C O M P U T E R S E C U R I T Y 

Recommendation for Block 

Cipher Modes of Operation 

Methods and Techniques

Morris Dworkin 

NIST Special Publication 800-38A 

2001 Edition 
 

ii 
 

iii 

Computer Security Division 

Information Technology Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-8930 

December 2001 

U.S. Department of Commerce 

Donald L. Evans, Secretary 

Technology Administration

Phillip J. Bond, Under Secretary of Commerce for Technology 

National Institute of Standards and Technology 

Arden L. Bement, Jr., Director

C O M P U T E R S E C U R I T Y 
 

iv 

Reports on Information Security 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 technical, physical, 

administrative, and management standards and guidelines for the cost-effective security and privacy of 

sensitive unclassified information in Federal computer systems. This Special Publication 800-series 

reports on ITL’s research, guidance, and outreach efforts in computer security, and its collaborative 

activities with industry, government, and academic organizations. 

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 the National Institute of Standards and Technology, nor is it intended to imply that the entities, 

materials, or equipment are necessarily the best available for the purpose.

National Institute of Standards and Technology Special Publication 800-38A 2001 ED 

Natl. Inst. Stand. Technol. Spec. Publ. 800-38A 2001 ED, 66 pages (December 2001) 

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE 

WASHINGTON: 2001 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Internet: bookstore.gpo.gov — Phone: (202) 512-1800 — Fax: (202) 512-2250 

Mail: Stop SSOP, Washington, DC 20402-0001
 

v 

Abstract 

This recommendation defines five confidentiality modes of operation for use with an underlying 

symmetric key block cipher algorithm: Electronic Codebook (ECB), Cipher Block Chaining 

(CBC), Cipher Feedback (CFB), Output Feedback (OFB), and Counter (CTR). Used with an 

underlying block cipher algorithm that is approved in a Federal Information Processing Standard 

(FIPS), these modes can provide cryptographic protection for sensitive, but unclassified, 

computer data. 

KEY WORDS: Computer security; cryptography; data security; block cipher; encryption; 

Federal Information Processing Standard; mode of operation. 
 

vi 

Table of Contents 

1 PURPOSE .......................................................................................................................................................... 1

2 AUTHORITY .................................................................................................................................................... 1

3 INTRODUCTION ............................................................................................................................................. 1

4 DEFINITIONS, ABBREVIATIONS, AND SYMBOLS................................................................................. 3

4.1 DEFINITIONS AND ABBREVIATIONS ............................................................................................................ 3

4.2 SYMBOLS.................................................................................................................................................... 5

4.2.1 Variables ............................................................................................................................................... 5

4.2.2 Operations and Functions..................................................................................................................... 5

5 PRELIMINARIES............................................................................................................................................. 7

5.1 UNDERLYING BLOCK CIPHER ALGORITHM................................................................................................. 7

5.2 REPRESENTATION OF THE PLAINTEXT AND THE CIPHERTEXT..................................................................... 7

5.3 INITIALIZATION VECTORS........................................................................................................................... 8

5.4 EXAMPLES OF OPERATIONS AND FUNCTIONS ............................................................................................. 8

6 BLOCK CIPHER MODES OF OPERATION ............................................................................................... 9

6.1 THE ELECTRONIC CODEBOOK MODE.......................................................................................................... 9

6.2 THE CIPHER BLOCK CHAINING MODE ...................................................................................................... 10

6.3 THE CIPHER FEEDBACK MODE ................................................................................................................. 11

6.4 THE OUTPUT FEEDBACK MODE................................................................................................................ 13

6.5 THE COUNTER MODE ............................................................................................................................... 15

APPENDIX A: PADDING ...................................................................................................................................... 17

APPENDIX B: GENERATION OF COUNTER BLOCKS ................................................................................. 18

B.1 THE STANDARD INCREMENTING FUNCTION ............................................................................................. 18

B.2 CHOOSING INITIAL COUNTER BLOCKS ..................................................................................................... 19

APPENDIX C: GENERATION OF INITIALIZATION VECTORS ................................................................. 20

APPENDIX D: ERROR PROPERTIES ................................................................................................................ 21

APPENDIX E: MODES OF TRIPLE DES............................................................................................................ 23

APPENDIX F: EXAMPLE VECTORS FOR MODES OF OPERATION OF THE AES ................................ 24

F.1 ECB EXAMPLE VECTORS ......................................................................................................................... 24

F.1.1 ECB-AES128.Encrypt ......................................................................................................................... 24

F.1.2 ECB-AES128.Decrypt ......................................................................................................................... 24

F.1.3 ECB-AES192.Encrypt ......................................................................................................................... 25

F.1.4 ECB-AES192.Decrypt ......................................................................................................................... 25

F.1.5 ECB-AES256.Encrypt ......................................................................................................................... 26

F.1.6 ECB-AES256.Decrypt ......................................................................................................................... 26

F.2 CBC EXAMPLE VECTORS......................................................................................................................... 27

F.2.1 CBC-AES128.Encrypt ......................................................................................................................... 27

F.2.2 CBC-AES128.Decrypt......................................................................................................................... 27

F.2.3 CBC-AES192.Encrypt ......................................................................................................................... 28

F.2.4 CBC-AES192.Decrypt......................................................................................................................... 28
 

vii 

F.2.5 CBC-AES256.Encrypt ......................................................................................................................... 28

F.2.6 CBC-AES256.Decrypt......................................................................................................................... 29

F.3 CFB EXAMPLE VECTORS ......................................................................................................................... 29

F.3.1 CFB1-AES128.Encrypt ....................................................................................................................... 29

F.3.2 CFB1-AES128.Decrypt ....................................................................................................................... 31

F.3.3 CFB1-AES192.Encrypt ....................................................................................................................... 33

F.3.4 CFB1-AES192.Decrypt ....................................................................................................................... 34

F.3.5 CFB1-AES256.Encrypt ....................................................................................................................... 36

F.3.6 CFB1-AES256.Decrypt ....................................................................................................................... 37

F.3.7 CFB8-AES128.Encrypt ....................................................................................................................... 39

F.3.8 CFB8-AES128.Decrypt ....................................................................................................................... 41

F.3.9 CFB8-AES192.Encrypt ....................................................................................................................... 42

F.3.10 CFB8-AES192.Decrypt .................................................................................................................. 44

F.3.11 CFB8-AES256.Encrypt .................................................................................................................. 46

F.3.12 CFB8-AES256.Decrypt .................................................................................................................. 48

F.3.13 CFB128-AES128.Encrypt .............................................................................................................. 50

F.3.14 CFB128-AES128.Decrypt .............................................................................................................. 50

F.3.15 CFB128-AES192.Encrypt .............................................................................................................. 50

F.3.16 CFB128-AES192.Decrypt .............................................................................................................. 51

F.3.17 CFB128-AES256.Encrypt .............................................................................................................. 51

F.3.18 CFB128-AES256.Decrypt .............................................................................................................. 52

F.4 OFB EXAMPLE VECTORS ......................................................................................................................... 52

F.4.1 OFB-AES128.Encrypt......................................................................................................................... 52

F.4.2 OFB-AES128.Decrypt......................................................................................................................... 53

F.4.3 OFB-AES192.Encrypt......................................................................................................................... 53

F.4.4 OFB-AES192.Decrypt......................................................................................................................... 54

F.4.5 OFB-AES256.Encrypt......................................................................................................................... 54

F.4.6 OFB-AES256.Decrypt......................................................................................................................... 55

F.5 CTR EXAMPLE VECTORS ......................................................................................................................... 55

F.5.1 CTR-AES128.Encrypt ......................................................................................................................... 55

F.5.2 CTR-AES128.Decrypt ......................................................................................................................... 56

F.5.3 CTR-AES192.Encrypt ......................................................................................................................... 56

F.5.4 CTR-AES192.Decrypt ......................................................................................................................... 57

F.5.5 CTR-AES256.Encrypt ......................................................................................................................... 57

F.5.6 CTR-AES256.Decrypt ......................................................................................................................... 57

APPENDIX G: REFERENCES.............................................................................................................................. 59

Table of Figures 

Figure 1: The ECB Mode ................................................................................................................9

Figure 2: The CBC Mode ..............................................................................................................10

Figure 3: The CFB Mode ..............................................................................................................12

Figure 4: The OFB Mode ..............................................................................................................14

Figure 5: The CTR Mode ..............................................................................................................16
 

1 

1 Purpose 

This publication provides recommendations regarding modes of operation to be used with 

symmetric key block cipher algorithms. 

2 Authority 

This document has been developed by the National Institute of Standards and Technology 

(NIST) in furtherance of its statutory responsibilities under the Computer Security Act of 1987 

(Public Law 100-235) and the Information Technology Management Reform Act of 1996, 

specifically 15 U.S.C. 278 g-3(a)(5). This is not a guideline within the meaning of 15 U.S.C. 278 

g-3 (a)(5). 

This recommendation is neither a standard nor a guideline, and as such, is neither mandatory nor 

binding on Federal agencies. Federal agencies and non-government organizations may use this 

recommendation on a voluntary basis. It is not subject to copyright. 

Nothing in this recommendation should be taken to contradict standards and guidelines that have 

been made mandatory and binding upon Federal agencies by the Secretary of Commerce under 

his statutory authority. Nor should this recommendation be interpreted as altering or superseding 

the existing authorities of the Secretary of Commerce, the Director of the Office of Management 

and Budget, or any other Federal official. 

Conformance testing for implementations of the modes of operation that are specified in this 

recommendation will be conducted within the framework of the Cryptographic Module 

Validation Program (CMVP), a joint effort of the NIST and the Communications Security 

Establishment of the Government of Canada. An implementation of a mode of operation must 

adhere to the requirements in this recommendation in order to be validated under the CMVP. 

3 Introduction 

This recommendation specifies five confidentiality modes of operation for symmetric key block 

cipher algorithms, such as the algorithm specified in FIPS Pub. 197, the Advanced Encryption 

Standard (AES) [2]. The modes may be used in conjunction with any symmetric key block cipher 

algorithm that is approved by a Federal Information Processing Standard (FIPS). The five 

modes—the Electronic Codebook (ECB), Cipher Block Chaining (CBC), Cipher Feedback 

(CFB), Output Feedback (OFB), and Counter (CTR) modes—can provide data confidentiality. 

 

Two FIPS publications already approve confidentiality modes of operation for two particular 

block cipher algorithms. FIPS Pub. 81 [4] specifies the ECB, CBC, CFB, and OFB modes of the 

Data Encryption Standard (DES). FIPS Pub. 46-3 [3] approves the seven modes that are 

specified in ANSI X9.52 [1]. Four of these modes are equivalent to the ECB, CBC, CFB, and 

OFB modes with the Triple DES algorithm (TDEA) as the underlying block cipher; the other 
 

2 

three modes in ANSI X9.52 are variants of the CBC, CFB, and OFB modes of Triple DES that 

use interleaving or pipelining. 

Thus, there are three new elements in this recommendation: 1) the extension of the four 

confidentiality modes in FIPS Pub 81 for use with any FIPS-approved block cipher; 2) the 

revision of the requirements for these modes; and 3) the specification of an additional 

confidentiality mode, the CTR mode, for use with any FIPS-approved block cipher. 
 

3 

4 Definitions, Abbreviations, and Symbols 

4.1 Definitions and Abbreviations 

Bit A binary digit: 0 or 1. 

Bit Error The substitution of a ‘0’ bit for a ‘1’ bit, or vice versa. 

Bit String An ordered sequence of 0’s and 1’s. 

Block Cipher A family of functions and their inverse functions that is parameterized 

by cryptographic keys; the functions map bit strings of a fixed length to 

bit strings of the same length. 

Block Size The number of bits in an input (or output) block of the block cipher. 

CBC Cipher Block Chaining. 

CFB Cipher Feedback. 

Ciphertext Encrypted data. 

Confidentiality Mode A mode that is used to encipher plaintext and decipher ciphertext. The 

confidentiality modes in this recommendation are the ECB, CBC, CFB, 

OFB, and CTR modes. 

CTR Counter. 

Cryptographic Key A parameter used in the block cipher algorithm that determines the 

forward cipher operation and the inverse cipher operation. 

Data Block (Block) A sequence of bits whose length is the block size of the block cipher. 

Data Segment 

(Segment) 

In the CFB mode, a sequence of bits whose length is a parameter that 

does not exceed the block size. 

Decryption 

(Deciphering) 

The process of a confidentiality mode that transforms encrypted data 

into the original usable data. 

ECB Electronic Codebook. 

Encryption 

(Enciphering) 

The process of a confidentiality mode that transforms usable data into 

an unreadable form. 

 
 

4 

Exclusive-OR The bitwise addition, modulo 2, of two bit strings of equal length. 

FIPS Federal Information Processing Standard. 

Forward Cipher 

Function (Forward 

Cipher Operation) 

One of the two functions of the block cipher algorithm that is selected 

by the cryptographic key. 

Initialization Vector 

(IV) 

A data block that some modes of operation require as an additional 

initial input. 

Input Block A data block that is an input to either the forward cipher function or the 

inverse cipher function of the block cipher algorithm. 

Inverse Cipher 

Function (Inverse 

Cipher Operation) 

The function that reverses the transformation of the forward cipher 

function when the same cryptographic key is used. 

Least Significant 

Bit(s) 

The right-most bit(s) of a bit string. 

Mode of Operation 

(Mode) 

An algorithm for the cryptographic transformation of data that features 

a symmetric key block cipher algorithm. 

Most Significant Bit(s) The left-most bit(s) of a bit string. 

Nonce A value that is used only once. 

Octet A group of eight binary digits. 

OFB Output Feedback. 

Output Block A data block that is an output of either the forward cipher function or 

the inverse cipher function of the block cipher algorithm. 

Plaintext Usable data that is formatted as input to a mode. 
 

5 

4.2 Symbols 

4.2.1 Variables 

b The block size, in bits. 

j The index to a sequence of data blocks or data segments ordered from left 

 to right. 

n The number of data blocks or data segments in the plaintext. 

s The number of bits in a data segment. 

u The number of bits in the last plaintext or ciphertext block.

Cj

 The j

th ciphertext block. 

C#

j The j

th ciphertext segment. 

C*

n The last block of the ciphertext, which may be a partial block. 

Ij The j

th input block. 

IV The initialization vector. 

K The secret key. 

Oj

 The j

th output block. 

Pj

 The j

th plaintext block. 

P#

j The j

th plaintext segment. 

P*

n The last block of the plaintext, which may be a partial block. 

Tj

 The j

th counter block. 

4.2.2 Operations and Functions 

X | Y The concatenation of two bit strings X and Y. 

X ⊕ Y The bitwise exclusive-OR of two bit strings X and Y of the same length. 

CIPHK(X) The forward cipher function of the block cipher algorithm under the key K applied 

to the data block X. 
 

6 

CIPH -1

K(X) The inverse cipher function of the block cipher algorithm under the key K applied 

to the data block X. 

LSBm(X) The bit string consisting of the m least significant bits of the bit string X. 

MSBm(X) The bit string consisting of the m most significant bits of the bit string X. 

[x]m The binary representation of the non-negative integer x, in m bits, where x<2m. 
 

7 

5 Preliminaries 

5.1 Underlying Block Cipher Algorithm 

This recommendation assumes that a FIPS-approved symmetric key block cipher algorithm has 

been chosen as the underlying algorithm, and that a secret, random key, denoted K, has been 

established among all of the parties to the communication. The cryptographic key regulates the 

functioning of the block cipher algorithm and, thus, by extension, regulates the functioning of the 

mode. The specifications of the block cipher and algorithms and the modes are public, so the 

security of the mode depends, at a minimum, on the secrecy of the key. 

A confidentiality mode of operation of the block cipher algorithm consists of two processes that 

are inverses of each other: encryption and decryption. Encryption is the transformation of a 

usable message, called the plaintext, into an unreadable form, called the ciphertext; decryption is 

the transformation that recovers the plaintext from the ciphertext. 

For any given key, the underlying block cipher algorithm of the mode also consists of two 

functions that are inverses of each other. These two functions are often called encryption and 

decryption, but in this recommendation, those terms are reserved for the processes of the 

confidentiality modes. Instead, as part of the choice of the block cipher algorithm, one of the two 

functions is designated as the forward cipher function, denoted CIPHK; the other function is then 

called the inverse cipher function, denoted CIPH –1

K . The inputs and outputs of both functions are 

called input blocks and output blocks. The input and output blocks of the block cipher algorithm 

have the same bit length, called the block size, denoted b. 

5.2 Representation of the Plaintext and the Ciphertext 

For all of the modes in this recommendation, the plaintext must be represented as a sequence of 

bit strings; the requirements on the lengths of the bit strings vary according to the mode: 

For the ECB and CBC modes, the total number of bits in the plaintext must be a multiple of the 

block size, b; in other words, for some positive integer n, the total number of bits in the plaintext 

must be nb. The plaintext consists of a sequence of n bit strings, each with bit length b. The bit 

strings in the sequence are called data blocks, and the plaintext is denoted P1, P2,..., Pn. 

For the CFB mode, the total number of bits in the plaintext must be a multiple of a parameter, 

denoted s, that does not exceed the block size; in other words, for some positive integer n, the 

total number of bits in the message must be ns. The plaintext consists of a sequence of n bit 

strings, each with bit length s. The bit strings in the sequence are called data segments, and the 

plaintext is denoted P#

1, P#2,..., P#

n. 

For the OFB and CTR modes, the plaintext need not be a multiple of the block size. Let n and u

denote the unique pair of positive integers such that the total number of bits in the message is 

(n-1)b+u, where 1≤ u≤ b. The plaintext consists of a sequence of n bit strings, in which the bit 

length of the last bit string is u, and the bit length of the other bit strings is b. The sequence is 

denoted P1, P2,..., Pn-1, P*

n, and the bit strings are called data blocks, although the last bit string, 
 

8 

P*

n , may not be a complete block. 

For each mode, the encryption process transforms every plaintext data block or segment into a 

corresponding ciphertext data block or segment with the same bit length, so that the ciphertext is 

a sequence of data blocks or segments. The ciphertext is denoted as follows: for the ECB and 

CBC modes, C1, C2,..., Cn; for the CFB mode, C#

1, C# 2,..., C#

n; and, for the OFB and CTR modes, 

C1, C2,..., Cn-1, C*

n, where C*n may be a partial block. 

The formatting of the plaintext, including in some cases the appending of padding bits to form 

complete data blocks or data segments, is outside the scope of this recommendation. Padding is 

discussed in Appendix A. 

5.3 Initialization Vectors 

The input to the encryption processes of the CBC, CFB, and OFB modes includes, in addition to 

the plaintext, a data block called the initialization vector (IV), denoted IV. The IV is used in an 

initial step in the encryption of a message and in the corresponding decryption of the message. 

The IV need not be secret; however, for the CBC and CFB modes, the IV for any particular 

execution of the encryption process must be unpredictable, and, for the OFB mode, unique IVs 

must be used for each execution of the encryption process. The generation of IVs is discussed in 

Appendix C. 

5.4 Examples of Operations and Functions 

The concatenation operation on bit strings is denoted | ; for example, 001 | 10111 = 00110111. 

Given bit strings of equal length, the exclusive-OR operation, denoted ⊕, specifies the addition, 

modulo 2, of the bits in each bit position, i.e., without carries. Thus, 10011 ⊕ 10101= 00110, for 

example. 

The functions LSBs and MSBs return the s least significant bits and the s most significant bits of 

their arguments. For example, LSB3(111011010) = 010, and MSB4(111011010) = 1110. 

Given a positive integer m and a non-negative (decimal) integer x that is less than 2m

, the binary 

representation of x in m bits is denoted [x]m. For example, [45]8 = 00101101. 
 

9 

6 Block Cipher Modes of Operation 

The mathematical specifications of the five modes are given in Sections 6.1-6.5, along with 

descriptions, illustrations, and comments on the potential for parallel processing. 

6.1 The Electronic Codebook Mode 

The Electronic Codebook (ECB) mode is a confidentiality mode that features, for a given key, 

the assignment of a fixed ciphertext block to each plaintext block, analogous to the assignment of 

code words in a codebook. The Electronic Codebook (ECB) mode is defined as follows: 

ECB Encryption: Cj = CIPHK(Pj) for j = 1 ... n. 

ECB Decryption: Pj

 = CIPH -1

K(Cj

) for j = 1 ... n. 

In ECB encryption, the forward cipher function is applied directly and independently to each 

block of the plaintext. The resulting sequence of output blocks is the ciphertext. 

In ECB decryption, the inverse cipher function is applied directly and independently to each 

block of the ciphertext. The resulting sequence of output blocks is the plaintext. 

 

PLAINTEXT

CIPHERTEXT

CIPHK

INPUT BLOCK

OUTPUT BLOCK

CIPHERTEXT

PLAINTEXT

CIPH-1

K

INPUT BLOCK

OUTPUT BLOCK

ECB Encryption ECB Decryption

Figure 1: The ECB Mode 

In ECB encryption and ECB decryption, multiple forward cipher functions and inverse cipher 

functions can be computed in parallel. 

In the ECB mode, under a given key, any given plaintext block always gets encrypted to the 
 

10 

same ciphertext block. If this property is undesirable in a particular application, the ECB mode 

should not be used. 

The ECB mode is illustrated in Figure 1. 

6.2 The Cipher Block Chaining Mode 

The Cipher Block Chaining (CBC) mode is a confidentiality mode whose encryption process 

features the combining (“chaining”) of the plaintext blocks with the previous ciphertext blocks. 

The CBC mode requires an IV to combine with the first plaintext block. The IV need not be 

secret, but it must be unpredictable; the generation of such IVs is discussed in Appendix C. 

Also, the integrity of the IV should be protected, as discussed in Appendix D. The CBC mode is 

defined as follows: 

CBC Encryption: C1 = CIPHK(P1 ⊕ IV); 

 Cj = CIPHK(Pj⊕ Cj-1) for j = 2 ... n. 

CBC Decryption: P1 = CIPH -1

K(C1) ⊕ IV;

 Pj

 = CIPH -1

K(Cj

) ⊕ Cj-1 for j = 2 ... n. 

CIPHK

OUTPUT BLOCK 1

⊕

OUTPUT BLOCK 2

⊕

OUTPUT BLOCK n

⊕

PLAINTEXT 1 PLAINTEXT 2 INITIALIZATION

 VECTOR 

INPUT BLOCK 1 INPUT BLOCK 2 INPUT BLOCK n

PLAINTEXT n

ENCRYPT DECRYPT

⊕ ⊕ ⊕

INPUT BLOCK 1 INPUT BLOCK 2 INPUT BLOCK n

CIPH-1K

PLAINTEXT 1 PLAINTEXT 2 PLAINTEXT n

OUTPUT BLOCK 1 OUTPUT BLOCK 2 OUTPUT BLOCK n

INITIALIZATION

 VECTOR 

CIPHERTEXT 1 CIPHERTEXT 2

CIPHERTEXT 1 CIPHERTEXT 2

CIPHERTEXT n

CIPHERTEXT n

CIPHK CIPHK

CIPH-1K CIPH-1K

Figure 2: The CBC Mode 

In CBC encryption, the first input block is formed by exclusive-ORing the first block of the 

plaintext with the IV. The forward cipher function is applied to the first input block, and the 
 

11 

resulting output block is the first block of the ciphertext. This output block is also exclusiveORed with the second plaintext data block to produce the second input block, and the forward 

cipher function is applied to produce the second output block. This output block, which is the 

second ciphertext block, is exclusive-ORed with the next plaintext block to form the next input 

block. Each successive plaintext block is exclusive-ORed with the previous output/ciphertext 

block to produce the new input block. The forward cipher function is applied to each input block 

to produce the ciphertext block. 

In CBC decryption, the inverse cipher function is applied to the first ciphertext block, and the 

resulting output block is exclusive-ORed with the initialization vector to recover the first 

plaintext block. The inverse cipher function is also applied to the second ciphertext block, and 

the resulting output block is exclusive-ORed with the first ciphertext block to recover the second 

plaintext block. In general, to recover any plaintext block (except the first), the inverse cipher 

function is applied to the corresponding ciphertext block, and the resulting block is exclusiveORed with the previous ciphertext block. 

In CBC encryption, the input block to each forward cipher operation (except the first) depends on 

the result of the previous forward cipher operation, so the forward cipher operations cannot be 

performed in parallel. In CBC decryption, however, the input blocks for the inverse cipher 

function, i.e., the ciphertext blocks, are immediately available, so that multiple inverse cipher 

operations can be performed in parallel. 

The CBC mode is illustrated in Figure 2. 

6.3 The Cipher Feedback Mode 

The Cipher Feedback (CFB) mode is a confidentiality mode that features the feedback of 

successive ciphertext segments into the input blocks of the forward cipher to generate output 

blocks that are exclusive-ORed with the plaintext to produce the ciphertext, and vice versa. The 

CFB mode requires an IV as the initial input block. The IV need not be secret, but it must be 

unpredictable; the generation of such IVs is discussed in Appendix C. 

The CFB mode also requires an integer parameter, denoted s, such that 1 ≤ s ≤ b. In the 

specification of the CFB mode below, each plaintext segment (P#

j

) and ciphertext segment (C#

j

) 

consists of s bits. The value of s is sometimes incorporated into the name of the mode, e.g., the 

1-bit CFB mode, the 8-bit CFB mode, the 64-bit CFB mode, or the 128-bit CFB mode. 

The CFB mode is defined as follows: 

CFB Encryption: I1 = IV;

 Ij = LSBb-s(Ij –1) | C#

j -1 for j = 2 ... n; 

 Oj

 = CIPHK(Ij

) for j = 1, 2 ... n; 

 C#

j= P#j ⊕ MSBs(Oj

) for j = 1, 2 ... n. 

CFB Decryption: I1 = IV;

 Ij

 = LSBb-s(Ij -1 )| C#

j -1 for j = 2 ... n; 
 

12 

 Oj

 = CIPHK(Ij

) for j = 1, 2 ... n; 

 P#

j= C#j ⊕ MSBs(Oj

) for j = 1, 2 ... n. 

In CFB encryption, the first input block is the IV, and the forward cipher operation is applied to 

the IV to produce the first output block. The first ciphertext segment is produced by exclusiveORing the first plaintext segment with the s most significant bits of the first output block. (The 

remaining b-s bits of the first output block are discarded.) The b-s least significant bits of the IV 

are then concatenated with the s bits of the first ciphertext segment to form the second input 

block. An alternative description of the formation of the second input block is that the bits of 

the first input block circularly shift s positions to the left, and then the ciphertext segment 

replaces the s least significant bits of the result. 

The process is repeated with the successive input blocks until a ciphertext segment is produced 

from every plaintext segment. In general, each successive input block is enciphered to produce 

an output block. The s most significant bits of each output block are exclusive-ORed with the 

corresponding plaintext segment to form a ciphertext segment. Each ciphertext segment (except 

the last one) is “fed back” into the previous input block, as described above, to form a new input 

block. The feedback can be described in terms of the individual bits in the strings as follows: if 

i1i2...ib is the jth input block, and c1c2...cs is the jth ciphertext segment, then the (j+1)th input block 

is is+1is+2...ib c1c2...cs. 

OUTPUT BLOCK 1

Select Discard

s Bits (b-s) Bits

INPUT BLOCK 1

OUTPUT BLOCK 1

Select Discard

s Bits (b-s) Bits

CIPHK

INITIALIZATION

VECTOR

⊕ PLAINTEXT 1

s Bits

CIPHERTEXT 1

s Bits

INPUT BLOCK 1

⊕ CIPHERTEXT 1

s Bits

PLAINTEXT 1

s Bits

ENCRYPT DECRYPT

OUTPUT BLOCK n

Select Discard

s Bits (b-s) Bits

INPUT BLOCK n

(b-s) Bits s Bits

OUTPUT BLOCK n

Select Discard

s Bits (b-s) Bits

⊕ PLAINTEXT n

s Bits

CIPHERTEXT n

s Bits

INPUT BLOCK n

(b-s) Bits s Bits

⊕ CIPHERTEXT n

s Bits

PLAINTEXT n

s Bits

OUTPUT BLOCK 2

Select Discard

s Bits (b-s) Bits

INPUT BLOCK 2

(b-s) Bits s Bits

OUTPUT BLOCK 2

Select Discard

s Bits (b-s) Bits

⊕ PLAINTEXT 2

s Bits

CIPHERTEXT 2

s Bits

INPUT BLOCK 2

(b-s) Bits s Bits

⊕ CIPHERTEXT 2

s Bits

PLAINTEXT 2

s Bits

INITIALIZATION

VECTOR

CIPHK CIPHK

CIPHK CIPHK CIPHK

Figure 3: The CFB Mode 

In CFB decryption, the IV is the first input block, and each successive input block is formed as in 

CFB encryption, by concatenating the b-s least significant bits of the previous input block with 
 

13 

the s most significant bits of the previous ciphertext. The forward cipher function is applied to 

each input block to produce the output blocks. The s most significant bits of the output blocks 

are exclusive-ORed with the corresponding ciphertext segments to recover the plaintext 

segments. 

In CFB encryption, like CBC encryption, the input block to each forward cipher function (except 

the first) depends on the result of the previous forward cipher function; therefore, multiple 

forward cipher operations cannot be performed in parallel. In CFB decryption, the required 

forward cipher operations can be performed in parallel if the input blocks are first constructed (in 

series) from the IV and the ciphertext. 

The CFB mode is illustrated in Figure 3. 

6.4 The Output Feedback Mode 

The Output Feedback (OFB) mode is a confidentiality mode that features the iteration of the 

forward cipher on an IV to generate a sequence of output blocks that are exclusive-ORed with 

the plaintext to produce the ciphertext, and vice versa. The OFB mode requires that the IV is a 

nonce, i.e., the IV must be unique for each execution of the mode under the given key; the 

generation of such IVs is discussed in Appendix C. The OFB mode is defined as follows: 

OFB Encryption: I1 = IV;

 Ij

 = Oj -1 for j = 2 ... n; 

 Oj

 = CIPHK(Ij

) for j = 1, 2 ... n; 

 Cj= Pj ⊕ Oj for j = 1, 2 ... n-1; 

 C*

n= P*n ⊕ MSBu(On). 

OFB Decryption: I1 = IV;

 Ij

 = Oj -1 for j = 2 ... n; 

 Oj

 = CIPHK(Ij

) for j = 1, 2 ... n; 

 Pj= Cj ⊕ Oj

 for j = 1, 2 ... n-1; 

P*

n = C*n ⊕ MSBu(On). 

In OFB encryption, the IV is transformed by the forward cipher function to produce the first 

output block. The first output block is exclusive-ORed with the first plaintext block to produce 

the first ciphertext block. The forward cipher function is then invoked on the first output block 

to produce the second output block. The second output block is exclusive-ORed with the second 

plaintext block to produce the second ciphertext block, and the forward cipher function is 

invoked on the second output block to produce the third output block. Thus, the successive 

output blocks are produced from applying the forward cipher function to the previous output 

blocks, and the output blocks are exclusive-ORed with the corresponding plaintext blocks to 

produce the ciphertext blocks. For the last block, which may be a partial block of u bits, the 

most significant u bits of the last output block are used for the exclusive-OR operation; the 

remaining b-u bits of the last output block are discarded. 

In OFB decryption, the IV is transformed by the forward cipher function to produce the first 
 

14 

output block. The first output block is exclusive-ORed with the first ciphertext block to recover 

the first plaintext block. The first output block is then transformed by the forward cipher 

function to produce the second output block. The second output block is exclusive-ORed with 

the second ciphertext block to produce the second plaintext block, and the second output block is 

also transformed by the forward cipher function to produce the third output block. Thus, the 

successive output blocks are produced from applying the forward cipher function to the previous 

output blocks, and the output blocks are exclusive-ORed with the corresponding ciphertext 

blocks to recover the plaintext blocks. For the last block, which may be a partial block of u bits, 

the most significant u bits of the last output block are used for the exclusive-OR operation; the 

remaining b-u bits of the last output block are discarded. 

OUTPUT BLOCK 1

INPUT BLOCK 1

OUTPUT BLOCK 1

CIPHK

INITIALIZATION

VECTOR

PLAINTEXT 1 ⊕

CIPHERTEXT 1 

INPUT BLOCK 1

CIPHERTEXT 1 ⊕

PLAINTEXT 1

ENCRYPT DECRYPT

OUTPUT BLOCK n

INPUT BLOCK n

OUTPUT BLOCK n

PLAINTEXT n ⊕

CIPHERTEXT n

INPUT BLOCK n

CIPHERTEXT n ⊕

PLAINTEXT n

OUTPUT BLOCK 2

INPUT BLOCK 2

OUTPUT BLOCK 2

PLAINTEXT 2 ⊕

CIPHERTEXT 2 

INPUT BLOCK 2

CIPHERTEXT 2 ⊕

PLAINTEXT 2

INITIALIZATION

VECTOR

CIPHK CIPHK

CIPHK CIPHK CIPHK

 

Figure 4: The OFB Mode 

In both OFB encryption and OFB decryption, each forward cipher function (except the first) 

depends on the results of the previous forward cipher function; therefore, multiple forward cipher 

functions cannot be performed in parallel. However, if the IV is known, the output blocks can be 

generated prior to the availability of the plaintext or ciphertext data. 

The OFB mode requires a unique IV for every message that is ever encrypted under the given 

key. If, contrary to this requirement, the same IV is used for the encryption of more than one 

message, then the confidentiality of those messages may be compromised. In particular, if a

plaintext block of any of these messages is known, say, the jth plaintext block, then the jth output 

of the forward cipher function can be determined easily from the jth ciphertext block of the 

message. This information allows the jth plaintext block of any other message that is encrypted 
 

15 

using the same IV to be easily recovered from the jth ciphertext block of that message. 

Confidentiality may similarly be compromised if any of the input blocks to the forward cipher 

function for the encryption of a message is designated as the IV for the encryption of another 

message under the given key. 

The OFB mode is illustrated in Figure 4. 

6.5 The Counter Mode 

The Counter (CTR) mode is a confidentiality mode that features the application of the forward 

cipher to a set of input blocks, called counters, to produce a sequence of output blocks that are 

exclusive-ORed with the plaintext to produce the ciphertext, and vice versa. The sequence of 

counters must have the property that each block in the sequence is different from every other 

block. This condition is not restricted to a single message: across all of the messages that are 

encrypted under the given key, all of the counters must be distinct. In this recommendation, the 

counters for a given message are denoted T1, T2, ... , Tn. Methods for generating counters are 

discussed in Appendix B. Given a sequence of counters, T1 , T2 , ... , Tn, the CTR mode is 

defined as follows: 

CTR Encryption: Oj

 = CIPHK(Tj

) for j = 1, 2 ... n; 

 Cj= Pj ⊕ Oj for j = 1, 2 ... n-1; 

 C*

n = P*n ⊕ MSBu(On). 

CTR Decryption: Oj

 = CIPHK(Tj

) for j = 1, 2 ... n; 

 Pj= Cj ⊕ Oj

 for j = 1, 2 ... n-1; 

P*

n = C*n ⊕ MSBu(On). 

In CTR encryption, the forward cipher function is invoked on each counter block, and the 

resulting output blocks are exclusive-ORed with the corresponding plaintext blocks to produce 

the ciphertext blocks. For the last block, which may be a partial block of u bits, the most 

significant u bits of the last output block are used for the exclusive-OR operation; the remaining 

b-u bits of the last output block are discarded. 

In CTR decryption, the forward cipher function is invoked on each counter block, and the 

resulting output blocks are exclusive-ORed with the corresponding ciphertext blocks to recover 

the plaintext blocks. For the last block, which may be a partial block of u bits, the most 

significant u bits of the last output block are used for the exclusive-OR operation; the remaining 

b-u bits of the last output block are discarded. 

In both CTR encryption and CTR decryption, the forward cipher functions can be performed in 

parallel; similarly, the plaintext block that corresponds to any particular ciphertext block can be 

recovered independently from the other plaintext blocks if the corresponding counter block can 

be determined. Moreover, the forward cipher functions can be applied to the counters prior to the 

availability of the plaintext or ciphertext data. 
 

16 

OUTPUT BLOCK 1

INPUT BLOCK 1

OUTPUT BLOCK 1

CIPHK

COUNTER 1

PLAINTEXT 1 ⊕

CIPHERTEXT 1

INPUT BLOCK 1

CIPHERTEXT 1 ⊕

PLAINTEXT 1

ENCRYPT DECRYPT

COUNTER 1

OUTPUT BLOCK 2

INPUT BLOCK 2

OUTPUT BLOCK 2

COUNTER 2

PLAINTEXT 2 ⊕

CIPHERTEXT 2

INPUT BLOCK 2

CIPHERTEXT 2 ⊕

PLAINTEXT 2

COUNTER 2

OUTPUT BLOCK n

INPUT BLOCK n

OUTPUT BLOCK n

COUNTER n

PLAINTEXT n ⊕

CIPHERTEXT n

INPUT BLOCK n

CIPHERTEXT n ⊕

PLAINTEXT n

COUNTER n

. . . . .

. . . . .

CIPHK CIPHK

CIPHK CIPHK CIPHK

Figure 5: The CTR Mode 

The CTR mode is illustrated in Figure 5. 
 

17 

Appendix A: Padding 

For the ECB, CBC, and CFB modes, the plaintext must be a sequence of one or more complete 

data blocks (or, for CFB mode, data segments). In other words, for these three modes, the total 

number of bits in the plaintext must be a positive multiple of the block (or segment) size. 

If the data string to be encrypted does not initially satisfy this property, then the formatting of the 

plaintext must entail an increase in the number of bits. A common way to achieve the necessary 

increase is to append some extra bits, called padding, to the trailing end of the data string as the 

last step in the formatting of the plaintext. An example of a padding method is to append a 

single ‘1’ bit to the data string and then to pad the resulting string by as few ‘0’ bits, possibly 

none, as are necessary to complete the final block (segment). Other methods may be used; in 

general, the formatting of the plaintext is outside the scope of this recommendation. 

For the above padding method, the padding bits can be removed unambiguously, provided the 

receiver can determine that the message is indeed padded. One way to ensure that the receiver 

does not mistakenly remove bits from an unpadded message is to require the sender to pad every 

message, including messages in which the final block (segment) is already complete. For such 

messages, an entire block (segment) of padding is appended. Alternatively, such messages can 

be sent without padding if, for every message, the existence of padding can be reliably inferred, 

e.g., from a message length indicator. 
 

18 

Appendix B: Generation of Counter Blocks

The specification of the CTR mode requires a unique counter block for each plaintext block that 

is ever encrypted under a given key, across all messages. If, contrary to this requirement, a 

counter block is used repeatedly, then the confidentiality of all of the plaintext blocks 

corresponding to that counter block may be compromised. In particular, if any plaintext block 

that is encrypted using a given counter block is known, then the output of the forward cipher 

function can be determined easily from the associated ciphertext block. This output allows any 

other plaintext blocks that are encrypted using the same counter block to be easily recovered 

from their associated ciphertext blocks. 

There are two aspects to satisfying the uniqueness requirement. First, an incrementing function 

for generating the counter blocks from any initial counter block can ensure that counter blocks do 

not repeat within a given message. Second, the initial counter blocks, T1, must be chosen to 

ensure that counters are unique across all messages that are encrypted under the given key. 

B.1 The Standard Incrementing Function 

In general, given the initial counter block for a message, the successive counter blocks are 

derived by applying an incrementing function. As in the above specifications of the modes, n is 

the number of blocks in the given plaintext message, and b is the number of bits in the block. 

The standard incrementing function can apply either to an entire block or to a part of a block. 

Let m be the number of bits in the specific part of the block to be incremented; thus, m is a 

positive integer such that m ≤ b. Any string of m bits can be regarded as the binary representation 

of a non-negative integer x that is strictly less than 2m

. The standard incrementing function takes 

[x]m and returns [x+1 mod 2m

]m. 

For example, let the standard incrementing function apply to the five least significant bits of 

eight bit blocks, so that b=8 and m=5 (unrealistically small values); let * represent each unknown 

bit in this example, and let ***11110 represent a block to be incremented. The following 

sequence of blocks results from four applications of the standard incrementing function: 

* * * 1 1 1 1 0 

* * * 1 1 1 1 1 

* * * 0 0 0 0 0 

* * * 0 0 0 0 1 

* * * 0 0 0 1 0. 

Counter blocks in which a given set of m bits are incremented by the standard incrementing 

function satisfy the uniqueness requirement within the given message provided that n ≤ 2m

. 

Whether the uniqueness requirement for counter blocks is satisfied across all messages that are 

encrypted under a given key then depends on the choices of the initial counter blocks for the 

messages, as discussed in the next section. 
 

19 

This recommendation permits the use of any other incrementing function that generates n unique 

strings of m bits in succession from the allowable initial strings. For example, if the initial string 

of m bits is not the “zero” string, i.e., if it contains at least one ‘1’ bit, then an incrementing 

function can be constructed from a linear feedback shift register that is specialized to ensure a 

sufficiently large period; see Ref. [5] for information about linear feedback shift registers. 

B.2 Choosing Initial Counter Blocks 

The initial counter blocks, T1, for each message that is encrypted under the given key must be 

chosen in a manner than ensures the uniqueness of all the counter blocks across all the messages. 

Two examples of approaches to choosing the initial counter blocks are given in this section. 

In the first approach, for a given key, all plaintext messages are encrypted sequentially. Within 

the messages, the same fixed set of m bits of the counter block is incremented by the standard 

incrementing function. The initial counter block for the initial plaintext message may be any 

string of b bits. The initial counter block for any subsequent message can be obtained by 

applying the standard incrementing function to the fixed set of m bits of the final counter block 

of the previous message. In effect, all of the plaintext messages that are ever encrypted under the 

given key are concatenated into a single message; consequently, the total number of plaintext 

blocks must not exceed 2m

. Procedures should be established to ensure the maintenance of the 

state of the final counter block of the latest encrypted message, and to ensure the proper 

sequencing of the messages. 

A second approach to satisfying the uniqueness property across messages is to assign to each 

message a unique string of b/2 bits (rounding up, if b is odd), in other words, a message nonce, 

and to incorporate the message nonce into every counter block for the message. The leading b/2 

bits (rounding up, if b is odd) of each counter block would be the message nonce, and the 

standard incrementing function would be applied to the remaining m bits to provide an index to 

the counter blocks for the message. Thus, if N is the message nonce for a given message, then 

the jth counter block is given by Tj

 = N | [j]m, for j = 1...n. The number of blocks, n, in any 

message must satisfy n < 2

m

. A procedure should be established to ensure the uniqueness of the 

message nonces. 

This recommendation allows other methods and approaches for achieving the uniqueness 

property. Validation that an implementation of the CTR mode conforms to this recommendation 

will typically include an examination of the procedures for assuring the uniqueness of counter 

blocks within messages and across all messages that are encrypted under a given key. 
 

20 

Appendix C: Generation of Initialization Vectors 

The CBC, CFB, and OFB modes require an initialization vector as input, in addition to the 

plaintext. An IV must be generated for each execution of the encryption operation, and the same 

IV is necessary for the corresponding execution of the decryption operation. Therefore, the IV, or 

information that is sufficient to calculate the IV, must be available to each party to the 

communication. 

The IV need not be secret, so the IV, or information sufficient to determine the IV, may be 

transmitted with the ciphertext. 

For the CBC and CFB modes, the IVs must be unpredictable. In particular, for any given 

plaintext, it must not be possible to predict the IV that will be associated to the plaintext in 

advance of the generation of the IV. 

There are two recommended methods for generating unpredictable IVs. The first method is to 

apply the forward cipher function, under the same key that is used for the encryption of the 

plaintext, to a nonce. The nonce must be a data block that is unique to each execution of the 

encryption operation. For example, the nonce may be a counter, as described in Appendix B, or 

a message number. The second method is to generate a random data block using a FIPSapproved random number generator. 

 

For the OFB mode, the IV need not be unpredictable, but it must be a nonce that is unique to 

each execution of the encryption operation. For example, the nonce may be a counter, as 

described in Appendix B, or a message number. 

If, contrary to this requirement, the same IV is used for the OFB encryption of more than one 

message, then the confidentiality of those messages may be compromised. In particular, if a

plaintext block of any of these messages is known, say, the jth plaintext block, then the jth output 

of the forward cipher function can be determined easily from the jth ciphertext block of the 

message. This information allows the jth plaintext block of any other message that is encrypted 

using the same IV to be easily recovered from the jth ciphertext block of that message. 

Confidentiality may similarly be compromised if any of the input blocks to the forward cipher 

function for the OFB encryption of a message is designated as the IV for the encryption of 

another message under the given key. One consequence of this observation is that IVs for the 

OFB mode should not be generated by invoking the block cipher on another IV. 

Validation that an implementation of the CBC, CFB, or OFB mode conforms to this 

recommendation will typically include an examination of the procedures for assuring the 

unpredictability or uniqueness of the IV. 
 

21 

Appendix D: Error Properties 

A bit error is the substitution of a ‘0’ bit for a ‘1’ bit, or vice versa. This appendix contains a 

discussion of the effects of bit errors in ciphertext blocks (or segments), counter blocks, and IVs 

on the modes in this recommendation. Insertion or deletion of bits into ciphertext blocks (or 

segments) is also discussed. 

For any confidentiality mode, if there are any bit errors in a single ciphertext block (or segment), 

then the decryption of that ciphertext block (or segment) will be incorrect, i.e., it will differ from 

the original plaintext block (or segment). In the CFB, OFB, and CTR modes, the bit error(s) in 

the decrypted ciphertext block (or segment) occur in the same bit position(s) as in the ciphertext 

block (or segment); the other bit positions are not affected. In the ECB and CBC modes, a bit 

error may occur, independently, in any bit position of the decrypted ciphertext block, with an 

expected error rate of fifty percent, depending on the strength of the underlying block cipher. 

For the ECB, OFB, and CTR modes, bit errors within a ciphertext block do not affect the 

decryption of any other blocks. In the CBC mode, any bit positions that contain bit errors in a 

ciphertext block will also contain bit errors in the decryption of the succeeding ciphertext block; 

the other bit positions are not affected. In the CFB mode, bit errors in a ciphertext segment affect 

the decryption of the next b/s (rounded up to the nearest integer) ciphertext segments. A bit error 

may occur, independently, in any bit position in these decrypted segments, with an expected 

error rate of fifty percent. 

 

Similarly, for the CTR mode, if there is a bit error in a counter block, then a bit error may occur, 

independently, in any bit position of the decryption of the corresponding ciphertext, with an 

expected error rate of fifty percent. 

Bit errors in IVs also affect the decryption process. In the OFB mode, bit errors in the IV affect 

the decryption of every ciphertext block. In the CFB mode, bit errors in the IV affect, at a 

minimum, the decryption of the first ciphertext segment, and possibly successive ciphertext 

segments, depending on the bit position of the rightmost bit error in the IV. (In general, a bit 

error in the ith most significant bit position affects the decryptions of the first i/s (rounding up) 

ciphertext segments.) For both the OFB and CFB modes, a bit error may occur, independently, 

in any bit position of the affected ciphertext blocks (or segments), with an expected error rate of 

fifty percent. In the CBC mode, if bit errors occur in the IV, then the first ciphertext block will 

be decrypted incorrectly, and bit errors will occur in exactly the same bit positions as in the IV; 

the decryptions of the other ciphertext blocks are not affected. 

Consequently, for the CBC mode, the decryption of the first ciphertext block is vulnerable to the 

(deliberate) introduction of bit errors in specific bit positions of the IV if the integrity of the IV is 

not protected. Similarly, for the OFB and CTR modes, the decryption of any ciphertext block is 

vulnerable to the introduction of specific bit errors into that ciphertext block if its integrity is not 

protected. The same property also holds for the ciphertext segments in the CFB mode; however, 

for every ciphertext segment except the last one, the existence of such bit errors may be detected 

by their randomizing effect on the decryption of the succeeding ciphertext segment. 
 

22 

Table D.1 summarizes the effects of bit errors in a ciphertext block or IV on the decryption of the 

ciphertext for each of the five confidentiality modes. 

Table D.1e five confidentiality modes. 

Table D.2: Summary of Effect of Bit Errors on Decryption 

Mode Effect of Bit Errors in Cj Effect of Bit Errors in the IV 

ECB RBE in the decryption of Cj

 Not applicable 

CBC RBE in the decryption of Cj

SBE in the decryption of Cj+1 SBE in the decryption of C1

CFB SBE in the decryption of Cj

RBE in the decryption of Cj+1,...,Cj+b/s

RBE in the decryption of C1, C2, ..., Cj 

for some j between 1 and b/s 

OFB SBE in the decryption of Cj

 RBE in the decryption of C1, C2, ..., Cn

CTR SBE in the decryption of Cj

 Not applicable * 

RBE: random bit errors, i.e., bit errors occur independently in any bit position with an 

expected probability of 1⁄2. 

SBE: specific bit errors, i.e., bit errors occur in the same bit position(s) as the original bit 

error(s). 

* Bit errors in the jth counter block, Tj

, result in RBE in the decryption of Cj. 

The deletion or insertion of bits into a ciphertext block (or segment) spoils the synchronization of 

the block (or segment) boundaries; in effect, bit errors may occur in the bit position of the 

inserted or deleted bit, and in every subsequent bit position. Therefore, the decryptions of the 

subsequent ciphertext blocks (or segments) will almost certainly be incorrect until the 

synchronization is restored. When the 1-bit CFB mode is used, then the synchronization is 

automatically restored b+1 positions after the inserted or deleted bit. For other values of s in the 

CFB mode, and for the other confidentiality modes in this recommendation, the synchronization 

must be restored externally. 
 

23 

Appendix E: Modes of Triple DES 

FIPS Pub 46-3 [FIPS 46-3] specifies the Data Encryption Standard (DES) algorithm and 

approves its three-fold, compound operation that is specified in ANSI X9.52 [1]: the Triple Data 

Encryption Algorithm (TDEA). Essentially, the TDEA consists of the application of the forward 

DES algorithm, i.e, DES encryption, under one key, followed by the application of the inverse 

DES algorithm, i.e., DES decryption, under a second key, followed by the application of the 

forward DES algorithm under a third key. The TDEA is often called Triple DES. 

FIPS Pub 46-3 also approves the seven modes of operation of Triple DES that are specified in 

ANSI X9.52. Four of those modes are equivalent to modes in this recommendation with the 

TDEA as the underlying block cipher. In particular, the TECB, TCBC, and TOFB modes in 

ANSI X9.52 are equivalent to the ECB, CBC, and OFB modes in this recommendation, with the 

TDEA as the underlying block cipher; the TCFB mode in ANSI X9.52 is equivalent to the CFB 

mode in this recommendation, with the TDEA as the underlying block cipher, provided that the 

possible choices of the parameter s (the segment size) are restricted to three values: 1, 8, and 64. 

The remaining three modes in ANSI X9.52 are TCBC-I, TCFB-P, and TOFB-I; they are mode 

variants that allow for interleaving or pipelining; this recommendation does not provide 

analogues of these three modes. 

The Triple DES modes in ANSI X9.52 should not be used as the underlying block cipher 

algorithm for the modes in this recommendation. However, the Triple DES algorithm, i.e., 

TDEA, as described above, may be used as the underlying block cipher algorithm for the six 

modes in this recommendation. One of the resulting modes of Triple DES is new, i.e., not 

specified in ANSI X9.52: the CTR mode of the TDEA. 
 

24 

Appendix F: Example Vectors for Modes of Operation of the AES 

In this appendix, three examples are provided for each of the modes in this recommendation with 

the AES algorithm [2] as the underlying block cipher: one example is given for each of the 

allowed key sizes (128, 192, and 256 bits). Some intermediate results are presented. For the five 

confidentiality modes, examples are provided for both encryption and decryption. Examples are 

provided for 1-bit, 8-bit, and 128 bit CFB. The plaintext for all but two of these examples is 

equivalent to the following string of hexadecimal characters, formatted into four 128 bit blocks: 

6bc1bee22e409f96e93d7e117393172a 

ae2d8a571e03ac9c9eb76fac45af8e51 

30c81c46a35ce411e5fbc1191a0a52ef 

f69f2445df4f9b17ad2b417be66c3710. 

For the example of 1-bit CFB, the plaintext is the first 16 bits in the above string; for the example 

of 8-bit CFB, the plaintext is the first 18 octets in the above string. All strings are presented in 

hexadecimal notation, except in the example of 1-bit CFB, where the plaintext and ciphertext 

segments are single bits. 

F.1 ECB Example Vectors 

F.1.1 ECB-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

Block #1 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Input Block 6bc1bee22e409f96e93d7e117393172a 

Output Block 3ad77bb40d7a3660a89ecaf32466ef97 

Ciphertext 3ad77bb40d7a3660a89ecaf32466ef97 

Block #2 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Input Block ae2d8a571e03ac9c9eb76fac45af8e51 

Output Block f5d3d58503b9699de785895a96fdbaaf 

Ciphertext f5d3d58503b9699de785895a96fdbaaf 

Block #3 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Input Block 30c81c46a35ce411e5fbc1191a0a52ef 

Output Block 43b1cd7f598ece23881b00e3ed030688 

Ciphertext 43b1cd7f598ece23881b00e3ed030688 

Block #4 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Input Block f69f2445df4f9b17ad2b417be66c3710 

Output Block 7b0c785e27e8ad3f8223207104725dd4 

Ciphertext 7b0c785e27e8ad3f8223207104725dd4 

F.1.2 ECB-AES128.Decrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

Block #1 

Ciphertext 3ad77bb40d7a3660a89ecaf32466ef97 

Input Block 3ad77bb40d7a3660a89ecaf32466ef97 
 

25 

Output Block 6bc1bee22e409f96e93d7e117393172a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Ciphertext f5d3d58503b9699de785895a96fdbaaf 

Input Block f5d3d58503b9699de785895a96fdbaaf 

Output Block ae2d8a571e03ac9c9eb76fac45af8e51 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Ciphertext 43b1cd7f598ece23881b00e3ed030688 

Input Block 43b1cd7f598ece23881b00e3ed030688 

Output Block 30c81c46a35ce411e5fbc1191a0a52ef 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Ciphertext 7b0c785e27e8ad3f8223207104725dd4 

Input Block 7b0c785e27e8ad3f8223207104725dd4 

Output Block f69f2445df4f9b17ad2b417be66c3710 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.1.3 ECB-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

Block #1 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Input Block 6bc1bee22e409f96e93d7e117393172a 

Output Block bd334f1d6e45f25ff712a214571fa5cc 

Ciphertext bd334f1d6e45f25ff712a214571fa5cc 

Block #2 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Input Block ae2d8a571e03ac9c9eb76fac45af8e51 

Output Block 974104846d0ad3ad7734ecb3ecee4eef 

Ciphertext 974104846d0ad3ad7734ecb3ecee4eef 

Block #3 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Input Block 30c81c46a35ce411e5fbc1191a0a52ef 

Output Block ef7afd2270e2e60adce0ba2face6444e 

Ciphertext ef7afd2270e2e60adce0ba2face6444e 

Block #4 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Input Block f69f2445df4f9b17ad2b417be66c3710 

Output Block 9a4b41ba738d6c72fb16691603c18e0e 

Ciphertext 9a4b41ba738d6c72fb16691603c18e0e 

F.1.4 ECB-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

Block #1 

Ciphertext bd334f1d6e45f25ff712a214571fa5cc 

Input Block bd334f1d6e45f25ff712a214571fa5cc 

Output Block 6bc1bee22e409f96e93d7e117393172a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Ciphertext 974104846d0ad3ad7734ecb3ecee4eef 

Input Block 974104846d0ad3ad7734ecb3ecee4eef 

Output Block ae2d8a571e03ac9c9eb76fac45af8e51 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 
 

26 

Block #3 

Ciphertext ef7afd2270e2e60adce0ba2face6444e 

Input Block ef7afd2270e2e60adce0ba2face6444e 

Output Block 30c81c46a35ce411e5fbc1191a0a52ef 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Ciphertext 9a4b41ba738d6c72fb16691603c18e0e 

Input Block 9a4b41ba738d6c72fb16691603c18e0e 

Output Block f69f2445df4f9b17ad2b417be66c3710 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.1.5 ECB-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 

1f352c073b6108d72d9810a30914dff4 

Block #1 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Input Block 6bc1bee22e409f96e93d7e117393172a 

Output Block f3eed1bdb5d2a03c064b5a7e3db181f8 

Ciphertext f3eed1bdb5d2a03c064b5a7e3db181f8 

Block #2 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Input Block ae2d8a571e03ac9c9eb76fac45af8e51 

Output Block 591ccb10d410ed26dc5ba74a31362870 

Ciphertext 591ccb10d410ed26dc5ba74a31362870 

Block #3 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Input Block 30c81c46a35ce411e5fbc1191a0a52ef 

Output Block b6ed21b99ca6f4f9f153e7b1beafed1d 

Ciphertext b6ed21b99ca6f4f9f153e7b1beafed1d 

Block #4 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Input Block f69f2445df4f9b17ad2b417be66c3710 

Output Block 23304b7a39f9f3ff067d8d8f9e24ecc7 

Ciphertext 23304b7a39f9f3ff067d8d8f9e24ecc7 

F.1.6 ECB-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

Block #1 

Ciphertext f3eed1bdb5d2a03c064b5a7e3db181f8 

Input Block f3eed1bdb5d2a03c064b5a7e3db181f8 

Output Block 6bc1bee22e409f96e93d7e117393172a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Ciphertext 591ccb10d410ed26dc5ba74a31362870 

Input Block 591ccb10d410ed26dc5ba74a31362870 

Output Block ae2d8a571e03ac9c9eb76fac45af8e51 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Ciphertext b6ed21b99ca6f4f9f153e7b1beafed1d 

Input Block b6ed21b99ca6f4f9f153e7b1beafed1d 

Output Block 30c81c46a35ce411e5fbc1191a0a52ef 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 
 

27 

Block #4 

Ciphertext 23304b7a39f9f3ff067d8d8f9e24ecc7 

Input Block 23304b7a39f9f3ff067d8d8f9e24ecc7 

Output Block f69f2445df4f9b17ad2b417be66c3710 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.2 CBC Example Vectors 

F.2.1 CBC-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Input Block 6bc0bce12a459991e134741a7f9e1925 

Output Block 7649abac8119b246cee98e9b12e9197d 

Ciphertext 7649abac8119b246cee98e9b12e9197d 

Block #2 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Input Block d86421fb9f1a1eda505ee1375746972c 

Output Block 5086cb9b507219ee95db113a917678b2 

Ciphertext 5086cb9b507219ee95db113a917678b2 

Block #3 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Input Block 604ed7ddf32efdff7020d0238b7c2a5d 

Output Block 73bed6b8e3c1743b7116e69e22229516 

Ciphertext 73bed6b8e3c1743b7116e69e22229516 

Block #4 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Input Block 8521f2fd3c8eef2cdc3da7e5c44ea206 

Output Block 3ff1caa1681fac09120eca307586e1a7 

Ciphertext 3ff1caa1681fac09120eca307586e1a7 

F.2.2 CBC-AES128.Decrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Ciphertext 7649abac8119b246cee98e9b12e9197d 

Input Block 7649abac8119b246cee98e9b12e9197d 

Output Block 6bc0bce12a459991e134741a7f9e1925 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Ciphertext 5086cb9b507219ee95db113a917678b2 

Input Block 5086cb9b507219ee95db113a917678b2 

Output Block d86421fb9f1a1eda505ee1375746972c 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Ciphertext 73bed6b8e3c1743b7116e69e22229516 

Input Block 73bed6b8e3c1743b7116e69e22229516 

Output Block 604ed7ddf32efdff7020d0238b7c2a5d 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Ciphertext 3ff1caa1681fac09120eca307586e1a7 

Input Block 3ff1caa1681fac09120eca307586e1a7 
 

28 

Output Block 8521f2fd3c8eef2cdc3da7e5c44ea206 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.2.3 CBC-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Input Block 6bc0bce12a459991e134741a7f9e1925 

Output Block 4f021db243bc633d7178183a9fa071e8 

Ciphertext 4f021db243bc633d7178183a9fa071e8 

Block #2 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Input Block e12f97e55dbfcfa1efcf7796da0fffb9 

Output Block b4d9ada9ad7dedf4e5e738763f69145a 

Ciphertext b4d9ada9ad7dedf4e5e738763f69145a 

Block #3 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Input Block 8411b1ef0e2109e5001cf96f256346b5 

Output Block 571b242012fb7ae07fa9baac3df102e0 

Ciphertext 571b242012fb7ae07fa9baac3df102e0 

Block #4 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Input Block a1840065cdb4e1f7d282fbd7db9d35f0 

Output Block 08b0e27988598881d920a9e64f5615cd 

Ciphertext 08b0e27988598881d920a9e64f5615cd 

F.2.4 CBC-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Ciphertext 4f021db243bc633d7178183a9fa071e8 

Input Block 4f021db243bc633d7178183a9fa071e8 

Output Block 6bc0bce12a459991e134741a7f9e1925 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Ciphertext b4d9ada9ad7dedf4e5e738763f69145a 

Input Block b4d9ada9ad7dedf4e5e738763f69145a 

Output Block e12f97e55dbfcfa1efcf7796da0fffb9 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Ciphertext 571b242012fb7ae07fa9baac3df102e0 

Input Block 571b242012fb7ae07fa9baac3df102e0 

Output Block 8411b1ef0e2109e5001cf96f256346b5 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Ciphertext 08b0e27988598881d920a9e64f5615cd 

Input Block 08b0e27988598881d920a9e64f5615cd 

Output Block a1840065cdb4e1f7d282fbd7db9d35f0 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.2.5 CBC-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 
 

29 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Input Block 6bc0bce12a459991e134741a7f9e1925 

Output Block f58c4c04d6e5f1ba779eabfb5f7bfbd6 

Ciphertext f58c4c04d6e5f1ba779eabfb5f7bfbd6 

Block #2 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Input Block 5ba1c653c8e65d26e929c4571ad47587 

Output Block 9cfc4e967edb808d679f777bc6702c7d 

Ciphertext 9cfc4e967edb808d679f777bc6702c7d 

Block #3 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Input Block ac3452d0dd87649c8264b662dc7a7e92 

Output Block 39f23369a9d9bacfa530e26304231461 

Ciphertext 39f23369a9d9bacfa530e26304231461 

Block #4 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Input Block cf6d172c769621d8081ba318e24f2371 

Output Block b2eb05e2c39be9fcda6c19078c6a9d1b 

Ciphertext b2eb05e2c39be9fcda6c19078c6a9d1b 

F.2.6 CBC-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Ciphertext f58c4c04d6e5f1ba779eabfb5f7bfbd6 

Input Block f58c4c04d6e5f1ba779eabfb5f7bfbd6 

Output Block 6bc0bce12a459991e134741a7f9e1925 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Ciphertext 9cfc4e967edb808d679f777bc6702c7d 

Input Block 9cfc4e967edb808d679f777bc6702c7d 

Output Block 5ba1c653c8e65d26e929c4571ad47587 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Ciphertext 39f23369a9d9bacfa530e26304231461 

Input Block 39f23369a9d9bacfa530e26304231461 

Output Block ac3452d0dd87649c8264b662dc7a7e92 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Ciphertext b2eb05e2c39be9fcda6c19078c6a9d1b 

Input Block b2eb05e2c39be9fcda6c19078c6a9d1b 

Output Block cf6d172c769621d8081ba318e24f2371 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.3 CFB Example Vectors 

F.3.1 CFB1-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 
 

30 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Plaintext 0 

Ciphertext 0 

Segment #2 

Input Block 00020406080a0c0e10121416181a1c1e 

Output Block 19cf576c7596e702f298b35666955c79 

Plaintext 1 

Ciphertext 1 

Segment #3 

Input Block 0004080c1014181c2024282c3034383d 

Output Block 59e17759acd02b801fa321ea059e331f 

Plaintext 1 

Ciphertext 1 

Segment #4 

Input Block 0008101820283038404850586068707b 

Output Block 71f415b0cc109e8b0faa14ab740c22f4 

Plaintext 0 

Ciphertext 0 

Segment #5 

Input Block 00102030405060708090a0b0c0d0e0f6 

Output Block 3fb76d3d1048179964597a0f64d5adad 

Plaintext 1 

Ciphertext 1 

Segment #6 

Input Block 0020406080a0c0e10121416181a1c1ed 

Output Block 4c943b4bac54ab974e3e52326d29aaa1 

Plaintext 0 

Ciphertext 0 

Segment #7 

Input Block 004080c1014181c2024282c3034383da 

Output Block c94da41eb3d3acf1993a512ab1e8203f 

Plaintext 1 

Ciphertext 0 

Segment #8 

Input Block 008101820283038404850586068707b4 

Output Block e07f5e98778f75dbb2691c3f582c3953 

Plaintext 1 

Ciphertext 0 

Segment #9 

Input Block 0102030405060708090a0b0c0d0e0f68 

Output Block 02ef5fc8961efcce8568bc0731262dc7 

Plaintext 1 

Ciphertext 1 

Segment #10 

Input Block 020406080a0c0e10121416181a1c1ed1 

Output Block 9f5a30367065efbe914b53698c8716b7 

Plaintext 1 

Ciphertext 0 

Segment #11 

Input Block 04080c1014181c2024282c3034383da2 

Output Block d018cfb81d0580edbff955ed74d382db 

Plaintext 0 
 

31 

Ciphertext 1 

Segment #12 

Input Block 08101820283038404850586068707b45 

Output Block 81272ab351e08e0b695b94b8164d86f4 

Plaintext 0 

Ciphertext 1 

Segment #13 

Input Block 102030405060708090a0b0c0d0e0f68b 

Output Block 094d33f856483d3fa01ba94f7e5ab3e7 

Plaintext 0 

Ciphertext 0 

Segment #14 

Input Block 20406080a0c0e10121416181a1c1ed16 

Output Block 609900ad61923c8c102cd8d0d7947a2c 

Plaintext 0 

Ciphertext 0 

Segment #15 

Input Block 4080c1014181c2024282c3034383da2c 

Output Block 9e5a154de966ab4db9c88b22a398134e 

Plaintext 0 

Ciphertext 1 

Segment #16 

Input Block 8101820283038404850586068707b459 

Output Block 7fe16252b338bc4de3725c4156dfed20 

Plaintext 1 

Ciphertext 1 

F.3.2 CFB1-AES128.Decrypt

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Ciphertext 0 

Plaintext 0 

Segment #2 

Input Block 00020406080a0c0e10121416181a1c1e 

Output Block 19cf576c7596e702f298b35666955c79 

Ciphertext 1 

Plaintext 1 

Segment #3 

Input Block 0004080c1014181c2024282c3034383d 

Output Block 59e17759acd02b801fa321ea059e331f 

Ciphertext 1 

Plaintext 1 

Segment #4 

Input Block 0008101820283038404850586068707b 

Output Block 71f415b0cc109e8b0faa14ab740c22f4 

Ciphertext 0 

Plaintext 0 

Segment #5 

Input Block 00102030405060708090a0b0c0d0e0f6 

Output Block 3fb76d3d1048179964597a0f64d5adad 
 

32 

Ciphertext 1 

Plaintext 1 

Segment #6 

Input Block 0020406080a0c0e10121416181a1c1ed 

Output Block 4c943b4bac54ab974e3e52326d29aaa1 

Ciphertext 0 

Plaintext 0 

Segment #7 

Input Block 004080c1014181c2024282c3034383da 

Output Block c94da41eb3d3acf1993a512ab1e8203f 

Ciphertext 0 

Plaintext 1 

Segment #8 

Input Block 008101820283038404850586068707b4 

Output Block e07f5e98778f75dbb2691c3f582c3953 

Ciphertext 0 

Plaintext 1 

Segment #9 

Input Block 0102030405060708090a0b0c0d0e0f68 

Output Block 02ef5fc8961efcce8568bc0731262dc7 

Ciphertext 1 

Plaintext 1 

Segment #10 

Input Block 020406080a0c0e10121416181a1c1ed1 

Output Block 9f5a30367065efbe914b53698c8716b7 

Ciphertext 0 

Plaintext 1 

Segment #11 

Input Block 04080c1014181c2024282c3034383da2 

Output Block d018cfb81d0580edbff955ed74d382db 

Ciphertext 1 

Plaintext 0 

Segment #12 

Input Block 08101820283038404850586068707b45 

Output Block 81272ab351e08e0b695b94b8164d86f4 

Ciphertext 1 

Plaintext 0 

Segment #13 

Input Block 102030405060708090a0b0c0d0e0f68b 

Output Block 094d33f856483d3fa01ba94f7e5ab3e7 

Ciphertext 0 

Plaintext 0 

Segment #14 

Input Block 20406080a0c0e10121416181a1c1ed16 

Output Block 609900ad61923c8c102cd8d0d7947a2c 

Ciphertext 0 

Plaintext 0 

Segment #15 

Input Block 4080c1014181c2024282c3034383da2c 

Output Block 9e5a154de966ab4db9c88b22a398134e 

Ciphertext 1 

Plaintext 0 

Segment #16 

Input Block 8101820283038404850586068707b459 
 

33 

Output Block 7fe16252b338bc4de3725c4156dfed20 

Ciphertext 1 

Plaintext 1 

F.3.3 CFB1-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Plaintext 0 

Ciphertext 1 

Segment #2 

Input Block 00020406080a0c0e10121416181a1c1f 

Output Block a0e2bee6eb1734379bd4908be6a991a0 

Plaintext 1 

Ciphertext 0 

Segment #3 

Input Block 0004080c1014181c2024282c3034383e 

Output Block b1a1766bedec7ee3ba9cd3f34fbed4c6 

Plaintext 1 

Ciphertext 0 

Segment #4 

Input Block 0008101820283038404850586068707c 

Output Block b294ae5f393ae0179e6d3d8c45a7a4b9 

Plaintext 0 

Ciphertext 1 

Segment #5 

Input Block 00102030405060708090a0b0c0d0e0f9 

Output Block f0f703ff5d0634aa8aee7f1e26aafca3 

Plaintext 1 

Ciphertext 0 

Segment #6 

Input Block 0020406080a0c0e10121416181a1c1f2 

Output Block 4d67df426abdb8c89e7de9fb3069d8be 

Plaintext 0 

Ciphertext 0 

Segment #7 

Input Block 004080c1014181c2024282c3034383e4 

Output Block 30bc892338dfa10664118b9f4ba348d2 

Plaintext 1 

Ciphertext 1 

Segment #8 

Input Block 008101820283038404850586068707c9 

Output Block 763ad8c63ed78d66452bb44c8bb7a8c8 

Plaintext 1 

Ciphertext 1 

Segment #9 

Input Block 0102030405060708090a0b0c0d0e0f93 

Output Block bfc36f5cfbc1306859b48f8fa62a43df 

Plaintext 1 

Ciphertext 0 

Segment #10 
 

34 

Input Block 020406080a0c0e10121416181a1c1f26 

Output Block 16e27adac112a0bf6a69c95cbdf584a3 

Plaintext 1 

Ciphertext 1 

Segment #11 

Input Block 04080c1014181c2024282c3034383e4d 

Output Block 1e9d21c3da3de9186251160045756ce0 

Plaintext 0 

Ciphertext 0 

Segment #12 

Input Block 08101820283038404850586068707c9a 

Output Block b836e0f661b51d8bd38c448e0e5a11bb 

Plaintext 0 

Ciphertext 1 

Segment #13 

Input Block 102030405060708090a0b0c0d0e0f935 

Output Block c5efcdd09dbb92d1faada8f6c9bab052 

Plaintext 0 

Ciphertext 1 

Segment #14 

Input Block 20406080a0c0e10121416181a1c1f26b 

Output Block 7c99710018d88e40bd4ac8f1b2bf4dbb 

Plaintext 0 

Ciphertext 0 

Segment #15 

Input Block 4080c1014181c2024282c3034383e4d6 

Output Block 173bcd8b4dad60ae6646813fdcb81f5b 

Plaintext 0 

Ciphertext 0 

Segment #16 

Input Block 8101820283038404850586068707c9ac 

Output Block 09844c6d2272d148d5af1c7bf01bb439 

Plaintext 1 

Ciphertext 1 

F.3.4 CFB1-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Ciphertext 1 

Plaintext 0 

Segment #2 

Input Block 00020406080a0c0e10121416181a1c1f 

Output Block a0e2bee6eb1734379bd4908be6a991a0 

Ciphertext 0 

Plaintext 1 

Segment #3 

Input Block 0004080c1014181c2024282c3034383e 

Output Block b1a1766bedec7ee3ba9cd3f34fbed4c6 

Ciphertext 0 

Plaintext 1 
 

35 

Segment #4 

Input Block 0008101820283038404850586068707c 

Output Block b294ae5f393ae0179e6d3d8c45a7a4b9 

Ciphertext 1 

Plaintext 0 

Segment #5 

Input Block 00102030405060708090a0b0c0d0e0f9 

Output Block f0f703ff5d0634aa8aee7f1e26aafca3 

Ciphertext 0 

Plaintext 1 

Segment #6 

Input Block 0020406080a0c0e10121416181a1c1f2 

Output Block 4d67df426abdb8c89e7de9fb3069d8be 

Ciphertext 0 

Plaintext 0 

Segment #7 

Input Block 004080c1014181c2024282c3034383e4 

Output Block 30bc892338dfa10664118b9f4ba348d2 

Ciphertext 1 

Plaintext 1 

Segment #8 

Input Block 008101820283038404850586068707c9 

Output Block 763ad8c63ed78d66452bb44c8bb7a8c8 

Ciphertext 1 

Plaintext 1 

Segment #9 

Input Block 0102030405060708090a0b0c0d0e0f93 

Output Block bfc36f5cfbc1306859b48f8fa62a43df 

Ciphertext 0 

Plaintext 1 

Segment #10 

Input Block 020406080a0c0e10121416181a1c1f26 

Output Block 16e27adac112a0bf6a69c95cbdf584a3 

Ciphertext 1 

Plaintext 1 

Segment #11 

Input Block 04080c1014181c2024282c3034383e4d 

Output Block 1e9d21c3da3de9186251160045756ce0 

Ciphertext 0 

Plaintext 0 

Segment #12 

Input Block 08101820283038404850586068707c9a 

Output Block b836e0f661b51d8bd38c448e0e5a11bb 

Ciphertext 1 

Plaintext 0 

Segment #13 

Input Block 102030405060708090a0b0c0d0e0f935 

Output Block c5efcdd09dbb92d1faada8f6c9bab052 

Ciphertext 1 

Plaintext 0 

Segment #14 

Input Block 20406080a0c0e10121416181a1c1f26b 

Output Block 7c99710018d88e40bd4ac8f1b2bf4dbb 

Ciphertext 0 
 

36 

Plaintext 0 

Segment #15 

Input Block 4080c1014181c2024282c3034383e4d6 

Output Block 173bcd8b4dad60ae6646813fdcb81f5b 

Ciphertext 0 

Plaintext 0 

Segment #16 

Input Block 8101820283038404850586068707c9ac 

Output Block 09844c6d2272d148d5af1c7bf01bb439 

Ciphertext 1 

Plaintext 1 

F.3.5 CFB1-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 

1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Plaintext 0 

Ciphertext 1 

Segment #2 

Input Block 00020406080a0c0e10121416181a1c1f 

Output Block ee93d380e0f01117fffd78017599514a 

Plaintext 1 

Ciphertext 0 

Segment #3 

Input Block 0004080c1014181c2024282c3034383e 

Output Block 857749898b3602aad91e699911de89b0 

Plaintext 1 

Ciphertext 0 

Segment #4 

Input Block 0008101820283038404850586068707c 

Output Block dce81c80810e2ba343a6bb402716b7a8 

Plaintext 0 

Ciphertext 1 

Segment #5 

Input Block 00102030405060708090a0b0c0d0e0f9 

Output Block e5517bfcdccea00501350a601f754823 

Plaintext 1 

Ciphertext 0 

Segment #6 

Input Block 0020406080a0c0e10121416181a1c1f2 

Output Block 15799c7f4081a78cc41f29955349c5a0 

Plaintext 0 

Ciphertext 0 

Segment #7 

Input Block 004080c1014181c2024282c3034383e4 

Output Block 84d246bdb391f6a7979ff5ccb8467262 

Plaintext 1 

Ciphertext 0 

Segment #8 

Input Block 008101820283038404850586068707c8 
 

37 

Output Block bb9e05db9855a9e7e3837a648dd4c3b0 

Plaintext 1 

Ciphertext 0 

Segment #9 

Input Block 0102030405060708090a0b0c0d0e0f90 

Output Block a413c5714f70287dfcd943004bf7ac8e 

Plaintext 1 

Ciphertext 0 

Segment #10 

Input Block 020406080a0c0e10121416181a1c1f20 

Output Block a7310abf87610d66edf6c892a84460d5 

Plaintext 1 

Ciphertext 0 

Segment #11 

Input Block 04080c1014181c2024282c3034383e40 

Output Block 8aec6712d89bd147c83b51d787b11399 

Plaintext 0 

Ciphertext 1 

Segment #12 

Input Block 08101820283038404850586068707c81 

Output Block 2ff05b620f68134f4ba92deffbfc93b2 

Plaintext 0 

Ciphertext 0 

Segment #13 

Input Block 102030405060708090a0b0c0d0e0f902 

Output Block 819208afd5284316065a76bead028ad3 

Plaintext 0 

Ciphertext 1 

Segment #14 

Input Block 20406080a0c0e10121416181a1c1f205 

Output Block 1914ed64b2115167ce2ca4c813da5245 

Plaintext 0 

Ciphertext 0 

Segment #15 

Input Block 4080c1014181c2024282c3034383e40a 

Output Block 638abae8724a954ae9e1e2e119deb6e1 

Plaintext 0 

Ciphertext 0 

Segment #16 

Input Block 8101820283038404850586068707c814 

Output Block 2b4f488a3f958c52a3f1db2da938360e 

Plaintext 1 

Ciphertext 1 

F.3.6 CFB1-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Ciphertext 1 

Plaintext 0 
 

38 

Segment #2 

Input Block 00020406080a0c0e10121416181a1c1f 

Output Block ee93d380e0f01117fffd78017599514a 

Ciphertext 0 

Plaintext 1 

Segment #3 

Input Block 0004080c1014181c2024282c3034383e 

Output Block 857749898b3602aad91e699911de89b0 

Ciphertext 0 

Plaintext 1 

Segment #4 

Input Block 0008101820283038404850586068707c 

Output Block dce81c80810e2ba343a6bb402716b7a8 

Ciphertext 1 

Plaintext 0 

Segment #5 

Input Block 00102030405060708090a0b0c0d0e0f9 

Output Block e5517bfcdccea00501350a601f754823 

Ciphertext 0 

Plaintext 1 

Segment #6 

Input Block 0020406080a0c0e10121416181a1c1f2 

Output Block 15799c7f4081a78cc41f29955349c5a0 

Ciphertext 0 

Plaintext 0 

Segment #7 

Input Block 004080c1014181c2024282c3034383e4 

Output Block 84d246bdb391f6a7979ff5ccb8467262 

Ciphertext 0 

Plaintext 1 

Segment #8 

Input Block 008101820283038404850586068707c8 

Output Block bb9e05db9855a9e7e3837a648dd4c3b0 

Ciphertext 0 

Plaintext 1 

Segment #9 

Input Block 0102030405060708090a0b0c0d0e0f90 

Output Block a413c5714f70287dfcd943004bf7ac8e 

Ciphertext 0 

Plaintext 1 

Segment #10 

Input Block 020406080a0c0e10121416181a1c1f20 

Output Block a7310abf87610d66edf6c892a84460d5 

Ciphertext 0 

Plaintext 1 

Segment #11 

Input Block 04080c1014181c2024282c3034383e40 

Output Block 8aec6712d89bd147c83b51d787b11399 

Ciphertext 1 

Plaintext 0 

Segment #12 

Input Block 08101820283038404850586068707c81 

Output Block 2ff05b620f68134f4ba92deffbfc93b2 

Ciphertext 0 
 

39 

Plaintext 0 

Segment #13 

Input Block 102030405060708090a0b0c0d0e0f902 

Output Block 819208afd5284316065a76bead028ad3 

Ciphertext 1 

Plaintext 0 

Segment #14 

Input Block 20406080a0c0e10121416181a1c1f205 

Output Block 1914ed64b2115167ce2ca4c813da5245 

Ciphertext 0 

Plaintext 0 

Segment #15 

Input Block 4080c1014181c2024282c3034383e40a 

Output Block 638abae8724a954ae9e1e2e119deb6e1 

Ciphertext 0 

Plaintext 0 

Segment #16 

Input Block 8101820283038404850586068707c814 

Output Block 2b4f488a3f958c52a3f1db2da938360e 

Ciphertext 1 

Plaintext 1 

F.3.7 CFB8-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Plaintext 6b 

Ciphertext 3b 

Segment #2 

Input Block 0102030405060708090a0b0c0d0e0f3b 

Output Block b8eb865a2b026381abb1d6560ed20f68 

Plaintext c1 

Ciphertext 79 

Segment #3 

Input Block 02030405060708090a0b0c0d0e0f3b79 

Output Block fce6033b4edce64cbaed3f61ff5b927c 

Plaintext be 

Ciphertext 42 

Segment #4 

Input Block 030405060708090a0b0c0d0e0f3b7942 

Output Block ae4e5e7ffe805f7a4395b180004f8ca8 

Plaintext e2 

Ciphertext 4c 

Segment #5 

Input Block 0405060708090a0b0c0d0e0f3b79424c 

Output Block b205eb89445b62116f1deb988a81e6dd 

Plaintext 2e 

Ciphertext 9c 

Segment #6 

Input Block 05060708090a0b0c0d0e0f3b79424c9c 

Output Block 4d21d456a5e239064fff4be0c0f85488 
 

40 

Plaintext 40 

Ciphertext 0d 

Segment #7 

Input Block 060708090a0b0c0d0e0f3b79424c9c0d 

Output Block 4b2f5c3895b9efdc85ee0c5178c7fd33 

Plaintext 9f 

Ciphertext d4 

Segment #8 

Input Block 0708090a0b0c0d0e0f3b79424c9c0dd4 

Output Block a0976d856da260a34104d1a80953db4c 

Plaintext 96 

Ciphertext 36 

Segment #9 

Input Block 08090a0b0c0d0e0f3b79424c9c0dd436 

Output Block 53674e5890a2c71b0f6a27a094e5808c 

Plaintext e9 

Ciphertext ba 

Segment #10 

Input Block 090a0b0c0d0e0f3b79424c9c0dd436ba 

Output Block f34cd32ffed495f8bc8adba194eccb7a 

Plaintext 3d 

Ciphertext ce 

Segment #11 

Input Block 0a0b0c0d0e0f3b79424c9c0dd436bace 

Output Block e08cf2407d7ed676c9049586f1d48ba6 

Plaintext 7e 

Ciphertext 9e 

Segment #12 

Input Block 0b0c0d0e0f3b79424c9c0dd436bace9e 

Output Block 1f5c88a19b6ca28e99c9aeb8982a6dd8 

Plaintext 11 

Ciphertext 0e 

Segment #13 

Input Block 0c0d0e0f3b79424c9c0dd436bace9e0e 

Output Block a70e63df781cf395a208bd2365c8779b 

Plaintext 73 

Ciphertext d4 

Segment #14 

Input Block 0d0e0f3b79424c9c0dd436bace9e0ed4 

Output Block cbcfe8b3bcf9ac202ce18420013319ab 

Plaintext 93 

Ciphertext 58 

Segment #15 

Input Block 0e0f3b79424c9c0dd436bace9e0ed458 

Output Block 7d9fac6604b3c8c5b1f8c5a00956cf56 

Plaintext 17 

Ciphertext 6a 

Segment #16 

Input Block 0f3b79424c9c0dd436bace9e0ed4586a 

Output Block 65c3fa64bf0343986825c636f4a1efd2 

Plaintext 2a 

Ciphertext 4f 

Segment #17 

Input Block 3b79424c9c0dd436bace9e0ed4586a4f 
 

41 

Output Block 9cff5e5ff4f554d56c924b9d6a6de21d 

Plaintext ae 

Ciphertext 32 

Segment #18 

Input Block 79424c9c0dd436bace9e0ed4586a4f32 

Output Block 946c3dc1584cc18400ecd8c6052c44b1 

Plaintext 2d 

Ciphertext b9 

F.3.8 CFB8-AES128.Decrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Ciphertext 3b 

Plaintext 6b 

Segment #2 

Input Block 0102030405060708090a0b0c0d0e0f3b 

Output Block b8eb865a2b026381abb1d6560ed20f68 

Ciphertext 79 

Plaintext c1 

Segment #3 

Input Block 02030405060708090a0b0c0d0e0f3b79 

Output Block fce6033b4edce64cbaed3f61ff5b927c 

Ciphertext 42 

Plaintext be 

Segment #4 

Input Block 030405060708090a0b0c0d0e0f3b7942 

Output Block ae4e5e7ffe805f7a4395b180004f8ca8 

Ciphertext 4c 

Plaintext e2 

Segment #5 

Input Block 0405060708090a0b0c0d0e0f3b79424c 

Output Block b205eb89445b62116f1deb988a81e6dd 

Ciphertext 9c 

Plaintext 2e 

Segment #6 

Input Block 05060708090a0b0c0d0e0f3b79424c9c 

Output Block 4d21d456a5e239064fff4be0c0f85488 

Ciphertext 0d 

Plaintext 40 

Segment #7 

Input Block 060708090a0b0c0d0e0f3b79424c9c0d 

Output Block 4b2f5c3895b9efdc85ee0c5178c7fd33 

Ciphertext d4 

Plaintext 9f 

Segment #8 

Input Block 0708090a0b0c0d0e0f3b79424c9c0dd4 

Output Block a0976d856da260a34104d1a80953db4c 

Ciphertext 36 

Plaintext 96 

Segment #9 
 

42 

Input Block 08090a0b0c0d0e0f3b79424c9c0dd436 

Output Block 53674e5890a2c71b0f6a27a094e5808c 

Ciphertext ba 

Plaintext e9 

Segment #10 

Input Block 090a0b0c0d0e0f3b79424c9c0dd436ba 

Output Block f34cd32ffed495f8bc8adba194eccb7a 

Ciphertext ce 

Plaintext 3d 

Segment #11 

Input Block 0a0b0c0d0e0f3b79424c9c0dd436bace 

Output Block e08cf2407d7ed676c9049586f1d48ba6 

Ciphertext 9e 

Plaintext 7e 

Segment #12 

Input Block 0b0c0d0e0f3b79424c9c0dd436bace9e 

Output Block 1f5c88a19b6ca28e99c9aeb8982a6dd8 

Ciphertext 0e 

Plaintext 11 

Segment #13 

Input Block 0c0d0e0f3b79424c9c0dd436bace9e0e 

Output Block a70e63df781cf395a208bd2365c8779b 

Ciphertext d4 

Plaintext 73 

Segment #14 

Input Block 0d0e0f3b79424c9c0dd436bace9e0ed4 

Output Block cbcfe8b3bcf9ac202ce18420013319ab 

Ciphertext 58 

Plaintext 93 

Segment #15 

Input Block 0e0f3b79424c9c0dd436bace9e0ed458 

Output Block 7d9fac6604b3c8c5b1f8c5a00956cf56 

Ciphertext 6a 

Plaintext 17 

Segment #16 

Input Block 0f3b79424c9c0dd436bace9e0ed4586a 

Output Block 65c3fa64bf0343986825c636f4a1efd2 

Ciphertext 4f 

Plaintext 2a 

Segment #17 

Input Block 3b79424c9c0dd436bace9e0ed4586a4f 

Output Block 9cff5e5ff4f554d56c924b9d6a6de21d 

Ciphertext 32 

Plaintext ae 

Segment #18 

Input Block 79424c9c0dd436bace9e0ed4586a4f32 

Output Block 946c3dc1584cc18400ecd8c6052c44b1 

Ciphertext b9 

Plaintext 2d 

F.3.9 CFB8-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 
 

43 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Plaintext 6b 

Ciphertext cd 

Segment #2 

Input Block 0102030405060708090a0b0c0d0e0fcd 

Output Block 63c82e99e7289617c49e6851e082142a 

Plaintext c1 

Ciphertext a2 

Segment #3 

Input Block 02030405060708090a0b0c0d0e0fcda2 

Output Block ec40a5497264bfb4d6820aaae73f75af 

Plaintext be 

Ciphertext 52 

Segment #4 

Input Block 030405060708090a0b0c0d0e0fcda252 

Output Block fc011a96afe968c32bae6495173a9154 

Plaintext e2 

Ciphertext 1e 

Segment #5 

Input Block 0405060708090a0b0c0d0e0fcda2521e 

Output Block de019e09ac995ba46a42916ef77d8fe5 

Plaintext 2e 

Ciphertext f0 

Segment #6 

Input Block 05060708090a0b0c0d0e0fcda2521ef0 

Output Block e980477efb7f896e07c4a2d527e7b537 

Plaintext 40 

Ciphertext a9 

Segment #7 

Input Block 060708090a0b0c0d0e0fcda2521ef0a9 

Output Block 9a9a77b11709b36e08e9321ae8b1e539 

Plaintext 9f 

Ciphertext 05 

Segment #8 

Input Block 0708090a0b0c0d0e0fcda2521ef0a905 

Output Block 5ca1d192a780fbca1471e10588593c7c 

Plaintext 96 

Ciphertext ca 

Segment #9 

Input Block 08090a0b0c0d0e0fcda2521ef0a905ca 

Output Block addb26efd21de4d002474c7748e0bc1d 

Plaintext e9 

Ciphertext 44 

Segment #10 

Input Block 090a0b0c0d0e0fcda2521ef0a905ca44 

Output Block f0c410ad6512c5177a5ee40a60de01b8 

Plaintext 3d 

Ciphertext cd 

Segment #11 

Input Block 0a0b0c0d0e0fcda2521ef0a905ca44cd 

Output Block 7bbf71f2b4f5cf68f3c0c1b9235dbd53 
 

44 

Plaintext 7e 

Ciphertext 05 

Segment #12 

Input Block 0b0c0d0e0fcda2521ef0a905ca44cd05 

Output Block 6dafb26e3c63b350811394b382e14d69 

Plaintext 11 

Ciphertext 7c 

Segment #13 

Input Block 0c0d0e0fcda2521ef0a905ca44cd057c 

Output Block ccd6e25255a80e9bdbec9fbc26e5fad6 

Plaintext 73 

Ciphertext bf 

Segment #14 

Input Block 0d0e0fcda2521ef0a905ca44cd057cbf 

Output Block 9e33550f6d47bda77f4f3108181ab21c 

Plaintext 93 

Ciphertext 0d 

Segment #15 

Input Block 0e0fcda2521ef0a905ca44cd057cbf0d 

Output Block 50b3eae29a6623fbef6d726dbda675a8 

Plaintext 17 

Ciphertext 47 

Segment #16 

Input Block 0fcda2521ef0a905ca44cd057cbf0d47 

Output Block 8a2a57d1b9158539ef7ff42b33bf0a4a 

Plaintext 2a 

Ciphertext a0 

Segment #17 

Input Block cda2521ef0a905ca44cd057cbf0d47a0 

Output Block c94e9102ac731d2f127b657d810ef5a8 

Plaintext ae 

Ciphertext 67 

Segment #18 

Input Block a2521ef0a905ca44cd057cbf0d47a067 

Output Block a765ed650568fbe386660def5f8d491d 

Plaintext 2d 

Ciphertext 8a 

F.3.10 CFB8-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Ciphertext cd 

Plaintext 6b 

Segment #2 

Input Block 0102030405060708090a0b0c0d0e0fcd 

Output Block 63c82e99e7289617c49e6851e082142a 

Ciphertext a2 

Plaintext c1 

Segment #3 

Input Block 02030405060708090a0b0c0d0e0fcda2 
 

45 

Output Block ec40a5497264bfb4d6820aaae73f75af 

Ciphertext 52 

Plaintext be 

Segment #4 

Input Block 030405060708090a0b0c0d0e0fcda252 

Output Block fc011a96afe968c32bae6495173a9154 

Ciphertext 1e 

Plaintext e2 

Segment #5 

Input Block 0405060708090a0b0c0d0e0fcda2521e 

Output Block de019e09ac995ba46a42916ef77d8fe5 

Ciphertext f0 

Plaintext 2e 

Segment #6 

Input Block 05060708090a0b0c0d0e0fcda2521ef0 

Output Block e980477efb7f896e07c4a2d527e7b537 

Ciphertext a9 

Plaintext 40 

Segment #7 

Input Block 060708090a0b0c0d0e0fcda2521ef0a9 

Output Block 9a9a77b11709b36e08e9321ae8b1e539 

Ciphertext 05 

Plaintext 9f 

Segment #8 

Input Block 0708090a0b0c0d0e0fcda2521ef0a905 

Output Block 5ca1d192a780fbca1471e10588593c7c 

Ciphertext ca 

Plaintext 96 

Segment #9 

Input Block 08090a0b0c0d0e0fcda2521ef0a905ca 

Output Block addb26efd21de4d002474c7748e0bc1d 

Ciphertext 44 

Plaintext e9 

Segment #10 

Input Block 090a0b0c0d0e0fcda2521ef0a905ca44 

Output Block f0c410ad6512c5177a5ee40a60de01b8 

Ciphertext cd 

Plaintext 3d 

Segment #11 

Input Block 0a0b0c0d0e0fcda2521ef0a905ca44cd 

Output Block 7bbf71f2b4f5cf68f3c0c1b9235dbd53 

Ciphertext 05 

Plaintext 7e 

Segment #12 

Input Block 0b0c0d0e0fcda2521ef0a905ca44cd05 

Output Block 6dafb26e3c63b350811394b382e14d69 

Ciphertext 7c 

Plaintext 11 

Segment #13 

Input Block 0c0d0e0fcda2521ef0a905ca44cd057c 

Output Block ccd6e25255a80e9bdbec9fbc26e5fad6 

Ciphertext bf 

Plaintext 73 

Segment #14 
 

46 

Input Block 0d0e0fcda2521ef0a905ca44cd057cbf 

Output Block 9e33550f6d47bda77f4f3108181ab21c 

Ciphertext 0d 

Plaintext 93 

Segment #15 

Input Block 0e0fcda2521ef0a905ca44cd057cbf0d 

Output Block 50b3eae29a6623fbef6d726dbda675a8 

Ciphertext 47 

Plaintext 17 

Segment #16 

Input Block 0fcda2521ef0a905ca44cd057cbf0d47 

Output Block 8a2a57d1b9158539ef7ff42b33bf0a4a 

Ciphertext a0 

Plaintext 2a 

Segment #17 

Input Block cda2521ef0a905ca44cd057cbf0d47a0 

Output Block c94e9102ac731d2f127b657d810ef5a8 

Ciphertext 67 

Plaintext ae 

Segment #18 

Input Block a2521ef0a905ca44cd057cbf0d47a067 

Output Block a765ed650568fbe386660def5f8d491d 

Ciphertext 8a 

Plaintext 2d 

F.3.11 CFB8-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Plaintext 6b 

Ciphertext dc 

Segment #2 

Input Block 0102030405060708090a0b0c0d0e0fdc 

Output Block ded5faadb1068af80e774684b9f84870 

Plaintext c1 

Ciphertext 1f 

Segment #3 

Input Block 02030405060708090a0b0c0d0e0fdc1f 

Output Block a41e327e5273366ce9403cdbdb92c1cc 

Plaintext be 

Ciphertext 1a 

Segment #4 

Input Block 030405060708090a0b0c0d0e0fdc1f1a 

Output Block 67938ae7d34df4ec2c0aec33eb98318f 

Plaintext e2 

Ciphertext 85 

Segment #5 

Input Block 0405060708090a0b0c0d0e0fdc1f1a85 

Output Block 0e8f2e31efff615d3c93946609808c37 

Plaintext 2e 
 

47 

Ciphertext 20 

Segment #6 

Input Block 05060708090a0b0c0d0e0fdc1f1a8520 

Output Block e648bb37a95c94c72784162a79dfe306 

Plaintext 40 

Ciphertext a6 

Segment #7 

Input Block 060708090a0b0c0d0e0fdc1f1a8520a6 

Output Block d278f3147290fc5dd0b7d2e82764a1fd 

Plaintext 9f 

Ciphertext 4d 

Segment #8 

Input Block 0708090a0b0c0d0e0fdc1f1a8520a64d 

Output Block 2388d255a3e8a8059675e3a7de19dceb 

Plaintext 96 

Ciphertext b5 

Segment #9 

Input Block 08090a0b0c0d0e0fdc1f1a8520a64db5 

Output Block b6b8008f6c6dc2d6144641ed2023f0f5 

Plaintext e9 

Ciphertext 5f 

Segment #10 

Input Block 090a0b0c0d0e0fdc1f1a8520a64db55f 

Output Block f18f88a7aa3e3a6167dd93fb1137713a 

Plaintext 3d 

Ciphertext cc 

Segment #11 

Input Block 0a0b0c0d0e0fdc1f1a8520a64db55fcc 

Output Block f46c5e67bff7c070b26c0318c52d0ccd 

Plaintext 7e 

Ciphertext 8a 

Segment #12 

Input Block 0b0c0d0e0fdc1f1a8520a64db55fcc8a 

Output Block d4dceae622f8f21d27375d8c2c5f9fba 

Plaintext 11 

Ciphertext c5 

Segment #13 

Input Block 0c0d0e0fdc1f1a8520a64db55fcc8ac5 

Output Block 27e9e0d0a016709cd3ae0b5a9a242e31 

Plaintext 73 

Ciphertext 54 

Segment #14 

Input Block 0d0e0fdc1f1a8520a64db55fcc8ac554 

Output Block 17f69d50ce64ba0d085de70b9030bbb2 

Plaintext 93 

Ciphertext 84 

Segment #15 

Input Block 0e0fdc1f1a8520a64db55fcc8ac55484 

Output Block 59106ee400d18e104337669628c33cdd 

Plaintext 17 

Ciphertext 4e 

Segment #16 

Input Block 0fdc1f1a8520a64db55fcc8ac554844e 

Output Block a29c6ac87e2245ec0796772c1f5312a8 
 

48 

Plaintext 2a 

Ciphertext 88 

Segment #17 

Input Block dc1f1a8520a64db55fcc8ac554844e88 

Output Block 397b98fa2ec0ff8cc0cd821909551c9e 

Plaintext ae 

Ciphertext 97 

Segment #18 

Input Block 1f1a8520a64db55fcc8ac554844e8897 

Output Block 2d2d6fe9aef72f7b914b623a9c7abd54 

Plaintext 2d 

Ciphertext 00 

F.3.12 CFB8-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Ciphertext dc 

Plaintext 6b 

Segment #2 

Input Block 0102030405060708090a0b0c0d0e0fdc 

Output Block ded5faadb1068af80e774684b9f84870 

Ciphertext 1f 

Plaintext c1 

Segment #3 

Input Block 02030405060708090a0b0c0d0e0fdc1f 

Output Block a41e327e5273366ce9403cdbdb92c1cc 

Ciphertext 1a 

Plaintext be 

Segment #4 

Input Block 030405060708090a0b0c0d0e0fdc1f1a 

Output Block 67938ae7d34df4ec2c0aec33eb98318f 

Ciphertext 85 

Plaintext e2 

Segment #5 

Input Block 0405060708090a0b0c0d0e0fdc1f1a85 

Output Block 0e8f2e31efff615d3c93946609808c37 

Ciphertext 20 

Plaintext 2e 

Segment #6 

Input Block 05060708090a0b0c0d0e0fdc1f1a8520 

Output Block e648bb37a95c94c72784162a79dfe306 

Ciphertext a6 

Plaintext 40 

Segment #7 

Input Block 060708090a0b0c0d0e0fdc1f1a8520a6 

Output Block d278f3147290fc5dd0b7d2e82764a1fd 

Ciphertext 4d 

Plaintext 9f 

Segment #8 
 

49 

Input Block 0708090a0b0c0d0e0fdc1f1a8520a64d 

Output Block 2388d255a3e8a8059675e3a7de19dceb 

Ciphertext b5 

Plaintext 96 

Segment #9 

Input Block 08090a0b0c0d0e0fdc1f1a8520a64db5 

Output Block b6b8008f6c6dc2d6144641ed2023f0f5 

Ciphertext 5f 

Plaintext e9 

Segment #10 

Input Block 090a0b0c0d0e0fdc1f1a8520a64db55f 

Output Block f18f88a7aa3e3a6167dd93fb1137713a 

Ciphertext cc 

Plaintext 3d 

Segment #11 

Input Block 0a0b0c0d0e0fdc1f1a8520a64db55fcc 

Output Block f46c5e67bff7c070b26c0318c52d0ccd 

Ciphertext 8a 

Plaintext 7e 

Segment #12 

Input Block 0b0c0d0e0fdc1f1a8520a64db55fcc8a 

Output Block d4dceae622f8f21d27375d8c2c5f9fba 

Ciphertext c5 

Plaintext 11 

Segment #13 

Input Block 0c0d0e0fdc1f1a8520a64db55fcc8ac5 

Output Block 27e9e0d0a016709cd3ae0b5a9a242e31 

Ciphertext 54 

Plaintext 73 

Segment #14 

Input Block 0d0e0fdc1f1a8520a64db55fcc8ac554 

Output Block 17f69d50ce64ba0d085de70b9030bbb2 

Ciphertext 84 

Plaintext 93 

Segment #15 

Input Block 0e0fdc1f1a8520a64db55fcc8ac55484 

Output Block 59106ee400d18e104337669628c33cdd 

Ciphertext 4e 

Plaintext 17 

Segment #16 

Input Block 0fdc1f1a8520a64db55fcc8ac554844e 

Output Block a29c6ac87e2245ec0796772c1f5312a8 

Ciphertext 88 

Plaintext 2a 

Segment #17 

Input Block dc1f1a8520a64db55fcc8ac554844e88 

Output Block 397b98fa2ec0ff8cc0cd821909551c9e 

Ciphertext 97 

Plaintext ae 

Segment #18 

Input Block 1f1a8520a64db55fcc8ac554844e8897 

Output Block 2d2d6fe9aef72f7b914b623a9c7abd54 

Ciphertext 00 

Plaintext 2d 
 

50 

F.3.13 CFB128-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext 3b3fd92eb72dad20333449f8e83cfb4a 

Segment #2 

Input Block 3b3fd92eb72dad20333449f8e83cfb4a 

Output Block 668bcf60beb005a35354a201dab36bda 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext c8a64537a0b3a93fcde3cdad9f1ce58b 

Segment #3 

Input Block c8a64537a0b3a93fcde3cdad9f1ce58b 

Output Block 16bd032100975551547b4de89daea630 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 26751f67a3cbb140b1808cf187a4f4df 

Segment #4 

Input Block 26751f67a3cbb140b1808cf187a4f4df 

Output Block 36d42170a312871947ef8714799bc5f6 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext c04b05357c5d1c0eeac4c66f9ff7f2e6 

F.3.14 CFB128-AES128.Decrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Ciphertext 3b3fd92eb72dad20333449f8e83cfb4a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Segment #2 

Input Block 3b3fd92eb72dad20333449f8e83cfb4a 

Output Block 668bcf60beb005a35354a201dab36bda 

Ciphertext c8a64537a0b3a93fcde3cdad9f1ce58b 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Segment #3 

Input Block c8a64537a0b3a93fcde3cdad9f1ce58b 

Output Block 16bd032100975551547b4de89daea630 

Ciphertext 26751f67a3cbb140b1808cf187a4f4df 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Segment #4 

Input Block 26751f67a3cbb140b1808cf187a4f4df 

Output Block 36d42170a312871947ef8714799bc5f6 

Ciphertext c04b05357c5d1c0eeac4c66f9ff7f2e6 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.3.15 CFB128-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 
 

51 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext cdc80d6fddf18cab34c25909c99a4174 

Segment #2 

Input Block cdc80d6fddf18cab34c25909c99a4174 

Output Block c9e3f5289f149abd08ad44dc52b2b32b 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext 67ce7f7f81173621961a2b70171d3d7a 

Segment #3 

Input Block 67ce7f7f81173621961a2b70171d3d7a 

Output Block 1ed6965b76c76ca02d1dcef404f09626 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 2e1e8a1dd59b88b1c8e60fed1efac4c9 

Segment #4 

Input Block 2e1e8a1dd59b88b1c8e60fed1efac4c9 

Output Block 36c0bbd976ccd4b7ef85cec1be273eef 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext c05f9f9ca9834fa042ae8fba584b09ff 

F.3.16 CFB128-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Ciphertext cdc80d6fddf18cab34c25909c99a4174 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Segment #2 

Input Block cdc80d6fddf18cab34c25909c99a4174 

Output Block c9e3f5289f149abd08ad44dc52b2b32b 

Ciphertext 67ce7f7f81173621961a2b70171d3d7a 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Segment #3 

Input Block 67ce7f7f81173621961a2b70171d3d7a 

Output Block 1ed6965b76c76ca02d1dcef404f09626 

Ciphertext 2e1e8a1dd59b88b1c8e60fed1efac4c9 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Segment #4 

Input Block 2e1e8a1dd59b88b1c8e60fed1efac4c9 

Output Block 36c0bbd976ccd4b7ef85cec1be273eef 

Ciphertext c05f9f9ca9834fa042ae8fba584b09ff 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.3.17 CFB128-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext dc7e84bfda79164b7ecd8486985d3860 
 

52 

Segment #2 

Input Block dc7e84bfda79164b7ecd8486985d3860 

Output Block 97d26743252b1d54aca653cf744ace2a 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext 39ffed143b28b1c832113c6331e5407b 

Segment #3 

Input Block 39ffed143b28b1c832113c6331e5407b 

Output Block efd80f62b6b9af8344c511b13c70b016 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext df10132415e54b92a13ed0a8267ae2f9 

Segment #4 

Input Block df10132415e54b92a13ed0a8267ae2f9 

Output Block 833ca131c5f655ef8d1a2346b3ddd361 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext 75a385741ab9cef82031623d55b1e471 

F.3.18 CFB128-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Segment #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Ciphertext dc7e84bfda79164b7ecd8486985d3860 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Segment #2 

Input Block dc7e84bfda79164b7ecd8486985d3860 

Output Block 97d26743252b1d54aca653cf744ace2a 

Ciphertext 39ffed143b28b1c832113c6331e5407b 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Segment #3 

Input Block 39ffed143b28b1c832113c6331e5407b 

Output Block efd80f62b6b9af8344c511b13c70b016 

Ciphertext df10132415e54b92a13ed0a8267ae2f9 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Segment #4 

Input Block df10132415e54b92a13ed0a8267ae2f9 

Output Block 833ca131c5f655ef8d1a2346b3ddd361 

Ciphertext 75a385741ab9cef82031623d55b1e471 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.4 OFB Example Vectors 

F.4.1 OFB-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext 3b3fd92eb72dad20333449f8e83cfb4a 

Block #2 

Input Block 50fe67cc996d32b6da0937e99bafec60 
 

53 

Output Block d9a4dada0892239f6b8b3d7680e15674 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext 7789508d16918f03f53c52dac54ed825 

Block #3 

Input Block d9a4dada0892239f6b8b3d7680e15674 

Output Block a78819583f0308e7a6bf36b1386abf23 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 9740051e9c5fecf64344f7a82260edcc 

Block #4 

Input Block a78819583f0308e7a6bf36b1386abf23 

Output Block c6d3416d29165c6fcb8e51a227ba994e 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext 304c6528f659c77866a510d9c1d6ae5e 

F.4.2 OFB-AES128.Decrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block 50fe67cc996d32b6da0937e99bafec60 

Ciphertext 3b3fd92eb72dad20333449f8e83cfb4a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Input Block 50fe67cc996d32b6da0937e99bafec60 

Output Block d9a4dada0892239f6b8b3d7680e15674 

Ciphertext 7789508d16918f03f53c52dac54ed825 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Input Block d9a4dada0892239f6b8b3d7680e15674 

Output Block a78819583f0308e7a6bf36b1386abf23 

Ciphertext 9740051e9c5fecf64344f7a82260edcc 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Input Block a78819583f0308e7a6bf36b1386abf23 

Output Block c6d3416d29165c6fcb8e51a227ba994e 

Ciphertext 304c6528f659c77866a510d9c1d6ae5e 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.4.3 OFB-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext cdc80d6fddf18cab34c25909c99a4174 

Block #2 

Input Block a609b38df3b1133dddff2718ba09565e 

Output Block 52ef01da52602fe0975f78ac84bf8a50 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext fcc28b8d4c63837c09e81700c1100401 

Block #3 

Input Block 52ef01da52602fe0975f78ac84bf8a50 
 

54 

Output Block bd5286ac63aabd7eb067ac54b553f71d 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 8d9a9aeac0f6596f559c6d4daf59a5f2 

Block #4 

Input Block bd5286ac63aabd7eb067ac54b553f71d 

Output Block 9b00044d8885f729318713303fc0fe3a 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext 6d9f200857ca6c3e9cac524bd9acc92a 

F.4.4 OFB-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block a609b38df3b1133dddff2718ba09565e 

Ciphertext cdc80d6fddf18cab34c25909c99a4174 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Input Block a609b38df3b1133dddff2718ba09565e 

Output Block 52ef01da52602fe0975f78ac84bf8a50 

Ciphertext fcc28b8d4c63837c09e81700c1100401 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Input Block 52ef01da52602fe0975f78ac84bf8a50 

Output Block bd5286ac63aabd7eb067ac54b553f71d 

Ciphertext 8d9a9aeac0f6596f559c6d4daf59a5f2 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Input Block bd5286ac63aabd7eb067ac54b553f71d 

Output Block 9b00044d8885f729318713303fc0fe3a 

Ciphertext 6d9f200857ca6c3e9cac524bd9acc92a 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.4.5 OFB-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext dc7e84bfda79164b7ecd8486985d3860 

Block #2 

Input Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Output Block e1c656305ed1a7a6563805746fe03edc 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext 4febdc6740d20b3ac88f6ad82a4fb08d 

Block #3 

Input Block e1c656305ed1a7a6563805746fe03edc 

Output Block 41635be625b48afc1666dd42a09d96e7 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 71ab47a086e86eedf39d1c5bba97c408 

Block #4 
 

55 

Input Block 41635be625b48afc1666dd42a09d96e7 

Output Block f7b93058b8bce0fffea41bf0012cd394 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext 0126141d67f37be8538f5a8be740e484 

F.4.6 OFB-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

IV 000102030405060708090a0b0c0d0e0f 

Block #1 

Input Block 000102030405060708090a0b0c0d0e0f 

Output Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Ciphertext dc7e84bfda79164b7ecd8486985d3860 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Input Block b7bf3a5df43989dd97f0fa97ebce2f4a 

Output Block e1c656305ed1a7a6563805746fe03edc 

Ciphertext 4febdc6740d20b3ac88f6ad82a4fb08d 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Input Block e1c656305ed1a7a6563805746fe03edc 

Output Block 41635be625b48afc1666dd42a09d96e7 

Ciphertext 71ab47a086e86eedf39d1c5bba97c408 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Input Block 41635be625b48afc1666dd42a09d96e7 

Output Block f7b93058b8bce0fffea41bf0012cd394 

Ciphertext 0126141d67f37be8538f5a8be740e484 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.5 CTR Example Vectors 

F.5.1 CTR-AES128.Encrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

Init. Counter f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Block #1 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Output Block ec8cdf7398607cb0f2d21675ea9ea1e4 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext 874d6191b620e3261bef6864990db6ce 

Block #2 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff00 

Output Block 362b7c3c6773516318a077d7fc5073ae 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext 9806f66b7970fdff8617187bb9fffdff 

Block #3 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff01 

Output Block 6a2cc3787889374fbeb4c81b17ba6c44 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 5ae4df3edbd5d35e5b4f09020db03eab 

Block #4 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff02 

Output Block e89c399ff0f198c6d40a31db156cabfe 
 

56 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext 1e031dda2fbe03d1792170a0f3009cee 

F.5.2 CTR-AES128.Decrypt 

Key 2b7e151628aed2a6abf7158809cf4f3c 

Init. Counter f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Block #1 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Output Block ec8cdf7398607cb0f2d21675ea9ea1e4 

Ciphertext 874d6191b620e3261bef6864990db6ce 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff00 

Output Block 362b7c3c6773516318a077d7fc5073ae 

Ciphertext 9806f66b7970fdff8617187bb9fffdff 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff01 

Output Block 6a2cc3787889374fbeb4c81b17ba6c44 

Ciphertext 5ae4df3edbd5d35e5b4f09020db03eab 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff02 

Output Block e89c399ff0f198c6d40a31db156cabfe 

Ciphertext 1e031dda2fbe03d1792170a0f3009cee 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.5.3 CTR-AES192.Encrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

Init. Counter f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Block #1 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Output Block 717d2dc639128334a6167a488ded7921 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext 1abc932417521ca24f2b0459fe7e6e0b 

Block #2 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff00 

Output Block a72eb3bb14a556734b7bad6ab16100c5 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext 090339ec0aa6faefd5ccc2c6f4ce8e94 

Block #3 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff01 

Output Block 2efeae2d72b722613446dc7f4c2af918 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 1e36b26bd1ebc670d1bd1d665620abf7 

Block #4 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff02 

Output Block b9e783b30dd7924ff7bc9b97beaa8740 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext 4f78a7f6d29809585a97daec58c6b050 
 

57 

F.5.4 CTR-AES192.Decrypt 

Key 8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b 

Init. Counter f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Block #1 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Output Block 717d2dc639128334a6167a488ded7921 

Ciphertext 1abc932417521ca24f2b0459fe7e6e0b 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff00 

Output Block a72eb3bb14a556734b7bad6ab16100c5 

Ciphertext 090339ec0aa6faefd5ccc2c6f4ce8e94 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff01 

Output Block 2efeae2d72b722613446dc7f4c2af918 

Ciphertext 1e36b26bd1ebc670d1bd1d665620abf7 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff02 

Output Block b9e783b30dd7924ff7bc9b97beaa8740 

Ciphertext 4f78a7f6d29809585a97daec58c6b050 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

F.5.5 CTR-AES256.Encrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

Init. Counter f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Block #1 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Output Block 0bdf7df1591716335e9a8b15c860c502 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Ciphertext 601ec313775789a5b7a7f504bbf3d228 

Block #2 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff00 

Output Block 5a6e699d536119065433863c8f657b94 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Ciphertext f443e3ca4d62b59aca84e990cacaf5c5 

Block #3 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff01 

Output Block 1bc12c9c01610d5d0d8bd6a3378eca62 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Ciphertext 2b0930daa23de94ce87017ba2d84988d 

Block #4 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff02 

Output Block 2956e1c8693536b1bee99c73a31576b6 

Plaintext f69f2445df4f9b17ad2b417be66c3710 

Ciphertext dfc9c58db67aada613c2dd08457941a6 

F.5.6 CTR-AES256.Decrypt 

Key 603deb1015ca71be2b73aef0857d7781 

 1f352c073b6108d72d9810a30914dff4 

Init. Counter f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 
 

58 

Block #1 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff 

Output Block 0bdf7df1591716335e9a8b15c860c502 

Ciphertext 601ec313775789a5b7a7f504bbf3d228 

Plaintext 6bc1bee22e409f96e93d7e117393172a 

Block #2 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff00 

Output Block 5a6e699d536119065433863c8f657b94 

Ciphertext f443e3ca4d62b59aca84e990cacaf5c5 

Plaintext ae2d8a571e03ac9c9eb76fac45af8e51 

Block #3 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff01 

Output Block 1bc12c9c01610d5d0d8bd6a3378eca62 

Ciphertext 2b0930daa23de94ce87017ba2d84988d 

Plaintext 30c81c46a35ce411e5fbc1191a0a52ef 

Block #4 

Input Block f0f1f2f3f4f5f6f7f8f9fafbfcfdff02 

Output Block 2956e1c8693536b1bee99c73a31576b6 

Ciphertext dfc9c58db67aada613c2dd08457941a6 

Plaintext f69f2445df4f9b17ad2b417be66c3710 
 

59 

Appendix G: References 

[1] American National Standard for Financial Services X9.52-1998, “Triple Data Encryption 

Algorithm Modes of Operation.” American Bankers Association, Washington, D.C., July 

29, 1998. 

[2] FIPS Publication 197, “Advanced Encryption Standard (AES).” U.S. DoC/NIST, 

November 26, 2001. 

[3] FIPS Publication 46-3, “Data Encryption Standard (DES).” U.S. DoC/NIST, October 25, 

1999. 

[4] FIPS Publication 81, “DES Modes of Operation.” U.S. DoC/NIST, December 1980. 

[5] A. Menezes, P. van Oorschot, and S. Vanstone, “Handbook of Applied Cryptography.”

CRC Press, New York, 1997.