of one 

particular type or classification of information, either for full-time 

operation or for a specified period of time.

SOURCE: CNSSI-4009

Default Classification – Classification reflecting the highest classification being processed in 

an information system. Default classification is included in the 

caution statement affixed to an object.

SOURCE: CNSSI-4009

Defense-in-Breadth – A planned, systematic set of multidisciplinary activities that seek to 

identify, manage, and reduce risk of exploitable vulnerabilities at 

every stage of the system, network, or sub-component life cycle 

(system, network, or product design and development; 

manufacturing; packaging; assembly; system integration; 

distribution; operations; maintenance; and retirement).

SOURCE: CNSSI-4009

Defense-in-Depth – Information security strategy integrating people, technology, and 

operations capabilities to establish variable barriers across multiple 

layers and dimensions of the organization.

SOURCE: CNSSI-4009; SP 800-53

Degauss – Procedure that reduces the magnetic flux to virtual zero by applying a 

reverse magnetizing field. Also called demagnetizing.

SOURCE: CNSSI-4009

Delegated Development Program – INFOSEC program in which the Director, NSA, delegates, on a caseby-case basis, the development and/or production of an entire 

telecommunications product, including the INFOSEC portion, to a 

lead department or agency.

SOURCE: CNSSI-4009

Deleted File – A file that has been logically, but not necessarily physically, erased 

from the operating system, perhaps to eliminate potentially 

incriminating evidence. Deleting files does not always necessarily 

eliminate the possibility of recovering all or part of the original data.

SOURCE: SP 800-72
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Demilitarized Zone (DMZ) – An interface on a routing firewall that is similar to the interfaces 

found on the firewall’s protected side. Traffic moving between the 

DMZ and other interfaces on the protected side of the firewall still 

goes through the firewall and can have firewall protection policies 

applied.

SOURCE: SP 800-41

A host or network segment inserted as a “neutral zone” between an 

organization’s private network and the Internet.

SOURCE: SP 800-45

Perimeter network segment that is logically between internal and 

external networks. Its purpose is to enforce the internal network’s 

Information Assurance policy for external information exchange and 

to provide external, untrusted sources with restricted access to 

releasable information while shielding the internal networks from 

outside attacks. 

SOURCE: CNSSI-4009

Denial of Service (DoS) – The prevention of authorized access to resources or the delaying of 

time-critical operations. (Time-critical may be milliseconds or it may 

be hours, depending upon the service provided.) 

SOURCE: CNSSI-4009

Depth – An attribute associated with an assessment method that addresses the 

rigor and level of detail associated with the application of the 

method. The values for the depth attribute, hierarchically from less 

depth to more depth, are basic, focused, and comprehensive.

SOURCE: SP 800-53A

Descriptive Top-Level 

Specification (DTLS) –

A natural language descriptive of a system’s security requirements, 

an informal design notation, or a combination of the two.

SOURCE: CNSSI-4009

Designated Approval Authority –

(DAA)

Official with the authority to formally assume responsibility for 

operating a system at an acceptable level of risk. This term is 

synonymous with authorizing official, designated accrediting 

authority, and delegated accrediting authority.

SOURCE: CNSSI-4009

Designated Approving

(Accrediting) Authority – See Authorizing Official.
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Deterministic Random Bit Generator 

(DRBG) –

A Random Bit Generator (RBG) that includes a DRBG mechanism 

and (at least initially) has access to a source of entropy input. The 

DRBG produces a sequence of bits from a secret initial value called a 

seed, along with other possible inputs. A DRBG is often called a 

Pseudorandom Number (or Bit) Generator. 

SOURCE: SP 800-90A

Deterministic Random Bit Generator 

(DRBG) Mechanism –

The portion of an RBG that includes the functions necessary to 

instantiate and uninstantiate the RBG, generate pseudorandom bits, 

(optionally) reseed the RBG and test the health of the DRBG 

mechanism. 

SOURCE: SP 800-90A

Device Distribution Profile – An approval-based Access Control List (ACL) for a specific product 

that 1) names the user devices in a specific key management 

infrastructure (KMI) Operating Account (KOA) to which PRSNs 

distribute the product, and 2) states conditions of distribution for each 

device.

SOURCE: CNSSI-4009

Device Registration Manager – The management role that is responsible for performing activities 

related to registering users that are devices.

SOURCE: CNSSI-4009

Dial Back – Synonymous with call back.

SOURCE: CNSSI-4009

Differential Power Analysis –

(DPA)

An analysis of the variations of the electrical power consumption of a 

cryptographic module, using advanced statistical methods and/or 

other techniques, for the purpose of extracting information correlated 

to cryptographic keys used in a cryptographic algorithm.

SOURCE: FIPS 140-2

Digital Evidence – Electronic information stored or transferred in digital form.

SOURCE: SP 800-72

Digital Forensics – The application of science to the identification, collection, 

examination, and analysis of data while preserving the integrity of the 

information and maintaining a strict chain of custody for the data.

SOURCE: SP 800-86

Digital Signature – An asymmetric key operation where the private key is used to 

digitally sign data and the public key is used to verify the signature. 

Digital signatures provide authenticity protection, integrity 

protection, and non-repudiation.

SOURCE: SP 800-63
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

64

Digital Signature – A nonforgeable transformation of data that allows the proof of the 

source (with non-repudiation) and the verification of the integrity of 

that data.

SOURCE: FIPS 196

Digital Signature – The result of a cryptographic transformation of data which, when 

properly implemented, provides the services of:

1. origin authentication,

2. data integrity, and

3. signer non-repudiation.

SOURCE: FIPS 140-2

The result of a cryptographic transformation of data that, when 

properly implemented, provides a mechanism for verifying origin 

authentication, data integrity, and signatory non-repudiation.

SOURCE: FIPS 186-3

The result of a cryptographic transformation of data that, when 

properly implemented, provides origin authentication, data integrity,

and signatory non-repudiation.

SOURCE: SP 800-89

Cryptographic process used to assure data object originator 

authenticity, data integrity, and time stamping for prevention of 

replay.

SOURCE: CNSSI-4009

Digital Signature Algorithm – Asymmetric algorithms used for digitally signing data.

SOURCE: SP 800-49

Direct Shipment – Shipment of COMSEC material directly from NSA to user COMSEC 

accounts.

SOURCE: CNSSI-4009

Disaster Recovery Plan (DRP) – A written plan for recovering one or more information systems at an 

alternate facility in response to a major hardware or software failure 

or destruction of facilities.

SOURCE: SP 800-34

Management policy and procedures used to guide an enterprise 

response to a major loss of enterprise capability or damage to its 

facilities. The DRP is the second plan needed by the enterprise risk 

managers and is used when the enterprise must recover (at its original 

facilities) from a loss of capability over a period of hours or days. 

See Continuity of Operations Plan and Contingency Plan.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

65

Disconnection – The termination of an interconnection between two or more IT 

systems. A disconnection may be planned (e.g., due to changed 

business needs) or unplanned (i.e., due to an attack or other 

contingency).

SOURCE: SP 800-47

Discretionary Access Control – The basis of this kind of security is that an individual user, or 

program operating on the user’s behalf, is allowed to specify 

explicitly the types of access other users (or programs executing on 

their behalf) may have to information under the user’s control.

SOURCE: FIPS 191

A means of restricting access to objects (e.g., files, data entities) 

based on the identity and need-to-know of subjects (e.g., users, 

processes) and/or groups to which the object belongs. The controls 

are discretionary in the sense that a subject with a certain access 

permission is capable of passing that permission (perhaps indirectly) 

on to any other subject (unless restrained by mandatory access 

control). 

SOURCE: CNSSI-4009

Disk Imaging – Generating a bit-for-bit copy of the original media, including free 

space and slack space. 

SOURCE: SP 800-86

Disruption – An unplanned event that causes the general system or major 

application to be inoperable for an unacceptable length of time (e.g., 

minor or extended power outage, extended unavailable network, or 

equipment or facility damage or destruction).

SOURCE: CNSSI-4009

An unplanned event that causes an information system to be 

inoperable for a length of time (e.g., minor or extended power outage, 

extended unavailable network, or equipment or facility damage or 

destruction).

SOURCE: SP 800-34

Distinguished Name (DN) – A unique name or character string that unambiguously identifies an 

entity according to the hierarchical naming conventions of X.500 

directory service.

SOURCE: CNSSI-4009

Distinguishing Identifier – Information which unambiguously distinguishes an entity in the 

authentication process.

SOURCE: FIPS 196; CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Distributed Denial of Service –

(DDoS)

A Denial of Service technique that uses numerous hosts to perform 

the attack.

SOURCE: CNSSI-4009

DMZ – See Demilitarized Zone.

Domain – A set of subjects, their information objects, and a common security 

policy.

SOURCE: SP 800-27

An environment or context that includes a set of system resources 

and a set of system entities that have the right to access the resources 

as defined by a common security policy, security model, or security 

architecture. See Security Domain.

SOURCE: CNSSI-4009; SP 800-53; SP 800-37

Drop Accountability – Procedure under which a COMSEC account custodian initially 

receipts for COMSEC material, and provides no further accounting 

for it to its central office of record. Local accountability of the 

COMSEC material may continue to be required. See Accounting 

Legend Code.

SOURCE: CNSSI-4009

Dual-Use Certificate – A certificate that is intended for use with both digital signature and 

data encryption services.

SOURCE: SP 800-32

Duplicate Digital Evidence – A duplicate is an accurate digital reproduction of all data objects 

contained on the original physical item and associated media.

SOURCE: SP 800-72

Duration – A field within a certificate that is composed of two subfields; “date of 

issue” and “date of next issue.”

SOURCE: SP 800-32

Dynamic Subsystem – A subsystem that is not continually present during the execution

phase of an information system. Service-oriented architectures

and cloud computing architectures are examples of architectures

that employ dynamic subsystems.

SOURCE: SP 800-37

E-Government (e-gov) – The use by the U.S. government of Web-based Internet applications 

and other information technology. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Easter Egg – Hidden functionality within an application program, which becomes 

activated when an undocumented, and often convoluted, set of 

commands and keystrokes are entered. Easter eggs are typically used 

to display the credits for the development team and are intended to be 

nonthreatening.

SOURCE: SP 800-28

Eavesdropping Attack – An attack in which an Attacker listens passively to the authentication 

protocol to capture information which can be used in a subsequent 

active attack to masquerade as the Claimant. 

SOURCE: SP 800-63

Education (Information Security) – Education integrates all of the security skills and competencies of the 

various functional specialties into a common body of knowledge . . . 

and strives to produce IT security specialists and professionals 

capable of vision and proactive response.

SOURCE: SP 800-50

Egress Filtering – Filtering of outgoing network traffic.

SOURCE: SP 800-41

Electronic Authentication –

(E-authentication)

The process of establishing confidence in user identities 

electronically presented to an information system.

SOURCE: SP 800-63; CNSSI-4009

Electronic Business (e-business) – Doing business online.

SOURCE: CNSSI-4009

Electronic Credentials – Digital documents used in authentication that bind an identity or an 

attribute to a subscriber's token.

SOURCE: CNSSI-4009

Electronic Evidence – Information and data of investigative value that is stored on or 

transmitted by an electronic device.

SOURCE: SP 800-72

Electronic Key Entry – The entry of cryptographic keys into a cryptographic module using 

electronic methods such as a smart card or a key-loading device. (The 

operator of the key may have no knowledge of the value of the key 

being entered.)

SOURCE: FIPS 140-2
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Electronic Key Management System 

(EKMS) –

Interoperable collection of systems being developed by services and 

agencies of the U.S. government to automate the planning, ordering, 

generating, distributing, storing, filling, using, and destroying of 

electronic key and management of other types of COMSEC material.

SOURCE: CNSSI-4009

Electronic Messaging Services – Services providing interpersonal messaging capability; meeting 

specific functional, management, and technical requirements; and 

yielding a business-quality electronic mail service suitable for the 

conduct of official government business.

SOURCE: CNSSI-4009

Electronic Signature – The process of applying any mark in electronic form with the intent 

to sign a data object. See also Digital Signature.

SOURCE: CNSSI-4009

Electronically Generated Key – Key generated in a COMSEC device by introducing (either 

mechanically or electronically) a seed key into the device and then 

using the seed, together with a software algorithm stored in the 

device, to produce the desired key.

SOURCE: CNSSI-4009

Emanations Security (EMSEC) – Protection resulting from measures taken to deny unauthorized 

individuals information derived from intercept and analysis of 

compromising emissions from crypto-equipment or an information 

system. See TEMPEST.

SOURCE: CNSSI-4009

Embedded Computer – Computer system that is an integral part of a larger system.

SOURCE: CNSSI-4009

Embedded Cryptographic System – Cryptosystem performing or controlling a function as an integral 

element of a larger system or subsystem.

SOURCE: CNSSI-4009

Embedded Cryptography – Cryptography engineered into an equipment or system whose basic 

function is not cryptographic.

SOURCE: CNSSI-4009

Encipher – Convert plain text to cipher text by means of a cryptographic system.

SOURCE: CNSSI-4009
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Enclave – Collection of information systems connected by one or more internal 

networks under the control of a single authority and security policy. 

The systems may be structured by physical proximity or by function, 

independent of location.

SOURCE: CNSSI-4009

Enclave Boundary – Point at which an enclave’s internal network service layer connects to 

an external network’s service layer, i.e., to another enclave or to a 

Wide Area Network (WAN).

SOURCE: CNSSI-4009

Encode – Convert plain text to cipher text by means of a code.

SOURCE: CNSSI-4009

Encrypt – Generic term encompassing encipher and encode.

SOURCE: CNSSI-4009

Encrypted Key – A cryptographic key that has been encrypted using an Approved 

security function with a key encrypting key, a PIN, or a password in 

order to disguise the value of the underlying plaintext key.

SOURCE: FIPS 140-2

Encrypted Network – A network on which messages are encrypted (e.g., using DES, AES, 

or other appropriate algorithms) to prevent reading by unauthorized 

parties. 

SOURCE: SP 800-32

Encryption – Conversion of plaintext to ciphertext through the use of a 

cryptographic algorithm.

SOURCE: FIPS 185

Encryption – The process of changing plaintext into ciphertext for the purpose of 

security or privacy.

SOURCE: SP 800-21; CNSSI-4009

Encryption Algorithm – Set of mathematically expressed rules for rendering data 

unintelligible by executing a series of conversions controlled by a 

key.

SOURCE: CNSSI-4009

Encryption Certificate – A certificate containing a public key that is used to encrypt electronic 

messages, files, documents, or data transmissions, or to establish or 

exchange a session key for these same purposes.

SOURCE: SP 800-32
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End-Item Accounting – Accounting for all the accountable components of a COMSEC 

equipment configuration by a single short title.

SOURCE: CNSSI-4009

End Cryptographic Unit (ECU) – Device that (1) performs cryptographic functions, (2) typically is part 

of a larger system for which the device provides security services, 

and (3) from the viewpoint of a supporting security infrastructure 

(e.g., a key management system), is the lowest level of identifiable 

component with which a management transaction can be conducted.

SOURCE: CNSSI-4009

End-to-End Encryption – Communications encryption in which data is encrypted when being 

passed through a network, but routing information remains visible.

SOURCE: SP 800-12

Encryption of information at its origin and decryption at its intended 

destination without intermediate decryption.

SOURCE: CNSSI-4009

End-to-End Security – Safeguarding information in an information system from point of 

origin to point of destination.

SOURCE: CNSSI-4009

Enrollment Manager – The management role that is responsible for assigning user identities 

to management and non-management roles.

SOURCE: CNSSI-4009

Enterprise – An organization with a defined mission/goal and a defined boundary, 

using information systems to execute that mission, and with 

responsibility for managing its own risks and performance. An 

enterprise may consist of all or some of the following business 

aspects: acquisition, program management, financial management 

(e.g., budgets), human resources, security, and information systems, 

information and mission management.

SOURCE: CNSSI-4009

Enterprise Architecture (EA) – The description of an enterprise’s entire set of information systems: 

how they are configured, how they are integrated, how they interface 

to the external environment at the enterprise’s boundary, how they 

are operated to support the enterprise mission, and how they 

contribute to the enterprise’s overall security posture.

SOURCE: CNSSI-4009
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Enterprise Risk Management – The methods and processes used by an enterprise to manage risks to 

its mission and to establish the trust necessary for the enterprise to 

support shared missions. It involves the identification of mission 

dependencies on enterprise capabilities, the identification and 

prioritization of risks due to defined threats, the implementation of 

countermeasures to provide both a static risk posture and an effective 

dynamic response to active threats; and it assesses enterprise 

performance against threats and adjusts countermeasures as 

necessary.

SOURCE: CNSSI-4009

Enterprise Service – A set of one or more computer applications and middleware systems 

hosted on computer hardware that provides standard information 

systems capabilities to end users and hosted mission applications and 

services.

SOURCE: CNSSI-4009

Entity – Either a subject (an active element that operates on information or the 

system state) or an object (a passive element that contains or receives 

information).

SOURCE: SP 800-27

Entity – An active element in an open system.

SOURCE: FIPS 188

Entity – Any participant in an authentication exchange; such a participant may 

be human or nonhuman, and may take the role of a claimant and/or 

verifier.

SOURCE: FIPS 196

Entrapment – Deliberate planting of apparent flaws in an IS for the purpose of 

detecting attempted penetrations.

SOURCE: CNSSI-4009

Entropy – A measure of the amount of uncertainty that an Attacker faces to 

determine the value of a secret. Entropy is usually stated in bits.

SOURCE: SP 800-63

Environment – Aggregate of external procedures, conditions, and objects affecting 

the development, operation, and maintenance of an information 

system.

SOURCE: FIPS 200; CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Environment of Operation – The physical surroundings in which an information system

processes, stores, and transmits information.

SOURCE: SP 800-37; SP 800-53A

The physical, technical, and organizational setting in which an 

information system operates, including but not limited to: 

missions/business functions; mission/business processes; threat 

space; vulnerabilities; enterprise and information security 

architectures; personnel; facilities; supply chain relationships; 

information technologies; organizational governance and culture; 

acquisition and procurement processes; organizational policies and 

procedures; organizational assumptions, constraints, risk tolerance, 

and priorities/trade-offs). 

SOURCE: SP 800-30

Ephemeral Key – A cryptographic key that is generated for each execution of a key 

establishment process and that meets other requirements of the key 

type (e.g., unique to each message or session).

In some cases, ephemeral keys are used more than once within a 

single session (e.g., broadcast applications) where the sender 

generates only one ephemeral key pair per message, and the private 

key is combined separately with each recipient’s public key.

SOURCE: SP 800-57 Part 1

Erasure – Process intended to render magnetically stored information 

irretrievable by normal means.

SOURCE: CNSSI-4009

Error Detection Code – A code computed from data and comprised of redundant bits of 

information designed to detect, but not correct, unintentional changes 

in the data.

SOURCE: FIPS 140-2; CNSSI-4009

Escrow – Something (e.g., a document, an encryption key) that is "delivered to 

a third person to be given to the grantee only upon the fulfillment of a 

condition."

SOURCE: FIPS 185

Evaluation Products List (EPL) – List of validated products that have been successfully evaluated 

under the National Information Assurance Partnership (NIAP) 

Common Criteria Evaluation and Validation Scheme (CCEVS).

SOURCE: CNSSI-4009

Evaluation Assurance Level (EAL) – Set of assurance requirements that represent a point on the Common 

Criteria predefined assurance scale.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Event – Any observable occurrence in a network or system.

SOURCE: SP 800-61

Any observable occurrence in a system and/or network. Events 

sometimes provide indication that an incident is occurring.

SOURCE: CNSSI-4009

Examination – A technical review that makes the evidence visible and suitable for 

analysis; tests performed on the evidence to determine the presence 

or absence of specific data.

SOURCE: SP 800-72

Examine – A type of assessment method that is characterized by the process of 

checking, inspecting, reviewing, observing, studying, or analyzing 

one or more assessment objects to facilitate understanding, achieve 

clarification, or obtain evidence, the results of which are used to 

support the determination of security control effectiveness over time.

SOURCE: SP 800-53A

Exculpatory Evidence – Evidence that tends to decrease the likelihood of fault or guilt.

SOURCE: SP 800-72

Executive Agency – An executive department specified in 5 United States Code (U.S.C.), 

Sec. 101; a military department specified in 5 U.S.C., Sec. 102; an 

independent establishment as defined in 5 U.S.C., Sec. 104(1); and a 

wholly owned government corporation fully subject to the provisions 

of 31 U.S.C., Chapter 91.

SOURCE: SP 800-53; SP 800-37; FIPS 200; FIPS 199; 41 U.S.C.,

Sec. 403; CNSSI-4009

Exercise Key – Cryptographic key material used exclusively to safeguard 

communications transmitted over-the-air during military or organized 

civil training exercises.

SOURCE: CNSSI-4009

Expected Output – Any data collected from monitoring and assessments as part of the 

Information Security Continuous Monitoring (ISCM) strategy.

SOURCE: SP 800-137

Exploit Code – A program that allows attackers to automatically break into a system.

SOURCE: SP 800-40
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Exploitable Channel – Channel that allows the violation of the security policy governing an 

information system and is usable or detectable by subjects external to 

the trusted computing base. See Covert Channel.

SOURCE: CNSSI-4009

Extensible Configuration Checklist 

Description Format (XCCDF) –

SCAP language for specifying checklists and reporting checklist 

results. 

SOURCE: SP 800-128

External Information System (or 

Component) –

An information system or component of an information system that is 

outside of the authorization boundary established by the organization 

and for which the organization typically has no direct control over the 

application of required security controls or the assessment of security 

control effectiveness.

SOURCE: SP 800-37; SP 800-53; CNSSI-4009

External Information System 

Service –

An information system service that is implemented outside of the

authorization boundary of the organizational information system

(i.e., a service that is used by, but not a part of, the organizational

information system) and for which the organization typically has

no direct control over the application of required security controls

or the assessment of security control effectiveness.

SOURCE: SP 800-53; SP 800-37; CNSSI-4009

External Information System Service 

Provider –

A provider of external information system services to an organization 

through a variety of consumer-producer relationships, including but 

not limited to: joint ventures; business partnerships; outsourcing

arrangements (i.e., through contracts, interagency agreements, lines 

of business arrangements); licensing agreements; and/or supply chain 

exchanges.

SOURCE: SP 800-37; SP 800-53

External Network – A network not controlled by the organization.

SOURCE: SP 800-53; CNSSI-4009

External Security Testing – Security testing conducted from outside the organization’s security 

perimeter.

SOURCE: SP 800-115

Extraction Resistance – Capability of crypto-equipment or secure telecommunications 

equipment to resist efforts to extract key.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Extranet – A private network that uses Web technology, permitting the sharing 

of portions of an enterprise’s information or operations with 

suppliers, vendors, partners, customers, or other enterprises. 

SOURCE: CNSSI-4009

Fail Safe – Automatic protection of programs and/or processing systems when 

hardware or software failure is detected.

SOURCE: CNSSI-4009

Fail Soft – Selective termination of affected nonessential processing when 

hardware or software failure is determined to be imminent.

SOURCE: CNSSI-4009

Failover – The capability to switch over automatically (typically without human 

intervention or warning) to a redundant or standby information 

system upon the failure or abnormal termination of the previously 

active system.

SOURCE: SP 800-53; CNSSI-4009

Failure Access – Type of incident in which unauthorized access to data results from 

hardware or software failure.

SOURCE: CNSSI-4009

Failure Control – Methodology used to detect imminent hardware or software failure 

and provide fail safe or fail soft recovery.

SOURCE: CNSSI-4009

False Acceptance – When a biometric system incorrectly identifies an individual or 

incorrectly verifies an impostor against a claimed identity

SOURCE: SP 800-76

In biometrics, the instance of a security system incorrectly verifying 

or identifying an unauthorized person. It typically is considered the 

most serious of biometric security errors as it gives unauthorized 

users access to systems that expressly are trying to keep them out.

SOURCE: CNSSI-4009

False Acceptance Rate (FAR) – The probability that a biometric system will incorrectly identify an 

individual or will fail to reject an impostor. The rate given normally 

assumes passive impostor attempts. 

SOURCE: SP 800-76
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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The measure of the likelihood that the biometric security system will 

incorrectly accept an access attempt by an unauthorized user. A 

system’s false acceptance rate typically is stated as the ratio of the 

number of false acceptances divided by the number of identification 

attempts.

SOURCE: CNSSI-4009

False Positive – An alert that incorrectly indicates that malicious activity is occurring.

SOURCE: SP 800-61

False Rejection – When a biometric system fails to identify an applicant or fails to 

verify the legitimate claimed identity of an applicant. 

SOURCE: SP 800-76

In biometrics, the instance of a security system failing to verify or 

identify an authorized person. It does not necessarily indicate a flaw 

in the biometric system; for example, in a fingerprint-based system, 

an incorrectly aligned finger on the scanner or dirt on the scanner can 

result in the scanner misreading the fingerprint, causing a false 

rejection of the authorized user.

SOURCE: CNSSI-4009

False Rejection Rate (FRR) – The probability that a biometric system will fail to identify an 

applicant, or verify the legitimate claimed identity of an applicant. 

SOURCE: SP 800-76

The measure of the likelihood that the biometric security system will 

incorrectly reject an access attempt by an authorized user. A 

system’s false rejection rate typically is stated as the ratio of the 

number of false rejections divided by the number of identification 

attempts.

SOURCE: CNSSI-4009

Federal Agency – See Agency, See Executive Agency.

Federal Bridge Certification 

Authority (FBCA) –

The Federal Bridge Certification Authority consists of a collection of 

Public Key Infrastructure components (Certificate Authorities, 

Directories, Certificate Policies and Certificate Practice Statements) 

that are used to provide peer-to-peer interoperability among Agency 

Principal Certification Authorities.

SOURCE: SP 800-32; CNSSI-4009
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Federal Bridge Certification 

Authority Membrane –

The Federal Bridge Certification Authority Membrane consists of a 

collection of Public Key Infrastructure components including a 

variety of Certification Authority PKI products, Databases, CA 

specific Directories, Border Directory, Firewalls, Routers, 

Randomizers, etc.

SOURCE: SP 800-32

Federal Bridge Certification 

Authority Operational Authority –

The Federal Bridge Certification Authority Operational Authority is 

the organization selected by the Federal Public Key Infrastructure 

Policy Authority to be responsible for operating the Federal Bridge 

Certification Authority.

SOURCE: SP 800-32

Federal Enterprise Architecture – A business-based framework for governmentwide improvement 

developed by the Office of Management and Budget that is intended 

to facilitate efforts to transform the federal government to one that is 

citizen-centered, results-oriented, and market-based.

SOURCE: SP 800-53; SP 800-18; SP 800-60; CNSSI-4009

Federal Information Processing 

Standard (FIPS) –

A standard for adoption and use by federal departments and agencies 

that has been developed within the Information Technology 

Laboratory and published by the National Institute of Standards and 

Technology, a part of the U.S. Department of Commerce. A FIPS 

covers some topic in information technology in order to achieve a 

common level of quality or some level of interoperability.

SOURCE: FIPS 201

Federal Information Security 

Management Act (FISMA) –

A statute (Title III, P.L. 107-347) that requires agencies to assess risk 

to information systems and provide information security protections 

commensurate with the risk. FISMA also requires that agencies 

integrate information security into their capital planning and 

enterprise architecture processes, conduct annual information systems 

security reviews of all programs and systems, and report the results 

of those reviews to OMB.

SOURCE: CNSSI-4009

Title III of the E-Government Act requiring each federal agency to 

develop, document, and implement an agency-wide program to 

provide information security for the information and information 

systems that support the operations and assets of the agency, 

including those provided or managed by another agency, contractor, 

or other source. 

SOURCE: SP 800-63
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Federal Information System – An information system used or operated by an executive agency, by a 

contractor of an executive agency, or by another organization on 

behalf of an executive agency.

SOURCE: SP 800-53; FIPS 200; FIPS 199; 40 U.S.C., Sec. 11331;

CNSSI-4009

Federal Information Systems 

Security Educators’ Association –

(FISSEA)

An organization whose members come from federal agencies, 

industry, and academic institutions devoted to improving the IT 

security awareness and knowledge within the federal government and 

its related external workforce.

SOURCE: SP 800-16

Federal Public Key Infrastructure 

Policy Authority (FPKI PA) –

The Federal PKI Policy Authority is a federal government body 

responsible for setting, implementing, and administering policy 

decisions regarding interagency PKI interoperability that uses the 

FBCA.

SOURCE: SP 800-32

File Encryption – The process of encrypting individual files on a storage medium and 

permitting access to the encrypted data only after proper 

authentication is provided.

SOURCE: SP 800-111

File Name Anomaly – 1. A mismatch between the internal file header and its external 

extension; or

2. A file name inconsistent with the content of the file (e.g., renaming 

a graphics file with a non-graphical extension.

SOURCE: SP 800-72

File Protection – Aggregate of processes and procedures designed to inhibit 

unauthorized access, contamination, elimination, modification, or 

destruction of a file or any of its contents.

SOURCE: CNSSI-4009

File Security – Means by which access to computer files is limited to authorized 

users only.

SOURCE: CNSSI-4009

Fill Device – COMSEC item used to transfer or store key in electronic form or to 

insert key into cryptographic equipment.

SOURCE: CNSSI-4009

FIPS – See Federal Information Processing Standard.
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

79

FIPS-Approved Security Method – A security method (e.g., cryptographic algorithm, cryptographic key 

generation algorithm or key distribution technique, random number 

generator, authentication technique, or evaluation criteria) that is 

either a) specified in a FIPS, or b) adopted in a FIPS.

SOURCE: FIPS 196

FIPS-Validated Cryptography – A cryptographic module validated by the Cryptographic Module

Validation Program (CMVP) to meet requirements specified in

FIPS 140-2 (as amended). As a prerequisite to CMVP validation,

the cryptographic module is required to employ a cryptographic

algorithm implementation that has successfully passed validation

testing by the Cryptographic Algorithm Validation Program

(CAVP). See NSA-Approved Cryptography.

SOURCE: SP 800-53

FIPS PUB – An acronym for Federal Information Processing Standards 

Publication. FIPS publications (PUB) are issued by NIST after 

approval by the Secretary of Commerce. 

SOURCE: SP 800-64

FIREFLY – Key management protocol based on public key cryptography.

SOURCE: CNSSI-4009

Firewall – A gateway that limits access between networks in accordance with 

local security policy.

SOURCE: SP 800-32

A hardware/software capability that limits access between networks 

and/or systems in accordance with a specific security policy.

SOURCE: CNSSI-4009

A device or program that controls the flow of network traffic between 

networks or hosts that employ differing security postures.

SOURCE: SP 800-41

Firewall Control Proxy – The component that controls a firewall’s handling of a call. The 

firewall control proxy can instruct the firewall to open specific ports 

that are needed by a call, and direct the firewall to close these ports at 

call termination.

SOURCE: SP 800-58

Firmware – The programs and data components of a cryptographic module that 

are stored in hardware within the cryptographic boundary and cannot 

be dynamically written or modified during execution.

SOURCE: FIPS 140-2
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Computer programs and data stored in hardware - typically in readonly memory (ROM) or programmable read-only memory (PROM) -

such that the programs and data cannot be dynamically written or

modified during execution of the programs.

SOURCE: CNSSI-4009

FISMA – See Federal Information Security Management Act.

Fixed COMSEC Facility – COMSEC facility located in an immobile structure or aboard a ship.

SOURCE: CNSSI-4009

Flaw – Error of commission, omission, or oversight in an information system

that may allow protection mechanisms to be bypassed.

SOURCE: CNSSI-4009

Flaw Hypothesis Methodology – System analysis and penetration technique in which the specification 

and documentation for an information system are analyzed to 

produce a list of hypothetical flaws. This list is prioritized on the 

basis of the estimated probability that a flaw exists, on the ease of 

exploiting it, and on the extent of control or compromise it would 

provide. The prioritized list is used to perform penetration testing of 

a system.

SOURCE: CNSSI-4009

Flooding – An attack that attempts to cause a failure in a system by providing 

more input than the system can process properly.

SOURCE: CNSSI-4009

Focused Testing – A test methodology that assumes some knowledge of the internal 

structure and implementation detail of the assessment object. Also 

known as gray box testing.

SOURCE: SP 800-53A

Forensic Copy – An accurate bit-for-bit reproduction of the information contained on 

an electronic device or associated media, whose validity and integrity 

has been verified using an accepted algorithm.

SOURCE: SP 800-72; CNSSI-4009

Forensic Specialist – A professional who locates, identifies, collects, analyzes, and 

examines data while preserving the integrity and maintaining a strict 

chain of custody of information discovered.

SOURCE: SP 800-72
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Forensics – The practice of gathering, retaining, and analyzing computer-related 

data for investigative purposes in a manner that maintains the 

integrity of the data. 

SOURCE: CNSSI-4009

See Also Computer Forensics.

Forensically Clean – Digital media that is completely wiped of all data, including 

nonessential and residual data, scanned for malware, and verified 

before use.

SOURCE: SP 800-86

Formal Access Approval – A formalization of the security determination for authorizing access 

to a specific type of classified or sensitive information, based on 

specified access requirements, a determination of the individual’s 

security eligibility and a determination that the individual’s official 

duties require the individual be provided access to the information. 

SOURCE: CNSSI-4009

Formal Development 

Methodology –

Software development strategy that proves security design 

specifications.

SOURCE: CNSSI-4009

Formal Method – Mathematical argument which verifies that the system satisfies a 

mathematically-described security policy.

SOURCE: CNSSI-4009

Formal Proof – Complete and convincing mathematical argument presenting the full 

logical justification for each proof step and for the truth of a theorem 

or set of theorems. 

SOURCE: CNSSI-4009

Formal Security Policy – Mathematically-precise statement of a security policy.

SOURCE: CNSSI-4009

Formatting Function – The function that transforms the payload, associated data, and nonce 

into a sequence of complete blocks.

SOURCE: SP 800-38C

Forward Cipher – One of the two functions of the block cipher algorithm that is 

determined by the choice of a cryptographic key. The term “forward 

cipher operation” is used for TDEA, while the term “forward 

transformation” is used for DEA.

SOURCE: SP 800-67
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Frequency Hopping – Repeated switching of frequencies during radio transmission 

according to a specified algorithm, to minimize unauthorized 

interception or jamming of telecommunications.

SOURCE: CNSSI-4009

Full Disk Encryption (FDE) – The process of encrypting all the data on the hard disk drive used to 

boot a computer, including the computer’s operating system, and 

permitting access to the data only after successful authentication with 

the full disk encryption product.

SOURCE: SP 800-111

Full Maintenance – Complete diagnostic repair, modification, and overhaul of COMSEC 

equipment, including repair of defective assemblies by piece part 

replacement. See Limited Maintenance.

SOURCE: CNSSI-4009

Functional Testing – Segment of security testing in which advertised security mechanisms 

of an information system are tested under operational conditions.

SOURCE: CNSSI-4009

Gateway – Interface providing compatibility between networks by converting 

transmission speeds, protocols, codes, or security measures.

SOURCE: CNSSI-4009

General Support System – An interconnected set of information resources under the same direct 

management control that shares common functionality. It normally 

includes hardware, software, information, data, applications, 

communications, and people.

SOURCE: OMB Circular A-130, App. III

An interconnected set of information resources under the same direct 

management control which shares common functionality. A system 

normally includes hardware, software, information, data, 

applications, communications, and people. A system can be, for 

example, a local area network (LAN) including smart terminals that 

supports a branch office, an agency-wide backbone, a 

communications network, a departmental data processing center 

including its operating system and utilities, a tactical radio network, 

or a shared information processing service organization (IPSO).

SOURCE: CNSSI-4009
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Global Information Grid (GIG) – The globally interconnected, end-to-end set of information 

capabilities for collecting, processing, storing, disseminating, and 

managing information on demand to warfighters, policy makers, and 

support personnel. The GIG includes owned and leased 

communications and computing systems and services, software 

(including applications), data, security services, other associated 

services, and National Security Systems. Non-GIG IT includes 

stand-alone, self-contained, or embedded IT that is not, and will not 

be, connected to the enterprise network.

SOURCE: CNSSI-4009

Global Information Infrastructure –

(GII)

Worldwide interconnections of the information systems of all 

countries, international and multinational organizations, and 

international commercial communications.

SOURCE: CNSSI-4009

Graduated Security – A security system that provides several levels (e.g., low, moderate, 

high) of protection based on threats, risks, available technology, 

support services, time, human concerns, and economics.

SOURCE: FIPS 201

Gray Box Testing – See Focused Testing.

Group Authenticator – Used, sometimes in addition to a sign-on authenticator, to allow 

access to specific data or functions that may be shared by all 

members of a particular group. 

SOURCE: CNSSI-4009

Guard (System) – A mechanism limiting the exchange of information between 

information systems or subsystems.

SOURCE: CNSSI-4009

Guessing Entropy – A measure of the difficulty that an Attacker has to guess the average 

password used in a system. In this document, entropy is stated in bits. 

When a password has n-bits of guessing entropy then an attacker has 

as much difficulty guessing the average password as in guessing an 

n-bit random quantity. The attacker is assumed to know the actual 

password frequency distribution.

SOURCE: SP 800-63

Hacker – Unauthorized user who attempts to or gains access to an information 

system.

SOURCE: CNSSI-4009
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Handshaking Procedures – Dialogue between two information systems for synchronizing, 

identifying, and authenticating themselves to one another.

SOURCE: CNSSI-4009

Hard Copy Key – Physical keying material, such as printed key lists, punched or 

printed key tapes, or programmable, read-only memories (PROM).

SOURCE: CNSSI-4009

Hardening – Configuring a host’s operating systems and applications to reduce the 

host’s security weaknesses.

SOURCE: SP 800-123

Hardware – The physical components of an information system. See also 

Software and Firmware.

SOURCE: CNSSI-4009

Hardwired Key – Permanently installed key.

SOURCE: CNSSI-4009

Hash Function – A function that maps a bit string of arbitrary length to a fixed length 

bit string. Approved hash functions satisfy the following properties:

1) One-Way. It is computationally infeasible to find any input that 

maps to any prespecified output.

2) Collision Resistant. It is computationally infeasible to find any 

two distinct inputs that map to the same output.

SOURCE: SP 800-63; FIPS 201

Hash Function – A mathematical function that maps a string of arbitrary length (up to 

a predetermined maximum size) to a fixed length string. 

SOURCE: FIPS 198

A function that maps a bit string of arbitrary length to a fixed length 

bit string. Approved hash functions are specified in FIPS 180 and are 

designed to satisfy the following properties:

1. (One-way) It is computationally infeasible to find any input that 

maps to any new prespecified output, and

2. (Collision resistant) It is computationally infeasible to find any two 

distinct inputs that map to the same output.

SOURCE: FIPS 186

Hash Total – Value computed on data to detect error or manipulation. See 

Checksum.

SOURCE: CNSSI-4009
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Hash Value – The result of applying a cryptographic hash function to data (e.g., a 

message).

SOURCE: SP 800-106

Hash Value/Result – See Message Digest.

SOURCE: FIPS 186; CNSSI-4009

Hash-based Message Authentication 

Code (HMAC) –

Hash-based Message Authentication 

Code –

(HMAC)

A message authentication code that uses a cryptographic key in 

conjunction with a hash function.

SOURCE: FIPS 201; CNSSI-4009

Hash-based Message Authentication 

Code –

(HMAC)

A message authentication code that utilizes a keyed hash.

SOURCE: FIPS 140-2

Hashing – The process of using a mathematical algorithm against data to 

produce a numeric value that is representative of that data.

SOURCE: SP 800-72; CNSSI-4009

Hashword – Memory address containing hash total.

SOURCE: CNSSI-4009

Health Information Exchange –

(HIE)

A health information organization that brings together healthcare 

stakeholders within a defined geographic area and governs health 

information exchange among them for the purpose of improving 

health and care in that community. 

SOURCE: NISTIR-7497

High Assurance Guard (HAG) – An enclave boundary protection device that controls access between 

a local area network that an enterprise system has a requirement to 

protect, and an external network that is outside the control of the 

enterprise system, with a high degree of assurance.

SOURCE: SP 800-32

A guard that has two basic functional capabilities: a Message Guard 

and a Directory Guard. The Message Guard provides filter service 

for message traffic traversing the Guard between adjacent security 

domains. The Directory Guard provides filter service for directory 

access and updates traversing the Guard between adjacent security 

domains.

SOURCE: CNSSI-4009

High Availability – A failover feature to ensure availability during device or component 

interruptions.

SOURCE: SP 800-113
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High Impact – The loss of confidentiality, integrity, or availability that could be 

expected to have a severe or catastrophic adverse effect on 

organizational operations, organizational assets, individuals, other 

organizations, or the national security interests of the United States; 

(i.e., 1) causes a severe degradation in mission capability to an extent 

and duration that the organization is able to perform its primary 

functions, but the effectiveness of the functions is significantly 

reduced; 2) results in major damage to organizational assets; 3) 

results in major financial loss; or 4) results in severe or catastrophic 

harm to individuals involving loss of life or serious life threatening 

injuries).

SOURCE: FIPS 199; CNSSI-4009

High-Impact System – An information system in which at least one security objective (i.e., 

confidentiality, integrity, or availability) is assigned a FIPS 199 

potential impact value of high.

SOURCE: SP 800-37; SP 800-53; SP 800-60; FIPS 200

An information system in which at least one security objective (i.e., 

confidentiality, integrity, or availability) is assigned a potential 

impact value of high.

SOURCE: CNSSI-4009

Honeypot – A system (e.g., a Web server) or system resource (e.g., a file on a 

server) that is designed to be attractive to potential crackers and 

intruders and has no authorized users other than its administrators.

SOURCE: CNSSI-4009

Hot Site – A fully operational offsite data processing facility equipped with 

hardware and software, to be used in the event of an information 

system disruption.

SOURCE: SP 800-34

Backup site that includes phone systems with the phone lines already 

connected. Networks will also be in place, with any necessary routers 

and switches plugged in and turned on. Desks will have desktop PCs 

installed and waiting, and server areas will be replete with the 

necessary hardware to support business-critical functions. Within a 

few hours, a hot site can become a fully functioning element of an 

organization.

SOURCE: CNSSI-4009

Hot Wash – A debrief conducted immediately after an exercise or test with the 

staff and participants.

SOURCE: SP 800-84
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Hybrid Security Control – A security control that is implemented in an information system in 

part as a common control and in part as a system-specific control.

See also Common Control and System-Specific Security Control.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; CNSSI-4009 

IA Architecture – A description of the structure and behavior for an enterprise’s 

security processes, information security systems, personnel and 

organizational sub-units, showing their alignment with the 

enterprise’s mission and strategic plans.

SOURCE: CNSSI-4009

IA Infrastructure – The underlying security framework that lies beyond an enterprise’s 

defined boundary, but supports its IA and IA-enabled products, its 

security posture and its risk management plan. 

SOURCE: CNSSI-4009

IA Product – Product whose primary purpose is to provide security services (e.g., 

confidentiality, authentication, integrity, access control, nonrepudiation of data); correct known vulnerabilities; and/or provide 

layered defense against various categories of non-authorized or 

malicious penetrations of information systems or networks.

SOURCE: CNSSI-4009

IA-Enabled Information Technology 

Product –

Product or technology whose primary role is not security, but which 

provides security services as an associated feature of its intended 

operating capabilities. Examples include such products as securityenabled Web browsers, screening routers, trusted operating systems, 

and security-enabled messaging systems.

SOURCE: CNSSI-4009

IA-Enabled Product – Product whose primary role is not security, but provides security 

services as an associated feature of its intended operating 

capabilities.

 

Note: Examples include such products as security-enabled Web 

browsers, screening routers, trusted operating systems, and security 

enabling messaging systems.

SOURCE: CNSSI-4009

Identification – The process of verifying the identity of a user, process, or device, 

usually as a prerequisite for granting access to resources in an IT 

system.

SOURCE: SP 800-47
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Identification – The process of discovering the true identity (i.e., origin, initial 

history) of a person or item from the entire collection of similar 

persons or items.

SOURCE: FIPS 201

An act or process that presents an identifier to a system so that the 

system can recognize a system entity (e.g., user, process, or device) 

and distinguish that entity from all others.

SOURCE: CNSSI-4009

Identifier – Unique data used to represent a person’s identity and associated 

attributes. A name or a card number are examples of identifiers.

SOURCE: FIPS 201

A data object - often, a printable, non-blank character string - that 

definitively represents a specific identity of a system entity, 

distinguishing that identity from all others.

SOURCE: CNSSI-4009

Identity – A set of attributes that uniquely describe a person within a given 

context. 

SOURCE: SP 800-63

Identity – The set of physical and behavioral characteristics by which an 

individual is uniquely recognizable.

SOURCE: FIPS 201

The set of attribute values (i.e., characteristics) by which an entity is 

recognizable and that, within the scope of an identity manager’s 

responsibility, is sufficient to distinguish that entity from any other 

entity.

SOURCE: CNSSI-4009

Identity-Based Access Control – Access control based on the identity of the user (typically relayed as 

a characteristic of the process acting on behalf of that user) where 

access authorizations to specific objects are assigned based on user 

identity.

SOURCE: SP 800-53; CNSSI-4009

Identity-Based Security Policy – A security policy based on the identities and/or attributes of the 

object (system resource) being accessed and of the subject (user, 

group of users, process, or device) requesting access.

SOURCE: SP 800-33
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Identity Binding – Binding of the vetted claimed identity to the individual (through 

biometrics) according to the issuing authority.

SOURCE: FIPS 201

Identity Proofing – The process by which a Credentials Service Provider (CSP) and a 

Registration Authority (RA) collect and verify information about a 

person for the purpose of issuing credentials to that person. SOURCE: 

SP 800-63

Identity Proofing – The process of providing sufficient information (e.g., identity history, 

credentials, documents) to a Personal Identity Verification Registrar 

when attempting to establish an identity.

SOURCE: FIPS 201

Identity Registration – The process of making a person’s identity known to the Personal 

Identity Verification (PIV) system, associating a unique identifier 

with that identity, and collecting and recording the person’s relevant 

attributes into the system.

SOURCE: FIPS 201; CNSSI-4009

Identity Token – Smart card, metal key, or other physical object used to authenticate 

identity.

SOURCE: CNSSI-4009

Identity Validation – Tests enabling an information system to authenticate users or 

resources.

SOURCE: CNSSI-4009

Identity Verification – The process of confirming or denying that a claimed identity is 

correct by comparing the credentials (something you know, 

something you have, something you are) of a person requesting 

access with those previously proven and stored in the PIV Card of 

system and associated with the identity being claimed.

SOURCE: FIPS 201

Identity Verification – The process of confirming or denying that a claimed identity is 

correct by comparing the credentials (something you know, 

something you have, something you are) of a person requesting 

access with those previously proven and stored in the PIV Card or 

system and associated with the identity being claimed.

SOURCE: SP 800-79
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Image – An exact bit-stream copy of all electronic data on a device, 

performed in a manner that ensures that the information is not 

altered.

SOURCE: SP 800-72

Imitative Communications 

Deception –

Introduction of deceptive messages or signals into an adversary's 

telecommunications signals. See also Communications Deception 

and Manipulative Communications Deception.

SOURCE: CNSSI-4009

Impact – The magnitude of harm that can be expected to result from the 

consequences of unauthorized disclosure of information, 

unauthorized modification of information, unauthorized destruction 

of information, or loss of information or information system 

availability.

SOURCE: SP 800-60

Impact Level – The magnitude of harm that can be expected to result from the 

consequences of unauthorized disclosure of information, 

unauthorized modification of information, unauthorized destruction 

of information, or loss of information or information system 

availability.

SOURCE: CNSSI-4009

High, Moderate, or Low security categories of an information system 

established in FIPS 199 which classify the intensity of a potential 

impact that may occur if the information system is jeopardized.

SOURCE: SP 800-34

Impact Value – The assessed potential impact resulting from a compromise of the 

confidentiality, integrity, or availability of an information type, 

expressed as a value of low, moderate, or high. 

SOURCE: SP 800-30

Implant – Electronic device or electronic equipment modification designed to 

gain unauthorized interception of information-bearing emanations.

SOURCE: CNSSI-4009

Inadvertent Disclosure – Type of incident involving accidental exposure of information to an 

individual not authorized access.

SOURCE: CNSSI-4009

Incident – A violation or imminent threat of violation of computer security 

policies, acceptable use policies, or standard security practices.

SOURCE: SP 800-61
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Incident – An occurrence that actually or potentially jeopardizes the 

confidentiality, integrity, or availability of an information system or 

the information the system processes, stores, or transmits or that 

constitutes a violation or imminent threat of violation of security 

policies, security procedures, or acceptable use policies.

SOURCE: FIPS 200; SP 800-53

An assessed occurrence that actually or potentially jeopardizes the 

confidentiality, integrity, or availability of an information system; or 

the information the system processes, stores, or transmits; or that 

constitutes a violation or imminent threat of violation of security 

policies, security procedures, or acceptable use policies. 

SOURCE: CNSSI-4009

Incident Handling – The mitigation of violations of security policies and recommended 

practices.

SOURCE: SP 800-61

Incident Response Plan – The documentation of a predetermined set of instructions or 

procedures to detect, respond to, and limit consequences of a 

malicious cyber attacks against an organization’s information

system(s).

SOURCE: SP 800-34

The documentation of a predetermined set of instructions or 

procedures to detect, respond to, and limit consequences of an 

incident against an organization’s IT system(s).

SOURCE: CNSSI-4009

Incomplete Parameter Checking – System flaw that exists when the operating system does not check all 

parameters fully for accuracy and consistency, thus making the 

system vulnerable to penetration.

SOURCE: CNSSI-4009

Inculpatory Evidence – Evidence that tends to increase the likelihood of fault or guilt.

SOURCE: SP 800-72

Independent Validation Authority –

(IVA)

Entity that reviews the soundness of independent tests and system 

compliance with all stated security controls and risk mitigation 

actions. IVAs will be designated by the Authorizing Official as 

needed.

SOURCE: CNSSI-4009
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Independent Verification & 

Validation (IV&V) –

A comprehensive review, analysis, and testing (software and/or 

hardware) performed by an objective third party to confirm (i.e., 

verify) that the requirements are correctly defined, and to confirm 

(i.e., validate) that the system correctly implements the required 

functionality and security requirements.

SOURCE: CNSSI-4009

Indicator – Recognized action, specific, generalized, or theoretical, that an 

adversary might be expected to take in preparation for an attack.

SOURCE: CNSSI-4009

A sign that an incident may have occurred or may be currently 

occurring.

SOURCE: SP 800-61

Individual – A citizen of the United States or an alien lawfully admitted for 

permanent residence. Agencies may, consistent with individual 

practice, choose to extend the protections of the Privacy Act and EGovernment Act to businesses, sole proprietors, aliens, etc.

SOURCE: SP 800-60

Individual Accountability – Ability to associate positively the identity of a user with the time, 

method, and degree of access to an information system.

SOURCE: CNSSI-4009

Individuals – An assessment object that includes people applying specifications, 

mechanisms, or activities.

SOURCE: SP 800-53A

Industrial Control System – An information system used to control industrial processes such as 

manufacturing, product handling, production, and distribution. 

Industrial control systems include supervisory control and data 

acquisition systems (SCADA) used to control geographically 

dispersed assets, as well as distributed control systems (DCS) and 

smaller control systems using programmable logic controllers to 

control localized processes.

SOURCE: SP 800-53; SP 800-53A; SP 800-39; SP 800-30

Informal Security Policy – Natural language description, possibly supplemented by 

mathematical arguments, demonstrating the correspondence of the 

functional specification to the high-level design.

SOURCE: CNSSI-4009

Information – An instance of an information type.

SOURCE: FIPS 200; FIPS 199; SP 800-60; SP 800-53; SP 800-37
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Any communication or representation of knowledge such as facts, 

data, or opinions in any medium or form, including textual, 

numerical, graphic, cartographic, narrative, or audiovisual.

SOURCE: CNSSI-4009

Information Assurance (IA) – Measures that protect and defend information and information 

systems by ensuring their availability, integrity, authentication, 

confidentiality, and non-repudiation. These measures include 

providing for restoration of information systems by incorporating 

protection, detection, and reaction capabilities.

SOURCE: SP 800-59; CNSSI-4009

Information Assurance Component –

(IAC)

An application (hardware and/or software) that provides one or more 

Information Assurance capabilities in support of the overall security 

and operational objectives of a system.

SOURCE: CNSSI-4009

Information Assurance Manager –

(IAM)

See Information Systems Security Manager.

SOURCE: CNSSI-4009

Information Assurance Officer –

(IAO)

See Information Systems Security Officer.

SOURCE: CNSSI-4009

Information Assurance (IA)

Professional –

Individual who works IA issues and has real-world experience plus 

appropriate IA training and education commensurate with their level 

of IA responsibility.

SOURCE: CNSSI-4009

Information Assurance Vulnerability 

Alert (IAVA) –

Notification that is generated when an Information Assurance 

vulnerability may result in an immediate and potentially severe threat 

to DoD systems and information; this alert requires corrective action 

because of the severity of the vulnerability risk. 

SOURCE: CNSSI-4009

Information Domain – A three-part concept for information sharing, independent of, and 

across information systems and security domains that 1) identifies 

information sharing participants as individual members, 2) contains 

shared information objects, and 3) provides a security policy that 

identifies the roles and privileges of the members and the protections 

required for the information objects.

SOURCE: CNSSI-4009

Information Environment – Aggregate of individuals, organizations, and/or systems that collect, 

process, or disseminate information, also included is the information 

itself.

SOURCE: CNSSI-4009
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Information Flow Control – Procedure to ensure that information transfers within an information 

system are not made in violation of the security policy.

SOURCE: CNSSI-4009

Information Management – The planning, budgeting, manipulating, and controlling of 

information throughout its life cycle. 

SOURCE: CNSSI-4009

Information Operations (IO) – The integrated employment of the core capabilities of electronic 

warfare, computer network operations, psychological operations, 

military deception, and operations security, in concert with specified 

supporting and related capabilities, to influence, disrupt, corrupt, or 

usurp adversarial human and automated decision-making process, 

information, and information systems while protecting our own.

SOURCE: CNSSI-4009

Information Owner – Official with statutory or operational authority for specified 

information and responsibility for establishing the controls for its 

generation, collection, processing, dissemination, and disposal. See 

Information Steward.

SOURCE: FIPS 200; SP 800-37; SP 800-53; SP 800-60; SP 800-18

Official with statutory or operational authority for specified 

information and responsibility for establishing the controls for its 

generation, classification, collection, processing, dissemination, and 

disposal.

SOURCE: CNSSI-4009

Information Resources – Information and related resources, such as personnel, equipment, 

funds, and information technology.

SOURCE: FIPS 200; FIPS 199; SP 800-53; SP 800-18; SP 800-60; 

44 U.S.C., Sec. 3502; CNSSI-4009

Information Resources 

Management (IRM) –

The planning, budgeting, organizing, directing, training, controlling, 

and management activities associated with the burden, collection, 

creation, use, and dissemination of information by agencies.

SOURCE: CNSSI-4009

Information Security – The protection of information and information systems from 

unauthorized access, use, disclosure, disruption, modification, or 

destruction in order to provide confidentiality, integrity, and 

availability.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; SP 800-18; SP 800-

60; CNSSI-4009; FIPS 200; FIPS 199; 44 U.S.C., Sec. 3542
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Information Security – Protecting information and information systems from unauthorized 

access, use, disclosure, disruption, modification, or destruction in 

order to provide—

1) integrity, which means guarding against improper information 

modification or destruction, and includes ensuring information 

nonrepudiation and authenticity; 

2) confidentiality, which means preserving authorized restrictions on 

access and disclosure, including means for protecting personal 

privacy and proprietary information; and 

3) availability, which means ensuring timely and reliable access to 

and use of information.

SOURCE: SP 800-66; 44 U.S.C., Sec 3541

Information Security Architect – Individual, group, or organization responsible for ensuring that

the information security requirements necessary to protect the

organization’s core missions and business processes are

adequately addressed in all aspects of enterprise architecture

including reference models, segment and solution architectures,

and the resulting information systems supporting those missions

and business processes.

SOURCE: SP 800-37

Information Security Architecture – An embedded, integral part of the enterprise architecture that 

describes the structure and behavior for an enterprise’s security 

processes, information security systems, personnel and organizational 

sub-units, showing their alignment with the enterprise’s mission and 

strategic plans.

SOURCE: SP 800-39

Information Security Continuous 

Monitoring (ISCM) –

Maintaining ongoing awareness of information security, 

vulnerabilities, and threats to support organizational risk management 

decisions. 

[Note: The terms “continuous” and “ongoing” in this context mean 

that security controls and organizational risks are assessed and 

analyzed at a frequency sufficient to support risk-based security 

decisions to adequately protect organization information.] 

SOURCE: SP 800-137

Information Security Continuous 

Monitoring (ISCM) Process –

A process to: 

• Define an ISCM strategy; 

• Establish an ISCM program; 

• Implement an ISCM program; 

• Analyze data and Report findings; 

• Respond to findings; and 

• Review and Update the ISCM strategy and program. 

SOURCE: SP 800-137
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Information Security Continuous 

Monitoring (ISCM) Program –

A program established to collect information in accordance with preestablished metrics, utilizing information readily available in part 

through implemented security controls. 

SOURCE: SP 800-137

Information Security Policy – Aggregate of directives, regulations, rules, and practices that 

prescribes how an organization manages, protects, and distributes 

information.

SOURCE: SP 800-53; SP 800-37; SP 800-18; CNSSI-4009

Information Security Program Plan – Formal document that provides an overview of the security

requirements for an organization-wide information security program 

and describes the program management controls and common 

controls in place or planned for meeting those requirements.

SOURCE: SP 800-37; SP 800-53; SP 800-53A

Information Security Risk – The risk to organizational operations (including mission, functions, 

image, reputation), organizational assets, individuals, other 

organizations, and the Nation due to the potential for unauthorized 

access, use, disclosure, disruption, modification, or destruction of 

information and/or information systems. See Risk. 

SOURCE: SP 800-30

Information Sharing – The requirements for information sharing by an IT system with one 

or more other IT systems or applications, for information sharing to 

support multiple internal or external organizations, missions, or 

public programs.

SOURCE: SP 800-16

Information Sharing Environment – 1. An approach that facilitates the sharing of terrorism and 

homeland security information; or

2. ISE in its broader application enables those in a trusted partnership 

to share, discover, and access controlled information.

SOURCE: CNSSI-4009

Information Steward – An agency official with statutory or operational authority for 

specified information and responsibility for establishing the 

controls for its generation, collection, processing, dissemination, 

and disposal.

SOURCE: CNSSI-4009
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Individual or group that helps to ensure the careful and

responsible management of federal information belonging to the

Nation as a whole, regardless of the entity or source that may

have originated, created, or compiled the information.

Information stewards provide maximum access to federal

information to elements of the federal government and its

customers, balanced by the obligation to protect the information

in accordance with the provisions of FISMA and any associated

security-related federal policies, directives, regulations, standards,

and guidance.

SOURCE: SP 800-37

Information System – A discrete set of information resources organized for the collection, 

processing, maintenance, use, sharing, dissemination, or disposition 

of information.

SOURCE: FIPS 200; FIPS 199; SP 800-53A; SP 800-37; SP 800-60; 

SP 800-18; 44 U.S.C., Sec. 3502; OMB Circular A-130, 

App. III

A discrete set of information resources organized for the collection, 

processing, maintenance, use, sharing, dissemination, or disposition 

of information. 

[Note: Information systems also include specialized systems such as 

industrial/process controls systems, telephone switching and private 

branch exchange (PBX) systems, and environmental control 

systems.]

SOURCE: SP 800-53; CNSSI-4009

Information System Boundary – See Authorization Boundary.

Information System Contingency 

Plan (ISCP) –

Management policy and procedures designed to maintain or restore 

business operations, including computer operations, possibly at an 

alternate location, in the event of emergencies, system failures, or 

disasters.

SOURCE: SP 800-34

Information System Life Cycle – The phases through which an information system passes, typically 

characterized as initiation, development, operation, and termination 

(i.e., sanitization, disposal and/or destruction). 

SOURCE: CNSSI-4009

Information System Owner

(or Program Manager) –

Official responsible for the overall procurement, development, 

integration, modification, or operation and maintenance of an 

information system.

SOURCE: SP 800-53; SP 800-53A; SP 800-18; SP 800-60
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Information System Owner – Official responsible for the overall procurement, development, 

integration, modification, or operation and maintenance of an 

information system.

SOURCE: FIPS 200

Information System Resilience – The ability of an information system to continue to operate while 

under attack, even if in a degraded or debilitated state, and to rapidly 

recover operational capabilities for essential functions after a 

successful attack. 

SOURCE: SP 800-30

The ability of an information system to continue to: (i) operate under 

adverse conditions or stress, even if in a degraded or debilitated state, 

while maintaining essential operational capabilities; and (ii) recover 

to an effective operational posture in a time frame consistent with

mission needs.

SOURCE: SP 800-39

Information System Security 

Officer (ISSO) –

Individual with assigned responsibility for maintaining the 

appropriate operational security posture for an information system or 

program.

SOURCE: SP 800-37; SP 800-53

Individual assigned responsibility by the senior agency information 

security officer, authorizing official, management official, or 

information system owner for maintaining the appropriate operational 

security posture for an information system or program.

SOURCE: SP 800-53A; SP 800-60

Individual assigned responsibility by the senior agency information 

security officer, authorizing official, management official, or 

information system owner for ensuring that the appropriate 

operational security posture is maintained for an information system 

or program.

SOURCE: SP 800-18

Information System-Related 

Security Risks –

Information system-related security risks are those risks that arise

through the loss of confidentiality, integrity, or availability of

information or information systems and consider impacts to the

organization (including assets, mission, functions, image, or

reputation), individuals, other organizations, and the Nation.

See Risk.

SOURCE: SP 800-37; SP 800-53A
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Information Systems Security –

(INFOSEC)

Protection of information systems against unauthorized access to or 

modification of information, whether in storage, processing, or 

transit, and against the denial of service to authorized users, including 

those measures necessary to detect, document, and counter such 

threats.

SOURCE: CNSSI-4009

Information Systems Security 

Engineer (ISSE) –

Individual assigned responsibility for conducting information system 

security engineering activities.

SOURCE: SP 800-37; CNSSI-4009

Information Systems Security 

Engineering (ISSE) –

Process of capturing and refining information protection 

requirements to ensure their integration into information systems 

acquisition and information systems development through purposeful 

security design or configuration.

SOURCE: CNSSI-4009

Process that captures and refines information security requirements 

and ensures their integration into information technology component 

products and information systems through purposeful security design 

or configuration.

SOURCE: SP 800-37

Information Systems Security 

Equipment Modification –

Modification of any fielded hardware, firmware, software, or portion 

thereof, under NSA configuration control. There are three classes of 

modifications: mandatory (to include human safety); optional/special 

mission modifications; and repair actions. These classes apply to 

elements, subassemblies, equipment, systems, and software packages 

performing functions such as key generation, key distribution, 

message encryption, decryption, authentication, or those mechanisms 

necessary to satisfy security policy, labeling, identification, or 

accountability.

SOURCE: CNSSI-4009

Information Systems Security 

Manager (ISSM) –

Individual responsible for the information assurance of a program, 

organization, system, or enclave.

SOURCE: CNSSI-4009

Information Systems Security 

Officer (ISSO) –

Individual assigned responsibility for maintaining the appropriate 

operational security posture for an information system or program.

SOURCE: CNSSI-4009
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Individual assigned responsibility by the senior agency information 

security officer, authorizing official, management official, or 

information system owner for maintaining the appropriate operational 

security posture for an information system or program.

SOURCE: SP 800-39

Information Systems Security 

Product –

Item (chip, module, assembly, or equipment), technique, or service 

that performs or relates to information systems security.

SOURCE: CNSSI-4009

Information Technology – Any equipment or interconnected system or subsystem of equipment 

that is used in the automatic acquisition, storage, manipulation, 

management, movement, control, display, switching, interchange, 

transmission, or reception of data or information by the executive 

agency. For purposes of the preceding sentence, equipment is used by 

an executive agency if the equipment is used by the executive agency 

directly or is used by a contractor under a contract with the executive 

agency which—

1) requires the use of such equipment; or

2) requires the use, to a significant extent, of such equipment in the 

performance of a service or the furnishing of a product. 

The term information technology includes computers, ancillary 

equipment, software, firmware and similar procedures, services 

(including support services), and related resources.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-18; SP 800-

60; FIPS 200; FIPS 199; CNSSI-4009; 40 U.S.C., Sec. 11101 and 

Sec 1401

Information Type – A specific category of information (e.g., privacy, medical, 

proprietary, financial, investigative, contractor sensitive, security 

management), defined by an organization or in some instances, by a 

specific law, Executive Order, directive, policy, or regulation.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-18; SP 800-

60; FIPS 200; FIPS 199; CNSSI-4009

Information Value – A qualitative measure of the importance of the information based 

upon factors such as: level of robustness of the Information 

Assurance controls allocated to the protection of information based 

upon: mission criticality, the sensitivity (e.g., classification and 

compartmentalization) of the information, releasability to other 

countries, perishability/longevity of the information (e.g., short life 

data versus long life intelligence source data), and potential impact of

loss of confidentiality and integrity and/or availability of the 

information. 

SOURCE: CNSSI-4009

Inheritance – See Security Control Inheritance.
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Initialization Vector (IV) – A vector used in defining the starting point of an encryption process 

within a cryptographic algorithm.

SOURCE: FIPS 140-2

Initialize – Setting the state of a cryptographic logic prior to key generation, 

encryption, or other operating mode.

SOURCE: CNSSI-4009

Initiator – The entity that initiates an authentication exchange.

SOURCE: FIPS 196

Inside Threat – An entity with authorized access that has the potential to harm an 

information system through destruction, disclosure, modification of 

data, and/or denial of service.

SOURCE: SP 800-32

Inside(r) Threat – An entity with authorized access (i.e., within the security domain) 

that has the potential to harm an information system or enterprise 

through destruction, disclosure, modification of data, and/or denial of 

service.

SOURCE: CNSSI-4009

Inspectable Space – Three dimensional space surrounding equipment that processes

classified and/or sensitive information within which TEMPEST 

exploitation is not considered practical or where legal authority to 

identify and remove a potential TEMPEST exploitation exists. 

Synonymous with zone of control.

SOURCE: CNSSI-4009

Integrity – Guarding against improper information modification or destruction, 

and includes ensuring information non-repudiation and authenticity.

SOURCE: SP 800-53; SP 800-53A; SP 800-18; SP 800-27; SP 800-

37; SP 800-60; FIPS 200; FIPS 199; 44 U.S.C., Sec. 3542

Integrity – The property that sensitive data has not been modified or deleted in 

an unauthorized and undetected manner.

SOURCE: FIPS 140-2

The property whereby an entity has not been modified in an 

unauthorized manner.

SOURCE: CNSSI-4009

Integrity Check Value – Checksum capable of detecting modification of an information 

system.

SOURCE: CNSSI-4009
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Intellectual Property – Useful artistic, technical, and/or industrial information, knowledge or 

ideas that convey ownership and control of tangible or virtual usage 

and/or representation.

SOURCE: SP 800-32

Creations of the mind such as musical, literary, and artistic works; 

inventions; and symbols, names, images, and designs used in 

commerce, including copyrights, trademarks, patents, and related 

rights. Under intellectual property law, the holder of one of these 

abstract “properties” has certain exclusive rights to the creative work, 

commercial symbol, or invention by which it is covered.

SOURCE: CNSSI-4009

Interconnection Security 

Agreement (ISA) –

An agreement established between the organizations that own and 

operate connected IT systems to document the technical requirements 

of the interconnection. The ISA also supports a Memorandum of 

Understanding or Agreement (MOU/A) between the organizations.

SOURCE: SP 800-47

A document that regulates security-relevant aspects of an intended 

connection between an agency and an external system. It regulates 

the security interface between any two systems operating under two 

different distinct authorities. It includes a variety of descriptive, 

technical, procedural, and planning information. It is usually 

preceded by a formal MOA/MOU that defines high-level roles and 

responsibilities in management of a cross-domain connection.

SOURCE: CNSSI-4009

Interface – Common boundary between independent systems or modules where 

interactions take place.

SOURCE: CNSSI-4009

Interface Control Document – Technical document describing interface controls and identifying the 

authorities and responsibilities for ensuring the operation of such 

controls. This document is baselined during the preliminary design 

review and is maintained throughout the information system life

cycle.

SOURCE: CNSSI-4009

Interim Approval to Operate –

(IATO)

Temporary authorization granted by a DAA for an information 

system to process information based on preliminary results of a 

security evaluation of the system. (To be replaced by ATO and 

POA&M)

SOURCE: CNSSI-4009
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Interim Approval to Test (IATT) – Temporary authorization to test an information system in a specified 

operational information environment within the time frame and under 

the conditions or constraints enumerated in the written authorization.

SOURCE: CNSSI-4009

Intermediate Certification 

Authority (CA) –

A Certification Authority that is subordinate to another CA, and has a 

CA subordinate to itself.

SOURCE: SP 800-32

Internal Network – A network where: (i) the establishment, maintenance, and 

provisioning of security controls are under the direct control of 

organizational employees or contractors; or (ii) cryptographic 

encapsulation or similar security technology provides the same effect. 

An internal network is typically organization-owned, yet may be 

organization-controlled while not being organization-owned.

SOURCE: SP 800-53

A network where 1) the establishment, maintenance, and 

provisioning of security controls are under the direct control of 

organizational employees or contractors; or 2) cryptographic 

encapsulation or similar security technology implemented between 

organization-controlled endpoints provides the same effect (at least 

with regard to confidentiality and integrity). An internal network is 

typically organization-owned, yet may be organization-controlled 

while not being organization-owned.

SOURCE: CNSSI-4009

Internal Security Controls – Hardware, firmware, or software features within an information 

system that restrict access to resources only to authorized subjects.

SOURCE: CNSSI-4009

Internal Security Testing – Security testing conducted from inside the organization’s security 

perimeter.

SOURCE: SP 800-115

Internet – The Internet is the single, interconnected, worldwide system of 

commercial, governmental, educational, and other computer 

networks that share (a) the protocol suite specified by the Internet 

Architecture Board (IAB), and (b) the name and address spaces 

managed by the Internet Corporation for Assigned Names and 

Numbers (ICANN).

SOURCE: CNSSI-4009
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Internet Protocol (IP) – Standard protocol for transmission of data from source to destinations 

in packet-switched communications networks and interconnected 

systems of such networks.

SOURCE: CNSSI-4009

Interoperability – For the purposes of this standard, interoperability allows any 

government facility or information system, regardless of the PIV 

Issuer, to verify a cardholder’s identity using the credentials on the 

PIV Card.

SOURCE: FIPS 201

Interview – A type of assessment method that is characterized by the process of 

conducting discussions with individuals or groups within an 

organization to facilitate understanding, achieve clarification, or lead 

to the location of evidence, the results of which are used to support 

the determination of security control effectiveness over time.

SOURCE: SP 800-53A

Intranet – A private network that is employed within the confines of a given 

enterprise (e.g., internal to a business or agency).

SOURCE: CNSSI-4009

Intrusion – Unauthorized act of bypassing the security mechanisms of a system.

SOURCE: CNSSI-4009

Intrusion Detection Systems (IDS) – Hardware or software product that gathers and analyzes information 

from various areas within a computer or a network to identify 

possible security breaches, which include both intrusions (attacks 

from outside the organizations) and misuse (attacks from within the 

organizations.)

SOURCE: CNSSI-4009

Intrusion Detection Systems (IDS) –

(Host-Based)

IDSs which operate on information collected from within an 

individual computer system. This vantage point allows host-based 

IDSs to determine exactly which processes and user accounts are 

involved in a particular attack on the Operating System. 

Furthermore, unlike network-based IDSs, host-based IDSs can more 

readily “see” the intended outcome of an attempted attack, because 

they can directly access and monitor the data files and system 

processes usually targeted by attacks.

SOURCE: SP 800-36; CNSSI-4009
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Intrusion Detection Systems (IDS) –

(Network-Based)

IDSs which detect attacks by capturing and analyzing network 

packets. Listening on a network segment or switch, one networkbased IDS can monitor the network traffic affecting multiple hosts 

that are connected to the network segment. 

SOURCE: SP 800-36; CNSSI-4009

Intrusion Detection and Prevention 

System (IDPS) –

Software that automates the process of monitoring the events 

occurring in a computer system or network and analyzing them for 

signs of possible incidents and attempting to stop detected possible 

incidents. 

SOURCE: SP 800-61

Intrusion Prevention System(s) 

(IPS) –

System(s) which can detect an intrusive activity and can also attempt 

to stop the activity, ideally before it reaches its targets.

SOURCE: SP 800-36; CNSSI-4009

Inverse Cipher – Series of transformations that converts ciphertext to plaintext using 

the Cipher Key.

SOURCE: FIPS 197

IP Security (IPsec) – Suite of protocols for securing Internet Protocol (IP) communications 

at the network layer, layer 3 of the OSI model by authenticating 

and/or encrypting each IP packet in a data stream. IPsec also 

includes protocols for cryptographic key establishment.

SOURCE: CNSSI-4009

IT-Related Risk – The net mission/business impact considering 

1) the likelihood that a particular threat source will exploit, or 

trigger, a particular information system vulnerability, and 

2) the resulting impact if this should occur. IT-related risks arise 

from legal liability or mission/business loss due to, but not limited 

to:

 Unauthorized (malicious, non-malicious, or accidental) 

disclosure, modification, or destruction of information;

 Non-malicious errors and omissions;

 IT disruptions due to natural or man-made disasters; or

 Failure to exercise due care and diligence in the 

implementation and operation of the IT.

SOURCE: SP 800-27

IT Security Architecture – A description of security principles and an overall approach for 

complying with the principles that drive the system design; i.e., 

guidelines on the placement and implementation of specific security 

services within various distributed computing environments.

SOURCE: SP 800-27
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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IT Security Awareness – The purpose of awareness presentations is simply to focus attention 

on security. Awareness presentations are intended to allow 

individuals to recognize IT security concerns and respond 

accordingly.

SOURCE: SP 800-50

IT Security Awareness and Training 

Program –

Explains proper rules of behavior for the use of agency IT systems 

and information. The program communicates IT security policies and 

procedures that need to be followed.

SOURCE: SP 800-50

Explains proper rules of behavior for the use of agency information 

systems and information. The program communicates IT security 

policies and procedures that need to be followed (i.e., NSTISSD 501, 

NIST SP 800-50). 

SOURCE: CNSSI-4009

IT Security Education – IT Security Education seeks to integrate all of the security skills and 

competencies of the various functional specialties into a common 

body of knowledge, adds a multidisciplinary study of concepts, 

issues, and principles (technological and social), and strives to 

produce IT security specialists and professionals capable of vision 

and proactive response.

SOURCE: SP 800-50

IT Security Investment – An IT application or system that is solely devoted to security. For 

instance, intrusion detection systems (IDS) and public key 

infrastructure (PKI) are examples of IT security investments.

SOURCE: SP 800-65

IT Security Metrics – Metrics based on IT security performance goals and objectives.

SOURCE: SP 800-55
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IT Security Policy – The “documentation of IT security decisions” in an organization. 

NIST SP 800-12 categorizes IT Security Policy into three basic 

types:

1) Program Policy—high-level policy used to create an 

organization’s IT security program, define its scope within the 

organization, assign implementation responsibilities, establish 

strategic direction, and assign resources for implementation. 

2) Issue-Specific Policies—address specific issues of concern to the 

organization, such as contingency planning, the use of a particular 

methodology for systems risk management, and implementation 

of new regulations or law. These policies are likely to require 

more frequent revision as changes in technology and related 

factors take place. 

3) System-Specific Policies—address individual systems, such as 

establishing an access control list or in training users as to what 

system actions are permitted. These policies may vary from 

system to system within the same organization. In addition, policy 

may refer to entirely different matters, such as the specific 

managerial decisions setting an organization’s electronic mail 

(email) policy or fax security policy.

SOURCE: SP 800-35

IT Security Training – IT Security Training strives to produce relevant and needed security 

skills and competencies by practitioners of functional specialties 

other than IT security (e.g., management, systems design and 

development, acquisition, auditing). The most significant difference 

between training and awareness is that training seeks to teach skills, 

which allow a person to perform a specific function, while awareness 

seeks to focus an individual’s attention on an issue or set of issues. 

The skills acquired during training are built upon the awareness 

foundation, in particular, upon the security basics and literacy 

material.

SOURCE: SP 800-50

Jamming – An attack in which a device is used to emit electromagnetic energy 

on a wireless network’s frequency to make it unusable.

SOURCE: SP 800-48

An attack that attempts to interfere with the reception of broadcast 

communications.

SOURCE: CNSSI-4009

Joint Authorization – Security authorization involving multiple authorizing officials.

SOURCE: SP 800-37
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Kerberos – A widely used authentication protocol developed at the 

Massachusetts Institute of Technology (MIT). In “classic” Kerberos, 

users share a secret password with a Key Distribution Center (KDC). 

The user, Alice, who wishes to communicate with another user, Bob, 

authenticates to the KDC and is furnished a “ticket” by the KDC to 

use to authenticate with Bob. When Kerberos authentication is based 

on passwords, the protocol is known to be vulnerable to off-line 

dictionary attacks by eavesdroppers who capture the initial user-toKDC exchange. Longer password length and complexity provide 

some mitigation to this vulnerability, although sufficiently long 

passwords tend to be cumbersome for users.

SOURCE: SP 800-63

A means of verifying the identities of principals on an open network. 

It accomplishes this without relying on the authentication, 

trustworthiness, or physical security of hosts while assuming all 

packets can be read, modified and inserted at will. It uses a trust 

broker model and symmetric cryptography to provide authentication 

and authorization of users and systems on the network.

SOURCE: SP 800-95

Key – A value used to control cryptographic operations, such as decryption, 

encryption, signature generation, or signature verification.

SOURCE: SP 800-63

A numerical value used to control cryptographic operations, such as 

decryption, encryption, signature generation, or signature 

verification. 

SOURCE: CNSSI-4009

A parameter used in conjunction with a cryptographic algorithm that 

determines its operation. 

Examples applicable to this Standard include:

1. The computation of a digital signature from data, and

2. The verification of a digital signature.

SOURCE: FIPS 186

Key Bundle – The three cryptographic keys (Key1, Key2, Key3) that are used with 

a Triple Data Encryption Algorithm (TDEA) mode.

SOURCE: SP 800-67

Key Distribution Center (KDC) – COMSEC facility generating and distributing key in electronic form.

SOURCE: CNSSI-4009
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Key Escrow – A deposit of the private key of a subscriber and other pertinent 

information pursuant to an escrow agreement or similar contract 

binding upon the subscriber, the terms of which require one or more 

agents to hold the subscriber's private key for the benefit of the 

subscriber, an employer, or other party, upon provisions set forth in 

the agreement.

SOURCE: SP 800-32

Key Escrow – The processes of managing (e.g., generating, storing, transferring, 

auditing) the two components of a cryptographic key by two key 

component holders.

SOURCE: FIPS 185

1. The processes of managing (e.g., generating, storing, transferring, 

auditing) the two components of a cryptographic key by two key 

component holders. 

2. A key recovery technique for storing knowledge of a cryptographic 

key, or parts thereof, in the custody of one or more third parties 

called "escrow agents," so that the key can be recovered and used in 

specified circumstances.

SOURCE: CNSSI-4009

Key Escrow System – A system that entrusts the two components comprising a 

cryptographic key (e.g., a device unique key) to two key component 

holders (also called "escrow agents").

SOURCE: FIPS 185; CNSSI-4009

Key Establishment – The process by which cryptographic keys are securely established

among cryptographic modules using manual transport methods (e.g., 

key loaders), automated methods (e.g., key transport and/or key 

agreement protocols), or a combination of automated and manual 

methods (consists of key transport plus key agreement).

SOURCE: FIPS 140-2

The process by which cryptographic keys are securely established 

among cryptographic modules using key transport and/or key 

agreement procedures. See Key Distribution.

SOURCE: CNSSI-4009

Key Exchange – The process of exchanging public keys in order to establish secure 

communications.

SOURCE: SP 800-32

Process of exchanging public keys (and other information) in order to 

establish secure communications.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Key Expansion – Routine used to generate a series of Round Keys from the Cipher 

Key.

SOURCE: FIPS 197

Key Generation Material – Random numbers, pseudo-random numbers, and cryptographic 

parameters used in generating cryptographic keys.

SOURCE: SP 800-32; CNSSI-4009

Key List – Printed series of key settings for a specific cryptonet. Key lists may 

be produced in list, pad, or printed tape format.

SOURCE: CNSSI-4009

Key Loader – A self-contained unit that is capable of storing at least one plaintext 

or encrypted cryptographic key or key component that can be 

transferred, upon request, into a cryptographic module.

SOURCE: FIPS 140-2

A self-contained unit that is capable of storing at least one plaintext 

or encrypted cryptographic key or a component of a key that can be 

transferred, upon request, into a cryptographic module.

SOURCE: CNSSI-4009

Key Logger – A program designed to record which keys are pressed on a computer 

keyboard used to obtain passwords or encryption keys and thus 

bypass other security measures.

SOURCE: SP 800-82

Key Management – The activities involving the handling of cryptographic keys and other 

related security parameters (e.g., IVs and passwords) during the 

entire life cycle of the keys, including their generation, storage, 

establishment, entry and output, and zeroization.

SOURCE: FIPS 140-2; CNSSI-4009

Key Management Device – A unit that provides for secure electronic distribution of encryption 

keys to authorized users.

SOURCE: CNSSI-4009

Key Management Infrastructure –

(KMI)

All parts – computer hardware, firmware, software, and other 

equipment and its documentation; facilities that house the equipment 

and related functions; and companion standards, policies, procedures, 

and doctrine that form the system that manages and supports the 

ordering and delivery of cryptographic material and related 

information products and services to users.

SOURCE: CNSSI-4009
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Key Pair – Two mathematically related keys having the properties that (1) one 

key can be used to encrypt a message that can only be decrypted 

using the other key, and 2) even knowing one key, it is 

computationally infeasible to discover the other key.

SOURCE: SP 800-32

Key Pair – A public key and its corresponding private key; a key pair is used 

with a public key algorithm.

SOURCE: SP 800-21; CNSSI-4009

Key Production Key (KPK) – Key used to initialize a keystream generator for the production of 

other electronically generated key.

SOURCE: CNSSI-4009

Key Recovery – Mechanisms and processes that allow authorized parties to retrieve 

the cryptographic key used for data confidentiality.

SOURCE: CNSSI-4009

Key Stream – Sequence of symbols (or their electrical or mechanical equivalents) 

produced in a machine or auto-manual cryptosystem to combine with 

plain text to produce cipher text, control transmission security 

processes, or produce key.

SOURCE: CNSSI-4009

Key Tag – Identification information associated with certain types of electronic 

key.

SOURCE: CNSSI-4009

Key Tape – Punched or magnetic tape containing key. Printed key in tape form 

is referred to as a key list.

SOURCE: CNSSI-4009

Key Transport – The secure transport of cryptographic keys from one cryptographic 

module to another module.

SOURCE: FIPS 140-2; CNSSI-4009

Key Updating – Irreversible cryptographic process for modifying key.

SOURCE: CNSSI-4009

Key Wrap – A method of encrypting keying material (along with associated 

integrity information) that provides both confidentiality and integrity 

protection using a symmetric key algorithm.

SOURCE: SP 800-56A
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Key-Auto-Key (KAK) – Cryptographic logic using previous key to produce key.

SOURCE: CNSSI-4009

Key-Encryption-Key (KEK) – Key that encrypts or decrypts other key for transmission or storage.

SOURCE: CNSSI-4009

Keyed-hash based message 

authentication code (HMAC) –

A message authentication code that uses a cryptographic key in 

conjunction with a hash function.

SOURCE: FIPS 198; CNSSI-4009

Keying Material – Key, code, or authentication information in physical, electronic, or 

magnetic form.

SOURCE: CNSSI-4009

Keystroke Monitoring – The process used to view or record both the keystrokes entered by a 

computer user and the computer’s response during an interactive 

session. Keystroke monitoring is usually considered a special case of 

audit trails. 

SOURCE: SP 800-12; CNSSI-4009

KMI Operating Account (KOA) – A KMI business relationship that is established 1) to manage the set 

of user devices that are under the control of a specific KMI customer 

organization, and 2) to control the distribution of KMI products to 

those devices.

SOURCE: CNSSI-4009

KMI Protected Channel (KPC) – A KMI Communication Channel that provides 1) Information 

Integrity Service; 2) either Data Origin Authentication Service or 

Peer Entity Authentication Service, as is appropriate to the mode of 

communications; and 3) optionally, Information Confidentiality 

Service.

SOURCE: CNSSI-4009

KMI-Aware Device – A user device that has a user identity for which the registration has 

significance across the entire KMI (i.e., the identity’s registration 

data is maintained in a database at the PRSN level of the system, 

rather than only at an MGC) and for which a product can be 

generated and wrapped by a PSN for distribution to the specific 

device.

SOURCE: CNSSI-4009

KOA Agent – A user identity that is designated by a KOA manager to access PRSN 

product delivery enclaves for the purpose of retrieving wrapped 

products that have been ordered for user devices that are assigned to 

that KOA.

SOURCE: CNSSI-4009
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KOA Manager – The Management Role that is responsible for the operation of one or 

KOA’s (i.e., manages distribution of KMI products to the end 

cryptographic units, fill devices, and ADPs that are assigned to the 

manager’s KOA).

SOURCE: CNSSI-4009

KOA Registration Manager – The individual responsible for performing activities related to 

registering KOAs.

SOURCE: CNSSI-4009

Label – See Security Label.

Labeled Security Protections – Access control protection features of a system that use security labels 

to make access control decisions.

SOURCE: CNSSI-4009

Laboratory Attack – Use of sophisticated signal recovery equipment in a laboratory 

environment to recover information from data storage media.

SOURCE: SP 800-88; CNSSI-4009

Least Privilege – The security objective of granting users only those accesses they 

need to perform their official duties.

SOURCE: SP 800-12

The principle that a security architecture should be designed so that 

each entity is granted the minimum system resources and 

authorizations that the entity needs to perform its function.

SOURCE: CNSSI-4009

Least Trust – The principal that a security architecture should be designed in a way 

that minimizes 1) the number of components that require trust, and 2) 

the extent to which each component is trusted.

SOURCE: CNSSI-4009

Level of Concern – Rating assigned to an information system indicating the extent to 

which protection measures, techniques, and procedures must be 

applied. High, Medium, and Basic are identified levels of concern. 

A separate Level-of-Concern is assigned to each information system

for confidentiality, integrity, and availability.

SOURCE: CNSSI-4009
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Level of Protection – Extent to which protective measures, techniques, and procedures 

must be applied to information systems and networks based on risk, 

threat, vulnerability, system interconnectivity considerations, and 

information assurance needs. Levels of protection are: 1. Basic: 

information systems and networks requiring implementation of 

standard minimum security countermeasures. 2. Medium: 

information systems and networks requiring layering of additional 

safeguards above the standard minimum security countermeasures. 3. 

High: information systems and networks requiring the most stringent 

protection and rigorous security countermeasures.

SOURCE: CNSSI-4009

Likelihood of Occurrence – In Information Assurance risk analysis, a weighted factor based on a 

subjective analysis of the probability that a given threat is capable of 

exploiting a given vulnerability.

SOURCE: CNSSI-4009

Limited Maintenance – COMSEC maintenance restricted to fault isolation, removal, and 

replacement of plug-in assemblies. Soldering or unsoldering usually 

is prohibited in limited maintenance. See Full Maintenance.

SOURCE: CNSSI-4009

Line Conditioning – Elimination of unintentional signals or noise induced or conducted on 

a telecommunications or information system signal, power, control, 

indicator, or other external interface line.

SOURCE: CNSSI-4009

Line Conduction – Unintentional signals or noise induced or conducted on a 

telecommunications or information system signal, power, control, 

indicator, or other external interface line.

SOURCE: CNSSI-4009

Line of Business – The following OMB-defined process areas common to virtually

all federal agencies: Case Management, Financial Management,

Grants Management, Human Resources Management, Federal

Health Architecture, Information Systems Security, Budget

Formulation and Execution, Geospatial, and IT Infrastructure.

SOURCE: SP 800-53
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“Lines of business” or “areas of operation” describe the purpose of 

government in functional terms or describe the support functions that 

the government must conduct in order to effectively deliver services 

to citizens. Lines of business relating to the purpose of government 

and the mechanisms the government uses to achieve its purposes tend 

to be mission-based. Lines of business relating to support functions 

and resource management functions that are necessary to conduct 

government operations tend to be common to most agencies. The 

recommended information types provided in NIST SP 800-60 are 

established from the “business areas” and “lines of business” from 

OMB’s Business Reference Model (BRM) section of Federal 

Enterprise Architecture (FEA) Consolidated Reference Model 

Document Version 2.3 

SOURCE: SP 800-60

Link Encryption – Link encryption encrypts all of the data along a communications path 

(e.g., a satellite link, telephone circuit, or T1 line). Since link 

encryption also encrypts routing data, communications nodes need to 

decrypt the data to continue routing.

SOURCE: SP 800-12

Encryption of information between nodes of a communications 

system.

SOURCE: CNSSI-4009

List-Oriented – Information system protection in which each protected object has a 

list of all subjects authorized to access it. 

SOURCE: CNSSI-4009

Local Access – Access to an organizational information system by a user (or

process acting on behalf of a user) communicating through a

direct connection without the use of a network.

SOURCE: SP 800-53; CNSSI-4009

Local Authority – Organization responsible for generating and signing user certificates

in a PKI-enabled environment.

SOURCE: CNSSI-4009

Local Management Device/Key 

Processor (LMD/KP) –

EKMS platform providing automated management of COMSEC 

material and generating key for designated users.

SOURCE: CNSSI-4009

Local Registration Authority –

(LRA)

A Registration Authority with responsibility for a local community.

SOURCE: SP 800-32
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A Registration Authority with responsibility for a local community in 

a PKI-enabled environment.

SOURCE: CNSSI-4009

Logic Bomb – A piece of code intentionally inserted into a software system that will 

set off a malicious function when specified conditions are met.

SOURCE: CNSSI-4009

Logical Completeness Measure – Means for assessing the effectiveness and degree to which a set of 

security and access control mechanisms meets security specifications.

SOURCE: CNSSI-4009

Logical Perimeter – A conceptual perimeter that extends to all intended users of the 

system, both directly and indirectly connected, who receive output 

from the system without a reliable human review by an appropriate 

authority. The location of such a review is commonly referred to as 

an “air gap.” 

SOURCE: CNSSI-4009

Long Title – Descriptive title of a COMSEC item.

SOURCE: CNSSI-4009

Low Impact – The loss of confidentiality, integrity, or availability that could be 

expected to have a limited adverse effect on organizational 

operations, organizational assets, individuals, other organizations, or 

the national security interests of the United States; (i.e., 1) causes a 

degradation in mission capability to an extent and duration that the 

organization is able to perform its primary functions, but the 

effectiveness of the functions is noticeably reduced; 2) results in 

minor damage to organizational assets; 3) results in minor financial 

loss; or 4) results in minor harm to individuals).

SOURCE: CNSSI-4009

Low-Impact System – An information system in which all three security objectives (i.e., 

confidentiality, integrity, and availability) are assigned a FIPS 199 

potential impact value of low.

SOURCE: SP 800-37; SP 800-53; SP 800-60; FIPS 200

An information system in which all three security properties (i.e., 

confidentiality, integrity, and availability) are assigned a potential 

impact value of low.

SOURCE: CNSSI-4009

Low Probability of Detection – Result of measures used to hide or disguise intentional 

electromagnetic transmissions.

SOURCE: CNSSI-4009
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Low Probability of Intercept – Result of measures to prevent the intercept of intentional 

electromagnetic transmissions. The objective is to minimize an 

adversary’s capability of receiving, processing, or replaying an 

electronic signal.

SOURCE: CNSSI-4009

Macro Virus – A virus that attaches itself to documents and uses the macro 

programming capabilities of the document’s application to execute

and propagate.

SOURCE: CNSSI-4009

Magnetic Remanence – Magnetic representation of residual information remaining on a 

magnetic medium after the medium has been cleared. See Clearing.

SOURCE: CNSSI-4009

Maintenance Hook – Special instructions (trapdoors) in software allowing easy 

maintenance and additional feature development. Since maintenance 

hooks frequently allow entry into the code without the usual checks, 

they are a serious security risk if they are not removed prior to live 

implementation.

SOURCE: CNSSI-4009

Maintenance Key – Key intended only for in-shop use.

SOURCE: CNSSI-4009

Major Application – An application that requires special attention to security due to the 

risk and magnitude of harm resulting from the loss, misuse, or 

unauthorized access to or modification of the information in the 

application. Note: All federal applications require some level of 

protection. Certain applications, because of the information in them, 

however, require special management oversight and should be treated 

as major. Adequate security for other applications should be 

provided by security of the systems in which they operate.

SOURCE: OMB Circular A-130, App. III

Major Information System – An information system that requires special management attention 

because of its importance to an agency mission; its high 

development, operating, or maintenance costs; or its significant role 

in the administration of agency programs, finances, property, or other 

resources.

SOURCE: OMB Circular A-130, App. III

Malicious Applets – Small application programs that are automatically downloaded and 

executed and that perform an unauthorized function on an 

information system.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Malicious Code – Software or firmware intended to perform an unauthorized process 

that will have adverse impact on the confidentiality, integrity, or 

availability of an information system. A virus, worm, Trojan horse, 

or other code-based entity that infects a host. Spyware and some 

forms of adware are also examples of malicious code.

SOURCE: SP 800-53; CNSSI-4009

Malicious Logic – Hardware, firmware, or software that is intentionally included or 

inserted in a system for a harmful purpose.

SOURCE: CNSSI-4009

Malware – A program that is inserted into a system, usually covertly, with the 

intent of compromising the confidentiality, integrity, or availability 

of the victim’s data, applications, or operating system or of otherwise 

annoying or disrupting the victim.

SOURCE: SP 800-83

See Malicious Code. See also Malicious Applets and Malicious 

Logic.

SOURCE: SP 800-53; CNSSI-4009

A virus, worm, Trojan horse, or other code-based malicious entity 

that successfully infects a host.

SOURCE: SP 800-61

Man-in-the-middle Attack –

(MitM)

An attack on the authentication protocol run in which the Attacker 

positions himself in between the Claimant and Verifier so that he can 

intercept and alter data traveling between them.

SOURCE: SP 800-63

A form of active wiretapping attack in which the attacker intercepts 

and selectively modifies communicated data to masquerade as one or 

more of the entities involved in a communication association.

SOURCE: CNSSI-4009

Management Client (MGC) – A configuration of a client node that enables a KMI external 

operational manager to manage KMI products and services by either 

1) accessing a PRSN, or 2) exercising locally provided capabilities. 

An MGC consists of a client platform and an advanced key processor 

(AKP).

SOURCE: CNSSI-4009

Management Controls – The security controls (i.e., safeguards or countermeasures) for an 

information system that focus on the management of risk and the 

management of information system security.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; FIPS 200
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Actions taken to manage the development, maintenance, and use of 

the system, including system-specific policies, procedures and rules 

of behavior, individual roles and responsibilities, individual 

accountability, and personnel security decisions.

SOURCE: CNSSI-4009

Management Security Controls – The security controls (i.e., safeguards or countermeasures) for an 

information system that focus on the management of risk and the 

management of information systems security.

SOURCE: CNSSI-4009

Mandatory Access Control (MAC) – A means of restricting access to system resources based on the 

sensitivity (as represented by a label) of the information contained in 

the system resource and the formal authorization (i.e., clearance) of 

users to access information of such sensitivity.

SOURCE: SP 800-44

Mandatory Access Control – Access controls (which) are driven by the results of a comparison 

between the user’s trust level or clearance and the sensitivity 

designation of the information.

SOURCE: FIPS 191

A means of restricting access to objects based on the sensitivity (as 

represented by a security label) of the information contained in the 

objects and the formal authorization (i.e., clearance, formal access 

approvals, and need-to-know) of subjects to access information of 

such sensitivity.

SOURCE: CNSSI-4009

Mandatory Modification – Change to a COMSEC end-item that NSA requires to be completed 

and reported by a specified date. See Optional Modification.

SOURCE: CNSSI-4009

Manipulative Communications 

Deception –

Alteration or simulation of friendly telecommunications for the 

purpose of deception. See Communications Deception and Imitative 

Communications Deception.

SOURCE: CNSSI-4009

Manual Cryptosystem – Cryptosystem in which the cryptographic processes are performed 

without the use of crypto-equipment or auto-manual devices.

SOURCE: CNSSI-4009

Manual Key Transport – A non-automated means of transporting cryptographic keys by 

physically moving a device, document, or person containing or 

possessing the key or key component.

SOURCE: SP 800-57 Part 1
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Manual Key Transport – A nonelectronic means of transporting cryptographic keys.

SOURCE: FIPS 140-2

Manual Remote Rekeying – Procedure by which a distant crypto-equipment is rekeyed 

electronically, with specific actions required by the receiving 

terminal operator. Synonymous with cooperative remote rekeying. 

See also Automatic Remote Keying.

SOURCE: CNSSI-4009

Marking – See Security Marking.

Masquerading – When an unauthorized agent claims the identity of another agent, it is 

said to be masquerading.

SOURCE: SP 800-19

A type of threat action whereby an unauthorized entity gains access 

to a system or performs a malicious act by illegitimately posing as an 

authorized entity.

SOURCE: CNSSI-4009

Master Cryptographic Ignition Key – Key device with electronic logic and circuits providing the capability 

for adding more operational CIKs to a keyset.

SOURCE: CNSSI-4009

Match/matching – The process of comparing biometric information against a previously 

stored template(s) and scoring the level of similarity.

SOURCE: FIPS 201; CNSSI-4009

Maximum Tolerable Downtime – The amount of time mission/business processes can be disrupted 

without causing significant harm to the organization’s mission.

SOURCE: SP 800-34

Mechanisms – An assessment object that includes specific protection-related items 

(e.g., hardware, software, or firmware) employed within or at the 

boundary of an information system.

SOURCE: SP 800-53A

Media – Physical devices or writing surfaces including but not limited to 

magnetic tapes, optical disks, magnetic disks, Large Scale Integration 

(LSI) memory chips, and printouts (but not including display media) 

onto which information is recorded, stored, or printed within an 

information system.

SOURCE: FIPS 200; SP 800-53; CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Media Sanitization – A general term referring to the actions taken to render data written on 

media unrecoverable by both ordinary and extraordinary means.

SOURCE: SP 800-88

The actions taken to render data written on media unrecoverable by 

both ordinary and extraordinary means.

SOURCE: CNSSI-4009

Memorandum of 

Understanding/Agreement –

(MOU/A)

A document established between two or more parties to define their 

respective responsibilities in accomplishing a particular goal or 

mission. In this guide, an MOU/A defines the responsibilities of two 

or more organizations in establishing, operating, and securing a 

system interconnection. 

SOURCE: SP 800-47

A document established between two or more parties to define their 

respective responsibilities in accomplishing a particular goal or 

mission, e.g., establishing, operating, and securing a system 

interconnection.

SOURCE: CNSSI-4009

Memory Scavenging – The collection of residual information from data storage.

SOURCE: CNSSI-4009

Message Authentication Code –

(MAC)

A cryptographic checksum on data that uses a symmetric key to 

detect both accidental and intentional modifications of the data. 

MACs provide authenticity and integrity protection, but not nonrepudiation protection.

SOURCE: SP 800-63; FIPS 201

Message Authentication Code –

(MAC)

A cryptographic checksum that results from passing data through a 

message authentication algorithm. 

SOURCE: FIPS 198

1. See Checksum.

2. A specific ANSI standard for a checksum.

SOURCE: CNSSI-4009

Message Digest – The result of applying a hash function to a message. Also known as a 

“hash value” or “hash output”.

SOURCE: SP 800-107
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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A digital signature that uniquely identifies data and has the property 

that changing a single bit in the data will cause a completely different 

message digest to be generated.

SOURCE: SP 800-92

A cryptographic checksum, typically generated for a file that can be 

used to detect changes to the file. Synonymous with hash 

value/result.

SOURCE: CNSSI-4009

Message Externals – Information outside of the message text, such as the header, trailer, 

etc.

SOURCE: CNSSI-4009

Message Indicator – Sequence of bits transmitted over a communications system for 

synchronizing cryptographic equipment.

SOURCE: CNSSI-4009

Metrics – Tools designed to facilitate decision-making and improve 

performance and accountability through collection, analysis, and 

reporting of relevant performance-related data.

SOURCE: SP 800-55

MIME – See Multipurpose Internet Mail Extensions.

Mimicking – See Spoofing.

Min-Entropy – A measure of the difficulty that an Attacker has to guess the most 

commonly chosen password used in a system.

SOURCE: SP 800-63

Minimalist Cryptography – Cryptography that can be implemented on devices with very limited 

memory and computing capabilities, such as RFID tags.

SOURCE: SP 800-98

Minor Application – An application, other than a major application, that requires attention 

to security due to the risk and magnitude of harm resulting from the 

loss, misuse, or unauthorized access to or modification of the 

information in the application. Minor applications are typically 

included as part of a general support system.

SOURCE: SP 800-18
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Misnamed Files – A technique used to disguise a file’s content by changing the file’s 

name to something innocuous or altering its extension to a different 

type of file, forcing the examiner to identify the files by file signature 

versus file extension.

SOURCE: SP 800-72; CNSSI-4009

Mission Assurance Category –

(MAC)

A Department of Defense Information Assurance Certification and 

Accreditation Process (DIACAP) term primarily used to determine 

the requirements for availability and integrity.

SOURCE: CNSSI-4009

Mission Critical – Any telecommunications or information system that is defined as a 

national security system (Federal Information Security Management

Act of 2002 - FISMA) or processes any information the loss, misuse, 

disclosure, or unauthorized access to or modification of, would have 

a debilitating impact on the mission of an agency.

SOURCE: SP 800-60

Mission/Business Segment – Elements of organizations describing mission areas, common/shared 

business services, and organization-wide services. Mission/business 

segments can be identified with one or more information systems 

which collectively support a mission/business process.

SOURCE: SP 800-30

Mobile Code – Software programs or parts of programs obtained from remote 

information systems, transmitted across a network, and executed on a 

local information system without explicit installation or execution by 

the recipient.

SOURCE: SP 800-53; SP 800-18

A program (e.g., script, macro, or other portable instruction) that can 

be shipped unchanged to a heterogeneous collection of platforms and 

executed with identical semantics.

SOURCE: SP 800-28

Software programs or parts of programs obtained from remote 

information systems, transmitted across a network, and executed on a 

local information system without explicit installation or execution by 

the recipient.

Note: Some examples of software technologies that provide the 

mechanisms for the production and use of mobile code include Java, 

JavaScript, ActiveX, VBScript, etc.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Mobile Code Technologies – Software technologies that provide the mechanisms for the 

production and use of mobile code (e.g., Java, JavaScript, ActiveX, 

VBScript).

SOURCE: SP 800-53; SP 800-18

Mobile Device – Portable cartridge/disk-based, removable storage media (e.g., floppy 

disks, compact disks, USB flash drives, external hard drives, and 

other flash memory cards/drives that contain nonvolatile memory).

Portable computing and communications device with information

storage capability (e.g., notebook/laptop computers, personal

digital assistants, cellular telephones, digital cameras, and audio

recording devices).

SOURCE: SP 800-53

Mobile Software Agent – Programs that are goal-directed and capable of suspending their 

execution on one platform and moving to another platform where 

they resume execution.

SOURCE: SP 800-19

Mode of Operation – An algorithm for the cryptographic transformation of data that 

features a symmetric key block cipher algorithm.

SOURCE: SP 800-38C

Description of the conditions under which an information system 

operates based on the sensitivity of information processed and the 

clearance levels, formal access approvals, and need-to-know of its 

users. Four modes of operation are authorized for processing or 

transmitting information: dedicated mode, system high mode, 

compartmented/partitioned mode, and multilevel mode.

SOURCE: CNSSI-4009

Moderate Impact – The loss of confidentiality, integrity, or availability that could be 

expected to have a serious adverse effect on organizational 

operations, organizational assets, individuals, other organizations, or 

the national security interests of the United States; (i.e., 1) causes a 

significant degradation in mission capability to an extent and duration 

that the organization is able to perform its primary functions, but the 

effectiveness of the functions is significantly reduced; 2) results in 

significant damage to organizational assets; 3) results in significant 

financial loss; or 4) results in significant harm to individuals that does 

not involve loss of life or serious life threatening injuries).

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Moderate-Impact System – An information system in which at least one security objective (i.e., 

confidentiality, integrity, or availability) is assigned a FIPS 199 

potential impact value of moderate and no security objective is 

assigned a FIPS 199 potential impact value of high.

SOURCE: SP 800-53; SP 800-60; SP 800-37; FIPS 200

An information system in which at least one security objective (i.e., 

confidentiality, integrity, or availability) is assigned a potential 

impact value of moderate and no security objective is assigned a 

potential impact value of high.

SOURCE: CNSSI-4009

Multi-Hop Problem – The security risks resulting from a mobile software agent visiting 

several platforms.

SOURCE: SP 800-19

Multi-Releasable – A characteristic of an information domain where access control 

mechanisms enforce policy-based release of information to 

authorized users within the information domain.

SOURCE: CNSSI-4009

Multifactor Authentication – Authentication using two or more factors to achieve

authentication. Factors include: (i) something you know (e.g.

password/PIN); (ii) something you have (e.g., cryptographic

identification device, token); or (iii) something you are (e.g.,

biometric). See Authenticator.

SOURCE: SP 800-53

Multilevel Device – Equipment trusted to properly maintain and separate data of different 

security domains.

SOURCE: CNSSI-4009

Multilevel Mode – Mode of operation wherein all the following statements are satisfied 

concerning the users who have direct or indirect access to the system, 

its peripherals, remote terminals, or remote hosts: 1) some users do 

not have a valid security clearance for all the information processed 

in the information system; 2) all users have the proper security 

clearance and appropriate formal access approval for that information 

to which they have access; and 3) all users have a valid need-to-know 

only for information to which they have access.

SOURCE: CNSSI-4009

Multilevel Security (MLS) – Concept of processing information with different classifications and 

categories that simultaneously permits access by users with different 

security clearances and denies access to users who lack authorization.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Multiple Security Levels (MSL) – Capability of an information system that is trusted to contain, and 

maintain separation between, resources (particularly stored data) of 

different security domains.

SOURCE: CNSSI-4009

Mutual Authentication – Occurs when parties at both ends of a communication activity 

authenticate each other.

SOURCE: SP 800-32

The process of both entities involved in a transaction verifying each 

other.

SOURCE: CNSSI-4009

Mutual Suspicion – Condition in which two information systems need to rely upon each 

other to perform a service, yet neither trusts the other to properly 

protect shared data.

SOURCE: CNSSI-4009

Naming Authority – An organizational entity responsible for assigning distinguished 

names (DNs) and for assuring that each DN is meaningful and unique 

within its domain.

SOURCE: SP 800-32

National Information Assurance 

Partnership (NIAP) –

A U.S. government initiative established to promote the use of 

evaluated information systems products and champion the 

development and use of national and international standards for 

information technology security. NIAP was originally established as 

a collaboration between the National Institute of Standards and 

Technology (NIST) and the National Security Agency (NSA) in 

fulfilling their respective responsibilities under P.L. 100-235 

(Computer Security Act of 1987). NIST officially withdrew from the 

partnership in 2007 but NSA continues to manage and operate the 

program. The key operational component of NIAP is the Common 

Criteria Evaluation and Validation Scheme (CCEVS) which is the 

only U.S. government-sponsored and endorsed program for 

conducting internationally recognized security evaluations of 

commercial off-the-shelf (COTS) Information Assurance (IA) and 

IA-enabled information technology products. NIAP employs the 

CCEVS to provide government oversight or “validation” to U.S. CC 

evaluations to ensure correct conformance to the International 

Common Criteria for IT Security Evaluation (ISO/IEC 15408).

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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National Information 

Infrastructure –

Nationwide interconnection of communications networks, computers, 

databases, and consumer electronics that make vast amounts of 

information available to users. It includes both public and private 

networks, the Internet, the public switched network, and cable, 

wireless, and satellite communications.

SOURCE: CNSSI-4009

National Security Emergency 

Preparedness Telecommunications 

Services –

Telecommunications services that are used to maintain a state of 

readiness or to respond to and manage any event or crisis (local, 

national, or international) that causes or could cause injury or harm to 

the population, damage to or loss of property, or degrade or threaten 

the national security or emergency preparedness posture of the 

United States.

SOURCE: SP 800-53; CNSSI-4009; 47 C.F.R., Part 64, App A

National Security Information – Information that has been determined pursuant to Executive Order 

12958 as amended by Executive Order 13292, or any predecessor

order, or by the Atomic Energy Act of 1954, as amended, to require 

protection against unauthorized disclosure and is marked to indicate 

its classified status.

SOURCE: SP 800-53A; SP 800-60; FIPS 200

National Security Information 

(NSI) –

See Classified National Security Information.

SOURCE: CNSSI-4009

National Security System – Any information system (including any telecommunications system) 

used or operated by an agency or by a contractor of an agency, or 

other organization on behalf of an agency—(i) the function, 

operation, or use of which involves intelligence activities; involves 

cryptologic activities related to national security; involves command 

and control of military forces; involves equipment that is an integral 

part of a weapon or weapons system; or is critical to the direct 

fulfillment of military or intelligence missions (excluding a system 

that is to be used for routine administrative and business applications, 

for example, payroll, finance, logistics, and personnel management 

applications); or (ii) is protected at all times by procedures 

established for information that have been specifically authorized 

under criteria established by an Executive Order or an Act of 

Congress to be kept classified in the interest of national defense or 

foreign policy. [44 U.S.C., SEC. 3542]

SOURCE: FIPS 200; SP 800-37; SP 800-53; SP 800-53A; SP 800-60
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Any information system (including any telecommunications system) 

used or operated by an agency or by a contractor of any agency, or 

other organization on behalf of an agency, the function, operation, or 

use of which: I. involves intelligence activities; II. involves 

cryptologic activities related to national security; III. Involves 

command and control of military forces; IV. involves equipment that 

is an integral part of a weapon or weapon system; or V. subject to 

subparagraph (B), is critical to the direct fulfillment of military or 

intelligence missions; or is protected at all times by procedures 

established for information that have been specifically authorized 

under criteria established by an Executive Order or an Act of 

Congress to be kept classified in the interest of national defense or 

foreign policy.

Subparagraph (B). Does not include a system that is to be used for 

routine administrative and business applications (including payroll, 

finance, logistics, and personnel management applications). (Title 44 

U.S. Code Section 3542, Federal Information Security Management 

Act of 2002.)

SOURCE: CNSSI-4009

National Vulnerability Database –

(NVD)

The U.S. government repository of standards-based vulnerability 

management data. This data enables automation of vulnerability 

management, security measurement, and compliance (e.g., FISMA).

SOURCE: http://nvd.nist.gov/

Need To Know Determination – Decision made by an authorized holder of official information that a 

prospective recipient requires access to specific official information 

to carry out official duties.

SOURCE: CNSSI-4009

Need-To-Know – A method of isolating information resources based on a user’s need 

to have access to that resource in order to perform their job but no 

more. The terms ‘need-to know” and “least privilege” express the 

same idea. Need-to-know is generally applied to people, while least 

privilege is generally applied to processes.

SOURCE: CNSSI-4009

Needs Assessment (IT Security 

Awareness and Training) –

A process that can be used to determine an organization’s awareness 

and training needs. The results of a needs assessment can provide 

justification to convince management to allocate adequate resources 

to meet the identified awareness and training needs.

SOURCE: SP 800-50
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Net-centric Architecture – A complex system of systems composed of subsystems and

services that are part of a continuously evolving, complex

community of people, devices, information and services

interconnected by a network that enhances information sharing

and collaboration. Subsystems and services may or may not be

developed or owned by the same entity, and, in general, will not

be continually present during the full life cycle of the system of

systems. Examples of this architecture include service-oriented

architectures and cloud computing architectures.

SOURCE: SP 800-37

Network – Information system(s) implemented with a collection of 

interconnected components. Such components may include routers, 

hubs, cabling, telecommunications controllers, key distribution 

centers, and technical control devices. 

SOURCE: SP 800-53; CNSSI-4009

Network Access – Access to an organizational information system by a user (or a 

process acting on behalf of a user) communicating through a network 

(e.g., local area network, wide area network, Internet).

SOURCE: SP 800-53; CNSSI-4009

Network Access Control (NAC) – A feature provided by some firewalls that allows access based on a 

user’s credentials and the results of health checks performed on the 

telework client device.

SOURCE: SP 800-41

Network Address Translation 

(NAT) –

A routing technology used by many firewalls to hide internal system 

addresses from an external network through use of an addressing 

schema.

SOURCE: SP 800-41

Network Front-End – Device implementing protocols that allow attachment of a computer 

system to a network.

SOURCE: CNSSI-4009

Network Reference Monitor – See Reference Monitor.

Network Resilience – A computing infrastructure that provides continuous business 

operation (i.e., highly resistant to disruption and able to operate in a 

degraded mode if damaged), rapid recovery if failure does occur, and 

the ability to scale to meet rapid or unpredictable demands. 

SOURCE: CNSSI-4009

Network Security – See Information Assurance.

Network Security Officer – See Information Systems Security Officer.
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

130

Network Sniffing – A passive technique that monitors network communication, decodes 

protocols, and examines headers and payloads for information of 

interest. It is both a review technique and a target identification and 

analysis technique.

SOURCE: SP 800-115

Network Sponsor – Individual or organization responsible for stating the security policy 

enforced by the network, designing the network security architecture 

to properly enforce that policy, and ensuring that the network is 

implemented in such a way that the policy is enforced.

SOURCE: CNSSI-4009

Network System – System implemented with a collection of interconnected components. 

A network system is based on a coherent security architecture and 

design.

SOURCE: CNSSI-4009

Network Weaving – Penetration technique in which different communication networks are 

linked to access an information system to avoid detection and traceback.

SOURCE: CNSSI-4009

No-Lone Zone (NLZ) – Area, room, or space that, when staffed, must be occupied by two or 

more appropriately cleared individuals who remain within sight of 

each other. See Two-Person Integrity.

SOURCE: CNSSI-4009

Non-deterministic Random Bit 

Generator (NRBG) –

An RBG that (when working properly) produces outputs that have 

full entropy. Contrast with a DRBG. Other names for nondeterministic RBGs are True Random Number (or Bit) Generators 

and, simply, Random Number (or Bit) Generators. 

SOURCE: SP 800-90A

Non-Local Maintenance – Maintenance activities conducted by individuals communicating 

through a network; either an external network (e.g., the Internet) or 

an internal network.

SOURCE: SP 800-53

Non-Organizational User – A user who is not an organizational user (including public users).

SOURCE: SP 800-53

Non-repudiation – Assurance that the sender of information is provided with proof of 

delivery and the recipient is provided with proof of the sender’s 

identity, so neither can later deny having processed the information.

SOURCE: CNSSI-4009; SP 800-60
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

131

Protection against an individual falsely denying having performed a 

particular action. Provides the capability to determine whether a 

given individual took a particular action such as creating information, 

sending a message, approving information, and receiving a message.

SOURCE: SP 800-53; SP 800-18

Non-Repudiation – Is the security service by which the entities involved in a 

communication cannot deny having participated. Specifically, the 

sending entity cannot deny having sent a message (non-repudiation 

with proof of origin), and the receiving entity cannot deny having 

received a message (non-repudiation with proof of delivery).

SOURCE: FIPS 191

A service that is used to provide assurance of the integrity and origin

of data in such a way that the integrity and origin can be verified and

validated by a third party as having originated from a specific entity 

in possession of the private key (i.e., the signatory).

SOURCE: FIPS 186

Nonce – A value used in security protocols that is never repeated with the 

same key. For example, nonces used as challenges in challengeresponse authentication protocols generally must not be repeated 

until authentication keys are changed. Otherwise, there is a 

possibility of a replay attack. Using a nonce as a challenge is a 

different requirement than a random challenge, because a nonce is 

not necessarily unpredictable.

SOURCE: SP 800-63

A random or non-repeating value that is included in data exchanged 

by a protocol, usually for the purpose of guaranteeing the transmittal 

of live data rather than replayed data, thus detecting and protecting 

against replay attacks.

SOURCE: CNSSI-4009

NSA-Approved Cryptography – Cryptography that consists of: (i) an approved algorithm; (ii) an

implementation that has been approved for the protection of

classified information in a particular environment; and (iii) a

supporting key management infrastructure.

SOURCE: SP 800-53

Null – Dummy letter, letter symbol, or code group inserted into an 

encrypted message to delay or prevent its decryption or to complete 

encrypted groups for transmission or transmission security purposes.

SOURCE: CNSSI-4009
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132

Object – A passive entity that contains or receives information. 

SOURCE: SP 800-27

Passive information system-related entity (e.g., devices, files, 

records, tables, processes, programs, domains) containing or 

receiving information. Access to an object implies access to the 

information it contains.

SOURCE: CNSSI-4009

Passive information system-related entity (e.g., devices, files, 

records, tables, processes, programs, domains) containing or 

receiving information. Access to an object (by a subject) implies 

access to the information it contains. See Subject.

SOURCE: SP 800-53

Object Identifier – A specialized formatted number that is registered with an 

internationally recognized standards organization. The unique 

alphanumeric/numeric identifier registered under the ISO registration 

standard to reference a specific object or object class. In the federal 

government PKI, they are used to uniquely identify each of the four 

policies and cryptographic algorithms supported.

SOURCE: SP 800-32

Object Reuse – Reassignment and reuse of a storage medium containing one or more 

objects after ensuring no residual data remains on the storage 

medium.

SOURCE: CNSSI-4009

Off-Card – Refers to data that is not stored within the PIV card or computation 

that is not done by the Integrated Circuit Chip (ICC) of the PIV card.

SOURCE: FIPS 201

Off-line Attack – An attack where the Attacker obtains some data (typically by 

eavesdropping on an authentication protocol run, or by penetrating a 

system and stealing security files) that he/she is able to analyze in a 

system of his/her own choosing.

SOURCE: SP 800-63

Off-line Cryptosystem – Cryptographic system in which encryption and decryption are 

performed independently of the transmission and reception functions.

SOURCE: CNSSI-4009
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Official Information – All information in the custody and control of a U.S. government 

department or agency that was acquired by U.S. government 

employees as a part of their official duties or because of their official 

status and has not been cleared for public release.

SOURCE: CNSSI-4009

On-Card – Refers to data that is stored within the PIV card or computation that 

is done by the ICC of the PIV card.

SOURCE: FIPS 201

Online Attack – An attack against an authentication protocol where the Attacker 

either assumes the role of a Claimant with a genuine Verifier or 

actively alters the authentication channel. The goal of the attack may 

be to gain authenticated access or learn authentication secrets.

SOURCE: SP 800-63

Online Certificate Status 

Protocol (OCSP) –

An online protocol used to determine the status of a public key 

certificate.

SOURCE: FIPS 201

Online Cryptosystem – Cryptographic system in which encryption and decryption are 

performed in association with the transmitting and receiving 

functions.

SOURCE: CNSSI-4009

One-part Code – Code in which plain text elements and their accompanying code 

groups are arranged in alphabetical, numerical, or other systematic 

order, so one listing serves for both encoding and decoding. One-part 

codes are normally small codes used to pass small volumes of lowsensitivity information.

SOURCE: CNSSI-4009

One-time Cryptosystem – Cryptosystem employing key used only once.

SOURCE: CNSSI-4009

One-time Pad – Manual one-time cryptosystem produced in pad form.

SOURCE: CNSSI-4009

One-time Tape – Punched paper tape used to provide key streams on a one-time basis 

in certain machine cryptosystems.

SOURCE: CNSSI-4009
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One-Way Hash Algorithm – Hash algorithms which map arbitrarily long inputs into a fixed-size 

output such that it is very difficult (computationally infeasible) to 

find two different hash inputs that produce the same output. Such 

algorithms are an essential part of the process of producing fixed-size 

digital signatures that can both authenticate the signer and provide for 

data integrity checking (detection of input modification after 

signature).

SOURCE: SP 800-49; CNSSI-4009

Open Checklist Interactive 

Language (OCIL) –

SCAP language for expressing security checks that cannot be 

evaluated without some human interaction or feedback.

SOURCE: SP 800-128

Open Vulnerability and Assessment 

Language (OVAL) –

SCAP language for specifying low-level testing procedures used by 

checklists. 

SOURCE: SP 800-128

Open Storage – Any storage of classified national security information outside of 

approved containers. This includes classified information that is 

resident on information systems media and outside of an approved 

storage container, regardless of whether or not that media is in use 

(i.e., unattended operations).

SOURCE: CNSSI-4009

Operating System (OS) 

Fingerprinting –

Analyzing characteristics of packets sent by a target, such as packet 

headers or listening ports, to identify the operating system in use on 

the target.

SOURCE: SP 800-115

Operational Controls – The security controls (i.e., safeguards or countermeasures) for an 

information system that primarily are implemented and executed by 

people (as opposed to systems).

SOURCE: SP 800-53; SP 800-37; FIPS 200

The security controls (i.e., safeguards or countermeasures) for an 

information system that are primarily implemented and executed by 

people (as opposed to systems).

SOURCE: CNSSI-4009; SP 800-53A

Operational Key – Key intended for use over-the-air for protection of operational 

information or for the production or secure electrical transmission of 

key streams.

SOURCE: CNSSI-4009
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Operational Vulnerability 

Information –

Information that describes the presence of an information 

vulnerability within a specific operational setting or network.

SOURCE: CNSSI-4009

Operational Waiver – Authority for continued use of unmodified COMSEC end-items 

pending the completion of a mandatory modification.

SOURCE: CNSSI-4009

Operations Code – Code composed largely of words and phrases suitable for general 

communications use.

SOURCE: CNSSI-4009

Operations Security (OPSEC) – Systematic and proven process by which potential adversaries can be 

denied information about capabilities and intentions by identifying, 

controlling, and protecting generally unclassified evidence of the 

planning and execution of sensitive activities. The process involves 

five steps: identification of critical information, analysis of threats, 

analysis of vulnerabilities, assessment of risks, and application of 

appropriate countermeasures.

SOURCE: CNSSI-4009

Optional Modification – NSA-approved modification not required for universal 

implementation by all holders of a COMSEC end-item. This class of 

modification requires all of the engineering/doctrinal control of 

mandatory modification but is usually not related to security, safety, 

TEMPEST, or reliability. See Mandatory Modification.

SOURCE: CNSSI-4009

Organization – A federal agency, or, as appropriate, any of its operational elements.

SOURCE: FIPS 200

An entity of any size, complexity, or positioning within an 

organizational structure (e.g., a federal agency, or, as appropriate, any 

of its operational elements).

SOURCE: SP 800-53; SP 800-53A; SP 800-37

Organizational Information Security 

Continuous Monitoring –

Ongoing monitoring sufficient to ensure and assure effectiveness of 

security controls related to systems, networks, and cyberspace, by 

assessing security control implementation and organizational security 

status in accordance with organizational risk tolerance – and within a 

reporting structure designed to make real-time, data-driven risk 

management decisions. 

SOURCE: SP 800-137

Organizational Maintenance – Limited maintenance performed by a user organization.

SOURCE: CNSSI-4009
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Organizational Registration 

Authority (ORA) –

Entity within the PKI that authenticates the identity and the 

organizational affiliation of the users.

SOURCE: CNSSI-4009

Organizational User – An organizational employee or an individual the organization deems 

to have equivalent status of an employee (e.g., contractor, guest 

researcher, individual detailed from another organization, individual 

from allied nation).

SOURCE: SP 800-53

Outside Threat – An unauthorized entity from outside the domain perimeter that has 

the potential to harm an Information System through destruction, 

disclosure, modification of data, and/or denial of service.

SOURCE: SP 800-32

Outside(r) Threat – An unauthorized entity outside the security domain that has the 

potential to harm an information system through destruction, 

disclosure, modification of data, and/or denial of service.

SOURCE: CNSSI-4009

Over-The-Air Key Distribution – Providing electronic key via over-the-air rekeying, over-the-air key 

transfer, or cooperative key generation.

SOURCE: CNSSI-4009

Over-The-Air Key Transfer – Electronically distributing key without changing traffic encryption 

key used on the secured communications path over which the transfer 

is accomplished.

SOURCE: CNSSI-4009

Over-The-Air Rekeying (OTAR) – Changing traffic encryption key or transmission security key in 

remote cryptographic equipment by sending new key directly to the 

remote cryptographic equipment over the communications path it 

secures.

SOURCE: CNSSI-4009

Overt Channel – Communications path within a computer system or network designed

for the authorized transfer of data. See Covert Channel.

SOURCE: CNSSI-4009

Overt Testing – Security testing performed with the knowledge and consent of the 

organization’s IT staff.

SOURCE: SP 800-115
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Overwrite Procedure – A software process that replaces data previously stored on storage 

media with a predetermined set of meaningless data or random 

patterns.

SOURCE: CNSSI-4009

Packet Filter – A routing device that provides access control functionality for host 

addresses and communication sessions.

SOURCE: SP 800-41

Packet Sniffer – Software that observes and records network traffic.

SOURCE: CNSSI-4009

Parity – Bit(s) used to determine whether a block of data has been altered.

SOURCE: CNSSI-4009

Partitioned Security Mode – Information systems security mode of operation wherein all 

personnel have the clearance, but not necessarily formal access 

approval and need-to-know, for all information handled by an 

information system.

SOURCE: CNSSI-4009

Passive Attack – An attack against an authentication protocol where the Attacker 

intercepts data traveling along the network between the Claimant and 

Verifier, but does not alter the data (i.e., eavesdropping).

SOURCE: SP 800-63

An attack that does not alter systems or data.

SOURCE: CNSSI-4009

Passive Security Testing – Security testing that does not involve any direct interaction with the 

targets, such as sending packets to a target.

SOURCE: SP 800-115

Passive Wiretapping – The monitoring or recording of data while it is being transmitted over 

a communications link, without altering or affecting the data.

SOURCE: CNSSI-4009

Password – A secret that a Claimant memorizes and uses to authenticate his or 

her identity. Passwords are typically character strings.

SOURCE: SP 800-63

Password – A protected character string used to authenticate the identity of a 

computer system user or to authorize access to system resources.

SOURCE: FIPS 181
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Password – A string of characters (letters, numbers, and other symbols) used to 

authenticate an identity or to verify access authorization.

SOURCE: FIPS 140-2

A protected/private string of letters, numbers, and/or special 

characters used to authenticate an identity or to authorize access to 

data.

SOURCE: CNSSI-4009

Password Cracking – The process of recovering secret passwords stored in a computer 

system or transmitted over a network.

SOURCE: SP 800-115

Password Protected – The ability to protect a file using a password access control, 

protecting the data contents from being viewed with the appropriate 

viewer unless the proper password is entered.

SOURCE: SP 800-72

The ability to protect the contents of a file or device from being 

accessed until the correct password is entered.

SOURCE: SP 800-124

Patch – An update to an operating system, application, or other software 

issued specifically to correct particular problems with the software.

SOURCE: SP 800-123

Patch Management – The systematic notification, identification, deployment, installation, 

and verification of operating system and application software code 

revisions. These revisions are known as patches, hot fixes, and 

service packs.

SOURCE: CNSSI-4009

Path Histories – Maintaining an authenticatable record of the prior platforms visited 

by a mobile software agent, so that a newly visited platform can 

determine whether to process the agent and what resource constraints 

to apply.

SOURCE: SP 800-19

Payload – The input data to the CCM generation-encryption process that is both 

authenticated and encrypted.

SOURCE: SP 800-38C

Peer Entity Authentication – The process of verifying that a peer entity in an association is as 

claimed.

SOURCE: CNSSI-4009
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Penetration – See Intrusion.

Penetration Testing – A test methodology in which assessors, using all available 

documentation (e.g., system design, source code, manuals) and 

working under specific constraints, attempt to circumvent the security 

features of an information system.

SOURCE: SP 800-53A

A test methodology in which assessors, typically working under 

specific constraints, attempt to circumvent or defeat the security 

features of an information system.

SOURCE: SP 800-53; CNSSI-4009

Security testing in which evaluators mimic real-world attacks in an 

attempt to identify ways to circumvent the security features of an 

application, system, or network. Penetration testing often involves 

issuing real attacks on real systems and data, using the same tools and 

techniques used by actual attackers. Most penetration tests involve 

looking for combinations of vulnerabilities on a single system or 

multiple systems that can be used to gain more access than could be 

achieved through a single vulnerability.

SOURCE: SP 800-115

Per-Call Key – Unique traffic encryption key generated automatically by certain 

secure telecommunications systems to secure single voice or data 

transmissions. See Cooperative Key Generation.

SOURCE: CNSSI-4009

Performance Reference Model –

(PRM)

Framework for performance measurement providing common output 

measurements throughout the federal government. It allows agencies 

to better manage the business of government at a strategic level by 

providing a means for using an agency’s EA to measure the success 

of information systems investments and their impact on strategic 

outcomes. 

SOURCE: CNSSI-4009

Perimeter – (C&A) Encompasses all those components of the system that are to 

be accredited by the DAA, and excludes separately accredited 

systems to which the system is connected.

(Authorization) Encompasses all those components of the system or 

network for which a Body of Evidence is provided in support of a 

formal approval to operate.

SOURCE: CNSSI-4009
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Periods Processing – The processing of various levels of classified and unclassified 

information at distinctly different times. Under the concept of 

periods processing, the system must be purged of all information 

from one processing period before transitioning to the next.

SOURCE: CNSSI-4009

Perishable Data – Information whose value can decrease substantially during a 

specified time. A significant decrease in value occurs when the 

operational circumstances change to the extent that the information is 

no longer useful.

SOURCE: CNSSI-4009

Permuter – Device used in cryptographic equipment to change the order in which 

the contents of a shift register are used in various nonlinear 

combining circuits.

SOURCE: CNSSI-4009

Personal Firewall – A utility on a computer that monitors network activity and blocks 

communications that are unauthorized.

SOURCE: SP 800-69

Personal Identification Number –

(PIN)

A password consisting only of decimal digits.

SOURCE: SP 800-63

Personal Identification Number –

(PIN)

A secret that a claimant memorizes and uses to authenticate his or her 

identity. PINs are generally only decimal digits.

SOURCE: FIPS 201

Personal Identification Number –

(PIN)

An alphanumeric code or password used to authenticate an identity.

SOURCE: FIPS 140-2

A short numeric code used to confirm identity.

SOURCE: CNSSI-4009

Personal Identity Verification –

(PIV)

The process of creating and using a governmentwide secure and 

reliable form of identification for federal employees and contractors, 

in support of HSPD 12, Policy for a Common Identification Standard 

for Federal Employees and Contractors.

SOURCE: CNSSI-4009

Personal Identity Verification

Accreditation –

The official management decision to authorize operation of a PIV 

Card Issuer after determining that the Issuer’s reliability has 

satisfactorily been established through appropriate assessment and 

certification processes. 

SOURCE: CNSSI-4009
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Personal Identity Verification

Authorizing Official –

An individual who can act on behalf of an agency to authorize the 

issuance of a credential to an applicant. 

SOURCE: CNSSI-4009

Personal Identity Verification Card –

(PIV Card)

Physical artifact (e.g., identity card, “smart” card) issued to an 

individual that contains stored identity credentials (e.g., photograph, 

cryptographic keys, digitized fingerprint representation, etc.) such 

that a claimed identity of the cardholder may be verified against the 

stored credentials by another person (human-readable and verifiable) 

or an automated process (computer-readable and verifiable).

SOURCE: FIPS 201; CNSSI-4009

Personal Identity Verification 

Issuer –

An authorized identity card creator that procures FIPS-approved 

blank identity cards, initializes them with appropriate software and 

data elements for the requested identity verification and access 

control application, personalizes the cards with the identity 

credentials of the authorized subjects, and delivers the personalized 

card to the authorized subjects along with appropriate instructions for 

protection and use.

SOURCE: FIPS 201

Personal Identity Verification 

Registrar –

An entity that establishes and vouches for the identity of an applicant 

to a PIV Issuer. The PIV RA authenticates the applicant’s identity by 

checking identity source documents and identity proofing, and that 

ensures a proper background check has been completed, before the 

credential is issued.

SOURCE: FIPS 201

Personal Identity Verification 

Sponsor –

An individual who can act on behalf of a department or agency to 

request a PIV Card for an applicant.

SOURCE: FIPS 201

Personally Identifiable Information –

(PII)

Information which can be used to distinguish or trace an individual's 

identity, such as their name, social security number, biometric 

records, etc., alone, or when combined with other personal or 

identifying information which is linked or linkable to a specific 

individual, such as date and place of birth, mother’s maiden name, 

etc.

SOURCE: CNSSI-4009

Any information about an individual maintained by an agency, 

including (1) any information that can be used to distinguish or trace 

an individual‘s identity, such as name, social security number, date 

and place of birth, mother‘s maiden name, or biometric records; and 

(2) any other information that is linked or linkable to an individual, 

such as medical, educational, financial, and employment information.

SOURCE: SP 800-122
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Personnel Registration Manager – The management role that is responsible for registering human users, 

i.e., users that are people.

SOURCE: CNSSI-4009

Phishing – Tricking individuals into disclosing sensitive personal information 

through deceptive computer-based means.

SOURCE: SP 800-83

Deceiving individuals into disclosing sensitive personal information 

through deceptive computer-based means.

SOURCE: CNSSI-4009

A digital form of social engineering that uses authentic-looking—but 

bogus—emails to request information from users or direct them to a 

fake Web site that requests information.

SOURCE: SP 800-115

Physically Isolated Network – A network that is not connected to entities or systems outside a 

physically controlled space.

SOURCE: SP 800-32

Piconet – A small Bluetooth network created on an ad hoc basis that includes 

two or more devices.

SOURCE: SP 800-121

PII Confidentiality Impact Level – The PII confidentiality impact level—low, moderate, or high—

indicates the potential harm that could result to the subject 

individuals and/or the organization if PII were inappropriately 

accessed, used, or disclosed.

SOURCE: SP 800-122

Plaintext – Data input to the Cipher or output from the Inverse Cipher.

SOURCE: FIPS 197

Plaintext – Intelligible data that has meaning and can be understood without the 

application of decryption.

SOURCE: SP 800-21

Unencrypted information.

SOURCE: CNSSI-4009

Plaintext Key – An unencrypted cryptographic key.

SOURCE: FIPS 140-2
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Plan of Action and Milestones –

(POA&M)

A document that identifies tasks needing to be accomplished. It 

details resources required to accomplish the elements of the plan, any 

milestones in meeting the tasks, and scheduled completion dates for 

the milestones.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-64; CNSSI4009; OMB Memorandum 02-01

Policy Approving Authority –

(PAA)

First level of the PKI Certification Management Authority that 

approves the security policy of each PCA.

SOURCE: CNSSI-4009

Policy-Based Access Control –

(PBAC) 

A form of access control that uses an authorization policy that is 

flexible in the types of evaluated parameters (e.g., identity, role, 

clearance, operational need, risk, and heuristics).

SOURCE: CNSSI-4009

Policy Certification Authority –

(PCA)

Second level of the PKI Certification Management Authority that 

formulates the security policy under which it and its subordinate CAs 

will issue public key certificates.

SOURCE: CNSSI-4009

Policy Management Authority –

(PMA)

Body established to oversee the creation and update of Certificate 

Policies, review Certification Practice Statements, review the results

of CA audits for policy compliance, evaluate non-domain policies for 

acceptance within the domain, and generally oversee and manage the 

PKI certificate policies. For the FBCA, the PMA is the Federal PKI 

Policy Authority.

SOURCE: SP 800-32

Policy Mapping – Recognizing that, when a CA in one domain certifies a CA in another 

domain, a particular certificate policy in the second domain may be 

considered by the authority of the first domain to be equivalent (but 

not necessarily identical in all respects) to a particular certificate 

policy in the first domain.

SOURCE: SP 800-15

Port – A physical entry or exit point of a cryptographic module that 

provides access to the module for physical signals, represented by 

logical information flows (physically separated ports do not share the 

same physical pin or wire).

SOURCE: FIPS 140-2

Port Scanning – Using a program to remotely determine which ports on a system are 

open (e.g., whether systems allow connections through those ports).

SOURCE: CNSSI-4009
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Portal – A high-level remote access architecture that is based on a server that 

offers teleworkers access to one or more applications through a single 

centralized interface.

SOURCE: SP 800-46

Portable Electronic Device (PED) – Any nonstationary electronic apparatus with singular or multiple 

capabilities of recording, storing, and/or transmitting data, voice, 

video, or photo images. This includes but is not limited to laptops, 

personal digital assistants, pocket personal computers, palmtops, 

MP3 players, cellular telephones, thumb drives, video cameras, and 

pagers. 

SOURCE: CNSSI-4009

Positive Control Material – Generic term referring to a sealed authenticator system, permissive 

action link, coded switch system, positive enable system, or nuclear 

command and control documents, material, or devices.

SOURCE: CNSSI-4009

Potential Impact – The loss of confidentiality, integrity, or availability could be expected 

to have:

1) a limited adverse effect (FIPS 199 low);

2) a serious adverse effect (FIPS 199 moderate); or 

3) a severe or catastrophic adverse effect (FIPS 199 high) on 

organizational operations, organizational assets, or individuals.

SOURCE: SP 800-53; SP 800-60; SP 800-37; FIPS 199

Potential Impact – The loss of confidentiality, integrity, or availability could be expected 

to have a limited adverse effect; a serious adverse effect, or a severe 

or catastrophic adverse effect on organizational operations, 

organizational assets, or individuals.

SOURCE: FIPS 200

The loss of confidentiality, integrity, or availability that could be 

expected to have a limited (low) adverse effect, a serious (moderate) 

adverse effect, or a severe or catastrophic (high) adverse effect on 

organizational operations, organizational assets, or individuals. 

SOURCE: CNSSI-4009

Practice Statement – A formal statement of the practices followed by an authentication 

entity (e.g., RA, CSP, or Verifier). It usually describes the policies 

and practices of the parties and can become legally binding. SOURCE: 

SP 800-63

Precursor – A sign that an attacker may be preparing to cause an incident.

SOURCE: SP 800-61
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A sign that an attacker may be preparing to cause an incident. See 

Indicator.

SOURCE: CNSSI-4009

Prediction Resistance – Prediction resistance is provided relative to time T if there is 

assurance that an adversary who has knowledge of the internal state 

of the DRBG at some time prior to T would be unable to distinguish 

between observations of ideal random bitstrings and bitstrings output 

by the DRBG at or subsequent to time T. The complementary 

assurance is called Backtracking Resistance. 

SOURCE: SP 800-90A

Predisposing Condition – A condition that exists within an organization, a mission/business 

process, enterprise architecture, or information system including its 

environment of operation, which contributes to (i.e., increases or 

decreases) the likelihood that one or more threat events, once 

initiated, will result in undesirable consequences or adverse impact to 

organizational operations and assets, individuals, other organizations, 

or the Nation. 

SOURCE: SP 800-30

Preproduction Model – Version of INFOSEC equipment employing standard parts and 

suitable for complete evaluation of form, design, and performance. 

Preproduction models are often referred to as beta models.

SOURCE: CNSSI-4009

Primary Services Node (PRSN) – A Key Management Infrastructure core node that provides the users’ 

central point of access to KMI products, services, and information.

SOURCE: CNSSI-4009

Principal – An entity whose identity can be authenticated.

SOURCE: FIPS 196

Principal Accrediting Authority –

(PAA)

Senior official with authority and responsibility for all intelligence 

systems within an agency.

SOURCE: CNSSI-4009

Principal Certification Authority –

(CA)

The Principal Certification Authority is a CA designated by an 

agency to interoperate with the FBCA. An agency may designate 

multiple Principal CAs to interoperate with the FBCA.

SOURCE: SP 800-32

Print Suppression – Eliminating the display of characters in order to preserve their 

secrecy.

SOURCE: CNSSI-4009
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Privacy – Restricting access to subscriber or Relying Party information in 

accordance with federal law and agency policy.

SOURCE: SP 800-32

Privacy Impact Assessment (PIA) – An analysis of how information is handled: 1) to ensure handling 

conforms to applicable legal, regulatory, and policy requirements 

regarding privacy; 2) to determine the risks and effects of collecting, 

maintaining, and disseminating information in identifiable form in an 

electronic information system; and 3) to examine and evaluate 

protections and alternative processes for handling information to 

mitigate potential privacy risks.

SOURCE: SP 800-53; SP 800-18; SP 800-122; CNSSI-4009; OMB 

Memorandum 03-22

Privacy System – Commercial encryption system that affords telecommunications 

limited protection to deter a casual listener, but cannot withstand a 

technically competent cryptanalytic attack.

SOURCE: CNSSI-4009

Private Key – The secret part of an asymmetric key pair that is typically used to 

digitally sign or decrypt data.

SOURCE: SP 800-63

Private Key – A cryptographic key, used with a public key cryptographic algorithm, 

that is uniquely associated with an entity and is not made public. In 

an asymmetric (public) cryptosystem, the private key is associated 

with a public key. Depending on the algorithm, the private key may 

be used, for example, to:

1) Compute the corresponding public key,

2) Compute a digital signature that may be verified by the 

corresponding public key,

3) Decrypt keys that were encrypted by the corresponding public 

key, or

4) Compute a shared secret during a key-agreement transaction.

SOURCE: SP 800-57 Part 1

Private Key – A cryptographic key used with a public key cryptographic algorithm, 

which is uniquely associated with an entity, and not made public; it is 

used to generate a digital signature; this key is mathematically linked 

with a corresponding public key.

SOURCE: FIPS 196

Private Key – A cryptographic key, used with a public key cryptographic algorithm, 

that is uniquely associated with an entity and is not made public.

SOURCE: FIPS 140-2
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147

In an asymmetric cryptography scheme, the private or secret key of a 

key pair which must be kept confidential and is used to decrypt 

messages encrypted with the public key or to digitally sign messages, 

which can then be validated with the public key.

SOURCE: CNSSI-4009

Privilege – A right granted to an individual, a program, or a process.

SOURCE: CNSSI-4009

Privilege Management – The definition and management of policies and processes that define 

the ways in which the user is provided access rights to enterprise 

systems. It governs the management of the data that constitutes the 

user’s privileges and other attributes, including the storage, 

organization and access to information in directories.

SOURCE: NISTIR 7657

Privileged Account – An information system account with approved authorizations of a 

privileged user.

SOURCE: CNSSI-4009

An information system account with authorizations of a privileged 

user.

SOURCE: SP 800-53

Privileged Accounts – Individuals who have access to set “access rights” for users on a 

given system. Sometimes referred to as system or network 

administrative accounts.

SOURCE: SP 800-12

Privileged Command – A human-initiated command executed on an information system 

involving the control, monitoring, or administration of the system 

including security functions and associated security-relevant 

information.

SOURCE: SP 800-53; CNSSI-4009

Privileged Process – A computer process that is authorized (and, therefore, trusted) to 

perform security-relevant functions that ordinary processes are not 

authorized to perform.

SOURCE: CNSSI-4009

Privileged User – A user that is authorized (and, therefore, trusted) to perform securityrelevant functions that ordinary users are not authorized to perform.

SOURCE: SP 800-53; CNSSI-4009

Probability of Occurrence – See Likelihood of Occurrence.
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148

Probe – A technique that attempts to access a system to learn something about 

the system.

SOURCE: CNSSI-4009

Product Source Node (PSN) – The Key Management Infrastructure core node that provides central 

generation of cryptographic key material. 

SOURCE: CNSSI-4009

Production Model – INFOSEC equipment in its final mechanical and electrical form.

SOURCE: CNSSI-4009

Profiling – Measuring the characteristics of expected activity so that changes to 

it can be more easily identified.

SOURCE: SP 800-61; CNSSI-4009

Promiscuous Mode – A configuration setting for a network interface card that causes it to 

accept all incoming packets that it sees, regardless of their intended 

destinations.

SOURCE: SP 800-94

Proprietary Information (PROPIN) – Material and information relating to or associated with a company's 

products, business, or activities, including but not limited to financial 

information; data or statements; trade secrets; product research and 

development; existing and future product designs and performance 

specifications; marketing plans or techniques; schematics; client lists; 

computer programs; processes; and know-how that has been clearly 

identified and properly marked by the company as proprietary 

information, trade secrets, or company confidential information. The 

information must have been developed by the company and not be 

available to the government or to the public without restriction from 

another source.

SOURCE: CNSSI-4009

Protected Distribution System 

(PDS) –

Wire line or fiber optic system that includes adequate safeguards 

and/or countermeasures (e.g., acoustic, electric, electromagnetic, and 

physical) to permit its use for the transmission of unencrypted 

information through an area of lesser classification or control.

SOURCE: CNSSI-4009

Protection Philosophy – Informal description of the overall design of an information system 

delineating each of the protection mechanisms employed. 

Combination of formal and informal techniques, appropriate to the 

evaluation class, used to show the mechanisms are adequate to 

enforce the security policy.

SOURCE: CNSSI-4009
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Protection Profile – Common Criteria specification that represents an implementationindependent set of security requirements for a category of Target of 

Evaluations (TOE) that meets specific consumer needs.

SOURCE: CNSSI-4009

Protective Distribution System – Wire line or fiber optic system that includes adequate safeguards 

and/or countermeasures (e.g., acoustic, electric, electromagnetic, and 

physical) to permit its use for the transmission of unencrypted 

information.

SOURCE: SP 800-53

Protective Packaging – Packaging techniques for COMSEC material that discourage 

penetration, reveal a penetration has occurred or was attempted, or 

inhibit viewing or copying of keying material prior to the time it is 

exposed for use.

SOURCE: CNSSI-4009

Protective Technologies – Special tamper-evident features and materials employed for the 

purpose of detecting tampering and deterring attempts to 

compromise, modify, penetrate, extract, or substitute information 

processing equipment and keying material.

SOURCE: CNSSI-4009

Protocol – Set of rules and formats, semantic and syntactic, permitting 

information systems to exchange information.

SOURCE: CNSSI-4009

Protocol Data Unit – A unit of data specified in a protocol and consisting of protocol 

information and, possibly, user data.

SOURCE: FIPS 188

Protocol Entity – Entity that follows a set of rules and formats (semantic and syntactic) 

that determines the communication behavior of other entities.

SOURCE: FIPS 188

Proxy – A proxy is an application that “breaks” the connection between client 

and server. The proxy accepts certain types of traffic entering or 

leaving a network and processes it and forwards it. This effectively 

closes the straight path between the internal and external networks 

making it more difficult for an attacker to obtain internal addresses 

and other details of the organization’s internal network. Proxy 

servers are available for common Internet services; for example, a 

Hyper Text Transfer Protocol (HTTP) proxy used for Web access, 

and a Simple Mail Transfer Protocol (SMTP) proxy used for email.

SOURCE: SP 800-44
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An application that “breaks” the connection between client and 

server. The proxy accepts certain types of traffic entering or leaving 

a network and processes it and forwards it.

 

Note: This effectively closes the straight path between the internal 

and external networks, making it more difficult for an attacker to 

obtain internal addresses and other details of the organization’s 

internal network. Proxy servers are available for common Internet 

services; for example, a Hyper Text Transfer Protocol (HTTP) proxy 

used for Web access, and a Simple Mail Transfer Protocol (SMTP) 

proxy used for email. 

SOURCE: CNSSI-4009

Proxy Agent – A software application running on a firewall or on a dedicated proxy 

server that is capable of filtering a protocol and routing it between the 

interfaces of the device.

SOURCE: CNSSI-4009

Proxy Server – A server that services the requests of its clients by forwarding those 

requests to other servers.

SOURCE: CNSSI-4009

Pseudorandom number generator –

(PRNG)

An algorithm that produces a sequence of bits that are uniquely 

determined from an initial value called a seed. The output of the 

PRNG “appears” to be random, i.e., the output is statistically 

indistinguishable from random values. A cryptographic PRNG has 

the additional property that the output is unpredictable, given that the 

seed is not known.

SOURCE: CNSSI-4009

Pseudonym – A false name. 

SOURCE: SP 800-63

1. A subscriber name that has been chosen by the subscriber that is 

not verified as meaningful by identity proofing.

2. An assigned identity that is used to protect an individual’s true 

identity. 

SOURCE: CNSSI-4009

Public Domain Software – Software not protected by copyright laws of any nation that may be 

freely used without permission of, or payment to, the creator, and that 

carries no warranties from, or liabilities to the creator.

SOURCE: CNSSI-4009
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Public Key – The public part of an asymmetric key pair that is typically used to 

verify signatures or encrypt data.

SOURCE: FIPS 201; SP 800-63

Public Key – A cryptographic key, used with a public key cryptographic algorithm,

that is uniquely associated with an entity and may be made public. In 

an asymmetric (public) cryptosystem, the public key is associated 

with a private key. The public key may be

known by anyone and, depending on the algorithm, may be used, for 

example, to:

1) Verify a digital signature that is signed by the corresponding 

private key,

2) Encrypt keys that can be decrypted by the corresponding private 

key, or

3) Compute a shared secret during a key-agreement transaction.

SOURCE: SP 800-57 Part 1

Public Key – A cryptographic key used with a public key cryptographic algorithm, 

uniquely associated with an entity, and which may be made public; it 

is used to verify a digital signature; this key is mathematically linked 

with a corresponding private key.

SOURCE: FIPS 196

Public Key – A cryptographic key used with a public key cryptographic algorithm 

that is uniquely associated with an entity and that may be made 

public.

SOURCE: FIPS 140-2

A cryptographic key that may be widely published and is used to 

enable the operation of an asymmetric cryptography scheme. This 

key is mathematically linked with a corresponding private key. 

Typically, a public key can be used to encrypt, but not decrypt, or to 

validate a signature, but not to sign.

SOURCE: CNSSI-4009

Public Key Certificate – A digital document issued and digitally signed by the private key of a 

Certificate authority that binds the name of a Subscriber to a public 

key. The certificate indicates that the Subscriber identified in the 

certificate has sole control and access to the private key.

SOURCE: SP 800-63

Public Key Certificate – A set of data that unambiguously identifies an entity, contains the 

entity's public key, and is digitally signed by a trusted third party 

(certification authority).

SOURCE: FIPS 196
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Public Key Certificate – A set of data that uniquely identifies an entity, contains the entity’s 

public key, and is digitally signed by a trusted party, thereby binding 

the public key to the entity.

SOURCE: FIPS 140-2

See Also Certificate.

Public Key (Asymmetric) 

Cryptographic Algorithm –

A cryptographic algorithm that uses two related keys, a public key 

and a private key. The two keys have the property that deriving the 

private key from the public key is computationally infeasible.

SOURCE: FIPS 140-2

Public Key Cryptography – Encryption system that uses a public-private key pair for encryption 

and/or digital signature.

SOURCE: CNSSI-4009

Public Key Enabling (PKE) – The incorporation of the use of certificates for security services such 

as authentication, confidentiality, data integrity, and non-repudiation.

SOURCE: CNSSI-4009

Public Key Infrastructure (PKI) – A set of policies, processes, server platforms, software, and 

workstations used for the purpose of administering certificates and 

public-private key pairs, including the ability to issue, maintain, and 

revoke public key certificates.

SOURCE: SP 800-32; SP 800-63

Public Key Infrastructure – An architecture which is used to bind public keys to entities, enable 

other entities to verify public key bindings, revoke such bindings, and 

provide other services critical to managing public keys.

SOURCE: FIPS 196

A Framework that is established to issue, maintain, and revoke public 

key certificates.

SOURCE: FIPS 186

A support service to the PIV system that provides the cryptographic 

keys needed to perform digital signature-based identity verification 

and to protect communications and storage of sensitive verification 

system data within identity cards and the verification system.

SOURCE: FIPS 201
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The framework and services that provide for the generation, 

production, distribution, control, accounting, and destruction of 

public key certificates. Components include the personnel, policies, 

processes, server platforms, software, and workstations used for the 

purpose of administering certificates and public-private key pairs, 

including the ability to issue, maintain, recover, and revoke public 

key certificates.

SOURCE: CNSSI-4009

Public Seed – A starting value for a pseudorandom number generator. The value 

produced by the random number generator may be made public. The 

public seed is often called a “salt.”

SOURCE: CNSSI-4009

Purge – Rendering sanitized data unrecoverable by laboratory attack methods.

SOURCE: SP 800-88; CNSSI-4009

Quadrant – Short name referring to technology that provides tamper-resistant 

protection to cryptographic equipment.

SOURCE: CNSSI-4009

Qualitative Assessment – Use of a set of methods, principles, or rules for assessing risk based 

on nonnumeric categories or levels. 

SOURCE: SP 800-30

Quality of Service – The measurable end-to-end performance properties of a network 

service, which can be guaranteed in advance by a Service-Level 

Agreement between a user and a service provider, so as to satisfy 

specific customer application requirements. Note: These properties 

may include throughput (bandwidth), transit delay (latency), error 

rates, priority, security, packet loss, packet jitter, etc.

SOURCE: CNSSI-4009

Quantitative Assessment – Use of a set of methods, principles, or rules for assessing risks based 

on the use of numbers where the meanings and proportionality of 

values are maintained inside and outside the context of the 

assessment. 

SOURCE: SP 800-30

Quarantine – Store files containing malware in isolation for future disinfection or 

examination.

SOURCE: SP 800-69
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Radio Frequency Identification –

(RFID)

A form of automatic identification and data capture (AIDC) that uses 

electric or magnetic fields at radio frequencies to transmit 

information.

SOURCE: SP 800-98

Random Bit Generator (RBG) – A device or algorithm that outputs a sequence of binary bits that 

appears to be statistically independent and unbiased. An RBG is 

either a DRBG or an NRBG. 

SOURCE: SP 800-90A

Random Number Generator –

(RNG)

A process used to generate an unpredictable series of numbers. Each 

individual value is called random if each of the values in the total 

population of values has an equal probability of being selected.

SOURCE: CNSSI-4009

Random Number Generator –

(RNG)

Random Number Generators (RNGs) used for cryptographic 

applications typically produce a sequence of zero and one bits that 

may be combined into sub-sequences or blocks of random numbers. 

There are two basic classes: deterministic and nondeterministic. A 

deterministic RNG consists of an algorithm that produces a sequence 

of bits from an initial value called a seed. A nondeterministic RNG 

produces output that is dependent on some unpredictable physical 

source that is outside human control.

SOURCE: FIPS 140-2

Randomizer – Analog or digital source of unpredictable, unbiased, and usually 

independent bits. Randomizers can be used for several different 

functions, including key generation or to provide a starting state for a 

key generator.

SOURCE: CNSSI-4009

RBAC – See Role-Based Access Control.

Read – Fundamental operation in an information system that results only in 

the flow of information from an object to a subject.

SOURCE: CNSSI-4009

Read Access – Permission to read information in an information system.

SOURCE: CNSSI-4009

Real-Time Reaction – Immediate response to a penetration attempt that is detected and 

diagnosed in time to prevent access.

SOURCE: CNSSI-4009
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Recipient Usage Period – The period of time during the cryptoperiod of a symmetric key when 

protected information is processed. 

SOURCE: SP 800-57 Part 1

Reciprocity – Mutual agreement among participating enterprises to accept each 

other’s security assessments in order to reuse information system 

resources and/or to accept each other’s assessed security posture in 

order to share information.

SOURCE: CNSSI-4009

Mutual agreement among participating organizations to accept

each other’s security assessments in order to reuse information

system resources and/or to accept each other’s assessed security

posture in order to share information.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; SP 800-39

Records – The recordings (automated and/or manual) of evidence of activities 

performed or results achieved (e.g., forms, reports, test results), 

which serve as a basis for verifying that the organization and the 

information system are performing as intended. Also used to refer to 

units of related data fields (i.e., groups of data fields that can be 

accessed by a program and that contain the complete set of 

information on particular items).

SOURCE: SP 800-53; SP 800-53A; CNSSI-4009

All books, papers, maps, photographs, machine-readable materials, or 

other documentary materials, regardless of physical form or 

characteristics, made or received by an agency of the United States 

government under federal law or in connection with the transaction 

of public business and preserved or appropriate for preservation by 

that agency or its legitimate successor as evidence of the 

organization, functions, policies, decisions, procedures, operations, or 

other activities of the government or because of the informational 

value of the data in them. [44 U.S.C. SEC. 3301]

SOURCE: FIPS 200

Records Management – The process for tagging information for records-keeping 

requirements as mandated in the Federal Records Act and the 

National Archival and Records Requirements.

SOURCE: CNSSI-4009

Recovery Point Objective – The point in time to which data must be recovered after an outage.

SOURCE: SP 800-34
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Recovery Time Objective – The overall length of time an information system’s components can 

be in the recovery phase before negatively impacting the 

organization’s mission or mission/business functions.

SOURCE: SP 800-34

Recovery Procedures – Actions necessary to restore data files of an information system and 

computational capability after a system failure.

SOURCE: CNSSI-4009

RED – In cryptographic systems, refers to information or messages that 

contain sensitive or classified information that is not encrypted. See 

also BLACK.

SOURCE: CNSSI-4009

Red Signal – Any electronic emission (e.g., plain text, key, key stream, subkey 

stream, initial fill, or control signal) that would divulge national 

security information if recovered.

SOURCE: CNSSI-4009

Red Team – A group of people authorized and organized to emulate a potential 

adversary’s attack or exploitation capabilities against an enterprise’s 

security posture. The Red Team’s objective is to improve enterprise 

Information Assurance by demonstrating the impacts of successful 

attacks and by demonstrating what works for the defenders (i.e., the 

Blue Team) in an operational environment.

SOURCE: CNSSI-4009

Red Team Exercise – An exercise, reflecting real-world conditions, that is conducted as a 

simulated adversarial attempt to compromise organizational missions 

and/or business processes to provide a comprehensive assessment of 

the security capability of the information system and organization.

SOURCE: SP 800-53

Red/Black Concept – Separation of electrical and electronic circuits, components, 

equipment, and systems that handle unencrypted information (Red), 

in electrical form, from those that handle encrypted information 

(Black) in the same form.

SOURCE: CNSSI-4009

Reference Monitor – The security engineering term for IT functionality that—

1) controls all access,

2) cannot be bypassed,

3) is tamper-resistant, and 

4) provides confidence that the other three items are true.

SOURCE: SP 800-33
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Concept of an abstract machine that enforces Target of Evaluation 

(TOE) access control policies.

SOURCE: CNSSI-4009

Registration – The process through which a party applies to become a subscriber of 

a Credentials Service Provider (CSP) and a Registration Authority 

validates the identity of that party on behalf of the CSP.

SOURCE: CNSSI-4009

The process through which an Applicant applies to become a 

Subscriber of a CSP and an RA validates the identity of the Applicant 

on behalf of the CSP. 

SOURCE: SP 800-63

Registration Authority (RA) – A trusted entity that establishes and vouches for the identity of a 

Subscriber to a CSP. The RA may be an integral part of a CSP, or it 

may be independent of a CSP, but it has a relationship to the CSP(s).

SOURCE: SP 800-63; CNSSI-4009

Registration Authority –

(RA)

Organization responsible for assignment of unique identifiers to 

registered objects.

SOURCE: FIPS 188

Rekey – To change the value of a cryptographic key that is being used in a 

cryptographic system/application.

SOURCE: CNSSI-4009

Rekey (a certificate) – To change the value of a cryptographic key that is being used in a 

cryptographic system application; this normally entails issuing a new 

certificate on the new public key.

SOURCE: SP 800-32

Release Prefix – Prefix appended to the short title of U.S.-produced keying material to 

indicate its foreign releasability. "A" designates material that is 

releasable to specific allied nations, and "U.S." designates material 

intended exclusively for U. S. use.

SOURCE: CNSSI-4009

Relying Party – An entity that relies upon the subscriber’s credentials, typically to 

process a transaction or grant access to information or a system.

SOURCE: CNSSI-4009
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An entity that relies upon the Subscriber's token and credentials or a 

Verifier's assertion of a Claimant’s identity, typically to process a 

transaction or grant access to information or a system. 

SOURCE: SP 800-63

Remanence – Residual information remaining on storage media after clearing. See 

Magnetic Remanence and Clearing.

SOURCE: CNSSI-4009

Remediation – The act of correcting a vulnerability or eliminating a threat. Three 

possible types of remediation are installing a patch, adjusting 

configuration settings, or uninstalling a software application.

SOURCE: SP 800-40

The act of mitigating a vulnerability or a threat.

SOURCE: CNSSI-4009

Remediation Plan – A plan to perform the remediation of one or more threats or 

vulnerabilities facing an organization’s systems. The plan typically 

includes options to remove threats and vulnerabilities and priorities 

for performing the remediation.

SOURCE: SP 800-40

Remote Access – Access to an organizational information system by a user (or an 

information system acting on behalf of a user) communicating 

through an external network (e.g., the Internet).

SOURCE: SP 800-53

Access by users (or information systems) communicating external 

to an information system security perimeter. 

SOURCE: SP 800-18

The ability for an organization’s users to access its nonpublic 

computing resources from external locations other than the 

organization’s facilities.

SOURCE: SP 800-46

Access to an organization's nonpublic information system by an 

authorized user (or an information system) communicating through 

an external, non-organization-controlled network (e.g., the Internet).

SOURCE: CNSSI-4009

Remote Diagnostics/Maintenance – Maintenance activities conducted by authorized individuals 

communicating through an external network (e.g., the Internet).

SOURCE: CNSSI-4009
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Remote Maintenance – Maintenance activities conducted by individuals communicating 

external to an information system security perimeter.

SOURCE: SP 800-18

Maintenance activities conducted by individuals communicating 

through an external network (e.g., the Internet).

SOURCE: SP 800-53

Remote Rekeying – Procedure by which a distant crypto-equipment is rekeyed 

electrically. See Automatic Remote Rekeying and Manual Remote 

Rekeying.

SOURCE: CNSSI-4009

Removable Media – Portable electronic storage media such as magnetic, optical, and 

solid-state devices, which can be inserted into and removed from a 

computing device, and that is used to store text, video, audio, and 

image information. Such devices have no independent processing 

capabilities. Examples include hard disks, floppy disks, zip drives, 

compact disks (CDs), thumb drives, pen drives, and similar USB 

storage devices.

SOURCE: CNSSI-4009

Portable electronic storage media such as magnetic, optical, and

Solid-state devices, which can be inserted into and removed from

a computing device, and that is used to store text, video, audio,

and image information. Examples include hard disks, floppy

disks, zip drives, compact disks, thumb drives, pen drives, and

similar USB storage devices.

SOURCE: SP 800-53

Renew (a certificate) – The act or process of extending the validity of the data binding 

asserted by a public key certificate by issuing a new certificate.

SOURCE: SP 800-32

Repair Action – NSA-approved change to a COMSEC end-item that does not affect 

the original characteristics of the end-item and is provided for 

optional application by holders. Repair actions are limited to minor 

electrical and/or mechanical improvements to enhance operation, 

maintenance, or reliability. They do not require an identification 

label, marking, or control but must be fully documented by changes 

to the maintenance manual.

SOURCE: CNSSI-4009
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Replay Attacks – An attack that involves the capture of transmitted authentication or 

access control information and its subsequent retransmission with the 

intent of producing an unauthorized effect or gaining unauthorized 

access.

SOURCE: CNSSI-4009

Repository – A database containing information and data relating to certificates as 

specified in a CP; may also be referred to as a directory.

SOURCE: SP 800-32

Reserve Keying Material – Key held to satisfy unplanned needs. See Contingency Key.

SOURCE: CNSSI-4009

Residual Risk – The remaining potential risk after all IT security measures are 

applied. There is a residual risk associated with each threat.

SOURCE: SP 800-33

Portion of risk remaining after security measures have been applied.

SOURCE: CNSSI-4009; SP 800-30

Residue – Data left in storage after information-processing operations are 

complete, but before degaussing or overwriting has taken place.

SOURCE: CNSSI-4009

Resilience – The ability to quickly adapt and recover from any known or unknown 

changes to the environment through holistic implementation of risk 

management, contingency, and continuity planning.

SOURCE: SP 800-34

The ability to continue to: (i) operate under adverse conditions or 

stress, even if in a degraded or debilitated state, while maintaining 

essential operational capabilities; and (ii) recover to an effective 

operational posture in a time frame consistent with mission needs. 

SOURCE: SP 800-137

Resource Encapsulation – Method by which the reference monitor mediates accesses to an 

information system resource. Resource is protected and not directly 

accessible by a subject. Satisfies requirement for accurate auditing of 

resource usage.

SOURCE: CNSSI-4009

Responder – The entity that responds to the initiator of the authentication 

exchange.

SOURCE: FIPS 196
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Responsible Individual – A trustworthy person designated by a sponsoring organization to 

authenticate individual applicants seeking certificates on the basis of 

their affiliation with the sponsor.

SOURCE: SP 800-32

Responsibility to Provide – An information distribution approach whereby relevant essential 

information is made readily available and discoverable to the 

broadest possible pool of potential users.

SOURCE: CNSSI-4009

Restricted Data – All data concerning (i) design, manufacture, or utilization of atomic 

weapons; (ii) the production of special nuclear material; or (iii) the 

use of special nuclear material in the production of energy, but shall 

not include data declassified or removed from the Restricted Data 

category pursuant to Section 142 [of the Atomic Energy Act of 

1954].

SOURCE: SP 800-53; Atomic Energy Act of 1954

Revoke a Certificate – To prematurely end the operational period of a certificate effective at 

a specific date and time.

SOURCE: SP 800-32

RFID – See Radio Frequency Identification.

Rijndael – Cryptographic algorithm specified in the Advanced Encryption 

Standard (AES).

SOURCE: FIPS 197

Risk – The level of impact on organizational operations (including mission, 

functions, image, or reputation), organizational assets, or individuals 

resulting from the operation of an information system given the 

potential impact of a threat and the likelihood of that threat occurring.

SOURCE: FIPS 200

The level of impact on organizational operations (including mission, 

functions, image, or reputation), organizational assets, individuals, 

other organizations, or the Nation resulting from the operation of an 

information system given the potential impact of a threat and the 

likelihood of that threat occurring.

SOURCE: SP 800-60
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A measure of the extent to which an entity is threatened by a 

potential circumstance or event, and typically a function of: (i) the 

adverse impacts that would arise if the circumstance or event occurs; 

and (ii) the likelihood of occurrence.

Note: Information system-related security risks are those risks that 

arise from the loss of confidentiality, integrity, or availability of 

information or information systems and consider the adverse impacts 

to organizational operations (including mission, functions, image, or 

reputation), organizational assets, individuals, other organizations, 

and the Nation.

SOURCE: SP 800-53

A measure of the extent to which an entity is threatened by a 

potential circumstance or event, and typically a function of: (1) the 

adverse impacts that would arise if the circumstance or event occurs; 

and (2) the likelihood of occurrence.

Note: Information system-related security risks are those risks that arise 

from the loss of confidentiality, integrity, or availability of information or 

information systems and reflect the potential adverse impacts to 

organizational operations (including mission, functions, image, or 

reputation), organizational assets, individuals, other organizations, and the 

Nation.

SOURCE: CNSSI-4009

A measure of the extent to which an entity is threatened by a

potential circumstance or event, and typically a function of: (i)

the adverse impacts that would arise if the circumstance or event

occurs; and (ii) the likelihood of occurrence.

[Note: Information system-related security risks are those risks that arise from

the loss of confidentiality, integrity, or availability of information or information

systems and reflect the potential adverse impacts to organizational operations

(including mission, functions, image, or reputation), organizational assets,

individuals, other organizations, and the Nation. Adverse impacts to the Nation

include, for example, compromises to information systems that support critical

infrastructure applications or are paramount to government continuity of

operations as defined by the Department of Homeland Security.]

SOURCE: SP 800-37; SP 800-53A

Risk-Adaptable Access Control –

(RAdAC)

A form of access control that uses an authorization policy that takes 

into account operational need, risk, and heuristics.

SOURCE: CNSSI-4009

Risk Analysis – The process of identifying the risks to system security and 

determining the likelihood of occurrence, the resulting impact, and 

the additional safeguards that mitigate this impact. Part of risk 

management and synonymous with risk assessment.

SOURCE: SP 800-27
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Examination of information to identify the risk to an information 

system. See Risk Assessment.

SOURCE: CNSSI-4009

Risk Assessment – The process of identifying risks to organizational operations 

(including mission, functions, image, or reputation), organizational 

assets, individuals, other organizations, and the Nation, arising 

through the operation of an information system. 

Part of risk management, incorporates threat and vulnerability 

analyses and considers mitigations provided by security controls 

planned or in place. Synonymous with risk analysis.

SOURCE: SP 800-53; SP 800-53A; SP 800-37

The process of identifying, prioritizing, and estimating risks. This 

includes determining the extent to which adverse circumstances or 

events could impact an enterprise. Uses the results of threat and 

vulnerability assessments to identify risk to organizational operations 

and evaluates those risks in terms of likelihood of occurrence and 

impacts if they occur. The product of a risk assessment is a list of 

estimated potential impacts and unmitigated vulnerabilities. Risk 

assessment is part of risk management and is conducted throughout 

the Risk Management Framework (RMF).

SOURCE: CNSSI-4009

Risk Assessment Methodology – A risk assessment process, together with a risk model, assessment 

approach, and analysis approach. 

SOURCE: SP 800-30

Risk Assessment Report – The report which contains the results of performing a risk assessment 

or the formal output from the process of assessing risk. 

SOURCE: SP 800-30

Risk Assessor – The individual, group, or organization responsible for conducting a 

risk assessment. 

SOURCE: SP 800-30

Risk Executive –

(or Risk Executive Function)

An individual or group within an organization that helps to ensure 

that: (i) security risk-related considerations for individual information 

systems, to include the authorization decisions for those systems, are 

viewed from an organization-wide perspective with regard to the 

overall strategic goals and objectives of the organization in carrying 

out its missions and business functions; and (ii) managing risk from 

individual information systems is consistent across the organization, 

reflects organizational risk tolerance, and is considered along with 

other organizational risks affecting mission/business success.

SOURCE: CNSSI-4009; SP 800-53A; SP 800-37; SP 800-39
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Risk Management – The process of managing risks to organizational operations

(including mission, functions, image, reputation), organizational

assets, individuals, other organizations, and the Nation, resulting

from the operation of an information system, and includes: (i) the

conduct of a risk assessment; (ii) the implementation of a risk

mitigation strategy; and (iii) employment of techniques and

procedures for the continuous monitoring of the security state of

the information system.

SOURCE: SP 800-53; SP 800-53A; SP 800-37

Risk Management – The process of managing risks to organizational operations 

(including mission, functions, image, or reputation), organizational 

assets, or individuals resulting from the operation of an information 

system, and includes:

1) the conduct of a risk assessment; 

2) the implementation of a risk mitigation strategy; and 

3) employment of techniques and procedures for the continuous 

monitoring of the security state of the information system.

SOURCE: FIPS 200

Risk Management – The process of managing risks to agency operations (including 

mission, functions, image, or reputation), agency assets, or 

individuals resulting from the operation of an information system. It 

includes risk assessment; cost-benefit analysis; the selection, 

implementation, and assessment of security controls; and the formal 

authorization to operate the system. The process considers 

effectiveness, efficiency, and constraints due to laws, directives, 

policies, or regulations.

SOURCE: SP 800-82; SP 800-34

The process of managing risks to organizational operations 

(including mission, functions, image, or reputation), organizational 

assets, individuals, other organizations, or the nation resulting from 

the operation or use of an information system, and includes: (1) the 

conduct of a risk assessment; (2) the implementation of a risk 

mitigation strategy; (3) employment of techniques and procedures for 

the continuous monitoring of the security state of the information 

system; and (4) documenting the overall risk management program.

SOURCE: CNSSI-4009

The program and supporting processes to manage information 

security risk to organizational operations (including mission, 

functions, image, reputation), organizational assets, individuals, other 

organizations, and the Nation, and includes: (i) establishing the 

context for risk-related activities; (ii) assessing risk; (iii) responding 

to risk once determined; and (iv) monitoring risk over time. 

SOURCE: SP 800-39
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Risk Management Framework – A structured approach used to oversee and manage risk for an 

enterprise. 

SOURCE: CNSSI-4009

Risk Mitigation –

Prioritizing, evaluating, and implementing the appropriate riskreducing controls/countermeasures recommended from the risk 

management process.

SOURCE: CNSSI-4009; SP 800-30; SP 800-39

Risk Model – A key component of a risk assessment methodology (in addition to 

assessment approach and analysis approach) that defines key terms 

and assessable risk factors. 

SOURCE: SP 800-30

Risk Monitoring – Maintaining ongoing awareness of an organization’s risk 

environment, risk management program, and associated activities to 

support risk decisions. 

SOURCE: SP 800-30; SP 800-39

Risk Response – Accepting, avoiding, mitigating, sharing, or transferring risk to 

organizational operations (i.e., mission, functions, image, or 

reputation), organizational assets, individuals, other organizations, or 

the Nation. 

SOURCE: SP 800-30; SP 800-39

Risk Response Measure – A specific action taken to respond to an identified risk.

SOURCE: SP 800-39

Risk Tolerance – The level of risk an entity is willing to assume in order to achieve a 

potential desired result.

SOURCE: SP 800-32

The defined impacts to an enterprise’s information systems that an 

entity is willing to accept.

SOURCE: CNSSI-4009

Robust Security Network (RSN) – A wireless security network that only allows the creation of Robust 

Security Network Associations (RSNAs).

SOURCE: SP 800-48
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Robust Security Network 

Association (RSNA) –

A logical connection between communicating IEEE 802.11 entities 

established through the IEEE 802.11i key management scheme, also 

known as the four-way handshake.

SOURCE: SP 800-48

Robustness – The ability of an Information Assurance entity to operate correctly 

and reliably across a wide range of operational conditions, and to fail 

gracefully outside of that operational range.

SOURCE: CNSSI-4009

Rogue Device – An unauthorized node on a network.

SOURCE: SP 800-115

Role – A group attribute that ties membership to function. When an entity 

assumes a role, the entity is given certain rights that belong to that 

role. When the entity leaves the role, those rights are removed. The 

rights given are consistent with the functionality that the entity needs 

to perform the expected tasks.

SOURCE: CNSSI-4009

Role-Based Access Control –

(RBAC)

A model for controlling access to resources where permitted actions 

on resources are identified with roles rather than with individual 

subject identities.

SOURCE: SP 800-95

Access control based on user roles (i.e., a collection of access

authorizations a user receives based on an explicit or implicit

assumption of a given role). Role permissions may be inherited

through a role hierarchy and typically reflect the permissions needed 

to perform defined functions within an organization. A given role 

may apply to a single individual or to several individuals.

SOURCE: SP 800-53; CNSSI-4009

Root Cause Analysis – A principle-based, systems approach for the identification of 

underlying causes associated with a particular set of risks. 

SOURCE: SP 800-30; SP 800-39

Root Certification Authority – In a hierarchical Public Key Infrastructure, the Certification 

Authority whose public key serves as the most trusted datum (i.e., the 

beginning of trust paths) for a security domain.

SOURCE: SP 800-32; CNSSI-4009
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Rootkit – A set of tools used by an attacker after gaining root-level access to a 

host to conceal the attacker’s activities on the host and permit the 

attacker to maintain root-level access to the host through covert 

means.

SOURCE: CNSSI-4009

Round Key – Round keys are values derived from the Cipher Key using the Key 

Expansion routine; they are applied to the State in the Cipher and 

Inverse Cipher.

SOURCE: FIPS 197

Rule-Based Security Policy – A security policy based on global rules imposed for all subjects. 

These rules usually rely on a comparison of the sensitivity of the 

objects being accessed and the possession of corresponding attributes 

by the subjects requesting access.

SOURCE: SP 800-33

A security policy based on global rules imposed for all subjects. 

These rules usually rely on a comparison of the sensitivity of the 

objects being accessed and the possession of corresponding attributes 

by the subjects requesting access. Also known as discretionary 

access control (DAC). 

SOURCE: CNSSI-4009

Rules of Engagement (ROE) – Detailed guidelines and constraints regarding the execution of 

information security testing. The ROE is established before the start 

of a security test, and gives the test team authority to conduct defined 

activities without the need for additional permissions.

SOURCE: SP 800-115

Ruleset – A table of instructions used by a controlled interface to determine 

what data is allowable and how the data is handled between 

interconnected systems.

SOURCE: SP 800-115; CNSSI-4009

A set of directives that govern the access control functionality of a 

firewall. The firewall uses these directives to determine how packets 

should be routed between its interfaces.

SOURCE: SP 800-41

S-box – Nonlinear substitution table used in several byte substitution 

transformations and in the Key Expansion routine to perform a onefor-one substitution of a byte value.

SOURCE: FIPS 197
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S/MIME – A set of specifications for securing electronic mail. Secure/ 

Multipurpose Internet Mail Extensions (S/MIME) is based upon the 

widely used MIME standard and describes a protocol for adding 

cryptographic security services through MIME encapsulation of 

digitally signed and encrypted objects. The basic security services 

offered by S/MIME are authentication, non-repudiation of origin, 

message integrity, and message privacy. Optional security services 

include signed receipts, security labels, secure mailing lists, and an 

extended method of identifying the signer’s certificate(s).

SOURCE: SP 800-49

Safeguards – Protective measures prescribed to meet the security requirements 

(i.e., confidentiality, integrity, and availability) specified for an 

information system. Safeguards may include security features, 

management constraints, personnel security, and security of physical 

structures, areas, and devices. Synonymous with security controls and 

countermeasures.

SOURCE: SP 800-53; SP 800-37; FIPS 200; CNSSI-4009

Safeguarding Statement – Statement affixed to a computer output or printout that states the 

highest classification being processed at the time the product was 

produced and requires control of the product, at that level, until 

determination of the true classification by an authorized individual. 

Synonymous with banner.

SOURCE: CNSSI-4009

Salt – A non-secret value that is used in a cryptographic process, usually to 

ensure that the results of computations for one instance cannot be 

reused by an Attacker.

SOURCE: SP 800-63; CNSSI-4009

Sandboxing – A method of isolating application modules into distinct fault domains 

enforced by software. The technique allows untrusted programs 

written in an unsafe language, such as C, to be executed safely within 

the single virtual address space of an application. Untrusted machine 

interpretable code modules are transformed so that all memory 

accesses are confined to code and data segments within their fault 

domain. Access to system resources can also be controlled through a 

unique identifier associated with each domain.

SOURCE: SP 800-19

A restricted, controlled execution environment that prevents 

potentially malicious software, such as mobile code, from accessing 

any system resources except those for which the software is 

authorized.

SOURCE: CNSSI-4009
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Sanitization – Process to remove information from media such that information 

recovery is not possible. It includes removing all labels, markings, 

and activity logs.

SOURCE: FIPS 200

A general term referring to the actions taken to render data written on 

media unrecoverable by both ordinary and, for some forms of 

sanitization, extraordinary means.

SOURCE: SP 800-53; CNSSI-4009

SCADA – See Supervisory Control and Data Acquisition.

Scanning – Sending packets or requests to another system to gain information to 

be used in a subsequent attack.

SOURCE: CNSSI-4009

Scatternet – A chain of piconets created by allowing one or more Bluetooth 

devices to each be a slave in one piconet and act as the master for 

another piconet simultaneously. A scatternet allows several devices 

to be networked over an extended distance.

SOURCE: SP 800-121

Scavenging – Searching through object residue to acquire data.

SOURCE: CNSSI-4009

Scoping Guidance – A part of tailoring guidance providing organizations with specific

policy/regulatory-related, technology-related, system component

allocation-related, operational/environmental-related, physical

infrastructure-related, public access-related, scalability-related,

common control-related, and security objective-related

considerations on the applicability and implementation of individual 

security controls in the security control baseline.

SOURCE: SP 800-53

Scoping Guidance – Specific factors related to technology, infrastructure, public access, 

scalability, common security controls, and risk that can be considered 

by organizations in the applicability and implementation of 

individual security controls in the security control baseline.

SOURCE: FIPS 200; CNSSI-4009

Secret Key – A cryptographic key that is used with a secret-key (symmetric) 

cryptographic algorithm that is uniquely associated with one or more 

entities and is not made public. The use of the term “secret” in this 

context does not imply a classification level, but rather implies the

need to protect the key from disclosure.

SOURCE: SP 800-57 Part 1
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A cryptographic key that is used with a symmetric cryptographic 

algorithm that is uniquely associated with one or more entities and is 

not made public. The use of the term “secret” in this context does not 

imply a classification level, but rather implies the need to protect the 

key from disclosure.

SOURCE: CNSSI-4009

Secret Key – A cryptographic key that must be protected from unauthorized 

disclosure to protect data encrypted with the key. The use of the term 

“secret” in this context does not imply a classification level; rather, 

the term implies the need to protect the key from disclosure or 

substitution.

SOURCE: FIPS 201

Secret Key – A cryptographic key that is uniquely associated with one or more 

entities. The use of the term “secret” in this context does not imply a 

classification level, but rather implies the need to protect the key 

from disclosure or substitution.

SOURCE: FIPS 198

Secret Key – A cryptographic key, used with a secret key cryptographic algorithm, 

that is uniquely associated with one or more entities and should not 

be made public.

SOURCE: FIPS 140-2

Secret Key (symmetric) 

Cryptographic Algorithm –

A cryptographic algorithm that uses a single secret key for both 

encryption and decryption.

SOURCE: FIPS 140-2

A cryptographic algorithm that uses a single key (i.e., a secret key) 

for both encryption and decryption. 

SOURCE: CNSSI-4009

Secret Seed – A secret value used to initialize a pseudorandom number generator. 

SOURCE: CNSSI-4009

Secure/Multipurpose Internet Mail 

Extensions (S/MIME) –

A set of specifications for securing electronic mail. S/MIME is based 

upon the widely used MIME standard [MIME] and describes a 

protocol for adding cryptographic security services through MIME 

encapsulation of digitally signed and encrypted objects. The basic 

security services offered by S/MIME are authentication, nonrepudiation of origin, message integrity, and message privacy. 

Optional security services include signed receipts, security labels, 

secure mailing lists, and an extended method of identifying the 

signer’s certificate(s).

SOURCE: SP 800-49; CNSSI-4009
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Secure Communication Protocol – A communication protocol that provides the appropriate

confidentiality, authentication, and content-integrity protection.

SOURCE: SP 800-57 Part 1; CNSSI-4009

Secure Communications – Telecommunications deriving security through use of NSA-approved 

products and/or Protected Distribution Systems.

SOURCE: CNSSI-4009

Secure DNS (SECDNS) – Configuring and operating DNS servers so that the security goals of 

data integrity and source authentication are achieved and maintained.

SOURCE: SP 800-81

Secure Erase – An overwrite technology using firmware-based process to overwrite 

a hard drive. Is a drive command defined in the ANSI ATA and 

SCSI disk drive interface specifications, which runs inside drive 

hardware. It completes in about 1/8 the time of 5220 block erasure. 

SOURCE: SP 800-88

Secure Hash Algorithm (SHA) – A hash algorithm with the property that is computationally infeasible 

1) to find a message that corresponds to a given message digest, or 2) 

to find two different messages that produce the same message digest.

SOURCE: CNSSI-4009
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Secure Hash Standard –

This Standard specifies secure hash algorithms -SHA-1, SHA-224, 

SHA-256, SHA-384, SHA-512, SHA-512/224 and SHA-512/256 -for 

computing a condensed representation of electronic data (message). 

When a message of any length less than 2

64 

bits (for SHA-1, SHA224 and SHA-256) or less than 2

128 

bits (for SHA-384, SHA-512, 

SHA-512/224 and SHA-512/256) is input to a hash algorithm, the 

result is an output called a message digest. The message digests range 

in length from 160 to 512 bits, depending on the algorithm. Secure 

hash algorithms are typically used with other cryptographic 

algorithms, such as digital signature algorithms and keyed-hash 

message authentication codes, or in the generation of random 

numbers (bits). 

The hash algorithms specified in this Standard are called secure 

because, for a given algorithm, it is computationally infeasible 1) 

to find a message that corresponds to a given message digest, or 2) 

to find two different messages that produce the same message 

digest. Any change to a message will, with a very high 

probability, result in a different message digest. This will result in 

a verification failure when the secure hash algorithm is used with 

a digital signature algorithm or a keyed-hash message 

authentication algorithm.

SOURCE: FIPS 180-4

Specification for a secure hash algorithm that can generate a 

condensed message representation called a message digest.

SOURCE: CNSSI-4009

Secure Socket Layer (SSL) – A protocol used for protecting private information during 

transmission via the Internet. 

Note: SSL works by using a public key to encrypt data that's 

transferred over the SSL connection. Most Web browsers support 

SSL, and many Web sites use the protocol to obtain confidential user 

information, such as credit card numbers. By convention, URLs that 

require an SSL connection start with “https:” instead of “http:.”

SOURCE: CNSSI-4009

Secure State – Condition in which no subject can access any object in an 

unauthorized manner.

SOURCE: CNSSI-4009
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Secure Subsystem – Subsystem containing its own implementation of the reference 

monitor concept for those resources it controls. Secure subsystem 

must depend on other controls and the base operating system for the 

control of subjects and the more primitive system objects.

SOURCE: CNSSI-4009

Security – A condition that results from the establishment and maintenance of 

protective measures that enable an enterprise to perform its mission 

or critical functions despite risks posed by threats to its use of 

information systems. Protective measures may involve a 

combination of deterrence, avoidance, prevention, detection, 

recovery, and correction that should form part of the enterprise’s risk 

management approach. 

SOURCE: CNSSI-4009

Security Assertion Markup 

Language (SAML) –

An XML-based security specification developed by the Organization 

for the Advancement of Structured Information Standards (OASIS) 

for exchanging authentication (and authorization) information 

between trusted entities over the Internet. 

SOURCE: SP 800-63

A framework for exchanging authentication and authorization 

information. Security typically involves checking the credentials 

presented by a party for authentication and authorization. SAML 

standardizes the representation of these credentials in an XML format 

called “assertions,” enhancing the interoperability between disparate 

applications.

SOURCE: SP 800-95

A protocol consisting of XML-based request and response message 

formats for exchanging security information, expressed in the form of 

assertions about subjects, between online business partners.

SOURCE: CNSSI-4009

Security Association – A relationship established between two or more entities to enable 

them to protect data they exchange. 

SOURCE: CNSSI-4009

Security Attribute – A security-related quality of an object. Security attributes may be 

represented as hierarchical levels, bits in a bit map, or numbers. 

Compartments, caveats, and release markings are examples of 

security attributes.

SOURCE: FIPS 188
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An abstraction representing the basic properties or characteristics of 

an entity with respect to safeguarding information; typically 

associated with internal data structures (e.g., records, buffers, files) 

within the information system which are used to enable the 

implementation of access control and flow control policies; reflect 

special dissemination, handling, or distribution instructions; or 

support other aspects of the information security policy. 

SOURCE: SP 800-53; CNSSI-4009

Security Authorization – See Authorization.

Security Authorization –

(To Operate)

See Authorization (to operate).

SOURCE: CNSSI-4009

Security Authorization Boundary – See Authorization Boundary.

Security Automation Domain – An information security area that includes a grouping of tools, 

technologies, and data. 

SOURCE: SP 800-137

Security Banner – A banner at the top or bottom of a computer screen that states the 

overall classification of the system in large, bold type. Also can refer 

to the opening screen that informs users of the security implications 

of accessing a computer resource.

SOURCE: CNSSI-4009

Security Categorization – The process of determining the security category for information or 

an information system. See Security Category.

SOURCE: SP 800-53

The process of determining the security category for information

or an information system. Security categorization methodologies

are described in CNSS Instruction 1253 for national security

systems and in FIPS 199 for other than national security systems.

SOURCE: SP 800-37; SP 800-53A; SP 800-39

Security Category – The characterization of information or an information system based 

on an assessment of the potential impact that a loss of confidentiality, 

integrity, or availability of such information or information system 

would have on organizational operations, organizational assets, or 

individuals.

SOURCE: FIPS 200; FIPS 199; SP 800-18
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The characterization of information or an information system based 

on an assessment of the potential impact that a loss of confidentiality, 

integrity, or availability of such information or information system 

would have on organizational operations, organizational assets, 

individuals, other organizations, and the Nation. 

SOURCE: SP 800-53; CNSSI-4009; SP 800-60

Security Concept of Operations –

(Security CONOP)

A security-focused description of an information system, its 

operational policies, classes of users, interactions between the system 

and its users, and the system’s contribution to the operational 

mission.

SOURCE: CNSSI-4009

Security Content Automation 

Protocol (SCAP) –

A method for using specific standardized testing methods to enable 

automated vulnerability management, measurement, and policy 

compliance evaluation against a standardized set of security 

requirements.

SOURCE: CNSSI-4009

Security Control Assessment – The testing and/or evaluation of the management, operational, and 

technical security controls in an information system to determine the 

extent to which the controls are implemented correctly, operating as 

intended, and producing the desired outcome with respect to meeting 

the security requirements for the system. 

SOURCE: SP 800-37; SP 800-53; SP 800-53A

The testing and/or evaluation of the management, operational, and 

technical security controls to determine the extent to which the 

controls are implemented correctly, operating as intended, and 

producing the desired outcome with respect to meeting the security 

requirements for the system and/or enterprise.

SOURCE: CNSSI-4009

Security Control Assessor – The individual, group, or organization responsible for conducting

a security control assessment.

SOURCE: SP 800-37; SP 800-53A

Security Control Baseline – The set of minimum security controls defined for a low-impact, 

moderate-impact, or high-impact information system.

SOURCE: SP 800-53; FIPS 200

One of the sets of minimum security controls defined for federal 

information systems in NIST Special Publication 800-53 and CNSS 

Instruction 1253.

SOURCE: SP 800-53A
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Security Control Effectiveness – The measure of correctness of implementation (i.e., how consistently 

the control implementation complies with the security plan) and how 

well the security plan meets organizational needs in accordance with 

current risk tolerance. 

SOURCE: SP 800-137

Security Control Enhancements – Statements of security capability to 1) build in additional, but related, 

functionality to a basic control; and/or 2) increase the strength of a 

basic control.

SOURCE: CNSSI-4009; SP 800-53A; SP 800-39

Statements of security capability to: (i) build in additional, but 

related, functionality to a security control; and/or (ii) increase the 

strength of the control.

SOURCE: SP 800-53; SP 800-18

Security Control Inheritance – A situation in which an information system or application

receives protection from security controls (or portions of security

controls) that are developed, implemented, assessed, authorized,

and monitored by entities other than those responsible for the

system or application; entities either internal or external to the

organization where the system or application resides. 

See Common Control.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; CNSSI-4009

Security Controls – The management, operational, and technical controls (i.e., safeguards 

or countermeasures) prescribed for an information system to protect 

the confidentiality, integrity, and availability of the system and its 

information.

SOURCE: SP 800-53; SP 800-37; SP 800-53A; SP 800-60; FIPS 

200; FIPS 199; CNSSI-4009

Security Controls Baseline – The set of minimum security controls defined for a low-impact, 

moderate-impact, or high-impact information system.

SOURCE: CNSSI-4009

Security Domain – A set of subjects, their information objects, and a common security 

policy.

SOURCE: SP 800-27

Security Domain – A collection of entities to which applies a single security policy 

executed by a single authority.

SOURCE: FIPS 188
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A domain that implements a security policy and is administered by a 

single authority.

SOURCE: SP 800-37; SP 800-53; CNSSI-4009

Security Engineering – An interdisciplinary approach and means to enable the realization of 

secure systems. It focuses on defining customer needs, security 

protection requirements, and required functionality early in the 

systems development life cycle, documenting requirements, and then 

proceeding with design, synthesis, and system validation while 

considering the complete problem.

SOURCE: CNSSI-4009

Security Fault Analysis (SFA) – An assessment, usually performed on information system hardware, 

to determine the security properties of a device when hardware fault 

is encountered.

SOURCE: CNSSI-4009

Security Features Users Guide –

(SFUG)

Guide or manual explaining how the security mechanisms in a 

specific system work.

SOURCE: CNSSI-4009

Security Filter – A secure subsystem of an information system that enforces security 

policy on the data passing through it.

SOURCE: CNSSI-4009

Security Functions – The hardware, software, and/or firmware of the information system 

responsible for enforcing the system security policy and supporting 

the isolation of code and data on which the protection is based.

SOURCE: SP 800-53

Security Goals – The five security goals are confidentiality, availability, integrity, 

accountability, and assurance.

SOURCE: SP 800-27

Security Impact Analysis – The analysis conducted by an organizational official to determine the 

extent to which changes to the information system have affected the 

security state of the system.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; CNSSI-4009

Security Incident – See Incident.

Security Information and Event 

Management (SIEM) Tool –

Application that provides the ability to gather security data from 

information system components and present that data as actionable 

information via a single interface. 

SOURCE: SP 800-128
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Security Inspection – Examination of an information system to determine compliance with 

security policy, procedures, and practices.

SOURCE: CNSSI-4009

Security Kernel – Hardware, firmware, and software elements of a trusted computing 

base implementing the reference monitor concept. Security kernel 

must mediate all accesses, be protected from modification, and be 

verifiable as correct.

SOURCE: CNSSI-4009

Security Label – The means used to associate a set of security attributes with a specific 

information object as part of the data structure for that object.

SOURCE: SP 800-53

Security Label – A marking bound to a resource (which may be a data unit) that names 

or designates the security attributes of that resource.

SOURCE: FIPS 188

Information that represents or designates the value of one or more 

security relevant-attributes (e.g., classification) of a system resource.

SOURCE: CNSSI-4009

Security Level – A hierarchical indicator of the degree of sensitivity to a certain threat. 

It implies, according to the security policy being enforced, a specific 

level of protection.

SOURCE: FIPS 188

Security Management Dashboard – A tool that consolidates and communicates information relevant to 

the organizational security posture in near real-time to security 

management stakeholders. 

SOURCE: SP 800-128

Security Marking – Human-readable information affixed to information system 

components, removable media, or output indicating the distribution 

limitations, handling caveats, and applicable security markings.

SOURCE: SP 800-53

Security Markings – Human-readable indicators applied to a document, storage media, or 

hardware component to designate security classification, 

categorization, and/or handling restrictions applicable to the 

information contained therein. For intelligence information, these 

could include compartment and sub-compartment indicators and 

handling restrictions. 

SOURCE: CNSSI-4009
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Security Mechanism – A device designed to provide one or more security services usually 

rated in terms of strength of service and assurance of the design.

SOURCE: CNSSI-4009

Security Net Control Station – Management system overseeing and controlling implementation of 

network security policy.

SOURCE: CNSSI-4009

Security Objective – Confidentiality, integrity, or availability.

SOURCE: SP 800-53; SP 800-53A; SP 800-60; SP 800-37; FIPS 

200; FIPS 199

Security Perimeter – See Authorization Boundary.

A physical or logical boundary that is defined for a system, domain, 

or enclave, within which a particular security policy or security 

architecture is applied.

SOURCE: CNSSI-4009

Security Plan – Formal document that provides an overview of the security

requirements for an information system or an information security

program and describes the security controls in place or planned for 

meeting those requirements.

See ‘System Security Plan’ or ‘Information Security Program Plan.’

SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-18

Security Policy – The statement of required protection of the information objects.

SOURCE: SP 800-27

Security Policy – A set of criteria for the provision of security services. It defines and 

constrains the activities of a data processing facility in order to 

maintain a condition of security for systems and data.

SOURCE: FIPS 188

A set of criteria for the provision of security services.

SOURCE: SP 800-37; SP 800-53; CNSSI-4009

Security Posture – The security status of an enterprise’s networks, information, and 

systems based on IA resources (e.g., people, hardware, software, 

policies) and capabilities in place to manage the defense of the 

enterprise and to react as the situation changes.

SOURCE: CNSSI-4009
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Security Program Plan – Formal document that provides an overview of the security 

requirements for an organization-wide information security program 

and describes the program management security controls and 

common security controls in place or planned for meeting those 

requirements.

SOURCE: CNSSI-4009

Security Range – Highest and lowest security levels that are permitted in or on an 

information system, system component, subsystem, or network.

SOURCE: CNSSI-4009

Security-Relevant Change – Any change to a system’s configuration, environment, information 

content, functionality, or users which has the potential to change the 

risk imposed upon its continued operations.

SOURCE: CNSSI-4009

Security-Relevant Event – An occurrence (e.g., an auditable event or flag) considered to have 

potential security implications to the system or its environment that 

may require further action (noting, investigating, or reacting).

SOURCE: CNSSI-4009

Security-Relevant Information – Any information within the information system that can potentially 

impact the operation of security functions in a manner that could 

result in failure to enforce the system security policy or maintain 

isolation of code and data.

SOURCE: SP 800-53

Security Requirements –

Requirements –

Requirements levied on an information system that are derived from 

applicable laws, Executive Orders, directives, policies, standards, 

instructions, regulations, or procedures, or organizational 

mission/business case needs to ensure the confidentiality, integrity, 

and availability of the information being processed, stored, or 

transmitted.

SOURCE: FIPS 200; SP 800-53; SP 800-53A; SP 800-37; CNSSI4009

Security Requirements Baseline – Description of the minimum requirements necessary for an 

information system to maintain an acceptable level of risk.

SOURCE: CNSSI-4009

Security Requirements Traceability

Matrix (SRTM) –

Matrix that captures all security requirements linked to potential risks 

and addresses all applicable C&A requirements. It is, therefore, a 

correlation statement of a system’s security features and compliance 

methods for each security requirement.

SOURCE: CNSSI-4009
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Security Safeguards – Protective measures and controls prescribed to meet the security 

requirements specified for an information system. Safeguards may 

include security features, management constraints, personnel 

security, and security of physical structures, areas, and devices.

SOURCE: CNSSI-4009

Security Service – A capability that supports one, or many, of the security goals. 

Examples of security services are key management, access control, 

and authentication.

SOURCE: SP 800-27

A capability that supports one, or more, of the security requirements 

(Confidentiality, Integrity, Availability). Examples of security 

services are key management, access control, and authentication.

SOURCE: CNSSI-4009

Security Specification – Detailed description of the safeguards required to protect an 

information system.

SOURCE: CNSSI-4009

Security Strength – A measure of the computational complexity associated with 

recovering certain secret and/or security-critical information 

concerning a given cryptographic algorithm from known data (e.g. 

plaintext/ciphertext pairs for a given encryption algorithm).

SOURCE: SP 800-108

A number associated with the amount of work (that is, the number of 

operations) that is required to break a cryptographic algorithm or 

system. Sometimes referred to as a security level.

SOURCE: FIPS 186

Security Tag – Information unit containing a representation of certain securityrelated information (e.g., a restrictive attribute bit map).

SOURCE: FIPS 188

Security Target – Common Criteria specification that represents a set of security 

requirements to be used as the basis of an evaluation of an identified 

Target of Evaluation (TOE).

SOURCE: CNSSI-4009

Security Test & Evaluation –

(ST&E)

Examination and analysis of the safeguards required to protect an 

information system, as they have been applied in an operational 

environment, to determine the security posture of that system.

SOURCE: CNSSI-4009
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Security Testing – Process to determine that an information system protects data and 

maintains functionality as intended.

SOURCE: CNSSI-4009

Seed Key – Initial key used to start an updating or key generation process.

SOURCE: CNSSI-4009

Semi-Quantitative Assessment – Use of a set of methods, principles, or rules for assessing risk based 

on bins, scales, or representative numbers whose values and 

meanings are not maintained in other contexts. 

SOURCE: SP 800-30

Senior Agency Information Security 

Officer (SAISO) –

Official responsible for carrying out the Chief Information Officer 

responsibilities under the Federal Information Security Management 

Act (FISMA) and serving as the Chief Information Officer’s primary 

liaison to the agency’s authorizing officials, information system 

owners, and information system security officers.

SP 800-53 Note: Organizations subordinate to federal agencies may use the 

term Senior Information Security Officer or Chief Information Security 

Officer to denote individuals filling positions with similar responsibilities to 

Senior Agency Information Security Officers.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-60; FIPS 

200; CNSSI-4009; 44 U.S.C., Sec. 3544

Senior Information Security 

Officer –

See Senior Agency Information Security Officer.

Sensitive Compartmented 

Information (SCI) –

Classified information concerning or derived from intelligence 

sources, methods, or analytical processes, which is required to be 

handled within formal access control systems established by the 

Director of National Intelligence. 

SOURCE: SP 800-53; CNSSI-4009

Sensitive Compartmented 

Information Facility (SCIF) –

Accredited area, room, or group of rooms, buildings, or installation 

where SCI may be stored, used, discussed, and/or processed.

SOURCE: CNSSI-4009

Sensitive Information – Information, the loss, misuse, or unauthorized access to or 

modification of, that could adversely affect the national interest or the 

conduct of federal programs, or the privacy to which individuals are 

entitled under 5 U.S.C. Section 552a (the Privacy Act), but that has 

not been specifically authorized under criteria established by an 

Executive Order or an Act of Congress to be kept classified in the 

interest of national defense or foreign policy.

SOURCE: SP 800-53
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Information, the loss, misuse, or unauthorized access to or 

modification of, that could adversely affect the national interest or the 

conduct of federal programs, or the privacy to which individuals are 

entitled under 5 U.S.C. Section 552a (the Privacy Act), but that has 

not been specifically authorized under criteria established by an 

Executive Order or an Act of Congress to be kept classified in the 

interest of national defense or foreign policy. (Systems that are not 

national security systems, but contain sensitive information, are to be 

protected in accordance with the requirements of the Computer 

Security Act of 1987 [P.L.100-235].) 

SOURCE: CNSSI-4009

Sensitivity – A measure of the importance assigned to information by its owner, 

for the purpose of denoting its need for protection.

SOURCE: SP 800-60; CNSSI-4009

Sensitivity Label – Information representing elements of the security label(s) of a subject 

and an object. Sensitivity labels are used by the trusted computing 

base (TCB) as the basis for mandatory access control decisions. See 

Security Label.

SOURCE: CNSSI-4009

Service-Level Agreement – Defines the specific responsibilities of the service provider and sets 

the customer expectations.

SOURCE: CNSSI-4009

Shared Secret – A secret used in authentication that is known to the Claimant and the 

Verifier.

SOURCE: SP 800-63

Shielded Enclosure – Room or container designed to attenuate electromagnetic radiation, 

acoustic signals, or emanations.

SOURCE: CNSSI-4009

Short Title – Identifying combination of letters and numbers assigned to certain 

COMSEC materials to facilitate handling, accounting, and 

controlling.

SOURCE: CNSSI-4009

Signature – A recognizable, distinguishing pattern associated with an attack, such 

as a binary string in a virus or a particular set of keystrokes used to 

gain unauthorized access to a system.

SOURCE: SP 800-61
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A recognizable, distinguishing pattern. See also Attack Signature or 

Digital Signature.

SOURCE: CNSSI-4009

Signature Certificate – A public key certificate that contains a public key intended for 

verifying digital signatures rather than encrypting data or performing 

any other cryptographic functions.

SOURCE: SP 800-32; CNSSI-4009

Signature Generation – Uses a digital signature algorithm and a private key to generate a 

digital signature on data.

SOURCE: SP 800-57 Part 1

The process of using a digital signature algorithm and a private key 

to generate a digital signature on data.

SOURCE: FIPS 186

Signature Validation – The (mathematical) verification of the digital signature and obtaining

the appropriate assurances (e.g., public key validity, private key

possession, etc.).

SOURCE: FIPS 186

Signature Verification – The use of a digital signature algorithm and a public key to verify a 

digital signature on data.

SOURCE: SP 800-57 Part 1

The process of using a digital signature algorithm and a public key to 

verify a digital signature on data.

SOURCE: SP 800-89; FIPS 186

Signed Data – Data on which a digital signature is generated.

SOURCE: FIPS 196

Single Point Keying – Means of distributing key to multiple, local crypto equipment or 

devices from a single fill point.

SOURCE: CNSSI-4009

Single-Hop Problem – The security risks resulting from a mobile software agent moving 

from its home platform to another platform. 

SOURCE: SP 800-19
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Situational Awareness – Within a volume of time and space, the perception of an enterprise’s 

security posture and its threat environment; the 

comprehension/meaning of both taken together (risk); and the 

projection of their status into the near future.

SOURCE: CNSSI-4009

Skimming – The unauthorized use of a reader to read tags without the 

authorization or knowledge of the tag’s owner or the individual in 

possession of the tag.

SOURCE: SP 800-98

Smart Card – A credit card-sized card with embedded integrated circuits that can 

store, process, and communicate information.

SOURCE: CNSSI-4009

Sniffer – See Packet Sniffer or Passive Wiretapping.

Social Engineering – An attempt to trick someone into revealing information (e.g., a 

password) that can be used to attack systems or networks.

SOURCE: SP 800-61

A general term for attackers trying to trick people into revealing 

sensitive information or performing certain actions, such as 

downloading and executing files that appear to be benign but are 

actually malicious.

SOURCE: SP 800-114

The process of attempting to trick someone into revealing 

information (e.g., a password).

SOURCE: SP 800-115

An attempt to trick someone into revealing information (e.g., a 

password) that can be used to attack an enterprise. 

SOURCE: CNSSI-4009

Software – Computer programs and associated data that may be dynamically 

written or modified during execution.

SOURCE: CNSSI-4009

Software Assurance – Level of confidence that software is free from vulnerabilities, either 

intentionally designed into the software or accidentally inserted at 

any time during its life cycle, and that the software functions in the 

intended manner.

SOURCE: CNSSI-4009
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Software System Test and 

Evaluation Process –

Process that plans, develops, and documents the 

qualitative/quantitative demonstration of the fulfillment of all 

baseline functional performance, operational, and interface 

requirements.

SOURCE: CNSSI-4009

Software-Based Fault Isolation – A method of isolating application modules into distinct fault domains 

enforced by software. The technique allows untrusted programs 

written in an unsafe language, such as C, to be executed safely within 

the single virtual address space of an application. Untrusted machine 

interpretable code modules are transformed so that all memory 

accesses are confined to code and data segments within their fault 

domain. Access to system resources can also be controlled through a 

unique identifier associated with each domain.

SOURCE: SP 800-19

Spam – The abuse of electronic messaging systems to indiscriminately send 

unsolicited bulk messages.

SOURCE: SP 800-53

Unsolicited bulk commercial email messages.

SOURCE: SP 800-45

Electronic junk mail or the abuse of electronic messaging systems to 

indiscriminately send unsolicited bulk messages.

SOURCE: CNSSI-4009

Spam Filtering Software – A program that analyzes emails to look for characteristics of spam, 

and typically places messages that appear to be spam in a separate 

email folder.

SOURCE: SP 800-69

Special Access Program (SAP) – A program established for a specific class of classified information 

that imposes safeguarding and access requirements that exceed those 

normally required for information at the same classification level.

SOURCE: SP 800-53; CNSSI-4009

Special Access Program Facility –

(SAPF)

Facility formally accredited by an appropriate agency in accordance 

with DCID 6/9 in which SAP information may be processed.

SOURCE: CNSSI-4009
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Special Character – Any non-alphanumeric character that can be rendered on a standard 

American-English keyboard. Use of a specific special character may 

be application-dependent. 

The list of special characters follows:

` ~ ! @ # $ % ^ & * ( ) _ + | } { “ : ? > < [ ] \ ; ’ , . / - =

SOURCE: CNSSI-4009

Specification – An assessment object that includes document-based artifacts (e.g., 

policies, procedures, plans, system security requirements, functional 

specifications, and architectural designs) associated with an 

information system.

SOURCE: SP 800-53A

Spillage – Security incident that results in the transfer of classified or CUI 

information onto an information system not accredited (i.e., 

authorized) for the appropriate security level.

SOURCE: CNSSI-4009

Split Knowledge – A procedure by which a cryptographic key is split into n multiple key 

components, individually providing no knowledge of the original 

key, which can be subsequently combined to recreate the original 

cryptographic key. If knowledge of k (where k is less than or equal 

to n) components is required to construct the original key, then 

knowledge of any k-1 key components provides no information about 

the original key other than, possibly, its length.

SOURCE: SP 800-57 Part 1

Split Knowledge – A process by which a cryptographic key is split into multiple key 

components, individually sharing no knowledge of the original key, 

that can be subsequently input into, or output from, a cryptographic 

module by separate entities and combined to recreate the original 

cryptographic key.

SOURCE: FIPS 140-2

1. Separation of data or information into two or more parts, each part 

constantly kept under control of separate authorized individuals or 

teams so that no one individual or team will know the whole data.

2. A process by which a cryptographic key is split into multiple key 

components, individually sharing no knowledge of the original key, 

which can be subsequently input into, or output from, a cryptographic 

module by separate entities and combined to recreate the original 

cryptographic key.

SOURCE: CNSSI-4009
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Spoofing – “IP spoofing” refers to sending a network packet that appears to 

come from a source other than its actual source.

SOURCE: SP 800-48

Spoofing – Involves—

1) the ability to receive a message by masquerading as the legitimate 

receiving destination, or

2) masquerading as the sending machine and sending a message to a 

destination.

SOURCE: FIPS 191

1. Faking the sending address of a transmission to gain illegal entry 

into a secure system. Impersonating, masquerading, piggybacking, 

and mimicking are forms of spoofing.

2. The deliberate inducement of a user or resource to take incorrect 

action. 

SOURCE: CNSSI-4009

Spread Spectrum – Telecommunications techniques in which a signal is transmitted in a 

bandwidth considerably greater than the frequency content of the 

original information. Frequency hopping, direct sequence spreading, 

time scrambling, and combinations of these techniques are forms of 

spread spectrum.

SOURCE: CNSSI-4009

Spyware – Software that is secretly or surreptitiously installed into an 

information system to gather information on individuals or 

organizations without their knowledge; a type of malicious code.

SOURCE: SP 800-53; CNSSI-4009

SSL – See Secure Sockets Layer.

Standard – A published statement on a topic specifying characteristics, usually 

measurable, that must be satisfied or achieved in order to comply 

with the standard.

SOURCE: FIPS 201

Start-Up KEK Key-encryption-key held in common by a group of potential 

communicating entities and used to establish ad hoc tactical 

networks.

SOURCE: CNSSI-4009

State – Intermediate Cipher result that can be pictured as a rectangular array 

of bytes.

SOURCE: FIPS 197
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Static Key – A key that is intended for use for a relatively long period of time and 

is typically intended for use in many instances of a cryptographic key 

establish scheme

SOURCE: SP 800-57 Part 1

Status Monitoring – Monitoring the information security metrics defined by the 

organization in the information security ISCM strategy. 

SOURCE: SP 800-137

Steganography – The art and science of communicating in a way that hides the 

existence of the communication. For example, a child pornography 

image can be hidden inside another graphic image file, audio file, or 

other file format.

SOURCE: SP 800-72; SP 800-101

The art, science, and practice of communicating in a way that hides 

the existence of the communication. 

SOURCE: CNSSI-4009

Storage Object – Object supporting both read and write accesses to an information 

system.

SOURCE: CNSSI-4009

Strength of Mechanism (SoM) – A scale for measuring the relative strength of a security mechanism.

SOURCE: CNSSI-4009

Striped Core – A network architecture in which user data traversing a core IP 

network is decrypted, filtered and re-encrypted one or more times. 

Note: The decryption, filtering, and re-encryption are performed

within a “Red gateway”; consequently, the core is “striped” because 

the data path is alternately Black, Red, and Black. 

SOURCE: CNSSI-4009

Strong Authentication – The requirement to use multiple factors for authentication and 

advanced technology, such as dynamic passwords or digital 

certificates, to verify an entity’s identity. 

SOURCE: CNSSI-4009

Subassembly – Major subdivision of an assembly consisting of a package of parts, 

elements, and circuits that perform a specific function.

SOURCE: CNSSI-4009
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Subject – Generally an individual, process, or device causing information to 

flow among objects or changes to the system state. 

See Object.

SOURCE: SP 800-53

An active entity (generally an individual, process, or device) that 

causes information to flow among objects or changes the system 

state. See also Object.

SOURCE: CNSSI-4009

Subject Security Level – Sensitivity label(s) of the objects to which the subject has both read 

and write access. Security level of a subject must always be 

dominated by the clearance level of the user associated with the 

subject.

SOURCE: CNSSI-4009

Subordinate Certification 

Authority –

In a hierarchical PKI, a Certification Authority whose certificate 

signature key is certified by another CA, and whose activities are 

constrained by that other CA.

SOURCE: SP 800-32; CNSSI-4009

Subscriber – A party who receives a credential or token from a CSP (Credentials 

Service Provider) and becomes a claimant in an authentication 

protocol.

SOURCE: CNSSI-4009

A party who receives a credential or token from a CSP (Credentials 

Service Provider).

SOURCE: SP 800-63

Subsystem – A major subdivision or component of an information system 

consisting of information, information technology, and personnel that 

perform one or more specific functions. 

SOURCE: SP 800-53; SP 800-53A; SP 800-37

Suite A – A specific set of classified cryptographic algorithms used for the 

protection of some categories of restricted mission-critical 

information.

SOURCE: CNSSI-4009

Suite B – A specific set of cryptographic algorithms suitable for protecting 

national security systems and information throughout the U.S.

government and to support interoperability with allies and coalition 

partners.

SOURCE: CNSSI-4009, as modified
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Superencryption – Process of encrypting encrypted information. Occurs when a 

message, encrypted off-line, is transmitted over a secured, online 

circuit, or when information encrypted by the originator is 

multiplexed onto a communications trunk, which is then bulk 

encrypted.

SOURCE: CNSSI-4009

Superior Certification Authority – In a hierarchical PKI, a Certification Authority who has certified the 

certificate signature key of another CA, and who constrains the 

activities of that CA.

SOURCE: SP 800-32; CNSSI-4009

Supersession – Scheduled or unscheduled replacement of COMSEC material with a 

different edition.

SOURCE: CNSSI-4009

Supervisory Control and Data 

Acquisition (SCADA) – 

A generic name for a computerized system that is capable of 

gathering and processing data and applying operational controls over 

long distances. Typical uses include power transmission and 

distribution and pipeline systems. SCADA was designed for the 

unique communication challenges (delays, data integrity, etc.) posed 

by the various media that must be used, such as phone lines, 

microwave, and satellite. Usually shared rather than dedicated.

SOURCE: SP 800-82

Networks or systems generally used for industrial controls or to 

manage infrastructure such as pipelines and power systems.

SOURCE: CNSSI-4009

Supplementation (Assessment 

Procedures) –

The process of adding assessment procedures or assessment details to 

assessment procedures in order to adequately meet the organization’s 

risk management needs.

SOURCE: SP 800-53A

Supplementation 

(Security Controls) –

The process of adding security controls or control enhancements to a 

security control baseline from NIST Special Publication 800-53 or 

CNSS Instruction 1253 in order to adequately meet the organization’s 

risk management needs.

SOURCE: SP 800-53A; SP 800-39

Supply Chain – A system of organizations, people, activities, information, and 

resources, possibly international in scope, that provides products or 

services to consumers.

SOURCE: SP 800-53; CNSSI-4009
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Supply Chain Attack – Attacks that allow the adversary to utilize implants or other 

vulnerabilities inserted prior to installation in order to infiltrate data, 

or manipulate information technology hardware, software, operating 

systems, peripherals (information technology products) or services at 

any point during the life cycle.

SOURCE: CNSSI-4009

Suppression Measure – Action, procedure, modification, or device that reduces the level of, 

or inhibits the generation of, compromising emanations in an 

information system.

SOURCE: CNSSI-4009

Surrogate Access – See Discretionary Access Control.

Syllabary – List of individual letters, combination of letters, or syllables, with 

their equivalent code groups, used for spelling out words or proper 

names not present in the vocabulary of a code. A syllabary may also 

be a spelling table.

SOURCE: CNSSI-4009

Symmetric Encryption Algorithm – Encryption algorithms using the same secret key for encryption and 

decryption.

SOURCE: SP 800-49; CNSSI-4009

Symmetric Key – A cryptographic key that is used to perform both the cryptographic 

operation and its inverse, for example to encrypt and decrypt, or 

create a message authentication code and to verify the code.

SOURCE: SP 800-63; CNSSI-4009

Symmetric Key – A single cryptographic key that is used with a secret (symmetric) key 

algorithm.

SOURCE: SP 800-21 [2nd Ed]

Synchronous Crypto-Operation – Encryption algorithms using the same secret key for encryption and 

decryption. 

SOURCE: CNSSI-4009

System – See Information System.

Any organized assembly of resources and procedures united and 

regulated by interaction or interdependence to accomplish a set of 

specific functions.

SOURCE: CNSSI-4009

System Administrator – A person who manages the technical aspects of a system.

SOURCE: SP 800-40
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Individual responsible for the installation and maintenance of an 

information system, providing effective information system 

utilization, adequate security parameters, and sound implementation 

of established Information Assurance policy and procedures.

SOURCE: CNSSI-4009

System Assets – Any software, hardware, data, administrative, physical, 

communications, or personnel resource within an information system.

SOURCE: CNSSI-4009

System Development Life Cycle –

(SDLC)

The scope of activities associated with a system, encompassing the 

system’s initiation, development and acquisition, implementation, 

operation and maintenance, and ultimately its disposal that instigates 

another system initiation. 

SOURCE: SP 800-34; CNSSI-4009

System Development 

Methodologies –

Methodologies developed through software engineering to manage 

the complexity of system development. Development methodologies 

include software engineering aids and high-level design analysis 

tools.

SOURCE: CNSSI-4009

System High – Highest security level supported by an information system.

SOURCE: CNSSI-4009

System High Mode – Information systems security mode of operation wherein each user, 

with direct or indirect access to the information system, its 

peripherals, remote terminals, or remote hosts, has all of the 

following: a. valid security clearance for all information within an 

information system; b. formal access approval and signed 

nondisclosure agreements for all the information stored and/or 

processed (including all compartments, subcompartments and/or 

special access programs); and c. valid need-to-know for some of the 

information contained within the information system.

SOURCE: CNSSI-4009

System Indicator – Symbol or group of symbols in an off-line encrypted message 

identifying the specific cryptosystem or key used in the encryption.

SOURCE: CNSSI-4009

System Integrity – The quality that a system has when it performs its intended function 

in an unimpaired manner, free from unauthorized manipulation of the 

system, whether intentional or accidental.

SOURCE: SP 800-27
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Attribute of an information system when it performs its intended 

function in an unimpaired manner, free from deliberate or inadvertent 

unauthorized manipulation of the system.

SOURCE: CNSSI-4009

System Interconnection – The direct connection of two or more IT systems for the purpose of 

sharing data and other information resources.

SOURCE: SP 800-47; CNSSI-4009

System Low – Lowest security level supported by an information system.

SOURCE: CNSSI-4009

System Of Records – A group of any records under the control of any agency from which 

information is retrieved by the name of the individual or by some 

identifying number, symbol, or other identifying particular assigned 

to the individual.

SOURCE: SP 800-122

System Owner – Person or organization having responsibility for the development, 

procurement, integration, modification, operation and maintenance, 

and/or final disposition of an information system.

SOURCE: CNSSI-4009

System Profile – Detailed security description of the physical structure, equipment 

component, location, relationships, and general operating 

environment of an information system.

SOURCE: CNSSI-4009

System Security – See Information System Security.

System Security Plan – Formal document that provides an overview of the security 

requirements for the information system and describes the security 

controls in place or planned for meeting those requirements.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; SP 800-18; FIPS 200

The formal document prepared by the information system owner (or 

common security controls owner for inherited controls) that provides 

an overview of the security requirements for the system and describes 

the security controls in place or planned for meeting those 

requirements. The plan can also contain as supporting appendices or 

as references, other key security-related documents such as a risk 

assessment, privacy impact assessment, system interconnection 

agreements, contingency plan, security configurations, configuration 

management plan, and incident response plan.

SOURCE: CNSSI-4009
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System Software – The special software within the cryptographic boundary (e.g., 

operating system, compilers or utility programs) designed for a 

specific computer system or family of computer systems to facilitate 

the operation and maintenance of the computer system, associated 

programs, and data.

SOURCE: FIPS 140-2

System-Specific Security Control – A security control for an information system that has not been 

designated as a common security control or the portion of a hybrid 

control that is to be implemented within an information system.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; CNSSI-4009

Systems Security Engineering – See Information Systems Security Engineering.

Systems Security Officer – See Information Systems Security Officer.

Tabletop Exercise – A discussion-based exercise where personnel with roles and 

responsibilities in a particular IT plan meet in a classroom setting or 

in breakout groups to validate the content of the plan by discussing 

their roles during an emergency and their responses to a particular 

emergency situation. A facilitator initiates the discussion by 

presenting a scenario and asking questions based on the scenario.

SOURCE: SP 800-84

Tactical Data – Information that requires protection from disclosure and modification 

for a limited duration as determined by the originator or information 

owner.

SOURCE: CNSSI-4009

Tactical Edge – The platforms, sites, and personnel (U. S. military, allied, coalition 

partners, first responders) operating at lethal risk in a battle space or 

crisis environment characterized by 1) a dependence on information 

systems and connectivity for survival and mission success, 2) high 

threats to the operational readiness of both information systems and 

connectivity, and 3) users are fully engaged, highly stressed, and 

dependent on the availability, integrity, and transparency of their 

information systems.

SOURCE: CNSSI-4009

Tailored Security Control Baseline – A set of security controls resulting from the application of tailoring 

guidance to the security control baseline. See Tailoring.

SOURCE: SP 800-37; SP 800-53; SP 800-53A
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Tailoring – The process by which a security control baseline is modified based 

on: (i) the application of scoping guidance; (ii) the specification of 

compensating security controls, if needed; and (iii) the specification 

of organization-defined parameters in the security controls via 

explicit assignment and selection statements.

SOURCE: SP 800-37; SP 800-53; SP 800-53A; CNSSI-4009

Tailoring (Assessment Procedures) – The process by which assessment procedures defined in Special 

Publication 800-53A are adjusted, or scoped, to match the 

characteristics of the information system under assessment, providing 

organizations with the flexibility needed to meet specific 

organizational requirements and to avoid overly-constrained 

assessment approaches.

SOURCE: SP 800-53A

Tampering – An intentional event resulting in modification of a system, its 

intended behavior, or data.

SOURCE: CNSSI-4009

Target Of Evaluation (TOE) – In accordance with Common Criteria, an information system, part of 

a system or product, and all associated documentation, that is the 

subject of a security evaluation.

SOURCE: CNSSI-4009

Technical Controls – The security controls (i.e., safeguards or countermeasures) for an 

information system that are primarily implemented and executed by 

the information system through mechanisms contained in the 

hardware, software, or firmware components of the system.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; FIPS 200

Technical Non-repudiation – The contribution of public key mechanisms to the provision of 

technical evidence supporting a non-repudiation security service.

SOURCE: SP 800-32

Technical Reference Model(TRM) – A component-driven, technical framework that categorizes the 

standards and technologies to support and enable the delivery of 

service components and capabilities.

SOURCE: CNSSI-4009

Technical Security Controls – Security controls (i.e., safeguards or countermeasures) for an 

information system that are primarily implemented and executed by 

the information system through mechanisms contained in the 

hardware, software, or firmware components of the system.

SOURCE: CNSSI-4009
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Technical Vulnerability 

Information –

Detailed description of a weakness to include the implementable 

steps (such as code) necessary to exploit that weakness.

SOURCE: CNSSI-4009

Telecommunications – Preparation, transmission, communication, or related processing of 

information (writing, images, sounds, or other data) by electrical, 

electromagnetic, electromechanical, electro-optical, or electronic 

means.

SOURCE: CNSSI-4009

Telework – The ability for an organization’s employees and contractors to 

perform work from locations other than the organization’s facilities.

SOURCE: SP 800-46

Tempest – A name referring to the investigation, study, and control of 

unintentional compromising emanations from telecommunications 

and automated information systems equipment.

SOURCE: FIPS 140-2

TEMPEST – A name referring to the investigation, study, and control of 

compromising emanations from telecommunications and automated 

information systems equipment. 

SOURCE: CNSSI-4009

TEMPEST Test – Laboratory or on-site test to determine the nature of compromising 

emanations associated with an information system.

SOURCE: CNSSI-4009

TEMPEST Zone – Designated area within a facility where equipment with appropriate 

TEMPEST characteristics (TEMPEST zone assignment) may be 

operated.

SOURCE: CNSSI-4009

Test – A type of assessment method that is characterized by the process of 

exercising one or more assessment objects under specified conditions 

to compare actual with expected behavior, the results of which are 

used to support the determination of security control effectiveness 

over time.

SOURCE: SP 800-53A

Test Key – Key intended for testing of COMSEC equipment or systems.

SOURCE: CNSSI-4009
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Threat – Any circumstance or event with the potential to adversely impact 

organizational operations (including mission, functions, image, or 

reputation), organizational assets, individuals, other organizations, or 

the Nation through an information system via unauthorized access, 

destruction, disclosure, modification of information, and/or denial of 

service.

SOURCE: SP 800-53; SP 800-53A; SP 800-27; SP 800-60; SP 800-

37; CNSSI-4009

The potential source of an adverse event.

SOURCE: SP 800-61

Threat – Any circumstance or event with the potential to adversely impact 

organizational operations (including mission, functions, image, or 

reputation), organizational assets, or individuals through an 

information system via unauthorized access, destruction, disclosure, 

modification of information, and/or denial of service. Also, the 

potential for a threat-source to successfully exploit a particular 

information system vulnerability.

SOURCE: FIPS 200

Threat Analysis – The examination of threat sources against system vulnerabilities to 

determine the threats for a particular system in a particular 

operational environment.

SOURCE: SP 800-27

See Threat Assessment.

SOURCE: CNSSI-4009

Threat Assessment – Formal description and evaluation of threat to an information system.

SOURCE: SP 800-53; SP 800-18

Process of formally evaluating the degree of threat to an information 

system or enterprise and describing the nature of the threat.

SOURCE: CNSSI-4009; SP 800-53A

Threat Event – An event or situation that has the potential for causing undesirable 

consequences or impact. 

SOURCE: SP 800-30

Threat Monitoring – Analysis, assessment, and review of audit trails and other information 

collected for the purpose of searching out system events that may 

constitute violations of system security.

SOURCE: CNSSI-4009
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Threat Scenario – A set of discrete threat events, associated with a specific threat source 

or multiple threat sources, partially ordered in time. 

SOURCE: SP 800-30

Threat Shifting – Response from adversaries to perceived safeguards and/or 

countermeasures (i.e., security controls), in which the adversaries 

change some characteristic of their intent to do harm in order to avoid 

and/or overcome those safeguards/countermeasures. 

SOURCE: SP 800-30

Threat Source – The intent and method targeted at the intentional exploitation of a 

vulnerability or a situation and method that may accidentally trigger a 

vulnerability. Synonymous with Threat Agent.

SOURCE: FIPS 200; SP 800-53; SP 800-53A; SP 800-37

The intent and method targeted at the intentional exploitation of a 

vulnerability or a situation and method that may accidentally exploit

a vulnerability. 

SOURCE: CNSSI-4009

Time Bomb – Resident computer program that triggers an unauthorized act at a 

predefined time.

SOURCE: CNSSI-4009

Time-Compliance Date – Date by which a mandatory modification to a COMSEC end-item 

must be incorporated if the item is to remain approved for operational 

use.

SOURCE: CNSSI-4009

Time-Dependent Password – Password that is valid only at a certain time of day or during a 

specified interval of time.

SOURCE: CNSSI-4009

TOE Security Functions (TSF) – Set consisting of all hardware, software, and firmware of the TOE 

that must be relied upon for the correct enforcement of the TOE 

Security Policy (TSP).

SOURCE: CNSSI-4009

TOE Security Policy (TSP) – Set of rules that regulate how assets are managed, protected, and 

distributed within the TOE.

SOURCE: CNSSI-4009

Token – Something that the Claimant possesses and controls (typically a key 

or password) that is used to authenticate the Claimant’s identity.

SOURCE: SP 800-63
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Something that the claimant possesses and controls (such as a key or 

password) that is used to authenticate a claim. See also 

Cryptographic Token.

SOURCE: CNSSI-4009

Total Risk – The potential for the occurrence of an adverse event if no mitigating 

action is taken (i.e., the potential for any applicable threat to exploit a 

system vulnerability).

SOURCE: SP 800-16

Tracking Cookie – A cookie placed on a user’s computer to track the user’s activity on 

different Web sites, creating a detailed profile of the user’s behavior.

SOURCE: SP 800-83

Tradecraft Identity – An identity used for the purpose of work-related interactions that 

may or may not be synonymous with an individual’s true identity.

SOURCE: CNSSI-4009

Traditional INFOSEC Program – Program in which NSA acts as the central procurement agency for 

the development and, in some cases, the production of INFOSEC 

items. This includes the Authorized Vendor Program. Modifications 

to the INFOSEC end-items used in products developed and/or 

produced under these programs must be approved by NSA.

SOURCE: CNSSI-4009

Traffic Analysis – A form of passive attack in which an intruder observes information 

about calls (although not necessarily the contents of the messages) 

and makes inferences, e.g., from the source and destination numbers, 

or frequency and length of the messages.

SOURCE: SP 800-24

The analysis of patterns in communications for the purpose of 

gaining intelligence about a system or its users. It does not require 

examination of the content of the communications, which may or 

may not be decipherable. For example, an adversary may be able to 

detect a signal from a reader that could enable it to infer that a 

particular activity is occurring (e.g., a shipment has arrived, someone 

is entering a facility) without necessarily learning an identifier or 

associated data.

SOURCE: SP 800-98
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Gaining knowledge of information by inference from observable 

characteristics of a data flow, even if the information is not directly 

available (e.g., when the data is encrypted). These characteristics 

include the identities and locations of the source(s) and destination(s) 

of the flow, and the flow's presence, amount, frequency, and duration 

of occurrence.

SOURCE: CNSSI-4009

Traffic Encryption Key (TEK) – Key used to encrypt plain text or to superencrypt previously 

encrypted text and/or to decrypt cipher text.

SOURCE: CNSSI-4009

Traffic Padding – Generation of mock communications or data units to disguise the 

amount of real data units being sent.

SOURCE: CNSSI-4009

Traffic-Flow Security (TFS) – Techniques to counter Traffic Analysis.

SOURCE: CNSSI-4009

Training (Information Security) – Training strives to produce relevant and needed (information) 

security skills and competencies.

SOURCE: SP 800-50

Training Assessment – An evaluation of the training efforts.

SOURCE: SP 800-16

Training Effectiveness – A measurement of what a given student has learned from a specific 

course or training event.

SOURCE: SP 800-16

Training Effectiveness Evaluation – Information collected to assist employees and their supervisors in 

assessing individual students’ subsequent on-the-job performance, to 

provide trend data to assist trainers in improving both learning and 

teaching, and to be used in return-on-investment statistics to enable 

responsible officials to allocate limited resources in a thoughtful, 

strategic manner among the spectrum of IT security awareness, 

security literacy, training, and education options for optimal results 

among the workforce as a whole.

SOURCE: SP 800-16

Tranquility – Property whereby the security level of an object cannot change while 

the object is being processed by an information system.

SOURCE: CNSSI-4009
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Transmission – The state that exists when information is being electronically sent 

from one location to one or more other locations.

SOURCE: CNSSI-4009

Transmission Security –

(TRANSEC)

Measures (security controls) applied to transmissions in order to 

prevent interception, disruption of reception, communications 

deception, and/or derivation of intelligence by analysis of 

transmission characteristics such as signal parameters or message 

externals. 

Note: TRANSEC is that field of COMSEC which deals with the security of 

communication transmissions, rather than that of the information being 

communicated.

SOURCE: CNSSI-4009

Trap Door – 1. A means of reading cryptographically protected information by the 

use of private knowledge of weaknesses in the cryptographic 

algorithm used to protect the data.

2. In cryptography, one-to-one function that is easy to compute in one 

direction, yet believed to be difficult to invert without special 

information.

SOURCE: CNSSI-4009

Transport Layer Security (TLS) – An authentication and security protocol widely implemented in 

browsers and Web servers. 

SOURCE: SP 800-63

Triple DES – An implementation of the Data Encryption Standard (DES) algorithm 

that uses three passes of the DES algorithm instead of one as used in 

ordinary DES applications. Triple DES provides much stronger 

encryption than ordinary DES but it is less secure than AES.

SOURCE: CNSSI-4009

Trojan Horse – A computer program that appears to have a useful function, but

also has a hidden and potentially malicious function that evades

security mechanisms, sometimes by exploiting legitimate

authorizations of a system entity that invokes the program.

SOURCE: CNSSI-4009
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Trust Anchor – A public key and the name of a certification authority that is used to 

validate the first certificate in a sequence of certificates. The trust 

anchor’s public key is used to verify the signature on a certificate 

issued by a trust anchor certification authority. The security of the 

validation process depends upon the authenticity and integrity of the 

trust anchor. Trust anchors are often distributed as self-signed 

certificates.

SOURCE: SP 800-57 Part 1

An established point of trust (usually based on the authority of some 

person, office, or organization) from which an entity begins the 

validation of an authorized process or authorized (signed) package. 

A "trust anchor" is sometimes defined as just a public key used for 

different purposes (e.g., validating a Certification Authority, 

validating a signed software package or key, validating the process 

[or person] loading the signed software or key).

SOURCE: CNSSI-4009

A public or symmetric key that is trusted because it is directly built 

into hardware or software, or securely provisioned via out-of-band 

means, rather than because it is vouched for by another trusted entity 

(e.g. in a public key certificate). 

SOURCE: SP 800-63

Trust List – The collection of trusted certificates used by Relying Parties to 

authenticate other certificates.

SOURCE: SP 800-32; CNSSI-4009

Trusted Agent – Entity authorized to act as a representative of an agency in 

confirming Subscriber identification during the registration process. 

Trusted Agents do not have automated interfaces with Certification 

Authorities.

SOURCE: SP 800-32; CNSSI-4009

Trusted Certificate – A certificate that is trusted by the Relying Party on the basis of secure 

and authenticated delivery. The public keys included in trusted 

certificates are used to start certification paths. Also known as a 

"trust anchor."

SOURCE: SP 800-32; CNSSI-4009

Trusted Channel – A channel where the endpoints are known and data integrity is 

protected in transit. Depending on the communications protocol

used, data privacy may be protected in transit. Examples include 

SSL, IPSEC, and secure physical connection.

SOURCE: CNSSI-4009
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Trusted Computer System – A system that employs sufficient hardware and software assurance 

measures to allow its use for processing simultaneously a range of 

sensitive or classified information.

SOURCE: CNSSI-4009

Trusted Computing Base (TCB) – Totality of protection mechanisms within a computer system, 

including hardware, firmware, and software, the combination 

responsible for enforcing a security policy.

SOURCE: CNSSI-4009

Trusted Distribution – Method for distributing trusted computing base (TCB) hardware, 

software, and firmware components that protects the TCB from 

modification during distribution.

SOURCE: CNSSI-4009

Trusted Foundry – Facility that produces integrated circuits with a higher level of 

integrity assurance.

SOURCE: CNSSI-4009

Trusted Identification Forwarding – Identification method used in information system networks whereby 

the sending host can verify an authorized user on its system is 

attempting a connection to another host. The sending host transmits 

the required user authentication information to the receiving host.

SOURCE: CNSSI-4009

Trusted Path – A mechanism by which a user (through an input device) can 

communicate directly with the security functions of the information 

system with the necessary confidence to support the system security 

policy. This mechanism can only be activated by the user or the 

security functions of the information system and cannot be imitated 

by untrusted software.

SOURCE: SP 800-53; CNSSI-4009

Trusted Path – A means by which an operator and a target of evaluation security 

function can communicate with the necessary confidence to support 

the target of evaluation security policy.

SOURCE: FIPS 140-2

Trusted Platform Module (TPM)

Chip –

A tamper-resistant integrated circuit built into some computer 

motherboards that can perform cryptographic operations (including 

key generation) and protect small amounts of sensitive information, 

such as passwords and cryptographic keys.

SOURCE: SP 800-111

Trusted Process – Process that has been tested and verified to operate only as intended.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Trusted Recovery – Ability to ensure recovery without compromise after a system failure.

SOURCE: CNSSI-4009

Trusted Software – Software portion of a trusted computing base (TCB).

SOURCE: CNSSI-4009

Trusted Timestamp – A digitally signed assertion by a trusted authority that a specific 

digital object existed at a particular time.

SOURCE: SP 800-32; CNSSI-4009

Trustworthiness – The attribute of a person or organization that provides confidence to 

others of the qualifications, capabilities, and reliability of that entity 

to perform specific tasks and fulfill assigned responsibilities.

SOURCE: SP 800-79

The attribute of a person or enterprise that provides confidence to 

others of the qualifications, capabilities, and reliability of that entity 

to perform specific tasks and fulfill assigned responsibilities. 

SOURCE: CNSSI-4009; SP 800-39

Security decisions with respect to extended investigations to 

determine and confirm qualifications, and suitability to perform 

specific tasks and responsibilities.

SOURCE: FIPS 201

Trustworthy System – Computer hardware, software and procedures that—

1) are reasonably secure from intrusion and misuse;

2) provide a reasonable level of availability, reliability, and correct 

operation;

3) are reasonably suited to performing their intended functions; and

4) adhere to generally accepted security procedures.

SOURCE: SP 800-32

TSEC – Telecommunications Security.

SOURCE: CNSSI-4009

TSEC Nomenclature – System for identifying the type and purpose of certain items of 

COMSEC material.

SOURCE: CNSSI-4009

Tunneling – Technology enabling one network to send its data via another 

network’s connections. Tunneling works by encapsulating a network 

protocol within packets carried by the second network.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Two-Part Code – Code consisting of an encoding section, in which the vocabulary 

items (with their associated code groups) are arranged in alphabetical 

or other systematic order, and a decoding section, in which the code 

groups (with their associated meanings) are arranged in a separate 

alphabetical or numeric order.

SOURCE: CNSSI-4009

Two-Person Control (TPC) – Continuous surveillance and control of positive control material at all 

times by a minimum of two authorized individuals, each capable of 

detecting incorrect and unauthorized procedures with respect to the 

task being performed and each familiar with established security and 

safety requirements.

SOURCE: CNSSI-4009

Two-Person Integrity (TPI) – System of storage and handling designed to prohibit individual access 

by requiring the presence of at least two authorized individuals, each 

capable of detecting incorrect or unauthorized security procedures 

with respect to the task being performed. See No-Lone Zone.

SOURCE: CNSSI-4009

Type 1 Key – Generated and distributed under the auspices of NSA for use in a 

cryptographic device for the protection of national security 

information.

SOURCE: CNSSI-4009, as modified

Type 1 Product – Cryptographic equipment, assembly or component classified or 

certified by NSA for encrypting and decrypting national security 

information when appropriately keyed. Developed using established 

NSA business processes and containing NSA-approved algorithms. 

Used to protect systems requiring the most stringent protection 

mechanisms.

SOURCE: CNSSI-4009, as modified

Type 2 Key – Generated and distributed under the auspices of NSA for use in a 

cryptographic device for the protection of unclassified information.

SOURCE: CNSSI-4009, as modified

Type 2 Product – Cryptographic equipment, assembly, or component certified by NSA 

for encrypting or decrypting sensitive information when 

appropriately keyed. Developed using established NSA business 

processes and containing NSA-approved algorithms. Used to protect 

systems requiring protection mechanisms exceeding best commercial 

practices including systems used for the protection of unclassified 

information.

SOURCE: CNSSI-4009, as modified
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Type 3 Key – Used in a cryptographic device for the protection of unclassified 

sensitive information, even if used in a Type 1 or Type 2 product.

SOURCE: CNSSI-4009

Type 3 Product – Unclassified cryptographic equipment, assembly, or component used, 

when appropriately keyed, for encrypting or decrypting unclassified 

sensitive U.S. government or commercial information, and to protect 

systems requiring protection mechanisms consistent with standard 

commercial practices. Developed using established commercial 

standards and containing NIST-approved cryptographic 

algorithms/modules or successfully evaluated by the National 

Information Assurance Partnership (NIAP).

SOURCE: CNSSI-4009

Type 4 Key – Used by a cryptographic device in support of its Type 4 functionality,

i.e., any provision of key that lacks U.S. government endorsement or 

oversight.

SOURCE: CNSSI-4009

Type 4 Product – Unevaluated commercial cryptographic equipment, assemblies, or 

components that neither NSA nor NIST certify for any government 

usage. These products are typically delivered as part of commercial 

offerings and are commensurate with the vendor’s commercial 

practices. These products may contain either vendor proprietary 

algorithms, algorithms registered by NIST, or algorithms registered 

by NIST and published in a FIPS.

SOURCE: CNSSI-4009

Type Accreditation – A form of accreditation that is used to authorize multiple instances of 

a major application or general support system for operation at 

approved locations with the same type of computing environment. In 

situations where a major application or general support system is 

installed at multiple locations, a type accreditation will satisfy C&A 

requirements only if the application or system consists of a common 

set of tested and approved hardware, software, and firmware. 

SOURCE: CNSSI-4009

Type Certification – The certification acceptance of replica information systems based on 

the comprehensive evaluation of the technical and nontechnical 

security features of an information system and other safeguards, 

made as part of and in support of the formal approval process, to 

establish the extent to which a particular design and implementation 

meet a specified set of security requirements.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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U.S. Person – Federal law and Executive Order define a U.S. Person as: a citizen of 

the United States; an alien lawfully admitted for permanent 

residence; an unincorporated association with a substantial number of 

members who are citizens of the U.S. or are aliens lawfully admitted 

for permanent residence; and/or a corporation that is incorporated in 

the U.S.

SOURCE: CNSSI-4009

U.S.-Controlled Facility – Base or building to which access is physically controlled by U.S. 

individuals who are authorized U.S. government or U.S. government 

contractor employees.

SOURCE: CNSSI-4009

U.S.-Controlled Space – Room or floor within a facility that is not a U.S.-controlled facility, 

access to which is physically controlled by U.S. individuals who are 

authorized U.S. government or U.S. government contractor 

employees. Keys or combinations to locks controlling entrance to 

U.S.-controlled spaces must be under the exclusive control of U.S. 

individuals who are U.S. government or U.S. government contractor 

employees.

SOURCE: CNSSI-4009

Unauthorized Access –Unauthorized 

Access –

Occurs when a user, legitimate or unauthorized, accesses a resource 

that the user is not permitted to use.

SOURCE: FIPS 191

Any access that violates the stated security policy.

SOURCE: CNSSI-4009

Unauthorized Disclosure – An event involving the exposure of information to entities not 

authorized access to the information.

SOURCE: SP 800-57 Part 1; CNSSI-4009

Unsigned data – Data included in an authentication token, in addition to a digital 

signature. 

SOURCE: FIPS 196

Unclassified – Information that has not been determined pursuant to E.O. 12958, as 

amended, or any predecessor order, to require protection against 

unauthorized disclosure and that is not designated as classified.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

209

United States Government 

Configuration Baseline –

(USGCB)

The United States Government Configuration Baseline (USGCB) 

provides security configuration baselines for Information Technology 

products widely deployed across the federal agencies. The USGCB 

baseline evolved from the federal Desktop Core Configuration 

mandate. The USGCB is a Federal government-wide initiative that 

provides guidance to agencies on what should be done to improve 

and maintain an effective configuration settings focusing primarily 

on security. 

SOURCE: SP 800-128

Untrusted Process – Process that has not been evaluated or examined for correctness and 

adherence to the security policy. It may include incorrect or 

malicious code that attempts to circumvent the security mechanisms.

SOURCE: CNSSI-4009

Update (a Certificate) – The act or process by which data items bound in an existing public 

key certificate, especially authorizations granted to the subject, are 

changed by issuing a new certificate.

SOURCE: SP 800-32; CNSSI-4009

Update (key) – Automatic or manual cryptographic process that irreversibly modifies 

the state of a COMSEC key.

SOURCE: CNSSI-4009

US-CERT – A partnership between the Department of Homeland Security and the 

public and private sectors, established to protect the nation's Internet 

infrastructure. US-CERT coordinates defense against and responses 

to cyber attacks across the nation.

SOURCE: CNSSI-4009

User – Individual or (system) process authorized to access an information 

system.

SOURCE: FIPS 200

Individual, or (system) process acting on behalf of an individual, 

authorized to access an information system.

SOURCE: SP 800-53; SP 800-18; CNSSI-4009

User – An individual or a process (subject) acting on behalf of the individual 

that accesses a cryptographic module in order to obtain cryptographic 

services.

SOURCE: FIPS 140-2

User ID – Unique symbol or character string used by an information system to 

identify a specific user.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

210

User Initialization – A function in the life cycle of keying material; the process whereby a 

user initializes its cryptographic application (e.g., installing and 

initializing software and hardware).

SOURCE: SP 800-57 Part 1

User Partnership Program (UPP) – Partnership between the NSA and a U.S. government agency to 

facilitate development of secure information system equipment 

incorporating NSA-approved cryptography. The result of this 

program is the authorization of the product or system to safeguard 

national security information in the user’s specific application.

SOURCE: CNSSI-4009

User Registration – A function in the life cycle of keying material; a process whereby an 

entity becomes a member of a security domain.

SOURCE: SP 800-57 Part 1

User Representative (COMSEC) – Individual authorized by an organization to order COMSEC keying 

material and interface with the keying system, provide information to 

key users, and ensure the correct type of key is ordered.

SOURCE: CNSSI-4009

User Representative (Risk 

Management) –

The person that defines the system’s operational and functional 

requirements, and who is responsible for ensuring that user 

operational interests are met throughout the systems authorization 

process.

SOURCE: CNSSI-4009

Valid Data Element – A payload, an associated data string, or a nonce that satisfies the 

restrictions of the formatting function.

SOURCE: SP 800-38C

Validation – The process of demonstrating that the system under consideration 

meets in all respects the specification of that system. 

SOURCE: FIPS 201

Confirmation (through the provision of strong, sound, objective 

evidence) that requirements for a specific intended use or application 

have been fulfilled (e.g., a trustworthy credential has been presented, 

or data or information has been formatted in accordance with a 

defined set of rules, or a specific process has demonstrated that 

an entity under consideration meets, in all respects, its defined 

attributes or requirements).

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

211

Variant – One of two or more code symbols having the same plain text 

equivalent.

SOURCE: CNSSI-4009

Verification – Confirmation, through the provision of objective evidence, that 

specified requirements have been fulfilled (e.g., an entity’s 

requirements have been correctly defined, or an entity’s attributes 

have been correctly presented; or a procedure or function performs as 

intended and leads to the expected outcome).

SOURCE: CNSSI-4009

See Also Identity Verification.

Verified Name – A Subscriber name that has been verified by identity proofing.

SOURCE: SP 800-63

Verifier – An entity that verifies the Claimant’s identity by verifying the 

Claimant’s possession and control of a token using an authentication 

protocol. To do this, the Verifier may also need to validate 

credentials that link the token and identity and check their status.

SOURCE: SP 800-63

Verifier – An entity which is or represents the entity requiring an authenticated 

identity. A verifier includes the functions necessary for engaging in 

authentication exchanges.

SOURCE: FIPS 196

Verifier Impersonation Attack – A scenario where the Attacker impersonates the Verifier in an 

authentication protocol, usually to capture information that can be 

used to masquerade as a Claimant to the real Verifier. 

SOURCE: SP 800-63

Virtual Machine (VM) – Software that allows a single host to run one or more guest operating 

systems.

SOURCE: SP 800-115

Virtual Private Network (VPN) – A virtual network, built on top of existing physical networks, that 

provides a secure communications tunnel for data and other 

information transmitted between networks.

SOURCE: SP 800-46

Protected information system link utilizing tunneling, security 

controls (see Information Assurance), and endpoint address 

translation giving the impression of a dedicated line

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

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Virus – A computer program that can copy itself and infect a computer 

without permission or knowledge of the user. A virus might corrupt 

or delete data on a computer, use email programs to spread itself to 

other computers, or even erase everything on a hard disk. 

SOURCE: CNSSI-4009

Vulnerability – Weakness in an information system, system security procedures, 

internal controls, or implementation that could be exploited or 

triggered by a threat source.

SOURCE: SP 800-53; SP 800-53A; SP 800-37; SP 800-60; SP 800-

115; FIPS 200

A weakness in a system, application, or network that is subject to 

exploitation or misuse.

SOURCE: SP 800-61

Weakness in an information system, system security procedures, 

internal controls, or implementation that could be exploited by a 

threat source. 

SOURCE: CNSSI-4009

Vulnerability Analysis – See Vulnerability Assessment.

Vulnerability Assessment – Formal description and evaluation of the vulnerabilities in an 

information system.

SOURCE: SP 800-53; SP 800-37

Systematic examination of an information system or product to 

determine the adequacy of security measures, identify security 

deficiencies, provide data from which to predict the effectiveness of 

proposed security measures, and confirm the adequacy of such 

measures after implementation.

SOURCE: SP 800-53A; CNSSI-4009

Warm Site – An environmentally conditioned workspace that is partially equipped 

with information systems and telecommunications equipment to 

support relocated operations in the event of a significant disruption. 

SOURCE: SP 800-34

Backup site which typically contains the data links and preconfigured 

equipment necessary to rapidly start operations, but does not contain 

live data. Thus commencing operations at a warm site will (at a 

minimum) require the restoration of current data.

SOURCE: CNSSI-4009
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Web Bug – A tiny image, invisible to a user, placed on Web pages in such a way 

to enable third parties to track use of Web servers and collect 

information about the user, including IP address, host name, browser

type and version, operating system name and version, and cookies.

SOURCE: SP 800-28

Malicious code, invisible to a user, placed on Web sites in such a way 

that it allows third parties to track use of Web servers and collect 

information about the user, including IP address, host name, browser 

type and version, operating system name and version, and Web 

browser cookie. 

SOURCE: CNSSI-4009

Web Content Filtering Software – A program that prevents access to undesirable Web sites, typically by 

comparing a requested Web site address to a list of known bad Web 

sites.

SOURCE: SP 800-69

Web Risk Assessment – Processes for ensuring Web sites are in compliance with applicable 

policies.

SOURCE: CNSSI-4009

White Team – 1. The group responsible for refereeing an engagement between a 

Red Team of mock attackers and a Blue Team of actual defenders of 

their enterprise’s use of information systems. In an exercise, the 

White Team acts as the judges, enforces the rules of the exercise, 

observes the exercise, scores teams, resolves any problems that may 

arise, handles all requests for information or questions, and ensures 

that the competition runs fairly and does not cause operational 

problems for the defender's mission. The White Team helps to 

establish the rules of engagement, the metrics for assessing results 

and the procedures for providing operational security for the 

engagement. The White Team normally has responsibility for 

deriving lessons-learned, conducting the post engagement 

assessment, and promulgating results. 

2. Can also refer to a small group of people who have prior 

knowledge of unannounced Red Team activities. The White Team 

acts as observers during the Red Team activity and ensures the scope 

of testing does not exceed a predefined threshold.

SOURCE: CNSSI-4009

Whitelist – A list of discrete entities, such as hosts or applications that are known 

to be benign and are approved for use within an organization and/or 

information system. 

SOURCE: SP 800-128
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

214

Wi-Fi Protected Access-2 (WPA2) – The approved Wi-Fi Alliance interoperable implementation of the 

IEEE 802.11i security standard. For federal government use, the 

implementation must use FIPS-approved encryption, such as AES.

SOURCE: CNSSI-4009

Wiki – Web applications or similar tools that allow identifiable users to add 

content (as in an Internet forum) and allow anyone to edit that 

content collectively. 

SOURCE: CNSSI-4009

Wired Equivalent Privacy (WEP) – A security protocol, specified in the IEEE 802.11 standard, that is 

designed to provide a WLAN with a level of security and privacy 

comparable to what is usually expected of a wired LAN. WEP is no 

longer considered a viable encryption mechanism due to known 

weaknesses. 

SOURCE: SP 800-48

Wireless Access Point (WAP) – A device that acts as a conduit to connect wireless communication 

devices together to allow them to communicate and create a wireless 

network. 

SOURCE: CNSSI-4009

Wireless Application Protocol –

(WAP)

A standard that defines the way in which Internet communications 

and other advanced services are provided on wireless mobile devices.

SOURCE: CNSSI-4009

Wireless Local Area Network –

(WLAN)

A group of wireless networking devices within a limited geographic 

area, such as an office building, that exchange data through radio 

communications. The security of each WLAN is heavily dependent 

on how well each WLAN component—including client devices, APs, 

and wireless switches—is secured throughout the WLAN lifecycle, 

from initial WLAN design and deployment through ongoing 

maintenance and monitoring.

SOURCE: SP 800-153

Wireless Technology – Technology that permits the transfer of information between 

separated points without physical connection. 

Note: Currently wireless technologies use infrared, acoustic, radio 

frequency, and optical.

SOURCE: CNSSI-4009

Work Factor – Estimate of the effort or time needed by a potential perpetrator, with 

specified expertise and resources, to overcome a protective measure.

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

215

Workcraft Identity – Synonymous with Tradecraft Identity.

SOURCE: CNSSI-4009

Worm – A self-replicating, self-propagating, self-contained program that uses 

networking mechanisms to spread itself. See Malicious Code.

SOURCE: CNSSI-4009

Write – Fundamental operation in an information system that results only in 

the flow of information from a subject to an object. See Access 

Type. 

SOURCE: CNSSI-4009

Write Access – Permission to write to an object in an information system.

SOURCE: CNSSI-4009

Write-Blocker – A device that allows investigators to examine media while preventing 

data writes from occurring on the subject media.

SOURCE: SP 800-72

X.509 Certificate – The X.509 public-key certificate or the X.509 attribute certificate, as

defined by the ISO/ITU-T X.509 standard. Most commonly 

(including in this document), an X.509 certificate refers to the X.509 

public-key certificate.

SOURCE: SP 800-57 Part 1

X.509 Public Key Certificate – A digital certificate containing a public key for entity and a name for

the entity, together with some other information that is rendered 

unforgeable by the digital signature of the certification authority that

issued the certificate, encoded in the format defined in the ISO/ITU-T

X.509 standard. SOURCE: SP 800-57 Part 1; CNSSI-4009 adapted

Zero Fill – To fill unused storage locations in an information system with the 

representation of the character denoting "0."

SOURCE: CNSSI-4009

Zeroization – A method of erasing electronically stored data, cryptographic keys, 

and CSPs by altering or deleting the contents of the data storage to 

prevent recovery of the data.

SOURCE: FIPS 140-2

A method of erasing electronically stored data, cryptographic keys, 

and Credentials Service Providers (CSPs) by altering or deleting the 

contents of the data storage to prevent recovery of the data. 

SOURCE: CNSSI-4009
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

216

Zeroize – To remove or eliminate the key from a cryptographic equipment or 

fill device.

SOURCE: CNSSI-4009

Overwrite a memory location with data consisting entirely of bits 

with the value zero so that the data is destroyed and not recoverable. 

This is often contrasted with deletion methods that merely destroy 

reference to data within a file system rather than the data itself. 

SOURCE: SP 800-63

Zombie – A program that is installed on a system to cause it to attack other 

systems.

SOURCE: SP 800-83

Zone Of Control – Three-dimensional space surrounding equipment that processes 

classified and/or sensitive information within which TEMPEST 

exploitation is not considered practical or where legal authority to 

identify and remove a potential TEMPEST exploitation exists. 

SOURCE: CNSSI-4009
NIST IR 7298, Glossary of Key Information Security Terms

217

NON-NIST REFERENCES

40 U.S.C., Sec. 11101 U.S. Code, Title 40 – Public Buildings, Property, and Works, Subtitle 

III – Information Technology Management, Chapter 111 –

General, Section 11101. Definitions.

40 U.S.C., Sec. 11331 U.S. Code, Title 40 – Public Buildings, Property, and Works, Subtitle 

III – Information Technology Management, Chapter 113 –

Responsibility for Acquisitions of Information Technology, 

Subchapter III – Other Responsibilities, Section 11331. 

Responsibilities for federal information systems standards.

41 U.S.C., Sec. 403 Title 41 – Public Contracts, Chapter 7 – Office of Federal 

Procurement Policy, Section 403. Definitions.

44 U.S.C., Sec. 3502 U.S. Code, Title 44 – Public Printing and Documents, Chapter 35 –

Coordination of Federal Information Policy, Subchapter I –

Federal Information Policy, Section 3502. Definitions.

44 U.S.C., Sec. 3541 U.S. Code, Title 44 – Public Printing and Documents, Chapter 35 –

Coordination of Federal Information Policy, Subchapter III –

Information Security, Section 3541. Purposes.

44 U.S.C., Sec. 3542 U.S. Code, Title 44 – Public Printing and Documents, Chapter 35 –

Coordination of Federal Information Policy, Subchapter III –

Information Security, Section 3542. Definitions.

44 U.S.C., Sec. 3544 U.S. Code, Title 44 – Public Printing and Documents, Chapter 35 –

Coordination of Federal Information Policy, Subchapter III –

Information Security, Section 3544. Federal agency 

responsibilities.

47 C.F.R., Part 64, App A Code of Federal Regulations, Title 47 – Telecommunication, Chapter I 

– Federal Communications Commission, Subchapter B – Common 

Carrier Services, Part 64 – Miscellaneous Rules Relating to 

Common Carriers, Appendix A to Part 64 – Telecommunications 

Service Priority (TSP) System for National Security Emergency 

Preparedness (NSEP).

Atomic Energy Act of 1954 Definition of Restricted Data (42 U.S.C., Section 2011).

CNSSI-4009 The Committee on National Security Systems Instruction No 

4009”National Information Assurance Glossary.”

DCID 6/3 Director of Central Intelligence Directive 6/3 “Protecting Sensitive 

Compartmented Information Within Information Systems."

DCID 6/9 Director of Central Intelligence Directive 6/9 “Physical Security Standards 

for Sensitive Compartmented Information Facilities."
NIST IR 7298 Revision 2, Glossary of Key Information Security Terms

218

E.O. 13292 Executive Office of the President, Executive Order 13292— Further 

Amendment to Executive Order 12958, as Amended, Classified 

National Security Information, March 25, 2003.

Federal Information Security 

Management Act (FISMA)

P.L. 107-347, December 2002.

OMB Circular A-130, App. III U.S. Office of Management and Budget, Circular No. A-130 Revised, 

(Transmittal Memorandum No. 4), Appendix III, Security of 

Federal Automated information Resources. November 28, 2000.

OMB Memorandum 02-01 U.S. Office of Management and Budget, Memorandum 02-01, 

Guidance for Preparing and Submitting Security Plans of Action 

and Milestones. October 17, 2001.

OMB Memorandum 03-22 U.S. Office of Management and Budget, Memorandum 03-22, OMB 

Guidance for Implementing the Privacy Provisions of the EGovernment Act of 2002. September 29, 2003.

OMB Memorandum 04-04 U.S. Office of Management and Budget, Memorandum 04-04, OMB 

E-Authentication Guidance for Federal Agencies, December 16, 

2003.

Public Law 104-106 Sec. 

5125(b)

S. 1124, Division E [Public Law 104-106], 104th U.S. Cong., 

Information Technology Management Reform Act, February 10, 

1996. Section 5125(b).