Source: http://www.freepatentsonline.com/y2012/0308001.html
Timestamp: 2020-02-23 02:35:43
Document Index: 468545067

Matched Legal Cases: ['art.\n6', 'art.\n19', 'art 700', 'art 702', 'art 700', 'art 702']

SECURE KEY CREATION - INTERNATIONAL BUSINESS MACHINES CORPORATION
SECURE KEY CREATION
United States Patent Application 20120308001
Key creation includes sending a first public key part from a first system to a second system, receiving a second public key part sent by the second system to the first system and establishing a first secret material in the first system using the first and second public key parts, wherein the first secret material is identical to a second secret material established on the second system using the first and second key parts. Key creation also includes binding key control information to the first secret material in the first system, wherein the key control information includes information relating to key type and key management and deriving a first key material from the combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second system.
Arnold, Todd W. (Charlotte, NC, US)
Dames, Elizabeth A. (Concord, NC, US)
Kisley, Richard V. (Charlotte, NC, US)
Miele, Michael J. (Concord, NC, US)
Sweeny, James W. (Millbrook, NY, US)
13/150592
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1. A computer program product for key creation, the computer program product comprising: a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method, comprising: sending a first public key part from a first system to a second system; receiving a second public key part sent by the second system to the first system; establishing a first secret material in the first system using the first and second public key parts, wherein the first secret material is identical to a second secret material established on the second system using the first and second key parts; binding key control information to the first secret material in the first system, wherein the key control information comprises information relating to key type and key management; and deriving a first key material from a combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second system.
2. The computer program product of claim 1, wherein the second key material is derived from the second secret material and key control information that are bound in the second system, wherein the key control information on the first and second systems are identical.
3. The computer program product of claim 2, comprising establishing the first secret material in the first system using the first and second public key parts and a private key part on the first system and establishing the second secret material in the second system using the first and second public key parts and a private key part on the second system.
4. The computer program product of claim 1, comprising sending key control information from the first system to the second system.
5. The computer program product of claim 1, wherein establishing the first secret material in the first system using the first and second public key parts comprises establishing the first secret material using the first and second public key parts and a local private key part.
6. The computer program product of claim 1, wherein the information relating to key type comprises information relating to categories for use of the first key material.
7. The computer program product of claim 6, wherein the categories for use of the first key material comprises one selected from the group consisting of cipher key, importer key, exporter key, wrapping key, unwrapping key, data key, pin key, key generating key and message authentication code.
8. The computer program product of claim 1, wherein the information relating to key management comprises one selected from the group consisting of: a type of key that can be used to wrap the key material, if the key material is complete; how the key material was created; and limitations on distribution the key material.
9. The computer program product of claim 1, wherein binding the key control information to the first secret material comprises copying the key control information from a key token in the first system and binding the key control information to the first secret material.
10. A method for key creation, comprising: sending, by a first computing system, a first public key part to a second computing system; receiving, at the first computing system, a second public key part sent by the second computing system; establishing a first secret material in the first computing system using a first private key part, the first public key part, and the second public key part, wherein the first secret material is identical to a second secret material established on the second computing system using a second private key part, the first public key part, and the second public key part; binding key control information to the first secret material in the first computing system, wherein the key control information comprises information relating to key type and key management; and deriving a first key material from a combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second computing system.
11. The method of claim 10, wherein the second key material is derived from the second secret material and key control information that are bound in the second system, wherein the key control information on the first and second computing systems are identical.
12. The method of claim 11, comprising sending, from the first computing system, key control information to the second system.
13. The method of claim 11, wherein the information relating to key type comprises information relating to categories for use of the first key material, wherein the categories for use of the first key material comprises one selected from the group consisting of: cipher key, importer key, exporter key, wrapping key, unwrapping key, data key, pin key, key generating key and message authentication code.
14. The method of claim 10 wherein the information relating to key management comprises one selected from the group consisting of: a type of key that can be used to wrap the first key material, if the first key material is complete; how the first key material was created; and limitations on distribution the key material.
15. The method of claim 10, wherein binding the key control information to the first secret material comprises copying the key control information from a key token in the first system and binding the key control information to the first secret material.
16. A system for key creation, comprising: a computer processor; and an application configured to execute on the computer processor, the application implementing a method, the method comprising: sending a first public key part from a first system to a second system; receiving a second public key part sent by the second system to the first system; establishing a first secret material in the first system using the first and second public key parts, wherein the first secret material is identical to a second secret material established on the second system using the first and second key parts; binding key control information to the first secret material in the first system, wherein the key control information comprises information relating to key type and key management; and deriving a first key material from a combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second system.
17. The system of claim 16, wherein the second key material is derived from the second secret material and key control information that are bound in the second system, wherein the key control information on the first and second systems are identical.
18. The system of claim 16, wherein establishing the first secret material in the first system using the first and second public key parts comprises establishing the first secret material using the first and second public key parts and a local private key part.
19. The system of claim 16, wherein the information relating to key type comprises information relating to categories for use of the first key material, wherein the categories for use of the first key material comprises one selected from the group consisting of: cipher key, importer key, exporter key, wrapping key, unwrapping key, data key, pin key, key generating key and message authentication code.
20. The system of claim 16, wherein the information relating to key management comprises one selected from the group consisting of: a type of key that can be used to wrap the first key material, if the first key material is complete; how the first key material was created; and limitations on distribution the first key material.
The present invention relates to data processing, and more specifically, to cryptography methods and structures to enhance security of keys.
Two parties may use a selected method, such as an algorithm, to create secret key material without transmitting the key material itself over a potentially unsecured network. The substantially simultaneous creation of the key material locally by each party may be created from a shared secret that is identical, but formed independently by each party. Information relating to the type of key, management and usage of the key, however, may be in another location, making key management difficult for one or more of the parties.
According to one embodiment of the present invention, a method for key creation is provided. The method includes sending, from a first computing system, a first public key part to a second computing system, receiving, at the first computing system, a second public key part sent by the second computing system and establishing a first secret material in the first computing system using the first and second public key parts, wherein the first secret material is identical to a second secret material established on the second computing system using the first and second key parts. Key creation also includes binding key control information to the first secret material in the first computing system, wherein the key control information includes information relating to key type and key management and deriving a first key material from the combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second computing system.
According to another embodiment of the present invention, a system for key creation is provided. The system includes a computer processor and an application configured to execute on the computer processor, the application implementing a method. The method includes sending, from the first computing system, a first public key part to a second system, receiving, at the first computing system, a second public key part sent by the second system and establishing a first secret material in the first computing system using a first private key part, the first public key part, and the second public key part, wherein the first secret material is identical to a second secret material established on the second computing system using a second private key part, the first public key part, and the second public key part. Key creation also includes binding key control information to the first secret material in the first system, wherein the key control information includes information relating to key type and key management and deriving a first key material from the combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second system.
According to a further embodiment of the present invention, a computer program product for key creation is provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes sending a first public key part from a first system to a second system, receiving a second public key part sent by the second system to the first system and establishing a first secret material in the first system using the first and second public key parts, wherein the first secret material is identical to a second secret material established on the second system using the first and second key parts. Key creation also includes binding key control information to the first secret material in the first system, wherein the key control information includes information relating to key type and key management and deriving a first key material from the combination of the key control information and the first secret material, wherein the first key material is identical to a second key material derived by the second system.
FIG. 6 depicts a block diagram of a payload section of the token of FIG. 2; and
FIG. 7 depicts a block diagram of a process to create key material.
Exemplary embodiments of the invention provide for the secure creation and management of keys (also called “key material”) using a key agreement scheme. Embodiments may use a token (also called “key tokens”) or other suitable structure or device for key material management. An exemplary key token is a data structure that can hold a complete or partial cryptographic key along with a key's management and usage information associated with the key.
Exemplary embodiments enable multiple parties to create identical shared secure keys locally, wherein the key material is derived from secret material cryptographically bound to key control information, such as information relating to key type, key management and key usage, also collectively referred to as key control information. By having selected key control information bound in key material, key usage and management are more easily controlled.
In an embodiment, the key may be removed from the token by a secure module, described below, for accessing and key usage within the secure module. After accessing the key, it may be placed inside the secure key token before sending the token to a location outside the secure module, such as storage within the local system. While being accessed inside the secure module the key and the key control information may be used for any suitable purpose, such as for enciphering/deciphering operations or wrapping/unwrapping operations.
It should be understood that the systems and methods for shared key creation and management may be used with a structure including a key with a relationship with the associated data, metadata and/or other related information. A suitable secure structure contains the key material after its creation using the methods and systems described herein. One arrangement may utilize the key token structure described below to contain the key material after creation of the key.
With reference now to FIGS. 1 and 2, an exemplary system 100 and token 200 for providing secure key creation and management will now be described. The exemplary system 100 creates, uses and/or transmits key tokens and/or key material. The system of FIG. 1 includes a user system 102 in communication over one or more networks 104 with a host system 106. The user system 102 represents a first party that submits key material to be communicated to a second party (e.g., the host system 106). The user system 102 may be a point of sale (POS) terminal that is implemented using a computer executing a computer program for carrying out the processes described herein. The user system 102 may include a hardware security module (HSM), such as a card, software and firmware configured to create, populate and manage the token 200 containing the key material as described herein. An HSM may be described as a piece of hardware and associated software/firmware that acts as a highly secure peripheral device, or secure cryptoprocessor, for the management of cryptographic keys and for the protection of sensitive data and applications.
In the depicted embodiment, an application 108 is used by the HSM on the host system 106 to create, populate and manage the token 200. The user system 102 may be a payment terminal, such as an automated teller machine (ATM) or kiosk, configured to receive user information, such as account information or account PIN. The host system 106 may be a financial institution connected to the user system 102 via one or more of the network(s) 104. The key material resides in a token in storage within the host system 106. The financial institution receives encrypted data from the terminal user system 102 over the network 104, which may include an account number and PIN information. Then the application 108 retrieves the key material from local storage and passes it into the HSM along with the received encrypted data. Inside the HSM, the token with the key material is unwrapped and the unwrapped key from the token is then used to decrypt the encrypted data from user system 102. The data can then be checked and verified, which is then communicated to the application 108. In one exemplary embodiment, the user system 102 includes hardware and software to execute computer instructions to create the token 200 that securely wraps the key material for local use or for transmission to another party, such as the host system 106. In another exemplary embodiment, the host system 106 executes computer instructions to create the token 200 that securely wraps the key material for local use or for transmission to another party, such as the user system 102.
The network(s) 104 may be any type of known networks including, but not limited to, a wide area network (WAN), a local area network (LAN), a global network (e.g. Internet), a virtual private network (VPN), and an intranet. The network 104 may be implemented using a wireless network or any kind of physical network implementation known in the art. The user system 102 may be coupled to the host system 106 through multiple networks (e.g., intranet and Internet). One or more user systems 102 and host systems 106 may be connected to the network 104 in a wired or wireless fashion. In one embodiment, the network 104 is an intranet and one or more user systems 102 execute a user interface application (e.g., a web browser) to contact the host system 106 through the network 104. In another exemplary embodiment, one or more of the user systems 102 is connected directly (i.e., not through the network 104) to the host system 106. In one embodiment, the user system 102 and host system 106 may include a processor (such as a computer processor or microprocessor), associated hardware, software, firmware and/or a computer readable storage medium
The host system 106 depicted in FIG. 1 may be implemented using one or more servers operating in response to a computer program stored in a storage medium accessible by the server. The host system 106 may include one or more hardware security modules (HSM), such as a card, software and firmware configured to create and manage tokens containing the key material as described herein.
The exemplary secure key management methods and structures may be created and performed by components of the system 100 of FIG. 1. The token 200 may reside locally on and be created by the host system 106 or user system 102. For example, the user system 102 may include a token 200 containing key material used to encrypt account data to send to the host system 106. In this embodiment, the token 200 is a data structure that includes several sections (e.g., sections 300, 400, 500 and 600) dedicated to selected tasks such as describing the token and key material. A header section 300 includes data used to interpret fields within sections of the token 200. The exemplary header section 300 is a fixed-size section of the token 200. A wrapping information section 400 is also a fixed-size section that contains information pertinent to how (and if) the key material in a payload section 600 is wrapped. The wrapping information section 400 also includes information about how the key material in the payload section 600 is securely bound to the information in an associated data (AD) section 500. The associated data section 500 may also be described as a key control information section, wherein the section contains fields configured to store various types of key control information, such as a user-defined data to be associated with and/or relating to the key material. The associated data section 500 is a variable-size section that has a small fixed-size portion with some descriptive fields for the key material itself, along with length fields for the variable-size portions of this section. The term “key control information” may also be used to refer to one or more fields within the associated data section 500.
The payload section 600 is where the key material resides in a selected state. In an example, there are three states, including (1) not present, (2) clear and (3) encrypted/bound. In the not present state, the token is a “skeleton” which contains descriptive and policy information in a useful template that can be populated into a specific token with key material at a later time. The clear state may be used for testing purposes or low security applications, where it is useful to support tokens that have unencrypted key material. In the encrypted/bound state, the key material is accompanied with pre-pended and/or post-pended data (key binding material). The key material and pre-pended or post-pended data conforms to and is wrapped using a supported wrapping method indicated by token fields within the wrapping information section 400. The exemplary token 200 enables wrapping of the token sections via a suitable wrapping method, as described below, without altering the token 200 structure. Specifically, the structure of the header 300, wrapping information 400 and associated data 500 sections will not change based on the chosen wrapping method.
The sections of the exemplary token 200 may have fixed or variable sizes. For example, the header section 300 has the fixed size of 8 bytes and the wrapping information section 400 has the fixed size of 22 bytes. The associated data section 500 has an overall variable size composed of the fixed-size portion of 16 bytes plus a sum of variable-sized other portions of the section. Similarly, the payload section 600 has a variable-size depending on the state of the key material. Exemplary payload sizes include: 0 bits for tokens with no key material; the length of the key itself for unencrypted key material; and the length of the key plus the length of the key binding material for tokens that include encrypted key material.
Turning now to FIG. 3, the exemplary header section 300 of the token 200 will now be described. The header section 300 includes several fields used to describe aspects of the token 200. A token identifier field 302 indicates broad token type information to aid processing of the token 200. Token types that may be listed in the token identifier field include internal tokens for local use, external tokens for sending to another party, or zero token types, depending on usage needs and application requirements. A zero token is typically a placeholder, which may be a string of one or more bytes with all zero bits in the first byte, which is passed into an application program interface in a position that a full token is expected in return. A reserved field 304 is set aside for future use. An overall token length field 306 indicates the entire length of the token 200, including the header section 300. A token version number field 308 describes a version of the token 200, which separates this token from legacy token structure types supported by systems from the same manufacturer as the current system 100. This enables the system 100 to access and use current and legacy token types on the same machines. A reserved field 310 is also set aside for future use.
FIG. 4 shows the exemplary wrapping information section 400 which includes fields to describe how the key material in the payload section 600 is wrapped and secured to the associated data section 500 (key control information). A key material state field 402 describes a state of the key material in the payload section 600. Possible states include: no key present; the key is clear; the key and a representation of the key control information, such as a hash, is encrypted under a Key Encrypting Key (KEK); and the key and a representation of the key control information, such as a hash, is encrypted under the secret Master Key (MK) that stays in the HSM.
In the no key present state, the token is a “skeleton” which contains descriptive and policy information in a useful template that can be populated into a specific token with actual key material at a later time. The clear state is used for testing purposes or low security applications. In the encrypted state of KEK and MK, the key material is wrapped and bound by key binding material. The states available in the key material state field 402 are limited by the token identifier field 302, wherein an external token identifier may have a key material state of no key, a clear key or a KEK encryption. Similarly, an internal token identifier may have a key material state of no key, a clear key or an MK encryption. Accordingly, the KEK key material state is used to send the key material to another party, whereas the MK key material state is used locally by a host application.
With continued reference to FIG. 4, the wrapping key verification pattern (KVP) type field 404 specifies the calculation method, such as a cryptographic hash algorithm (also referred to as “hash algorithm”), to apply to the MK or KEK (as described in key material state field 402) used to wrap the payload field 600. The output of the calculation is then compared to the content of a wrapping KVP value field 406 to verify that the correct key has been identified as wrapping the payload section 600. If the values do not match, then the wrong key has been provided and the user is notified of the error. The KVP type field 404 and wrapping KVP value field 406 are not used if the key material state is no key or clear key.
A wrapping method field 408 is used to describe the payload section 600 wrapping method and how it is bound to the associated data section 500. In an embodiment, the user selects, via the HSM, the wrapping method to use when the token 200 is created. This wrapping method can include the layout of the payload section 600, the logical operations to perform on the key used for encryption, such as KEK or MK, and what steps to do with the key used for encryption to make up the final payload section 600, such as additional encryption steps or operations to bind associated data into the secure payload. The logical operations to perform on the key used for encryption are various steps performed in wrapping the payload section 600. As many as 255 wrapping methods, for example, can be described. In one embodiment, four values are assigned to corresponding wrapping methods. Examples of wrapping methods include advanced encryption standard key wrap (AESKW) or a public key encryption scheme that combines algorithms, such as RSAES (Rivest Shamir Adelman Encryption Scheme) with OAEP (Optimal Asymmetric Encryption Padding).
A hash method field 410 describes a hash algorithm applied to the associated data section 500, wherein the resulting hash value is then compared to a stored hash value (field 610) in the payload section 600. This check against the stored value is a mechanism to indicate if the associated data section 500 has been altered. A reserved field 412 is set aside for future use.
Referring now to FIG. 5, the exemplary associated data (AD) section 500 (also referred to as “key control information section” or “associated information section”) includes fields used to describe attributes of the key material and other fields to describe field sizes in this section. An AD version field 501 is used to identify the version of the current AD section 500, thus allowing for future expansion as well as support across multiple versions and layouts. A reserved field 502 is set aside for future use. In addition, reserved fields, in this and other sections, may be utilized to enable alignment of data in the section. A total length of AD field 504 describes the size of the AD section 500, thereby enabling the section to vary in size. A length of AD label field 506 describes the size of an optional AD label field 526 that is passed by the user. In an example, this field gives the label length in bytes wherein the length is either 64 or 0. A length of proprietary data field 508 describes a length in bytes of an extensible proprietary data field 528 (0-255) contained in the AD where the data is placed by the manufacturer of the HSM (either where the token is created or currently resides), such as control and tracking data outside the other data fields. A length of user data field 510 describes the size of an extensible user data field 530, wherein the user can populate the variable length field (0-255) via a provided interface, such as an API for the system. A reserved field 512 is set aside for future use.
A bit length of payload field 514 describes the length of the payload section 600 in bits, which is important for certain wrapping methods used to protect the payload. A reserved field 516 is set aside for future use. A cryptographic algorithm identified in key field 518 indicates which supported cryptographic algorithm can be used with the encrypted key material in the payload. Examples of the algorithm include those used with the following standards: AES, data encryption standard (DES), RSA, Elliptic Curve and message authentication code (MAC). A type of key field 520 defines the categories for use of the key material with the algorithm from field 518. Categories of use are broad and may include such categories as cipher key, importer KEK, exporter KEK, and MAC. Key usage fields (KUFs) 522 are a variable length and extensible field or set of fields that define narrower attributes for the key type defined in 520. Exemplary attributes in the key usage fields 522 describe how the key material can be used and/or limits actions that may be performed in various situations available for this key type. For example, if the key material is an AES key for importing or exporting other keys, it can be used as a wrapping key for exporting other AES keys from this HSM or as an unwrapping key to import other AES keys into this HSM. In another example, if the key material is a cipher key, the key usage fields 522 can further limit key material use to enciphering or deciphering. A plurality of usage description fields may be placed in the set of key usage fields 522. Accordingly, the key usage fields 522 vary in size and interpretation based on other fields, such as fields 518 and 520. The exemplary key usage fields 522 are in the following format—one byte: count of fields that follow this byte; two bytes each: fields with key usage fields data.
Still referring to FIG. 5, key management fields (KMFs) 524 are a variable length and extensible field or set of fields that define attributes of the key material wrapped in the token, including but not limited to what type of KEKs can be used to wrap this key material (if any), whether the wrapped key material is complete or expects more user contributed material, how the key was created, how the key was acquired by the current module and information relating to the protection of the key over time. Other examples of attributes include limiting what can be done to the key material, such as limiting distribution or export of the key material, such as a cipher key, after receipt of the key material by a party. The number of attributes or entries in the key management fields 524 is variable. The key management fields 524 vary in size and interpretation based on other fields, such as fields 518 and 520. Exemplary key management fields 524 are in the following format—one byte: count of fields that follow this byte; two bytes each: fields with key management fields data. In an embodiment, described in further detail below, exemplary key management fields 524 include fields that allow user policies to be implemented to manage and record the entire key material life cycle and are extensible to register key history and policies for the remaining key life cycle. For example, the fields allow updating of life cycle information after receiving the key material. Further, policies may be created after receipt to specify when the key material is to be retired or allowable methods for wrapping the key material itself.
As discussed above, the AD label field 526 is a user specified optional field that gives a meaningful name to the token 200. An exemplary AD label field 526 is 64 bytes. The label is within the token 200, thereby enabling recovery of the label via field 526. Further, the AD label field is securely bound to the key material due to being wrapped as part of the AD section 500 with the key material. In addition, since the label is unencrypted, it can be used by the host system to check if the user is authorized to use the key token. The proprietary data field 528 is for the HSM provider to include their own data or identifiers, which will be securely bound to the key material if an appropriate wrapping method is selected. The user data field 530 is for user populated data and may hold data as designated by the HSM-using host application. Accordingly, the user populates the data using an interface on a host application. The optional sections fields 532 allow for further extensibility of the token 200 at the discretion of the HSM-using host application or the HSM manufacturer. Each optional section field is in the format of unique identifier, length (must include length of identifier and length fields) and an optional data section.
Referring now to FIG. 6, the exemplary payload section 600 may have no content, or may not be wrapped (key material is here by itself and is not encrypted). If the payload section 600 contains wrapped content then fields 408 and 410 can be used to interpret the payload contents and the method for using the appropriate KEK or MK to unwrap the payload. As stated above, the payload section 600 layout depends on the wrapping method chosen, such as AESKW or RSAES-OAEP wrapping methods. Moreover, the structure and layout of the header section 300, wrapping information section 400, associated data section 500 and payload section 600 are independent and remain the same as the wrapping method for the token 200 and payload section 600 are changed. As an example, the AESKW wrapping method and corresponding payload layout will be described.
The integrity check constant value field 602 includes a known constant that is used to determine if the unwrap succeeded before looking at other fields in the section. If the constant is not correct then the payload and/or its associated data were corrupted or modified in some way outside the control of the HSM. The corruption or modification is then alerted to the user. A bit length of padding field 604 is used to describe if there is padding and the size of padding, depending on the bit length of the key material in the payload. Thus, this field indicates how much padding to remove. A length of hash options field 606 describes the length of a hash options field 608. The hash options field 608 describes various options that may be used in computing the hash of AD field 610, while still conforming to the AESKW standard. The hash of AD 610 is the hash value of the AD section 500, used to verify that the section has not been altered. A clear key material field 612 contains the key material or secret key that is carried in the payload section 600. A key padding field 614 is used to pad the key material and depends on the size of the key material in field 612.
In embodiments, the key in the token 200 is created within two or more systems, such as the host system 106 and/or user system 102 (FIG. 1). The host system 106 and user system 102 may be two parties configured to each create a shared secret key material using the methods discussed herein, wherein the key material is used to communicate between the parties over an unsecure network. The host system 106 and user system 102 may each include a secure module, such as an HSM, to manage the key material. Creation of the keys within each of the secure modules is accomplished by a suitable scheme or algorithm, such as an RSA scheme, a Diffie-Hellman key agreement scheme or any other suitable key exchange or key agreement scheme. Further, an exemplary Diffie-Hellman scheme may be an Elliptic Curve Diffie-Hellman key agreement scheme. The key agreement scheme may be used to produce an identical shared secret material on each of the parties' local systems, wherein the shared secret material (also called “shared secret” or “secret material”) is combined with or bound to selected key control information before key material is derived from the combination. By having the key control information cryptographically bound to the key material for each party, proper and consistent use of the key material for each of the parties is ensured.
In embodiments of a secure system, the HSM in the host system 106 is configured to create the key material and then place the key material in the key containing structure, such as the key token 200. Exemplary systems and methods may use any suitable data structure, token and/or hardware to provide a secure structure containing the key material and key control information (i.e., associated data section 500). For ease of explanation, the method and system below will be described with reference to the token 200 of FIGS. 2-6, although any suitable structure or key token configuration may be used. As described herein the terms key material and key refer to a secret key to enable, among other things, encrypted communication between parties.
FIG. 7 is an exemplary diagram illustrating a process for two parties to create identical or shared key material at two separate locations. Chart 700 shows the blocks for Party A to create the key material and chart 702 shows the blocks for Party B to create the key material. The operations for chart 700 may occur in a system for Party A and the operations for chart 702 may occur in a system for Party B, wherein the two systems (e.g., computing or processing systems) are connected by a network, such as the systems 102 and 106 of FIG. 1. In block 704, Party A establishes a structure used to contain the key material, such as a key token structure. The key token structure contains the key in a protected state when it is outside the secure HSM. The key containing structure may be any suitable secure software structure to contain the key material, such as the key token 200 (FIG. 2). Further, the structure includes information relating to the key material in selected sections, such as the key control information (i.e., selected portions of the associated data section 500 of FIG. 5), discussed above. The key containing structure is identical for both Parties A and B, and may be communicated to one another via any suitable means, such as a wired or wireless network. In block 706, Party B and Party A establish or agree upon identical key containing structures. The key containing structure may be transmitted from one party to the other, or the structure type may be communicated between the parties, wherein each party creates the structure locally. Exemplary key tokens are referred to as skeleton tokens, wherein the key tokens may be empty or may contain some information, but do not include key material. In blocks 708 and 710, Party A and Party B share selected key control information with one another, respectively. The key control information may include information relating to management and use of the key material. In an embodiment, the key control information is located within the key containing structures and may be shared or communicated with the structures are established during blocks 704 and 706. In addition, when the key containing structure, such as a key token, is established in each party's system, the key control information is located in the structure and removed from the structures in blocks 708 and 710. In another embodiment, the key containing structures are first established for the parties and the key control information is determined and/or communicated in blocks 708 and 710.
As part of the key agreement scheme (e.g., Elliptic Curve Diffie-Hellman), each party may establish their own private-public key pair to be maintained locally. The public key part is allowed to be transmitted to another party, while the private key part is kept locally and only accessed by the local secure module. In blocks 712 and 714, the public key parts of each party's private-public key pair are communicated or exchanged. Accordingly, after blocks 712 and 714, Party A will have Party A's public-private key pair and Party B's public key part. Similarly, Party B will have Party B's public-private key pair and Party A's public key part. Using the selected scheme or algorithm, each party can separately establish a secret material from the public and private key parts residing on the local system, as shown in blocks 716 and 718. The exemplary secret material established for both Party A and Party B is identical. After the secret material has been established, blocks 720 and 722 cryptographically bind the key control information to the secret material. In blocks 724 and 726, the key material for each party is derived from the bound key control information and secret material. The derived key material is identical for Party A and Party B, thereby enabling the parties to share and communicate secret information through use of the established key material. In an embodiment, after deriving the key material, the key material is placed back in the key containing structure, such as the key token.
The key control information bound to secret material within the key material may comprise information relating to the key type, key management and key usage. The key type information describes the broad capabilities or categories of use for the key. Exemplary categories of use may include enciphering and/or deciphering data, wrapping and/or unwrapping keys, importing and/or exporting keys, data keys, pin keys, key generating keys or use as a message authentication code (MAC). In addition, additional key type information, also referred to as key sub-type information, describes actions supported by the key type, such as limitations of the key material for only ciphering or deciphering data, or for only importing or exporting keys. The information relating to key management describes how or if the key material may be distributed from the local system. The information relating to key management may include information describing what type of key-encrypting-key (KEK) may be used to wrap the key material, whether the key material is exportable to other system, if the key material is complete and/or how the key material is created. The information relating to key usage may include descriptions of how the key material may be used in addition to those described by the key type and the key sub-type. Exemplary key usage information may include information limiting the types of data that can be processed in selected ways (e.g., encrypted or decrypted) in selected modes (e.g., Cipher Block Chaining (CBC) mode) or the types of keys that may be wrapped with the key material. The key usage material may be specific to a particular key type.
The actions of exchanging key parts between systems, establishing the secret material, binding the key control information to the secret material and deriving the key material may be performed by a secure HSM within in each party's system to ensure key security. By cryptographically binding the key control information to the secret material which then forms the key material, control over usage and distribution of the key material is ensured. The depicted arrangement provides improved management of key material that is created by using a selected key agreement scheme. The arrangement enables two or more parties to use the selected scheme to separately derive identical key material which is then used for secure encrypted communication between the parties.
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