Federal Information
Processing Standards Publication 197
November 26, 2001
Announcing the
ADVANCED ENCRYPTION STANDARD (AES)
Federal Information Processing Standards Publications (FIPS PUBS) are issued by the National
Institute of Standards and Technology (NIST) after approval by the Secretary of Commerce
pursuant to Section 5131 of the Information Technology Management Reform Act of 1996
(Public Law 104-106) and the Computer Security Act of 1987 (Public Law 100-235).
1.
Name of Standard. Advanced Encryption Standard (AES) (FIPS PUB 197).
2.
Category of Standard. Computer Security Standard, Cryptography.
3.
Explanation. The Advanced Encryption Standard (AES) specifies a FIPS-approved
cryptographic algorithm that can be used to protect electronic data. The AES algorithm is a
symmetric block cipher that can encrypt (encipher) and decrypt (decipher) information.
Encryption converts data to an unintelligible form called ciphertext; decrypting the ciphertext
converts the data back into its original form, called plaintext.
The AES algorithm is capable of using cryptographic keys of 128, 192, and 256 bits to encrypt
and decrypt data in blocks of 128 bits.
4.
Approving Authority. Secretary of Commerce.
5.
Maintenance Agency. Department of Commerce, National Institute of Standards and
Technology, Information Technology Laboratory (ITL).
6.
Applicability. This standard may be used by Federal departments and agencies when an
agency determines that sensitive (unclassified) information (as defined in P. L. 100-235) requires
cryptographic protection.
Other FIPS-approved cryptographic algorithms may be used in addition to, or in lieu of, this
standard. Federal agencies or departments that use cryptographic devices for protecting classified
information can use those devices for protecting sensitive (unclassified) information in lieu of
this standard.
In addition, this standard may be adopted and used by non-Federal Government organizations.
Such use is encouraged when it provides the desired security for commercial and private
organizations.





7.
Specifications. Federal Information Processing Standard (FIPS) 197, Advanced
Encryption Standard (AES) (affixed).
8.
Implementations. The algorithm specified in this standard may be implemented in
software, firmware, hardware, or any combination thereof. The specific implementation may
depend on several factors such as the application, the environment, the technology used, etc. The
algorithm shall be used in conjunction with a FIPS approved or NIST recommended mode of
operation. Object Identifiers (OIDs) and any associated parameters for AES used in these modes
are
available
at
the Computer Security Objects Register
(CSOR),
located at
http://csrc.nist.gov/csor/ [2].
Implementations of the algorithm that are tested by an accredited laboratory and validated will be
considered as complying with this standard. Since cryptographic security depends on many
factors besides the correct implementation of an encryption algorithm, Federal Government
employees, and others, should also refer to NIST Special Publication 800-21, Guideline for
Implementing Cryptography in the Federal Government, for additional information and guidance
(NIST SP 800-21 is available at http://csrc.nist.gov/publications/).
9.
Implementation Schedule. This standard becomes effective on May 26, 2002.
10.
Patents. Implementations of the algorithm specified in this standard may be covered by
U.S. and foreign patents.
11.
Export Control. Certain cryptographic devices and technical data regarding them are
subject to Federal export controls. Exports of cryptographic modules implementing this standard
and technical data regarding them must comply with these Federal regulations and be licensed by
the Bureau of Export Administration of the U.S. Department of Commerce. Applicable Federal
government export controls are specified in Title 15, Code of Federal Regulations (CFR) Part
740.17; Title 15, CFR Part 742; and Title 15, CFR Part 774, Category 5, Part 2.
12.
Qualifications.
NIST will continue to follow developments in the analysis of the AES
algorithm. As with its other cryptographic algorithm standards, NIST will formally reevaluate
this standard every five years.
Both this standard and possible threats reducing the security provided through the use of this
standard will undergo review by NIST as appropriate, taking into account newly available
analysis and technology. In addition, the awareness of any breakthrough in technology or any
mathematical weakness of the algorithm will cause NIST to reevaluate this standard and provide
necessary revisions.
13.
Waiver Procedure. Under certain exceptional circumstances, the heads of Federal
agencies, or their delegates, may approve waivers to Federal Information Processing Standards
(FIPS). The heads of such agencies may redelegate such authority only to a senior official
designated pursuant to Section 3506(b) of Title 44, U.S. Code. Waivers shall be granted only
when compliance with this standard would
a. adversely affect the accomplishment of the mission of an operator of Federal computer
system or
b. cause a major adverse financial impact on the operator that is not offset by government-
wide savings.
ii
Agency heads may act upon a written waiver request containing the information detailed above.
Agency heads may also act without a written waiver request when they determine that conditions
for meeting the standard cannot be met. Agency heads may approve waivers only by a written
decision that explains the basis on which the agency head made the required finding(s). A copy
of each such decision, with procurement sensitive or classified portions clearly identified, shall
be sent to: National Institute of Standards and Technology; ATTN: FIPS Waiver Decision,
Information Technology Laboratory, 100 Bureau Drive, Stop 8900, Gaithersburg, MD 20899­
8900.
In addition, notice of each waiver granted and each delegation of authority to approve waivers
shall be sent promptly to the Committee on Government Operations of the House of
Representatives and the Committee on Government Affairs of the Senate and shall be published
promptly in the Federal Register.
When the determination on a waiver applies to the procurement of equipment and/or services, a
notice of the waiver determination must be published in the Commerce Business Daily as a part
of the notice of solicitation for offers of an acquisition or, if the waiver determination is made
after that notice is published, by amendment to such notice.
A copy of the waiver, any supporting documents, the document approving the waiver and any
supporting and accompanying documents, with such deletions as the agency is authorized and
decides to make under Section 552(b) of Title 5, U.S. Code, shall be part of the procurement
documentation and retained by the agency.
14.
Where to obtain copies. This publication is available electronically by accessing
http://csrc.nist.gov/publications/. A list of other available computer security publications,
including ordering information, can be obtained from NIST Publications List 91, which is
available at the same web site. Alternatively, copies of NIST computer security publications are
available from: National Technical Information Service (NTIS), 5285 Port Royal Road,
Springfield, VA 22161.
iii
iv

Federal Information

Processing Standards Publication 197

November 26, 2001

Specification for the

ADVANCED ENCRYPTION STANDARD (AES)

Table of Contents
1.
INTRODUCTION............................................................................................................................................. 5

2.
DEFINITIONS .................................................................................................................................................. 5

2.1 GLOSSARY OF TERMS AND ACRONYMS........................................................................................................... 5

2.2 ALGORITHM PARAMETERS, SYMBOLS, AND FUNCTIONS................................................................................. 6

3.
NOTATION AND CONVENTIONS............................................................................................................... 7

3.1
INPUTS AND OUTPUTS ..................................................................................................................................... 7

3.2 BYTES ............................................................................................................................................................. 8

3.3 ARRAYS OF BYTES .......................................................................................................................................... 8

3.4 THE STATE ...................................................................................................................................................... 9

3.5 THE STATE AS AN ARRAY OF COLUMNS........................................................................................................ 10

4.
MATHEMATICAL PRELIMINARIES ....................................................................................................... 10

4.1 ADDITION...................................................................................................................................................... 10

4.2 MULTIPLICATION .......................................................................................................................................... 10

4.2.1
Multiplication by x .............................................................................................................................. 11

4.3 POLYNOMIALS WITH COEFFICIENTS IN GF(28) .............................................................................................. 12

5.
ALGORITHM SPECIFICATION................................................................................................................. 13

5.1 CIPHER .......................................................................................................................................................... 14

5.1.1 SubBytes()Transformation............................................................................................................ 15

5.1.2 ShiftRows() Transformation ........................................................................................................ 17

5.1.3 MixColumns() Transformation...................................................................................................... 17

5.1.4 AddRoundKey() Transformation .................................................................................................. 18

5.2 KEY EXPANSION ........................................................................................................................................... 19

5.3
INVERSE CIPHER............................................................................................................................................ 20


5.3.1 InvShiftRows() Transformation ................................................................................................. 21

5.3.2 InvSubBytes() Transformation ................................................................................................... 22

5.3.3 InvMixColumns() Transformation............................................................................................... 23

5.3.4
Inverse of the AddRoundKey() Transformation............................................................................. 23

5.3.5
Equivalent Inverse Cipher .................................................................................................................. 23

6.
IMPLEMENTATION ISSUES ...................................................................................................................... 25

6.1 KEY LENGTH REQUIREMENTS....................................................................................................................... 25

6.2 KEYING RESTRICTIONS ................................................................................................................................. 26

6.3 PARAMETERIZATION OF KEY LENGTH, BLOCK SIZE, AND ROUND NUMBER................................................. 26

6.4
IMPLEMENTATION SUGGESTIONS REGARDING VARIOUS PLATFORMS........................................................... 26

APPENDIX A - KEY EXPANSION EXAMPLES ................................................................................................ 27

A.1 EXPANSION OF A 128-BIT CIPHER KEY.......................................................................................................... 27

A.2 EXPANSION OF A 192-BIT CIPHER KEY.......................................................................................................... 28

A.3 EXPANSION OF A 256-BIT CIPHER KEY.......................................................................................................... 30

APPENDIX B – CIPHER EXAMPLE.................................................................................................................... 33

APPENDIX C – EXAMPLE VECTORS................................................................................................................ 35

C.1 AES-128 (NK=4, NR=10).............................................................................................................................. 35

C.2 AES-192 (NK=6, NR=12).............................................................................................................................. 38

C.3 AES-256 (NK=8, NR=14).............................................................................................................................. 42

APPENDIX D - REFERENCES.............................................................................................................................. 47

2

Table of Figures
Figure 1. Hexadecimal representation of bit patterns.................................................................. 8

Figure 2.
Indices for Bytes and Bits. ........................................................................................... 9

Figure 3. State array input and output. ........................................................................................ 9

Figure 4. Key-Block-Round Combinations............................................................................... 14

Figure 5. Pseudo Code for the Cipher. ...................................................................................... 15

Figure 6. SubBytes() applies the S-box to each byte of the State. ...................................... 16

Figure 7. S-box: substitution values for the byte xy (in hexadecimal format). ....................... 16

Figure 8. ShiftRows() cyclically shifts the last three rows in the State.............................. 17

Figure 9. MixColumns() operates on the State column-by-column. .................................... 18

Figure 10. AddRoundKey() XORs each column of the State with a word from the key

schedule....................................................................................................................... 19

Figure 11. Pseudo Code for Key Expansion................................................................................ 20

Figure 12. Pseudo Code for the Inverse Cipher. .......................................................................... 21

Figure 13. InvShiftRows()cyclically shifts the last three rows in the State. ....................... 22

Figure 14. Inverse S-box: substitution values for the byte xy (in hexadecimal format). ............ 22

Figure 15. Pseudo Code for the Equivalent Inverse Cipher......................................................... 25

3

4






1.
Introduction
This standard specifies the Rijndael algorithm ([3] and [4]), a symmetric block cipher that can
process data blocks of 128 bits, using cipher keys with lengths of 128, 192, and 256 bits.
Rijndael was designed to handle additional block sizes and key lengths, however they are not
adopted in this standard.
Throughout the remainder of this standard, the algorithm specified herein will be referred to as
“the AES algorithm.” The algorithm may be used with the three different key lengths indicated
above, and therefore these different “flavors” may be referred to as “AES-128”, “AES-192”, and
“AES-256”.
This specification includes the following sections:
2. Definitions of terms, acronyms, and algorithm parameters, symbols, and functions;
3. Notation and conventions used in the algorithm specification, including the ordering and
numbering of bits, bytes, and words;
4. Mathematical properties that are useful in understanding the algorithm;
5. Algorithm specification, covering the key expansion, encryption, and decryption routines;
6. Implementation issues, such as key length support, keying restrictions, and additional
block/key/round sizes.
The standard concludes with several appendices that include step-by-step examples for Key
Expansion and the Cipher, example vectors for the Cipher and Inverse Cipher, and a list of
references.
2. Definitions
2.1 Glossary of Terms and Acronyms
The following definitions are used throughout this standard:
AES
Advanced Encryption Standard
Affine
A transformation consisting of multiplication by a matrix followed by
Transformation
the addition of a vector.

Array
An enumerated collection of identical entities (e.g., an array of bytes).

Bit
A binary digit having a value of 0 or 1.

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

Round Key. The length of a sequence is the number of bits it contains.
Blocks are also interpreted as arrays of bytes.
Byte
A group of eight bits that is treated either as a single entity or as an
array of 8 individual bits.
5

Cipher
Series of transformations that converts plaintext to ciphertext using the
Cipher Key.
Cipher Key
Secret, cryptographic key that is used by the Key Expansion routine to
generate a set of Round Keys; can be pictured as a rectangular array of
bytes, having four rows and Nk columns.
Ciphertext
Data output from the Cipher or input to the Inverse Cipher.
Inverse Cipher
Series of transformations that converts ciphertext to plaintext using the
Cipher Key.
Key Expansion Routine used to generate a series of Round Keys from the Cipher Key.
Plaintext
Data input to the Cipher or output from the Inverse Cipher.
Rijndael
Cryptographic algorithm specified in this Advanced Encryption
Standard (AES).
Round Key
Round keys are values derived from the Cipher Key using the Key
Expansion routine; they are applied to the State in the Cipher and
Inverse Cipher.
State
Intermediate Cipher result that can be pictured as a rectangular array
of bytes, having four rows and Nb columns.
S-box
Non-linear substitution table used in several byte substitution
transformations and in the Key Expansion routine to perform a one-
for-one substitution of a byte value.
Word
A group of 32 bits that is treated either as a single entity or as an array
of 4 bytes.
2.2 Algorithm Parameters, Symbols, and Functions
The following algorithm parameters, symbols, and functions are used throughout this standard:
AddRoundKey() Transformation in the Cipher and Inverse Cipher in which a Round
Key is added to the State using an XOR operation. The length of a
Round Key equals the size of the State (i.e., for Nb = 4, the Round
Key length equals 128 bits/16 bytes).
InvMixColumns()Transformation in the Inverse Cipher that is the inverse of
MixColumns().
InvShiftRows() Transformation in the Inverse Cipher that is the inverse of
ShiftRows().
InvSubBytes() Transformation in the Inverse Cipher that is the inverse of
SubBytes().
K
Cipher Key.
6







MixColumns() Transformation in the Cipher that takes all of the columns of the
State and mixes their data (independently of one another) to
produce new columns.
Nb
Number of columns (32-bit words) comprising the State. For this
standard, Nb = 4. (Also see Sec. 6.3.)
Nk
Number of 32-bit words comprising the Cipher Key. For this
standard, Nk = 4, 6, or 8. (Also see Sec. 6.3.)
Nr
Number of rounds, which is a function of Nk and Nb (which is
fixed). For this standard, Nr = 10, 12, or 14. (Also see Sec. 6.3.)
Rcon[]
The round constant word array.
RotWord()
Function used in the Key Expansion routine that takes a four-byte
word and performs a cyclic permutation.
ShiftRows()
Transformation in the Cipher that processes the State by cyclically
shifting the last three rows of the State by different offsets.
SubBytes()
Transformation in the Cipher that processes the State using a non­
linear byte substitution table (S-box) that operates on each of the
State bytes independently.
SubWord()
Function used in the Key Expansion routine that takes a four-byte
input word and applies an S-box to each of the four bytes to
produce an output word.
XOR
Exclusive-OR operation.
¯
Exclusive-OR operation.
˜
Multiplication of two polynomials (each with degree < 4) modulo
x 4 + 1.
•
Finite field multiplication.
3. Notation and Conventions
3.1
Inputs and Outputs
The input and output for the AES algorithm each consist of sequences of 128 bits (digits with
values of 0 or 1). These sequences will sometimes be referred to as blocks and the number of
bits they contain will be referred to as their length. The Cipher Key for the AES algorithm is a
sequence of 128, 192 or 256 bits. Other input, output and Cipher Key lengths are not permitted
by this standard.
The bits within such sequences will be numbered starting at zero and ending at one less than the
sequence length (block length or key length). The number i attached to a bit is known as its index
and will be in one of the ranges 0 £ i < 128, 0 £ i < 192 or 0 £ i < 256 depending on the block
length and key length (specified above).
7







3.2 Bytes
The basic unit for processing in the AES algorithm is a byte, a sequence of eight bits treated as a
single entity. The input, output and Cipher Key bit sequences described in Sec. 3.1 are processed
as arrays of bytes that are formed by dividing these sequences into groups of eight contiguous
bits to form arrays of bytes (see Sec. 3.3). For an input, output or Cipher Key denoted by a, the
bytes in the resulting array will be referenced using one of the two forms, an or a[n], where n will
be in one of the following ranges:
Key length = 128 bits, 0 £ n < 16;
Block length = 128 bits, 0 £ n < 16;
Key length = 192 bits, 0 £ n < 24;
Key length = 256 bits, 0 £ n < 32.
All byte values in the AES algorithm will be presented as the concatenation of its individual bit
values (0 or 1) between braces in the order {b7, b6, b5, b4, b3, b2, b1, b0}. These bytes are
interpreted as finite field elements using a polynomial representation:
7
7
6
5
4
3
2
i
b x + b x + b x + b x + b x + b x + b x + b = �bi x .
(3.1)
7
6
5
4
3
2
1
0

i=0

For example, {01100011} identifies the specific finite field element x6 + x5 + x +1.
It is also convenient to denote byte values using hexadecimal notation with each of two groups of
four bits being denoted by a single character as in Fig. 1.
Bit Pattern Character
0000
0
0001
1
0010
2
0011
3
Bit Pattern Character
0100
4
0101
5
0110
6
0111
7
Bit Pattern Character
1000
8
1001
9
1010
a
1011
b
Bit Pattern Character
1100
c
1101
d
1110
e
1111
f
Figure 1. Hexadecimal representation of bit patterns.
Hence the element {01100011} can be represented as {63}, where the character denoting the
four-bit group containing the higher numbered bits is again to the left.
Some finite field operations involve one additional bit (b8) to the left of an 8-bit byte. Where this
extra bit is present, it will appear as ‘{01}’ immediately preceding the 8-bit byte; for example, a
9-bit sequence will be presented as {01}{1b}.
3.3 Arrays of Bytes
Arrays of bytes will be represented in the following form:
a a a ...a
0 1 2
15
The bytes and the bit ordering within bytes are derived from the 128-bit input sequence
input0 input1 input2 … input126 input127
as follows:
8








a0 = {input0, input1, …, input7};
a1 = {input8, input9, …, input15};
M
a15 = {input120, input121, …, input127}.
The pattern can be extended to longer sequences (i.e., for 192- and 256-bit keys), so that, in
general,
an = {input8n, input8n+1, …, input8n+7}.
(3.2)
Taking Sections 3.2 and 3.3 together, Fig. 2 shows how bits within each byte are numbered.
Input bit sequence
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 …
Byte number
0
1
2
…
Bit numbers in byte
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
…
Figure 2. Indices for Bytes and Bits.
3.4 The State
Internally, the AES algorithm’s operations are performed on a two-dimensional array of bytes
called the State. The State consists of four rows of bytes, each containing Nb bytes, where Nb is
the block length divided by 32. In the State array denoted by the symbol s, each individual byte
has two indices, with its row number r in the range 0 £ r < 4 and its column number c in the
range 0 £ c < Nb. This allows an individual byte of the State to be referred to as either sr,c or
s[r,c]. For this standard, Nb=4, i.e., 0 £ c < 4 (also see Sec. 6.3).
At the start of the Cipher and Inverse Cipher described in Sec. 5, the input – the array of bytes
in0, in1, … in15 – is copied into the State array as illustrated in Fig. 3. The Cipher or Inverse
Cipher operations are then conducted on this State array, after which its final value is copied to
the output – the array of bytes out0, out1, … out15.
input bytes
State array
output bytes
in0
in4
in8
in12
in1
in5
in9
in13
in2
in6
in10
in14
in3
in7
in11
in15
s0,0 s0,1 s0,2 s0,3
s1,0 s1,1 s1,2 s1,3
s2,0 s2,1 s2,2 s2,3
s3,0 s3,1 s3,2 s3,3
out0 out4 out8 out12
out1 out5 out9 out13
out2 out6 out10 out14
out3 out7 out11 out15
�
�
Figure 3. State array input and output.
Hence, at the beginning of the Cipher or Inverse Cipher, the input array, in, is copied to the State
array according to the scheme:
s[r, c] = in[r + 4c]
for 0 £ r < 4 and 0 £ c < Nb,
(3.3)
9





















and at the end of the Cipher and Inverse Cipher, the State is copied to the output array out as
follows:
out[r + 4c] = s[r, c]
for 0 £ r < 4 and 0 £ c < Nb.
(3.4)
3.5 The State as an Array of Columns
The four bytes in each column of the State array form 32-bit words, where the row number r
provides an index for the four bytes within each word. The state can hence be interpreted as a
one-dimensional array of 32 bit words (columns), w0...w3, where the column number c provides
an index into this array. Hence, for the example in Fig. 3, the State can be considered as an array
of four words, as follows:
w0 = s0,0 s1,0 s2,0 s3,0
w2 = s0,2 s1,2 s2,2 s3,2
w1 = s0,1 s1,1 s2,1 s3,1
w3 = s0,3 s1,3 s2,3 s3,3 .
(3.5)
4. Mathematical Preliminaries
All bytes in the AES algorithm are interpreted as finite field elements using the notation
introduced in Sec. 3.2. Finite field elements can be added and multiplied, but these operations
are different from those used for numbers. The following subsections introduce the basic
mathematical concepts needed for Sec. 5.
4.1 Addition
The addition of two elements in a finite field is achieved by “adding” the coefficients for the
corresponding powers in the polynomials for the two elements. The addition is performed with
the XOR operation (denoted by ¯ ) - i.e., modulo 2 - so that 1¯1 = 0 , 1¯ 0 = 1, and 0 ̄
0 = 0 .
Consequently, subtraction of polynomials is identical to addition of polynomials.
Alternatively, addition of finite field elements can be described as the modulo 2 addition of
corresponding bits in the byte. For two bytes {a7a6a5a4a3a2a1a0} and {b7b6b5b4b3b2b1b0}, the sum is
{c7c6c5c4c3c2c1c0}, where each ci = ai ¯ bi (i.e., c7 = a7 ¯ b7, c6 = a6 ¯ b6, ...c0 = a0 ¯ b0).
For example, the following expressions are equivalent to one another:
6
4
2
7
7
6
4
2
(x + x + x + x +1) + (x + x +1) = x + x + x + x
(polynomial notation);
{01010111} ¯ {10000011} = {11010100}
(binary notation);
{57} ¯ {83} = {d4}
(hexadecimal notation).
4.2 Multiplication
In the polynomial representation, multiplication in GF(28) (denoted by •) corresponds with the
multiplication of polynomials modulo an irreducible polynomial of degree 8. A polynomial is
irreducible if its only divisors are one and itself. For the AES algorithm, this irreducible
polynomial is
8
4
3
m(x) = x + x + x + x +1 ,
(4.1)
10



or {01}{1b} in hexadecimal notation.
For example, {57} • {83} = {c1}, because
6
4
2
7
13
11
9
8
7
(x + x + x + x +1) (x + x +1)
=
x + x + x + x + x +
7
5
3
2
x + x + x + x + x +
6
4
2
x + x + x + x +1
13
11
9
8
6
5
4
3
=
x + x + x + x + x + x + x + x +1
and
13
11
9
8
6
5
4
3
8
4
3
x + x + x + x + x + x + x + x +1 modulo ( x + x + x + x +1)
=
x 7 + x 6 +1.
The modular reduction by m(x) ensures that the result will be a binary polynomial of degree less
than 8, and thus can be represented by a byte. Unlike addition, there is no simple operation at the
byte level that corresponds to this multiplication.
The multiplication defined above is associative, and the element {01} is the multiplicative
identity. For any non-zero binary polynomial b(x) of degree less than 8, the multiplicative
inverse of b(x), denoted b-1(x), can be found as follows: the extended Euclidean algorithm [7] is
used to compute polynomials a(x) and c(x) such that
b(x)a(x) + m(x)c(x) = 1 .
(4.2)
Hence, a(x) • b(x) mod m(x) = 1, which means
-
b 1 (x) = a(x) mod m(x) .
(4.3)
Moreover, for any a(x), b(x) and c(x) in the field, it holds that
a(x) • (b(x) + c(x)) = a(x) • b(x) + a(x) • c(x) .
It follows that the set of 256 possible byte values, with XOR used as addition and the
multiplication defined as above, has the structure of the finite field GF(28).
4.2.1 Multiplication by x
Multiplying the binary polynomial defined in equation (3.1) with the polynomial x results in
8
7
6
5
4
3
2
b7 x + b6 x + b5 x + b4 x + b3 x + b2 x + b1 x + b0 x .
(4.4)
The result x • b(x) is obtained by reducing the above result modulo m(x), as defined in equation
(4.1). If b7 = 0, the result is already in reduced form. If b7 = 1, the reduction is accomplished by
subtracting (i.e., XORing) the polynomial m(x).
It follows that multiplication by x (i.e.,
{00000010} or {02}) can be implemented at the byte level as a left shift and a subsequent
conditional bitwise XOR with {1b}. This operation on bytes is denoted by xtime().
Multiplication by higher powers of x can be implemented by repeated application of xtime().
By adding intermediate results, multiplication by any constant can be implemented.
For example, {57} • {13} = {fe} because
11






{57} • {02} = xtime({57}) = {ae}
{57} • {04} = xtime({ae}) = {47}
{57} • {08} = xtime({47}) = {8e}
{57} • {10} = xtime({8e}) = {07},
thus,
{57} • {13} = {57} • ({01} ¯ {02} ¯ {10})
= {57} ¯ {ae} ¯ {07}
= {fe}.
4.3 Polynomials with Coefficients in GF(28)
Four-term polynomials can be defined - with coefficients that are finite field elements - as:
a(x) = a3 x
3 + a2 x
2 + a1 x + a0
(4.5)
which will be denoted as a word in the form [a0 , a1 , a2 , a3 ]. Note that the polynomials in this
section behave somewhat differently than the polynomials used in the definition of finite field
elements, even though both types of polynomials use the same indeterminate, x. The coefficients
in this section are themselves finite field elements, i.e., bytes, instead of bits; also, the
multiplication of four-term polynomials uses a different reduction polynomial, defined below.
The distinction should always be clear from the context.
To illustrate the addition and multiplication operations, let
b(x) = b x3 + b x2 + b x + b
(4.6)
3
2
1
0
define a second four-term polynomial. Addition is performed by adding the finite field
coefficients of like powers of x. This addition corresponds to an XOR operation between the
corresponding bytes in each of the words – in other words, the XOR of the complete word
values.
Thus, using the equations of (4.5) and (4.6),
a(x) + b(x) = (a ¯ b )x3 + (a ¯ b )x2 + (a ¯ b )x + (a ¯ b )
(4.7)
3
3
2
2
1
1
0
0
Multiplication is achieved in two steps. In the first step, the polynomial product c(x) = a(x) •
b(x) is algebraically expanded, and like powers are collected to give
6
5
4
3
2
c(x) = c x + c x + c x + c x + c x + c x + c
(4.8)
6
5
4
3
2
1
0
where
c = a • b
c = a • b ¯ a • b ¯ a • b
0
0
0
4
3
1
2
2
1
3
c1 = a1 • b0 ¯ a0 • b1
c5 = a3 • b2 ¯ a2 • b3
c2 = a2 • b0 ¯ a1 • b1 ¯ a0 • b2
c6 = a3 • b3
(4.9)
12



c = a • b ¯ a • b ¯ a • b ¯ a • b .
3
3
0
2
1
1
2
0
3
The result, c(x), does not represent a four-byte word. Therefore, the second step of the
multiplication is to reduce c(x) modulo a polynomial of degree 4; the result can be reduced to a
polynomial of degree less than 4. For the AES algorithm, this is accomplished with the
polynomial x4 + 1, so that
i
4
i mod 4
x mod(x +1) = x
.
(4.10)
The modular product of a(x) and b(x), denoted by a(x) ˜ b(x), is given by the four-term
polynomial d(x), defined as follows:
d (x) = d3 x
3 + d2 x
2 + d1 x + d0
(4.11)
with
d = (a • b ) ̄
(a • b ) ̄
(a • b ) ̄
(a • b )
0
0
0
3
1
2
2
1
3
d = (a • b ) ̄
(a • b ) ̄
(a • b ) ̄
(a • b )
(4.12)
1
1
0
0
1
3
2
2
3
d = (a • b ) ̄
(a • b ) ̄
(a • b ) ̄
(a • b )
2
2
0
1
1
0
2
3
3
= (a • b ) ̄
(a • b ) ̄
(a • b ) ̄
(a • b )
d3
3
0
2
1
1
2
0
3
When a(x) is a fixed polynomial, the operation defined in equation (4.11) can be written in
matrix form as:
Ød0 ø
Øa0 a3 a2 a1 ø Øb0 ø
Œ
œ
Œ
œ Œ
œ
d
a
a
a
a
b
1
1
0
3
2
1
Œ
œ =
Œ
œ Œ
œ
(4.13)
Œd œ
Œa
a
a
a œ Œb œ
2
2
1
0
3
2
Œ
œ
Œ
œ Œ
œ
a
ºd3 ß
ºa3
2 a1 a0 ß ºb3 ß
Because x 4 +1 is not an irreducible polynomial over GF(28), multiplication by a fixed four-term
polynomial is not necessarily invertible. However, the AES algorithm specifies a fixed four-term
polynomial that does have an inverse (see Sec. 5.1.3 and Sec. 5.3.3):
a(x) = {03}x 3 + {01}x 2 + {01}x + {02}
(4.14)
a -1(x) = {0b}x 3 + {0d}x 2 + {09}x + {0e}.
(4.15)
Another polynomial used in the AES algorithm (see the RotWord() function in Sec. 5.2) has a0
= a1 = a2 = {00} and a3 = {01}, which is the polynomial x
3. Inspection of equation (4.13) above
will show that its effect is to form the output word by rotating bytes in the input word. This
means that [b0, b1, b2, b3] is transformed into [b1, b2, b3, b0].
5. Algorithm Specification
For the AES algorithm, the length of the input block, the output block and the State is 128
bits. This is represented by Nb = 4, which reflects the number of 32-bit words (number of
columns) in the State.
13


For the AES algorithm, the length of the Cipher Key, K, is 128, 192, or 256 bits. The key
length is represented by Nk = 4, 6, or 8, which reflects the number of 32-bit words (number of
columns) in the Cipher Key.
For the AES algorithm, the number of rounds to be performed during the execution of the
algorithm is dependent on the key size. The number of rounds is represented by Nr, where Nr =
10 when Nk = 4, Nr = 12 when Nk = 6, and Nr = 14 when Nk = 8.
The only Key-Block-Round combinations that conform to this standard are given in Fig. 4.
For implementation issues relating to the key length, block size and number of rounds, see Sec.
6.3.
Key Length
(Nk words)
Block Size
(Nb words)
Number of
Rounds
(Nr)
AES-128
4
4
10
AES-192
6
4
12
AES-256
8
4
14
Figure 4. Key-Block-Round Combinations.
For both its Cipher and Inverse Cipher, the AES algorithm uses a round function that is
composed of four different byte-oriented transformations: 1) byte substitution using a
substitution table (S-box), 2) shifting rows of the State array by different offsets, 3) mixing the
data within each column of the State array, and 4) adding a Round Key to the State. These
transformations (and their inverses) are described in Sec. 5.1.1-5.1.4 and 5.3.1-5.3.4.
The Cipher and Inverse Cipher are described in Sec. 5.1 and Sec. 5.3, respectively, while the Key
Schedule is described in Sec. 5.2.
5.1 Cipher
At the start of the Cipher, the input is copied to the State array using the conventions described in
Sec. 3.4. After an initial Round Key addition, the State array is transformed by implementing a
round function 10, 12, or 14 times (depending on the key length), with the final round differing
slightly from the first Nr -1 rounds. The final State is then copied to the output as described in
Sec. 3.4.
The round function is parameterized using a key schedule that consists of a one-dimensional
array of four-byte words derived using the Key Expansion routine described in Sec. 5.2.
The Cipher is described in the pseudo code in Fig. 5. The individual transformations -
SubBytes(), ShiftRows(), MixColumns(), and AddRoundKey() – process the State
and are described in the following subsections. In Fig. 5, the array w[] contains the key
schedule, which is described in Sec. 5.2.
As shown in Fig. 5, all Nr rounds are identical with the exception of the final round, which does
not include the MixColumns() transformation.
14




Appendix B presents an example of the Cipher, showing values for the State array at the
beginning of each round and after the application of each of the four transformations described in
the following sections.
Cipher(byte in[4*Nb], byte out[4*Nb], word w[Nb*(Nr+1)])

begin

byte state[4,Nb]

state = in

AddRoundKey(state, w[0, Nb-1])
// See Sec. 5.1.4

for round = 1 step 1 to Nr–1

SubBytes(state)
// See Sec. 5.1.1

ShiftRows(state)
// See Sec. 5.1.2

MixColumns(state)
// See Sec. 5.1.3

AddRoundKey(state, w[round*Nb, (round+1)*Nb-1])

end for

SubBytes(state)

ShiftRows(state)

AddRoundKey(state, w[Nr*Nb, (Nr+1)*Nb-1])

out = state

end

Figure 5. Pseudo Code for the Cipher.1
5.1.1 SubBytes()Transformation
The SubBytes() transformation is a non-linear byte substitution that operates independently
on each byte of the State using a substitution table (S-box). This S-box (Fig. 7), which is
invertible, is constructed by composing two transformations:
1. Take the multiplicative inverse in the finite field GF(28), described in Sec. 4.2; the
element {00} is mapped to itself.
2. Apply the following affine transformation (over GF(2) ):
b
' = b ¯ b
¯ b
¯ b
¯ b
¯ c
(5.1)
i
i
(i +4) mod 8
(i +5) mod 8
(i +6) mod 8
(i +7) mod 8
i
for 0 £ i < 8 , where bi is the ith bit of the byte, and ci is the ith bit of a byte c with the
value {63} or {01100011}. Here and elsewhere, a prime on a variable (e.g., b¢ )
indicates that the variable is to be updated with the value on the right.
In matrix form, the affine transformation element of the S-box can be expressed as:
1 The various transformations (e.g., SubBytes(), ShiftRows(), etc.) act upon the State array that is addressed
by the ‘state’ pointer. AddRoundKey() uses an additional pointer to address the Round Key.
15

1
,1s
1
,1s
'
Ø

ø
Ø

ø
Ø
1 0 0 0 1 1 1 1

ø
Ø
1

b0
b0
ø

'
1 1 0 0 0 1 1 1

1

b1
b1
'
Figure 6 illustrates the effect of the SubBytes() transformation on the State.
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
μ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
μ

Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
μ

Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
Œ
μ

œ
œ
œ
œ
œ
œ
œ
œ
œ
œ
ϧ

œ
œ
œ
œ
œ
œ
œ
œ
œ
œ
ߜ

œ
œ
œ
œ
œ
œ
œ
œ
œ
œ
ߜ

œ
œ
œ
œ
œ
œ
œ
œ
œ
œ
ߜ

1 1 1 0 0 0 1 1
b2
0

b2
'
1 1 1 1 0 0 0 1
b3
0

b3
.
(5.2)

+

=

'
1 1 1 1 1 0 0 0
b4
0

b4
'
0 1 1 1 1 1 0 0
b5
1

b5
'
0 0 1 1 1 1 1 0
b6
1

b6
'
0 0 0 1 1 1 1 1
b7
0

b7
s0,0 s0,1 s0,2 s0,3
S-Box
'
s0,0
'
s0,1
'
s0,2
'
s0,3
'
'
'
'
s1,0
r
s
s1,2
c
s1,3
s1,0
'
s
s1,2 s1,3
,
r ,c
'
'
'
'
s2,0 s2,1 s2,2 s2,3
s2,0 s2,1 s2,2 s2,3
'
'
'
'
s3,0 s3,1 s3,2 s3,3
s3,0 s3,1 s3,2 s3,3
Figure 6. SubBytes() applies the S-box to each byte of the State.

The S-box used in the SubBytes() transformation is presented in hexadecimal form in Fig. 7.

For example, if s1,1 =
{53}, then the substitution value would be determined by the intersection
of the row with index ‘5’ and the column with index ‘3’ in Fig. 7. This would result in s1¢
,1 having
a value of {ed}.
y
0 1 2 3 4 5 6 7 8 9 a b c d e f
x
0 63 7c 77 7b f2 6b 6f c5 30 01 67 2b fe d7 ab 76
1 ca 82 c9 7d fa 59 47 f0 ad d4 a2 af 9c a4 72 c0
2 b7 fd 93 26 36 3f f7 cc 34 a5 e5 f1 71 d8 31 15
3 04 c7 23 c3 18 96 05 9a 07 12 80 e2 eb 27 b2 75
4 09 83 2c 1a 1b 6e 5a a0 52 3b d6 b3 29 e3 2f 84
5 53 d1 00 ed 20 fc b1 5b 6a cb be 39 4a 4c 58 cf
6 d0 ef aa fb 43 4d 33 85 45 f9 02 7f 50 3c 9f a8
7 51 a3 40 8f 92 9d 38 f5 bc b6 da 21 10 ff f3 d2
8 cd 0c 13 ec 5f 97 44 17 c4 a7 7e 3d 64 5d 19 73
9 60 81 4f dc 22 2a 90 88 46 ee b8 14 de 5e 0b db
a e0 32 3a 0a 49 06 24 5c c2 d3 ac 62 91 95 e4 79
b e7 c8 37 6d 8d d5 4e a9 6c 56 f4 ea 65 7a ae 08
c ba 78 25 2e 1c a6 b4 c6 e8 dd 74 1f 4b bd 8b 8a
d 70 3e b5 66 48 03 f6 0e 61 35 57 b9 86 c1 1d 9e
e e1 f8 98 11 69 d9 8e 94 9b 1e 87 e9 ce 55 28 df
f 8c a1 89 0d bf e6 42 68 41 99 2d 0f b0 54 bb 16
Figure 7. S-box: substitution values for the byte xy (in hexadecimal format).
16





5.1.2 ShiftRows() Transformation
In the ShiftRows() transformation, the bytes in the last three rows of the State are cyclically
shifted over different numbers of bytes (offsets). The first row, r = 0, is not shifted.
Specifically, the ShiftRows() transformation proceeds as follows:
s
' = s
for 0 < r < 4 and 0 £ c < Nb,
(5.3)
r ,c
r ,(c+ shift (r , Nb)) mod Nb
where the shift value shift(r,Nb) depends on the row number, r, as follows (recall that Nb = 4):
shift(1,4) = 1 ; shift(2,4) = 2 ; shift(3,4) = 3 .
(5.4)
This has the effect of moving bytes to “lower” positions in the row (i.e., lower values of c in a
given row), while the “lowest” bytes wrap around into the “top” of the row (i.e., higher values of

c in a given row).

Figure 8 illustrates the ShiftRows() transformation.

ShiftRows()
0
,
r
s
1
,
r
s
2
,
r
s
3
,
r
s
'
0
,
r
s
'
2
,
r
s
'
3
,
r
s
'
1
,
r
s
S
S ’
s0,0 s0,1 s0,2 s0,3
s0,0 s0,1 s0,2 s0,3
s1,0 s1,1 s1,2 s1,3
s1,1 s1,2 s1,3 s1,0
s2,0 s2,1 s2,2 s2,3
s2,2 s2,3 s2,0 s2,1
s3,0 s3,1 s3,2 s3,3
s3,3 s3,0 s3,1 s3,2
Figure 8. ShiftRows() cyclically shifts the last three rows in the State.
5.1.3 MixColumns() Transformation
The MixColumns() transformation operates on the State column-by-column, treating each
column as a four-term polynomial as described in Sec. 4.3. The columns are considered as
polynomials over GF(28) and multiplied modulo x 4 + 1 with a fixed polynomial a(x), given by
a(x) = {03}x 3 + {01}x 2 + {01}x + {02} .
(5.5)
As described in Sec. 4.3, this can be written as a matrix multiplication. Let
s¢(x) = a(x) ̃
s(x) :
17




















1
,
0s
1
,
0s
1
,1s
1
,1s
1
,
2
s
1
,
2
s
1
,
3s
1
,3s





'
Ø

Ø

02 03 01

Ø

ø

s0, ø

s0,
c
c
'
01 02 03

s1,
s1,
c
for 0 £ c < Nb.
(5.6)

c
'
01
01
01 01 02 03
ø
œ
œ
œ
œ
Œ
Œ
Œ
Œ
μ

Œ
Œ
Œ
Œ

Œ
Œ
Œ
Œ
º
=
œ
œ
œ
œ
ߜ
œ
œ
œ
œ

s
s
2,
2,
c
c
'
03 01 01 02
º
ß s3, ß

s3,
c
c
As a result of this multiplication, the four bytes in a column are replaced by the following:
0,
2,
3,
¢
¢
¢
¢
({02} • s
) ¯ ({03} • s
) ¯
0,c
1,c
¯

=

s
s
s
2,
3,
c
c
c
¯ ({02} • s
) ¯ ({03} • s
) ¯
1,c
2,c
=

s1,
s
s
0,
3,
c
c
c
¯
¯ ({02} • s
) ¯ ({03} • s
)
2,c
3,c
=

s
s
s1,
0,
c
c
c
({03} • s0,c ) ¯
¯
¯ ({02} • s3,c ).
=

s
s1,
s2,
c
c
c
Figure 9 illustrates the MixColumns() transformation.
0
,
0s
2
,
0s
3
,
0s
'
0
,
0s
'
'
2
,
0s
'
3
,
0s
0
,1s
2
,1s
3
,1s
'
0
,
1s
'
'
2
,
1s
'
3
,
1s
0
,
2
s
2
,
2
s
3
,
2
s
'
0
,
2
s
'
'
2
,
2
s
'
3
,
2
s
0
,
3s
2
,
3s
3
,
3s
'
0
,
3s
'
'
2
,
3s
'
3
,
3s
MixColumns()
c
s ,
0
c
s ,
1
c
s ,
2
c
,
'
,
0 c
s
'
,
1 c
s
'
,
2 c
s
'
,
3 c
s
Figure 9. MixColumns() operates on the State column-by-column.
5.1.4 AddRoundKey() Transformation
In the AddRoundKey() transformation, a Round Key is added to the State by a simple bitwise
XOR operation. Each Round Key consists of Nb words from the key schedule (described in Sec.
5.2). Those Nb words are each added into the columns of the State, such that
¯
[
wround*Nb+c ]

for 0 £ c < Nb,
(5.7)

[ '
,
'
,
'
,
'
]
[
, 1, ,
,
]
=

s
s
s
s
s
s
s
s
0,
1,
2,
3,
0,
2,
3,
c
c
c
c
c
c
c
c
where [wi] are the key schedule words described in Sec. 5.2, and round is a value in the range
0 £ round £ Nr. In the Cipher, the initial Round Key addition occurs when round = 0, prior to
the first application of the round function (see Fig. 5). The application of the AddRoundKey()
transformation to the Nr rounds of the Cipher occurs when 1 £ round £ Nr.
The action of this transformation is illustrated in Fig. 10, where l = round * Nb. The byte
address within words of the key schedule was described in Sec. 3.1.
18


1
,
0s
0s
1
,
0s
s
1
,1s
1s
1
,1s
s
1
,
2
s
s
1
,
2
s
s
1
,
3s
3s
1
+
l
w
lw
1
,3s
s





0
,
0s
2
,
3
,
0s
'
0
,
0s
'
'
2
,
0
'
3
,
0s
0
,1s
2
,
3
,1s
'
0
,
1s
'
'
2
,
1
'
3
,
1s
'
0
,
2
s
0
,
2
s
2
,
2
3
,
2s
'
'
2
,
2
'
3
,
2
s
0
,
3s
2
,
3
,
3s
lw
2
+
3
+
l
w
'
0
,
3s
'
'
2
,
3
'
3
,
3s
¯
c
s ,
0
c
s ,
1
c
s ,
2
c
s ,
3
'
,
0 c
s
'
,
1 c
s
'
,
2 c
s
'
,
3 c
s
wl+c
Nb
round
l
*
=
Figure 10. AddRoundKey() XORs each column of the State with a word
from the key schedule.
5.2 Key Expansion
The AES algorithm takes the Cipher Key, K, and performs a Key Expansion routine to generate a
key schedule. The Key Expansion generates a total of Nb (Nr + 1) words: the algorithm requires
an initial set of Nb words, and each of the Nr rounds requires Nb words of key data. The
resulting key schedule consists of a linear array of 4-byte words, denoted [wi ], with i in the range
0 £ i < Nb(Nr + 1).
The expansion of the input key into the key schedule proceeds according to the pseudo code in
Fig. 11.
SubWord() is a function that takes a four-byte input word and applies the S-box (Sec. 5.1.1,
Fig. 7) to each of the four bytes to produce an output word. The function RotWord() takes a
word [a0,a1,a2,a3] as input, performs a cyclic permutation, and returns the word [a1,a2,a3,a0]. The
round constant word array, Rcon[i], contains the values given by [xi-1,{00},{00},{00}], with
x i-1 being powers of x (x is denoted as {02}) in the field GF(28), as discussed in Sec. 4.2 (note
that i starts at 1, not 0).
From Fig. 11, it can be seen that the first Nk words of the expanded key are filled with the
Cipher Key. Every following word, w[i], is equal to the XOR of the previous word, w[i-1], and
the word Nk positions earlier, w[i-Nk]. For words in positions that are a multiple of Nk, a
transformation is applied to w[i-1] prior to the XOR, followed by an XOR with a round
constant, Rcon[i]. This transformation consists of a cyclic shift of the bytes in a word
(RotWord()), followed by the application of a table lookup to all four bytes of the word
(SubWord()).
It is important to note that the Key Expansion routine for 256-bit Cipher Keys (Nk = 8) is
slightly different than for 128- and 192-bit Cipher Keys. If Nk = 8 and i-4 is a multiple of Nk,
then SubWord() is applied to w[i-1] prior to the XOR.
19



KeyExpansion(byte key[4*Nk], word w[Nb*(Nr+1)], Nk)

begin

word temp

i = 0

while (i < Nk)

w[i] = word(key[4*i], key[4*i+1], key[4*i+2], key[4*i+3])

i = i+1

end while

i = Nk

while (i < Nb * (Nr+1)]

temp = w[i-1]

if (i mod Nk = 0)

temp = SubWord(RotWord(temp)) xor Rcon[i/Nk]

else if (Nk > 6 and i mod Nk = 4)

temp = SubWord(temp)

end if

w[i] = w[i-Nk] xor temp

i = i + 1

end while

end

Note that Nk=4, 6, and 8 do not all have to be implemented;

they are all included in the conditional statement above for

conciseness.
Specific implementation requirements for the

Cipher Key are presented in Sec. 6.1.

Figure 11. Pseudo Code for Key Expansion.2
Appendix A presents examples of the Key Expansion.
5.3
Inverse Cipher
The Cipher transformations in Sec. 5.1 can be inverted and then implemented in reverse order to
produce a straightforward Inverse Cipher for the AES algorithm. The individual transformations
used in the Inverse Cipher - InvShiftRows(), InvSubBytes(),InvMixColumns(),
and AddRoundKey() – process the State and are described in the following subsections.
The Inverse Cipher is described in the pseudo code in Fig. 12. In Fig. 12, the array w[] contains
the key schedule, which was described previously in Sec. 5.2.
2 The functions SubWord() and RotWord() return a result that is a transformation of the function input, whereas
the transformations in the Cipher and Inverse Cipher (e.g., ShiftRows(), SubBytes(), etc.) transform the
State array that is addressed by the ‘state’ pointer.
20








InvCipher(byte in[4*Nb], byte out[4*Nb], word w[Nb*(Nr+1)])

begin

byte state[4,Nb]

state = in

AddRoundKey(state, w[Nr*Nb, (Nr+1)*Nb-1]) // See Sec. 5.1.4

for round = Nr-1 step -1 downto 1

InvShiftRows(state)
// See Sec. 5.3.1

InvSubBytes(state)
// See Sec. 5.3.2

AddRoundKey(state, w[round*Nb, (round+1)*Nb-1])

InvMixColumns(state)
// See Sec. 5.3.3

end for

InvShiftRows(state)

InvSubBytes(state)

AddRoundKey(state, w[0, Nb-1])

out = state

end

Figure 12. Pseudo Code for the Inverse Cipher.3
5.3.1 InvShiftRows() Transformation
InvShiftRows() is the inverse of the ShiftRows() transformation. The bytes in the last
three rows of the State are cyclically shifted over different numbers of bytes (offsets). The first
row, r = 0, is not shifted. The bottom three rows are cyclically shifted by Nb - shift(r, Nb)
bytes, where the shift value shift(r,Nb) depends on the row number, and is given in equation (5.4)
(see Sec. 5.1.2).
Specifically, the InvShiftRows() transformation proceeds as follows:
s
'
= s
for 0 < r < 4 and 0 £ c < Nb
(5.8)
r ,(c+ shift (r , Nb)) mod Nb
r ,c
Figure 13 illustrates the InvShiftRows() transformation.
3 The various transformations (e.g., InvSubBytes(), InvShiftRows(), etc.) act upon the State array that is
addressed by the ‘state’ pointer. AddRoundKey() uses an additional pointer to address the Round Key.
21


InvShiftRows()
0
,
r
s
1
,
r
s
2
,
r
s
3
,
r
s
'
0
,
r
s
'
2
,
r
s
'
3
,
r
s
'
1
,
r
s
S
S ’
s0,0 s0,1 s0,2 s0,3
s1,0 s1,1 s1,2 s1,3
s2,0 s2,1 s2,2 s2,3
s3,0 s3,1 s3,2 s3,3
s0,0 s0,1 s0,2 s0,3
s1,3 s1,0
s1,1 s1,2
s2,2 s2,3 s2,0 s2,1
s3,1 s3,2 s3,3 s3,0
Figure 13. InvShiftRows()cyclically shifts the last three rows in the State.
5.3.2 InvSubBytes() Transformation
InvSubBytes() is the inverse of the byte substitution transformation, in which the inverse S-
box is applied to each byte of the State. This is obtained by applying the inverse of the affine
transformation (5.1) followed by taking the multiplicative inverse in GF(28).
The inverse S-box used in the InvSubBytes() transformation is presented in Fig. 14:
y
0 1 2 3 4 5 6 7 8 9 a b c d e f
x
0 52 09 6a d5 30 36 a5 38 bf 40 a3 9e 81 f3 d7 fb
1 7c e3 39 82 9b 2f ff 87 34 8e 43 44 c4 de e9 cb
2 54 7b 94 32 a6 c2 23 3d ee 4c 95 0b 42 fa c3 4e
3 08 2e a1 66 28 d9 24 b2 76 5b a2 49 6d 8b d1 25
4 72 f8 f6 64 86 68 98 16 d4 a4 5c cc 5d 65 b6 92
5 6c 70 48 50 fd ed b9 da 5e 15 46 57 a7 8d 9d 84
6 90 d8 ab 00 8c bc d3 0a f7 e4 58 05 b8 b3 45 06
7 d0 2c 1e 8f ca 3f 0f 02 c1 af bd 03 01 13 8a 6b
8 3a 91 11 41 4f 67 dc ea 97 f2 cf ce f0 b4 e6 73
9 96 ac 74 22 e7 ad 35 85 e2 f9 37 e8 1c 75 df 6e
a 47 f1 1a 71 1d 29 c5 89 6f b7 62 0e aa 18 be 1b
b fc 56 3e 4b c6 d2 79 20 9a db c0 fe 78 cd 5a f4
c 1f dd a8 33 88 07 c7 31 b1 12 10 59 27 80 ec 5f
d 60 51 7f a9 19 b5 4a 0d 2d e5 7a 9f 93 c9 9c ef
e a0 e0 3b 4d ae 2a f5 b0 c8 eb bb 3c 83 53 99 61
f 17 2b 04 7e ba 77 d6 26 e1 69 14 63 55 21 0c 7d
Figure 14. Inverse S-box: substitution values for the byte xy (in
hexadecimal format).
22



















5.3.3 InvMixColumns() Transformation
InvMixColumns()
is
the
inverse
of
the MixColumns()
transformation.
InvMixColumns() operates on the State column-by-column, treating each column as a four-
term polynomial as described in Sec. 4.3. The columns are considered as polynomials over
GF(28) and multiplied modulo x 4 + 1 with a fixed polynomial a -1(x), given by
a -1(x) = {0b}x 3 + {0d}x 2 + {09}x + {0e}.
(5.9)
As described in Sec. 4.3, this can be written as a matrix multiplication. Let
s (x)
¢
=
a -1 (x)˜
s(x) :
'
Ø

Ø

0e 0b 0d 09
Ø

ø

s ø

s
ø

0,
s1,
0,
c
c
Œ
Œ
Œ
Œ
μ

Œ
Œ
Œ
Œ

Œ
Œ
Œ
Œ
º
=
œ
œ
œ
œ
ߜ
œ
œ
œ
œ

œ
œ
œ
œ

'
09 0e 0b 0d
0d 09 0e 0b
s1,
c
for 0 £ c < Nb.
(5.10)

c
'
s
s
2,
2,
c
c
'
0b 0d 09 0e º
ß s3, ß

s3,
c
c
As a result of this multiplication, the four bytes in a column are replaced by the following:
0,
¢
({0e} • s0,c ) ¯ ({0b} •
¯
•
({
}
0d
) ¯ ({09} •

)

)

=

s
s1,
s
s
2,
3,
c
c
c
c
({09} • s
) ¯ ({0e} • s
) ¯ ({0b} • s
) ¯ ({0d} • s
)
0,c
1,c
2,c
3,c
s1,
2,
3,
¢
¢
¢
=

c
({0d} • s
) ¯ ({09} • s
) ¯ ({0e} • s
) ¯ ({0b} • s
)
0,c
1,c
2,c
3,c
=

s c
({0b} • s0,c ¯
•
)
({
}
0d
s1,c ) ¯ ({09} • s
) ¯ ({0e} • s
)
2,c
3,c
=

s c
5.3.4 Inverse of the AddRoundKey() Transformation
AddRoundKey(), which was described in Sec. 5.1.4, is its own inverse, since it only involves
an application of the XOR operation.
5.3.5 Equivalent Inverse Cipher
In the straightforward Inverse Cipher presented in Sec. 5.3 and Fig. 12, the sequence of the
transformations differs from that of the Cipher, while the form of the key schedules for
encryption and decryption remains the same. However, several properties of the AES algorithm
allow for an Equivalent Inverse Cipher that has the same sequence of transformations as the
Cipher (with the transformations replaced by their inverses). This is accomplished with a change
in the key schedule.
The two properties that allow for this Equivalent Inverse Cipher are as follows:
1. The SubBytes() and ShiftRows() transformations commute; that is, a
SubBytes()
transformation
immediately followed by a ShiftRows()
transformation is equivalent to a ShiftRows() transformation immediately
followed buy a SubBytes() transformation. The same is true for their inverses,
InvSubBytes() and InvShiftRows.
23

2. The column mixing operations - MixColumns() and InvMixColumns() - are
linear with respect to the column input, which means
InvMixColumns(state XOR Round Key) =

InvMixColumns(state) XOR InvMixColumns(Round Key).

These properties allow
the order of InvSubBytes()
and InvShiftRows()
transformations to be reversed. The order of the AddRoundKey() and InvMixColumns()
transformations can also be reversed, provided that the columns (words) of the decryption key
schedule are modified using the InvMixColumns() transformation.
The equivalent inverse cipher is defined by reversing the order of the InvSubBytes() and
InvShiftRows() transformations shown in Fig. 12, and by reversing the order of the
AddRoundKey() and InvMixColumns() transformations used in the “round loop” after
first modifying the decryption key schedule for round = 1 to Nr-1 using the
InvMixColumns() transformation. The first and last Nb words of the decryption key
schedule shall not be modified in this manner.
Given these changes, the resulting Equivalent Inverse Cipher offers a more efficient structure
than the Inverse Cipher described in Sec. 5.3 and Fig. 12. Pseudo code for the Equivalent
Inverse Cipher appears in Fig. 15. (The word array dw[] contains the modified decryption key
schedule. The modification to the Key Expansion routine is also provided in Fig. 15.)
24


EqInvCipher(byte in[4*Nb], byte out[4*Nb], word dw[Nb*(Nr+1)])

begin

byte state[4,Nb]

state = in

AddRoundKey(state, dw[Nr*Nb, (Nr+1)*Nb-1])

for round = Nr-1 step -1 downto 1

InvSubBytes(state)

InvShiftRows(state)

InvMixColumns(state)

AddRoundKey(state, dw[round*Nb, (round+1)*Nb-1])

end for

InvSubBytes(state)

InvShiftRows(state)

AddRoundKey(state, dw[0, Nb-1])

out = state

end

For the Equivalent Inverse Cipher, the following pseudo code is added at

the end of the Key Expansion routine (Sec. 5.2):

for i = 0 step 1 to (Nr+1)*Nb-1

dw[i] = w[i]

end for

for round = 1 step 1 to Nr-1

InvMixColumns(dw[round*Nb, (round+1)*Nb-1])
// note change of

type

end for

Note that, since InvMixColumns operates on a two-dimensional array of bytes

while the Round Keys are held in an array of words, the call to

InvMixColumns in this code sequence involves a change of type (i.e. the

input to InvMixColumns() is normally the State array, which is considered

to be a two-dimensional array of bytes, whereas the input here is a Round

Key computed as a one-dimensional array of words).

Figure 15. Pseudo Code for the Equivalent Inverse Cipher.
6.
Implementation Issues
6.1 Key Length Requirements
An implementation of the AES algorithm shall support at least one of the three key lengths
specified in Sec. 5: 128, 192, or 256 bits (i.e., Nk = 4, 6, or 8, respectively). Implementations
25



may optionally support two or three key lengths, which may promote the interoperability of
algorithm implementations.
6.2 Keying Restrictions
No weak or semi-weak keys have been identified for the AES algorithm, and there is no
restriction on key selection.
6.3 Parameterization of Key Length, Block Size, and Round Number
This standard explicitly defines the allowed values for the key length (Nk), block size (Nb), and
number of rounds (Nr) – see Fig. 4. However, future reaffirmations of this standard could
include changes or additions to the allowed values for those parameters.
Therefore,
implementers may choose to design their AES implementations with future flexibility in mind.
6.4
Implementation Suggestions Regarding Various Platforms
Implementation variations are possible that may, in many cases, offer performance or other
advantages. Given the same input key and data (plaintext or ciphertext), any implementation that
produces the same output (ciphertext or plaintext) as the algorithm specified in this standard is an
acceptable implementation of the AES.
Reference [3] and other papers located at Ref. [1] include suggestions on how to efficiently
implement the AES algorithm on a variety of platforms.
26

Appendix A - Key Expansion Examples
This appendix shows the development of the key schedule for various key sizes. Note that multi-
byte values are presented using the notation described in Sec. 3. The intermediate values
produced during the development of the key schedule (see Sec. 5.2) are given in the following
table (all values are in hexadecimal format, with the exception of the index column (i)).
A.1 Expansion of a 128-bit Cipher Key
This section contains the key expansion of the following cipher key:
Cipher Key = 2b 7e 15 16 28 ae d2 a6 ab f7 15 88 09 cf 4f 3c

for Nk = 4, which results in
w0 = 2b7e1516
w1 = 28aed2a6
w2 = abf71588
w3 = 09cf4f3c
i
(dec)
temp
After
RotWord()
After
SubWord()
Rcon[i/Nk]
After XOR
with Rcon
w[i–Nk]
w[i]=
temp XOR
w[i-Nk]
4
09cf4f3c cf4f3c09 8a84eb01 01000000 8b84eb01 2b7e1516 a0fafe17
5
a0fafe17
28aed2a6 88542cb1
6
88542cb1
abf71588 23a33939
7
23a33939
09cf4f3c 2a6c7605
8
2a6c7605 6c76052a 50386be5 02000000 52386be5 a0fafe17 f2c295f2
9
f2c295f2
88542cb1 7a96b943
10 7a96b943
23a33939 5935807a
11 5935807a
2a6c7605 7359f67f
12 7359f67f 59f67f73 cb42d28f 04000000 cf42d28f f2c295f2 3d80477d
13 3d80477d
7a96b943 4716fe3e
14 4716fe3e
5935807a 1e237e44
15 1e237e44
7359f67f 6d7a883b
16 6d7a883b 7a883b6d dac4e23c 08000000 d2c4e23c 3d80477d ef44a541
17 ef44a541
4716fe3e a8525b7f
18 a8525b7f
1e237e44 b671253b
19 b671253b
6d7a883b db0bad00
20 db0bad00 0bad00db 2b9563b9 10000000 3b9563b9 ef44a541 d4d1c6f8
21 d4d1c6f8
a8525b7f 7c839d87
22 7c839d87
b671253b caf2b8bc
23 caf2b8bc
db0bad00 11f915bc
27

24 11f915bc f915bc11 99596582 20000000 b9596582 d4d1c6f8 6d88a37a
25 6d88a37a
7c839d87 110b3efd
26 110b3efd
caf2b8bc dbf98641
27 dbf98641
11f915bc ca0093fd
28 ca0093fd 0093fdca 63dc5474 40000000 23dc5474 6d88a37a 4e54f70e
29 4e54f70e
110b3efd 5f5fc9f3
30 5f5fc9f3
dbf98641 84a64fb2
31 84a64fb2
ca0093fd 4ea6dc4f
32 4ea6dc4f a6dc4f4e 2486842f 80000000 a486842f 4e54f70e ead27321
33 ead27321
5f5fc9f3 b58dbad2
34 b58dbad2
84a64fb2 312bf560
35 312bf560
4ea6dc4f 7f8d292f
36 7f8d292f 8d292f7f 5da515d2 1b000000 46a515d2 ead27321 ac7766f3
37 ac7766f3
b58dbad2 19fadc21
38 19fadc21
312bf560 28d12941
39 28d12941
7f8d292f 575c006e
40 575c006e 5c006e57 4a639f5b 36000000 7c639f5b ac7766f3 d014f9a8
41 d014f9a8
19fadc21 c9ee2589
42 c9ee2589
28d12941 e13f0cc8
43 e13f0cc8
575c006e b6630ca6
A.2 Expansion of a 192-bit Cipher Key
This section contains the key expansion of the following cipher key:
Cipher Key =
8e 73 b0 f7 da 0e 64 52 c8 10 f3 2b
80 90 79 e5 62 f8 ea d2 52 2c 6b 7b
for Nk = 6, which results in
w0 = 8e73b0f7
w1 = da0e6452
w2 = c810f32b
w3 = 809079e5
w4 = 62f8ead2
w5 = 522c6b7b
i
(dec)
temp
After
RotWord()
After
SubWord()
Rcon[i/Nk]
After XOR
with Rcon
w[i–Nk]
w[i]=
temp XOR
w[i-Nk]
6
522c6b7b 2c6b7b52 717f2100 01000000 707f2100 8e73b0f7 fe0c91f7
7
fe0c91f7
da0e6452 2402f5a5
8
2402f5a5
c810f32b ec12068e
28

9
ec12068e
809079e5 6c827f6b
10 6c827f6b
62f8ead2 0e7a95b9
11 0e7a95b9
522c6b7b 5c56fec2
12 5c56fec2 56fec25c b1bb254a 02000000 b3bb254a fe0c91f7 4db7b4bd
13 4db7b4bd
2402f5a5 69b54118
14 69b54118
ec12068e 85a74796
15 85a74796
6c827f6b e92538fd
16 e92538fd
0e7a95b9 e75fad44
17 e75fad44
5c56fec2 bb095386
18 bb095386 095386bb 01ed44ea 04000000 05ed44ea 4db7b4bd 485af057
19 485af057
69b54118 21efb14f
20 21efb14f
85a74796 a448f6d9
21 a448f6d9
e92538fd 4d6dce24
22 4d6dce24
e75fad44 aa326360
23 aa326360
bb095386 113b30e6
24 113b30e6 3b30e611 e2048e82 08000000 ea048e82 485af057 a25e7ed5
25 a25e7ed5
21efb14f 83b1cf9a
26 83b1cf9a
a448f6d9 27f93943
27 27f93943
4d6dce24 6a94f767
28 6a94f767
aa326360 c0a69407
29 c0a69407
113b30e6 d19da4e1
30 d19da4e1 9da4e1d1 5e49f83e 10000000 4e49f83e a25e7ed5 ec1786eb
31 ec1786eb
83b1cf9a 6fa64971
32 6fa64971
27f93943 485f7032
33 485f7032
6a94f767 22cb8755
34 22cb8755
c0a69407 e26d1352
35 e26d1352
d19da4e1 33f0b7b3
36 33f0b7b3 f0b7b333 8ca96dc3 20000000 aca96dc3 ec1786eb 40beeb28
37 40beeb28
6fa64971 2f18a259
38 2f18a259
485f7032 6747d26b
39 6747d26b
22cb8755 458c553e
40 458c553e
e26d1352 a7e1466c
41 a7e1466c
33f0b7b3 9411f1df
42 9411f1df 11f1df94 82a19e22 40000000 c2a19e22 40beeb28 821f750a
43 821f750a
2f18a259 ad07d753
29

44 ad07d753
6747d26b ca400538
45 ca400538
458c553e 8fcc5006
46 8fcc5006
a7e1466c 282d166a
47 282d166a
9411f1df bc3ce7b5
48 bc3ce7b5 3ce7b5bc eb94d565 80000000 6b94d565 821f750a e98ba06f
49 e98ba06f
ad07d753 448c773c
50 448c773c
ca400538 8ecc7204
51 8ecc7204
8fcc5006 01002202
A.3 Expansion of a 256-bit Cipher Key
This section contains the key expansion of the following cipher key:
Cipher Key =
60 3d eb 10 15 ca 71 be 2b 73 ae f0 85 7d 77 81
1f 35 2c 07 3b 61 08 d7 2d 98 10 a3 09 14 df f4
for Nk = 8, which results in
w0 = 603deb10
w1 = 15ca71be
w2 = 2b73aef0
w3 = 857d7781
w4 = 1f352c07
w5 = 3b6108d7
w6 = 2d9810a3
w7 = 0914dff4
i
(dec)
temp
After
RotWord()
After
SubWord()
Rcon[i/Nk]
After XOR
with Rcon
w[i–Nk]
w[i]=
temp XOR
w[i-Nk]
8
0914dff4 14dff409 fa9ebf01 01000000 fb9ebf01 603deb10 9ba35411
9
9ba35411
15ca71be 8e6925af
10 8e6925af
2b73aef0 a51a8b5f
11 a51a8b5f
857d7781 2067fcde
12 2067fcde
b785b01d
1f352c07 a8b09c1a
13 a8b09c1a
3b6108d7 93d194cd
14 93d194cd
2d9810a3 be49846e
15 be49846e
0914dff4 b75d5b9a
16 b75d5b9a 5d5b9ab7 4c39b8a9 02000000 4e39b8a9 9ba35411 d59aecb8
17 d59aecb8
8e6925af 5bf3c917
18 5bf3c917
a51a8b5f fee94248
19 fee94248
2067fcde de8ebe96
20 de8ebe96
1d19ae90
a8b09c1a b5a9328a
21 b5a9328a
93d194cd 2678a647
22 2678a647
be49846e 98312229
30

23 98312229
b75d5b9a 2f6c79b3
24 2f6c79b3 6c79b32f 50b66d15 04000000 54b66d15 d59aecb8 812c81ad
25 812c81ad
5bf3c917 dadf48ba
26 dadf48ba
fee94248 24360af2
27 24360af2
de8ebe96 fab8b464
28 fab8b464
2d6c8d43
b5a9328a 98c5bfc9
29 98c5bfc9
2678a647 bebd198e
30 bebd198e
98312229 268c3ba7
31 268c3ba7
2f6c79b3 09e04214
32 09e04214 e0421409 e12cfa01 08000000 e92cfa01 812c81ad 68007bac
33 68007bac
dadf48ba b2df3316
34 b2df3316
24360af2 96e939e4
35 96e939e4
fab8b464 6c518d80
36 6c518d80
50d15dcd
98c5bfc9 c814e204
37 c814e204
bebd198e 76a9fb8a
38 76a9fb8a
268c3ba7 5025c02d
39 5025c02d
09e04214 59c58239
40 59c58239 c5823959 a61312cb 10000000 b61312cb 68007bac de136967
41 de136967
b2df3316 6ccc5a71
42 6ccc5a71
96e939e4 fa256395
43 fa256395
6c518d80 9674ee15
44 9674ee15
90922859
c814e204 5886ca5d
45 5886ca5d
76a9fb8a 2e2f31d7
46 2e2f31d7
5025c02d 7e0af1fa
47 7e0af1fa
59c58239 27cf73c3
48 27cf73c3 cf73c327 8a8f2ecc 20000000 aa8f2ecc de136967 749c47ab
49 749c47ab
6ccc5a71 18501dda
50 18501dda
fa256395 e2757e4f
51 e2757e4f
9674ee15 7401905a
52 7401905a
927c60be
5886ca5d cafaaae3
53 cafaaae3
2e2f31d7 e4d59b34
54 e4d59b34
7e0af1fa 9adf6ace
55 9adf6ace
27cf73c3 bd10190d
56 bd10190d 10190dbd cad4d77a 40000000 8ad4d77a 749c47ab fe4890d1
57 fe4890d1
18501dda e6188d0b
31

58 e6188d0b
e2757e4f 046df344
59 046df344
7401905a 706c631e
32

Appendix B – Cipher Example
The following diagram shows the values in the State array as the Cipher progresses for a block
length and a Cipher Key length of 16 bytes each (i.e., Nb = 4 and Nk = 4).
Input =
32 43 f6 a8 88 5a 30 8d 31 31 98 a2 e0 37 07 34

Cipher Key = 2b 7e 15 16 28 ae d2 a6 ab f7 15 88 09 cf 4f 3c

The Round Key values are taken from the Key Expansion example in Appendix A.
Round
Start of
After
After
After
Round Key

Number
Round
SubBytes
ShiftRows
MixColumns
Value

32 88 31 e0
43 5a 31 37
f6 30 98 07
a8 8d a2 34
2b 28 ab 09
7e ae f7 cf
15 d2 15 4f
16 a6 88 3c
input

=

¯
19 a0 9a e9
3d f4 c6 f8
e3 e2 8d 48
be 2b 2a 08
d4 e0 b8 1e
27 bf b4 41
11 98 5d 52
ae f1 e5 30
d4 e0 b8 1e
bf b4 41 27
5d 52 11 98
30 ae f1 e5
04 e0 48 28
66 cb f8 06
81 19 d3 26
e5 9a 7a 4c
a0 88 23 2a
fa 54 a3 6c
fe 2c 39 76
17 b1 39 05
1

=

¯
2

a4
68
6b
02

9c
9f
5b
6a

7f
35
ea
50

f2
2b
43
49

=

49 45 7f 77
de db 39 02
d2 96 87 53
89 f1 1a 3b
¯
49 45 7f 77
db 39 02 de
87 53 d2 96
3b 89 f1 1a
f2 7a 59 73
c2 96 35 59
95 b9 80 f6
f2 43 7a 7f
58 1b db 1b
4d 4b e7 6b
ca 5a ca b0
f1 ac a8 e5
3

aa
61
82
68

8f
dd
d2
32

5f
e3
4a
46

03
ef
d2
9a

=

ac ef 13 45
73 c1 b5 23
cf 11 d6 5a
7b df b5 b8
¯
ac ef 13 45
c1 b5 23 73
d6 5a cf 11
b8 7b df b5
3d 47 1e 6d
80 16 23 7a
47 fe 7e 88
7d 3e 44 3b
75 20 53 bb
ec 0b c0 25
09 63 cf d0
93 33 7c dc
4

48
67
4d
d6

6c
1d
e3
5f

4e
9d
b1
58

ee
0d
38
e7

=

52 85 e3 f6
50 a4 11 cf
2f 5e c8 6a
28 d7 07 94
¯
52 85 e3 f6
a4 11 cf 50
c8 6a 2f 5e
94 28 d7 07
ef a8 b6 db
44 52 71 0b
a5 5b 25 ad
41 7f 3b 00
0f 60 6f 5e
d6 31 c0 b3
da 38 10 13
a9 bf 6b 01
5

=

¯
e0 c8 d9 85
92 63 b1 b8
7f 63 35 be
e8 c0 50 01
e1 e8 35 97
4f fb c8 6c
d2 fb 96 ae
9b ba 53 7c
e1 e8 35 97
fb c8 6c 4f
96 ae d2 fb
7c 9b ba 53
25 bd b6 4c
d1 11 3a 4c
a9 d1 33 c0
ad 68 8e b0
d4 7c ca 11
d1 83 f2 f9
c6 9d b8 15
f8 87 bc bc
33

6
10
=

¯
f1 c1 7c 5d
00 92 c8 b5
6f 4c 8b d5
55 ef 32 0c
a1 78 10 4c
63 4f e8 d5
a8 29 3d 03
fc df 23 fe
a1 78 10 4c
4f e8 d5 63
3d 03 a8 29
fe fc df 23
4b 2c 33 37
86 4a 9d d2
8d 89 f4 18
6d 80 e8 d8
6d 11 db ca
88 0b f9 00
a3 3e 86 93
7a fd 41 fd
26 3d e8 fd
0e 41 64 d2
2e b7 72 8b
17 7d a9 25
f7 27 9b 54
ab 83 43 b5
31 a9 40 3d
f0 ff d3 3f
f7 27 9b 54
83 43 b5 ab
40 3d 31 a9
3f f0 ff d3
14 46 27 34
15 16 46 2a
b5 15 56 d8
bf ec d7 43
4e 5f 84 4e
54 5f a6 a6
f7 c9 4f dc
0e f3 b2 4f
7

=

¯
8

5a
19
a3
7a

41
49
e0
8c

42
dc
19
04

b1
1f
65
0c

=

be d4 0a da
83 3b e1 64
2c 86 d4 f2
c8 c0 4d fe
¯
be d4 0a da
3b e1 64 83
d4 f2 2c 86
fe c8 c0 4d
ea b5 31 7f
d2 8d 2b 8d
73 ba f5 29
21 d2 60 2f
00 b1 54 fa
51 c8 76 1b
2f 89 6d 99
d1 ff cd ea
9

=

¯
ea 04 65 85
83 45 5d 96
5c 33 98 b0
f0 2d ad c5
87 f2 4d 97
ec 6e 4c 90
4a c3 46 e7
8c d8 95 a6
87 f2 4d 97
6e 4c 90 ec
46 e7 4a c3
a6 8c d8 95
47 40 a3 4c
37 d4 70 9f
94 e4 3a 42
ed a5 a6 bc
ac 19 28 57
77 fa d1 5c
66 dc 29 00
f3 21 41 6e
eb 59 8b 1b
40 2e a1 c3
f2 38 13 42
1e 84 e7 d2
e9 cb 3d af
09 31 32 2e
89 07 7d 2c
72 5f 94 b5
e9 cb 3d af
31 32 2e 09
7d 2c 89 07
b5 72 5f 94
d0 c9 e1 b6
14 ee 3f 63
f9 25 0c 0c
a8 89 c8 a6
=

¯
39 02 dc 19
25 dc 11 6a
84 09 85 0b
1d fb 97 32
output

34




Appendix C – Example Vectors
This appendix contains example vectors, including intermediate values – for all three AES key
lengths (Nk = 4, 6, and 8), for the Cipher, Inverse Cipher, and Equivalent Inverse Cipher that are
described in Sec. 5.1, 5.3, and 5.3.5, respectively. Additional examples may be found at [1] and
[5].
All vectors are in hexadecimal notation, with each pair of characters giving a byte value in which
the left character of each pair provides the bit pattern for the 4 bit group containing the higher
numbered bits using the notation explained in Sec. 3.2, while the right character provides the bit
pattern for the lower-numbered bits. The array index for all bytes (groups of two hexadecimal
digits) within these test vectors starts at zero and increases from left to right.
Legend for CIPHER (ENCRYPT) (round number r = 0 to 10, 12 or 14):

input: cipher input
start: state at start of round[r]
s_box: state after SubBytes()
s_row: state after ShiftRows()
m_col: state after MixColumns()
k_sch: key schedule value for round[r]
output: cipher output
Legend for INVERSE CIPHER (DECRYPT) (round number r = 0 to 10, 12 or 14):

iinput: inverse cipher input

istart: state at start of round[r]

is_box: state after InvSubBytes()

is_row: state after InvShiftRows()

ik_sch: key schedule value for round[r]

ik_add: state after AddRoundKey()

ioutput: inverse cipher output

Legend for EQUIVALENT INVERSE CIPHER (DECRYPT) (round number r = 0 to 10, 12

or 14):

iinput: inverse cipher input

istart: state at start of round[r]

is_box: state after InvSubBytes()

is_row: state after InvShiftRows()

im_col: state after InvMixColumns()

ik_sch: key schedule value for round[r]

ioutput: inverse cipher output

C.1 AES-128 (Nk=4, Nr=10)
PLAINTEXT:
00112233445566778899aabbccddeeff

KEY:
000102030405060708090a0b0c0d0e0f

CIPHER (ENCRYPT):

35
























































round[ 0].input
00112233445566778899aabbccddeeff

round[ 0].k_sch
000102030405060708090a0b0c0d0e0f

round[ 1].start
00102030405060708090a0b0c0d0e0f0

round[ 1].s_box
63cab7040953d051cd60e0e7ba70e18c

round[ 1].s_row
6353e08c0960e104cd70b751bacad0e7

round[ 1].m_col
5f72641557f5bc92f7be3b291db9f91a

round[ 1].k_sch
d6aa74fdd2af72fadaa678f1d6ab76fe

round[ 2].start
89d810e8855ace682d1843d8cb128fe4

round[ 2].s_box
a761ca9b97be8b45d8ad1a611fc97369

round[ 2].s_row
a7be1a6997ad739bd8c9ca451f618b61

round[ 2].m_col
ff87968431d86a51645151fa773ad009

round[ 2].k_sch
b692cf0b643dbdf1be9bc5006830b3fe

round[ 3].start
4915598f55e5d7a0daca94fa1f0a63f7

round[ 3].s_box
3b59cb73fcd90ee05774222dc067fb68

round[ 3].s_row
3bd92268fc74fb735767cbe0c0590e2d

round[ 3].m_col
4c9c1e66f771f0762c3f868e534df256

round[ 3].k_sch
b6ff744ed2c2c9bf6c590cbf0469bf41

round[ 4].start
fa636a2825b339c940668a3157244d17

round[ 4].s_box
2dfb02343f6d12dd09337ec75b36e3f0

round[ 4].s_row
2d6d7ef03f33e334093602dd5bfb12c7

round[ 4].m_col
6385b79ffc538df997be478e7547d691

round[ 4].k_sch
47f7f7bc95353e03f96c32bcfd058dfd

round[ 5].start
247240236966b3fa6ed2753288425b6c

round[ 5].s_box
36400926f9336d2d9fb59d23c42c3950

round[ 5].s_row
36339d50f9b539269f2c092dc4406d23

round[ 5].m_col
f4bcd45432e554d075f1d6c51dd03b3c

round[ 5].k_sch
3caaa3e8a99f9deb50f3af57adf622aa

round[ 6].start
c81677bc9b7ac93b25027992b0261996

round[ 6].s_box
e847f56514dadde23f77b64fe7f7d490

round[ 6].s_row
e8dab6901477d4653ff7f5e2e747dd4f

round[ 6].m_col
9816ee7400f87f556b2c049c8e5ad036

round[ 6].k_sch
5e390f7df7a69296a7553dc10aa31f6b

round[ 7].start
c62fe109f75eedc3cc79395d84f9cf5d

round[ 7].s_box
b415f8016858552e4bb6124c5f998a4c

round[ 7].s_row
b458124c68b68a014b99f82e5f15554c

round[ 7].m_col
c57e1c159a9bd286f05f4be098c63439

round[ 7].k_sch
14f9701ae35fe28c440adf4d4ea9c026

round[ 8].start
d1876c0f79c4300ab45594add66ff41f

round[ 8].s_box
3e175076b61c04678dfc2295f6a8bfc0

round[ 8].s_row
3e1c22c0b6fcbf768da85067f6170495

round[ 8].m_col
baa03de7a1f9b56ed5512cba5f414d23

round[ 8].k_sch
47438735a41c65b9e016baf4aebf7ad2

round[ 9].start
fde3bad205e5d0d73547964ef1fe37f1

round[ 9].s_box
5411f4b56bd9700e96a0902fa1bb9aa1

round[ 9].s_row
54d990a16ba09ab596bbf40ea111702f

round[ 9].m_col
e9f74eec023020f61bf2ccf2353c21c7

round[ 9].k_sch
549932d1f08557681093ed9cbe2c974e

round[10].start
bd6e7c3df2b5779e0b61216e8b10b689

round[10].s_box
7a9f102789d5f50b2beffd9f3dca4ea7

round[10].s_row
7ad5fda789ef4e272bca100b3d9ff59f

round[10].k_sch
13111d7fe3944a17f307a78b4d2b30c5

round[10].output 69c4e0d86a7b0430d8cdb78070b4c55a

INVERSE CIPHER (DECRYPT):

round[ 0].iinput 69c4e0d86a7b0430d8cdb78070b4c55a

round[ 0].ik_sch 13111d7fe3944a17f307a78b4d2b30c5

round[ 1].istart 7ad5fda789ef4e272bca100b3d9ff59f

36























































round[ 1].is_row 7a9f102789d5f50b2beffd9f3dca4ea7

round[ 1].is_box bd6e7c3df2b5779e0b61216e8b10b689

round[ 1].ik_sch 549932d1f08557681093ed9cbe2c974e

round[ 1].ik_add e9f74eec023020f61bf2ccf2353c21c7

round[ 2].istart 54d990a16ba09ab596bbf40ea111702f

round[ 2].is_row 5411f4b56bd9700e96a0902fa1bb9aa1

round[ 2].is_box fde3bad205e5d0d73547964ef1fe37f1

round[ 2].ik_sch 47438735a41c65b9e016baf4aebf7ad2

round[ 2].ik_add baa03de7a1f9b56ed5512cba5f414d23

round[ 3].istart 3e1c22c0b6fcbf768da85067f6170495

round[ 3].is_row 3e175076b61c04678dfc2295f6a8bfc0

round[ 3].is_box d1876c0f79c4300ab45594add66ff41f

round[ 3].ik_sch 14f9701ae35fe28c440adf4d4ea9c026

round[ 3].ik_add c57e1c159a9bd286f05f4be098c63439

round[ 4].istart b458124c68b68a014b99f82e5f15554c

round[ 4].is_row b415f8016858552e4bb6124c5f998a4c

round[ 4].is_box c62fe109f75eedc3cc79395d84f9cf5d

round[ 4].ik_sch 5e390f7df7a69296a7553dc10aa31f6b

round[ 4].ik_add 9816ee7400f87f556b2c049c8e5ad036

round[ 5].istart e8dab6901477d4653ff7f5e2e747dd4f

round[ 5].is_row e847f56514dadde23f77b64fe7f7d490

round[ 5].is_box c81677bc9b7ac93b25027992b0261996

round[ 5].ik_sch 3caaa3e8a99f9deb50f3af57adf622aa

round[ 5].ik_add f4bcd45432e554d075f1d6c51dd03b3c

round[ 6].istart 36339d50f9b539269f2c092dc4406d23

round[ 6].is_row 36400926f9336d2d9fb59d23c42c3950

round[ 6].is_box 247240236966b3fa6ed2753288425b6c

round[ 6].ik_sch 47f7f7bc95353e03f96c32bcfd058dfd

round[ 6].ik_add 6385b79ffc538df997be478e7547d691

round[ 7].istart 2d6d7ef03f33e334093602dd5bfb12c7

round[ 7].is_row 2dfb02343f6d12dd09337ec75b36e3f0

round[ 7].is_box fa636a2825b339c940668a3157244d17

round[ 7].ik_sch b6ff744ed2c2c9bf6c590cbf0469bf41

round[ 7].ik_add 4c9c1e66f771f0762c3f868e534df256

round[ 8].istart 3bd92268fc74fb735767cbe0c0590e2d

round[ 8].is_row 3b59cb73fcd90ee05774222dc067fb68

round[ 8].is_box 4915598f55e5d7a0daca94fa1f0a63f7

round[ 8].ik_sch b692cf0b643dbdf1be9bc5006830b3fe

round[ 8].ik_add ff87968431d86a51645151fa773ad009

round[ 9].istart a7be1a6997ad739bd8c9ca451f618b61

round[ 9].is_row a761ca9b97be8b45d8ad1a611fc97369

round[ 9].is_box 89d810e8855ace682d1843d8cb128fe4

round[ 9].ik_sch d6aa74fdd2af72fadaa678f1d6ab76fe

round[ 9].ik_add 5f72641557f5bc92f7be3b291db9f91a

round[10].istart 6353e08c0960e104cd70b751bacad0e7

round[10].is_row 63cab7040953d051cd60e0e7ba70e18c

round[10].is_box 00102030405060708090a0b0c0d0e0f0

round[10].ik_sch 000102030405060708090a0b0c0d0e0f

round[10].ioutput 00112233445566778899aabbccddeeff

EQUIVALENT INVERSE CIPHER (DECRYPT):

round[ 0].iinput 69c4e0d86a7b0430d8cdb78070b4c55a

round[ 0].ik_sch 13111d7fe3944a17f307a78b4d2b30c5

round[ 1].istart 7ad5fda789ef4e272bca100b3d9ff59f

round[ 1].is_box bdb52189f261b63d0b107c9e8b6e776e

round[ 1].is_row bd6e7c3df2b5779e0b61216e8b10b689

round[ 1].im_col 4773b91ff72f354361cb018ea1e6cf2c

37

















































round[ 1].ik_sch 13aa29be9c8faff6f770f58000f7bf03

round[ 2].istart 54d990a16ba09ab596bbf40ea111702f

round[ 2].is_box fde596f1054737d235febad7f1e3d04e

round[ 2].is_row fde3bad205e5d0d73547964ef1fe37f1

round[ 2].im_col 2d7e86a339d9393ee6570a1101904e16

round[ 2].ik_sch 1362a4638f2586486bff5a76f7874a83

round[ 3].istart 3e1c22c0b6fcbf768da85067f6170495

round[ 3].is_box d1c4941f7955f40fb46f6c0ad68730ad

round[ 3].is_row d1876c0f79c4300ab45594add66ff41f

round[ 3].im_col 39daee38f4f1a82aaf432410c36d45b9

round[ 3].ik_sch 8d82fc749c47222be4dadc3e9c7810f5

round[ 4].istart b458124c68b68a014b99f82e5f15554c

round[ 4].is_box c65e395df779cf09ccf9e1c3842fed5d

round[ 4].is_row c62fe109f75eedc3cc79395d84f9cf5d

round[ 4].im_col 9a39bf1d05b20a3a476a0bf79fe51184

round[ 4].ik_sch 72e3098d11c5de5f789dfe1578a2cccb

round[ 5].istart e8dab6901477d4653ff7f5e2e747dd4f

round[ 5].is_box c87a79969b0219bc2526773bb016c992

round[ 5].is_row c81677bc9b7ac93b25027992b0261996

round[ 5].im_col 18f78d779a93eef4f6742967c47f5ffd

round[ 5].ik_sch 2ec410276326d7d26958204a003f32de

round[ 6].istart 36339d50f9b539269f2c092dc4406d23

round[ 6].is_box 2466756c69d25b236e4240fa8872b332

round[ 6].is_row 247240236966b3fa6ed2753288425b6c

round[ 6].im_col 85cf8bf472d124c10348f545329c0053

round[ 6].ik_sch a8a2f5044de2c7f50a7ef79869671294

round[ 7].istart 2d6d7ef03f33e334093602dd5bfb12c7

round[ 7].is_box fab38a1725664d2840246ac957633931

round[ 7].is_row fa636a2825b339c940668a3157244d17

round[ 7].im_col fc1fc1f91934c98210fbfb8da340eb21

round[ 7].ik_sch c7c6e391e54032f1479c306d6319e50c

round[ 8].istart 3bd92268fc74fb735767cbe0c0590e2d

round[ 8].is_box 49e594f755ca638fda0a59a01f15d7fa

round[ 8].is_row 4915598f55e5d7a0daca94fa1f0a63f7

round[ 8].im_col 076518f0b52ba2fb7a15c8d93be45e00

round[ 8].ik_sch a0db02992286d160a2dc029c2485d561

round[ 9].istart a7be1a6997ad739bd8c9ca451f618b61

round[ 9].is_box 895a43e485188fe82d121068cbd8ced8

round[ 9].is_row 89d810e8855ace682d1843d8cb128fe4

round[ 9].im_col ef053f7c8b3d32fd4d2a64ad3c93071a

round[ 9].ik_sch 8c56dff0825dd3f9805ad3fc8659d7fd

round[10].istart 6353e08c0960e104cd70b751bacad0e7

round[10].is_box 0050a0f04090e03080d02070c01060b0

round[10].is_row 00102030405060708090a0b0c0d0e0f0

round[10].ik_sch 000102030405060708090a0b0c0d0e0f

round[10].ioutput 00112233445566778899aabbccddeeff

C.2 AES-192 (Nk=6, Nr=12)
PLAINTEXT: 00112233445566778899aabbccddeeff

KEY:
000102030405060708090a0b0c0d0e0f1011121314151617

CIPHER (ENCRYPT):

round[ 0].input
00112233445566778899aabbccddeeff

round[ 0].k_sch
000102030405060708090a0b0c0d0e0f

round[ 1].start
00102030405060708090a0b0c0d0e0f0

38


























































round[ 1].s_box
63cab7040953d051cd60e0e7ba70e18c
round[ 1].s_row
6353e08c0960e104cd70b751bacad0e7
round[ 1].m_col
5f72641557f5bc92f7be3b291db9f91a
round[ 1].k_sch
10111213141516175846f2f95c43f4fe
round[ 2].start
4f63760643e0aa85aff8c9d041fa0de4
round[ 2].s_box
84fb386f1ae1ac977941dd70832dd769
round[ 2].s_row
84e1dd691a41d76f792d389783fbac70
round[ 2].m_col
9f487f794f955f662afc86abd7f1ab29
round[ 2].k_sch
544afef55847f0fa4856e2e95c43f4fe
round[ 3].start
cb02818c17d2af9c62aa64428bb25fd7
round[ 3].s_box
1f770c64f0b579deaaac432c3d37cf0e
round[ 3].s_row
1fb5430ef0accf64aa370cde3d77792c
round[ 3].m_col
b7a53ecbbf9d75a0c40efc79b674cc11
round[ 3].k_sch
40f949b31cbabd4d48f043b810b7b342
round[ 4].start
f75c7778a327c8ed8cfebfc1a6c37f53
round[ 4].s_box
684af5bc0acce85564bb0878242ed2ed
round[ 4].s_row
68cc08ed0abbd2bc642ef555244ae878
round[ 4].m_col
7a1e98bdacb6d1141a6944dd06eb2d3e
round[ 4].k_sch
58e151ab04a2a5557effb5416245080c
round[ 5].start
22ffc916a81474416496f19c64ae2532
round[ 5].s_box
9316dd47c2fa92834390a1de43e43f23
round[ 5].s_row
93faa123c2903f4743e4dd83431692de
round[ 5].m_col
aaa755b34cffe57cef6f98e1f01c13e6
round[ 5].k_sch
2ab54bb43a02f8f662e3a95d66410c08
round[ 6].start
80121e0776fd1d8a8d8c31bc965d1fee
round[ 6].s_box
cdc972c53854a47e5d64c765904cc028
round[ 6].s_row
cd54c7283864c0c55d4c727e90c9a465
round[ 6].m_col
921f748fd96e937d622d7725ba8ba50c
round[ 6].k_sch
f501857297448d7ebdf1c6ca87f33e3c
round[ 7].start
671ef1fd4e2a1e03dfdcb1ef3d789b30
round[ 7].s_box
8572a1542fe5727b9e86c8df27bc1404
round[ 7].s_row
85e5c8042f8614549ebca17b277272df
round[ 7].m_col
e913e7b18f507d4b227ef652758acbcc
round[ 7].k_sch
e510976183519b6934157c9ea351f1e0
round[ 8].start
0c0370d00c01e622166b8accd6db3a2c
round[ 8].s_box
fe7b5170fe7c8e93477f7e4bf6b98071
round[ 8].s_row
fe7c7e71fe7f807047b95193f67b8e4b
round[ 8].m_col
6cf5edf996eb0a069c4ef21cbfc25762
round[ 8].k_sch
1ea0372a995309167c439e77ff12051e
round[ 9].start
7255dad30fb80310e00d6c6b40d0527c
round[ 9].s_box
40fc5766766c7bcae1d7507f09700010
round[ 9].s_row
406c501076d70066e17057ca09fc7b7f
round[ 9].m_col
7478bcdce8a50b81d4327a9009188262
round[ 9].k_sch
dd7e0e887e2fff68608fc842f9dcc154
round[10].start
a906b254968af4e9b4bdb2d2f0c44336
round[10].s_box
d36f3720907ebf1e8d7a37b58c1c1a05
round[10].s_row
d37e3705907a1a208d1c371e8c6fbfb5
round[10].m_col
0d73cc2d8f6abe8b0cf2dd9bb83d422e
round[10].k_sch
859f5f237a8d5a3dc0c02952beefd63a
round[11].start
88ec930ef5e7e4b6cc32f4c906d29414
round[11].s_box
c4cedcabe694694e4b23bfdd6fb522fa
round[11].s_row
c494bffae62322ab4bb5dc4e6fce69dd
round[11].m_col
71d720933b6d677dc00b8f28238e0fb7
round[11].k_sch
de601e7827bcdf2ca223800fd8aeda32
round[12].start
afb73eeb1cd1b85162280f27fb20d585
round[12].s_box
79a9b2e99c3e6cd1aa3476cc0fb70397
round[12].s_row
793e76979c3403e9aab7b2d10fa96ccc
39
























































round[12].k_sch
a4970a331a78dc09c418c271e3a41d5d

round[12].output dda97ca4864cdfe06eaf70a0ec0d7191

INVERSE CIPHER (DECRYPT):

round[ 0].iinput dda97ca4864cdfe06eaf70a0ec0d7191

round[ 0].ik_sch a4970a331a78dc09c418c271e3a41d5d

round[ 1].istart 793e76979c3403e9aab7b2d10fa96ccc

round[ 1].is_row 79a9b2e99c3e6cd1aa3476cc0fb70397

round[ 1].is_box afb73eeb1cd1b85162280f27fb20d585

round[ 1].ik_sch de601e7827bcdf2ca223800fd8aeda32

round[ 1].ik_add 71d720933b6d677dc00b8f28238e0fb7

round[ 2].istart c494bffae62322ab4bb5dc4e6fce69dd

round[ 2].is_row c4cedcabe694694e4b23bfdd6fb522fa

round[ 2].is_box 88ec930ef5e7e4b6cc32f4c906d29414

round[ 2].ik_sch 859f5f237a8d5a3dc0c02952beefd63a

round[ 2].ik_add 0d73cc2d8f6abe8b0cf2dd9bb83d422e

round[ 3].istart d37e3705907a1a208d1c371e8c6fbfb5

round[ 3].is_row d36f3720907ebf1e8d7a37b58c1c1a05

round[ 3].is_box a906b254968af4e9b4bdb2d2f0c44336

round[ 3].ik_sch dd7e0e887e2fff68608fc842f9dcc154

round[ 3].ik_add 7478bcdce8a50b81d4327a9009188262

round[ 4].istart 406c501076d70066e17057ca09fc7b7f

round[ 4].is_row 40fc5766766c7bcae1d7507f09700010

round[ 4].is_box 7255dad30fb80310e00d6c6b40d0527c

round[ 4].ik_sch 1ea0372a995309167c439e77ff12051e

round[ 4].ik_add 6cf5edf996eb0a069c4ef21cbfc25762

round[ 5].istart fe7c7e71fe7f807047b95193f67b8e4b

round[ 5].is_row fe7b5170fe7c8e93477f7e4bf6b98071

round[ 5].is_box 0c0370d00c01e622166b8accd6db3a2c

round[ 5].ik_sch e510976183519b6934157c9ea351f1e0

round[ 5].ik_add e913e7b18f507d4b227ef652758acbcc

round[ 6].istart 85e5c8042f8614549ebca17b277272df

round[ 6].is_row 8572a1542fe5727b9e86c8df27bc1404

round[ 6].is_box 671ef1fd4e2a1e03dfdcb1ef3d789b30

round[ 6].ik_sch f501857297448d7ebdf1c6ca87f33e3c

round[ 6].ik_add 921f748fd96e937d622d7725ba8ba50c

round[ 7].istart cd54c7283864c0c55d4c727e90c9a465

round[ 7].is_row cdc972c53854a47e5d64c765904cc028

round[ 7].is_box 80121e0776fd1d8a8d8c31bc965d1fee

round[ 7].ik_sch 2ab54bb43a02f8f662e3a95d66410c08

round[ 7].ik_add aaa755b34cffe57cef6f98e1f01c13e6

round[ 8].istart 93faa123c2903f4743e4dd83431692de

round[ 8].is_row 9316dd47c2fa92834390a1de43e43f23

round[ 8].is_box 22ffc916a81474416496f19c64ae2532

round[ 8].ik_sch 58e151ab04a2a5557effb5416245080c

round[ 8].ik_add 7a1e98bdacb6d1141a6944dd06eb2d3e

round[ 9].istart 68cc08ed0abbd2bc642ef555244ae878

round[ 9].is_row 684af5bc0acce85564bb0878242ed2ed

round[ 9].is_box f75c7778a327c8ed8cfebfc1a6c37f53

round[ 9].ik_sch 40f949b31cbabd4d48f043b810b7b342

round[ 9].ik_add b7a53ecbbf9d75a0c40efc79b674cc11

round[10].istart 1fb5430ef0accf64aa370cde3d77792c

round[10].is_row 1f770c64f0b579deaaac432c3d37cf0e

round[10].is_box cb02818c17d2af9c62aa64428bb25fd7

round[10].ik_sch 544afef55847f0fa4856e2e95c43f4fe

round[10].ik_add 9f487f794f955f662afc86abd7f1ab29

round[11].istart 84e1dd691a41d76f792d389783fbac70

40























































round[11].is_row 84fb386f1ae1ac977941dd70832dd769

round[11].is_box 4f63760643e0aa85aff8c9d041fa0de4

round[11].ik_sch 10111213141516175846f2f95c43f4fe

round[11].ik_add 5f72641557f5bc92f7be3b291db9f91a

round[12].istart 6353e08c0960e104cd70b751bacad0e7

round[12].is_row 63cab7040953d051cd60e0e7ba70e18c

round[12].is_box 00102030405060708090a0b0c0d0e0f0

round[12].ik_sch 000102030405060708090a0b0c0d0e0f

round[12].ioutput 00112233445566778899aabbccddeeff

EQUIVALENT INVERSE CIPHER (DECRYPT):

round[ 0].iinput dda97ca4864cdfe06eaf70a0ec0d7191

round[ 0].ik_sch a4970a331a78dc09c418c271e3a41d5d

round[ 1].istart 793e76979c3403e9aab7b2d10fa96ccc

round[ 1].is_box afd10f851c28d5eb62203e51fbb7b827

round[ 1].is_row afb73eeb1cd1b85162280f27fb20d585

round[ 1].im_col 122a02f7242ac8e20605afce51cc7264

round[ 1].ik_sch d6bebd0dc209ea494db073803e021bb9

round[ 2].istart c494bffae62322ab4bb5dc4e6fce69dd

round[ 2].is_box 88e7f414f532940eccd293b606ece4c9

round[ 2].is_row 88ec930ef5e7e4b6cc32f4c906d29414

round[ 2].im_col 5cc7aecce3c872194ae5ef8309a933c7

round[ 2].ik_sch 8fb999c973b26839c7f9d89d85c68c72

round[ 3].istart d37e3705907a1a208d1c371e8c6fbfb5

round[ 3].is_box a98ab23696bd4354b4c4b2e9f006f4d2

round[ 3].is_row a906b254968af4e9b4bdb2d2f0c44336

round[ 3].im_col b7113ed134e85489b20866b51d4b2c3b

round[ 3].ik_sch f77d6ec1423f54ef5378317f14b75744

round[ 4].istart 406c501076d70066e17057ca09fc7b7f

round[ 4].is_box 72b86c7c0f0d52d3e0d0da104055036b

round[ 4].is_row 7255dad30fb80310e00d6c6b40d0527c

round[ 4].im_col ef3b1be1b9b0e64bdcb79f1e0a707fbb

round[ 4].ik_sch 1147659047cf663b9b0ece8dfc0bf1f0

round[ 5].istart fe7c7e71fe7f807047b95193f67b8e4b

round[ 5].is_box 0c018a2c0c6b3ad016db7022d603e6cc

round[ 5].is_row 0c0370d00c01e622166b8accd6db3a2c

round[ 5].im_col 592460b248832b2952e0b831923048f1

round[ 5].ik_sch dcc1a8b667053f7dcc5c194ab5423a2e

round[ 6].istart 85e5c8042f8614549ebca17b277272df

round[ 6].is_box 672ab1304edc9bfddf78f1033d1e1eef

round[ 6].is_row 671ef1fd4e2a1e03dfdcb1ef3d789b30

round[ 6].im_col 0b8a7783417ae3a1f9492dc0c641a7ce

round[ 6].ik_sch c6deb0ab791e2364a4055fbe568803ab

round[ 7].istart cd54c7283864c0c55d4c727e90c9a465

round[ 7].is_box 80fd31ee768c1f078d5d1e8a96121dbc

round[ 7].is_row 80121e0776fd1d8a8d8c31bc965d1fee

round[ 7].im_col 4ee1ddf9301d6352c9ad769ef8d20515

round[ 7].ik_sch dd1b7cdaf28d5c158a49ab1dbbc497cb

round[ 8].istart 93faa123c2903f4743e4dd83431692de

round[ 8].is_box 2214f132a896251664aec94164ff749c

round[ 8].is_row 22ffc916a81474416496f19c64ae2532

round[ 8].im_col 1008ffe53b36ee6af27b42549b8a7bb7

round[ 8].ik_sch 78c4f708318d3cd69655b701bfc093cf

round[ 9].istart 68cc08ed0abbd2bc642ef555244ae878

round[ 9].is_box f727bf53a3fe7f788cc377eda65cc8c1

round[ 9].is_row f75c7778a327c8ed8cfebfc1a6c37f53

round[ 9].im_col 7f69ac1ed939ebaac8ece3cb12e159e3

41


















































round[ 9].ik_sch 60dcef10299524ce62dbef152f9620cf

round[10].istart 1fb5430ef0accf64aa370cde3d77792c

round[10].is_box cbd264d717aa5f8c62b2819c8b02af42

round[10].is_row cb02818c17d2af9c62aa64428bb25fd7

round[10].im_col cfaf16b2570c18b52e7fef50cab267ae

round[10].ik_sch 4b4ecbdb4d4dcfda5752d7c74949cbde

round[11].istart 84e1dd691a41d76f792d389783fbac70

round[11].is_box 4fe0c9e443f80d06affa76854163aad0

round[11].is_row 4f63760643e0aa85aff8c9d041fa0de4

round[11].im_col 794cf891177bfd1d8a327086f3831b39

round[11].ik_sch 1a1f181d1e1b1c194742c7d74949cbde

round[12].istart 6353e08c0960e104cd70b751bacad0e7

round[12].is_box 0050a0f04090e03080d02070c01060b0

round[12].is_row 00102030405060708090a0b0c0d0e0f0

round[12].ik_sch 000102030405060708090a0b0c0d0e0f

round[12].ioutput 00112233445566778899aabbccddeeff

C.3 AES-256 (Nk=8, Nr=14)
PLAINTEXT: 00112233445566778899aabbccddeeff

KEY:
000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f

CIPHER (ENCRYPT):

round[ 0].input
00112233445566778899aabbccddeeff

round[ 0].k_sch
000102030405060708090a0b0c0d0e0f

round[ 1].start
00102030405060708090a0b0c0d0e0f0

round[ 1].s_box
63cab7040953d051cd60e0e7ba70e18c

round[ 1].s_row
6353e08c0960e104cd70b751bacad0e7

round[ 1].m_col
5f72641557f5bc92f7be3b291db9f91a

round[ 1].k_sch
101112131415161718191a1b1c1d1e1f

round[ 2].start
4f63760643e0aa85efa7213201a4e705

round[ 2].s_box
84fb386f1ae1ac97df5cfd237c49946b

round[ 2].s_row
84e1fd6b1a5c946fdf4938977cfbac23

round[ 2].m_col
bd2a395d2b6ac438d192443e615da195

round[ 2].k_sch
a573c29fa176c498a97fce93a572c09c

round[ 3].start
1859fbc28a1c00a078ed8aadc42f6109

round[ 3].s_box
adcb0f257e9c63e0bc557e951c15ef01

round[ 3].s_row
ad9c7e017e55ef25bc150fe01ccb6395

round[ 3].m_col
810dce0cc9db8172b3678c1e88a1b5bd

round[ 3].k_sch
1651a8cd0244beda1a5da4c10640bade

round[ 4].start
975c66c1cb9f3fa8a93a28df8ee10f63

round[ 4].s_box
884a33781fdb75c2d380349e19f876fb

round[ 4].s_row
88db34fb1f807678d3f833c2194a759e

round[ 4].m_col
b2822d81abe6fb275faf103a078c0033

round[ 4].k_sch
ae87dff00ff11b68a68ed5fb03fc1567

round[ 5].start
1c05f271a417e04ff921c5c104701554

round[ 5].s_box
9c6b89a349f0e18499fda678f2515920

round[ 5].s_row
9cf0a62049fd59a399518984f26be178

round[ 5].m_col
aeb65ba974e0f822d73f567bdb64c877

round[ 5].k_sch
6de1f1486fa54f9275f8eb5373b8518d

round[ 6].start
c357aae11b45b7b0a2c7bd28a8dc99fa

round[ 6].s_box
2e5bacf8af6ea9e73ac67a34c286ee2d

round[ 6].s_row
2e6e7a2dafc6eef83a86ace7c25ba934

round[ 6].m_col
b951c33c02e9bd29ae25cdb1efa08cc7

round[ 6].k_sch
c656827fc9a799176f294cec6cd5598b

round[ 7].start
7f074143cb4e243ec10c815d8375d54c

round[ 7].s_box
d2c5831a1f2f36b278fe0c4cec9d0329

42
























































round[ 7].s_row
d22f0c291ffe031a789d83b2ecc5364c

round[ 7].m_col
ebb19e1c3ee7c9e87d7535e9ed6b9144

round[ 7].k_sch
3de23a75524775e727bf9eb45407cf39

round[ 8].start
d653a4696ca0bc0f5acaab5db96c5e7d

round[ 8].s_box
f6ed49f950e06576be74624c565058ff

round[ 8].s_row
f6e062ff507458f9be50497656ed654c

round[ 8].m_col
5174c8669da98435a8b3e62ca974a5ea

round[ 8].k_sch
0bdc905fc27b0948ad5245a4c1871c2f

round[ 9].start
5aa858395fd28d7d05e1a38868f3b9c5

round[ 9].s_box
bec26a12cfb55dff6bf80ac4450d56a6

round[ 9].s_row
beb50aa6cff856126b0d6aff45c25dc4

round[ 9].m_col
0f77ee31d2ccadc05430a83f4ef96ac3

round[ 9].k_sch
45f5a66017b2d387300d4d33640a820a

round[10].start
4a824851c57e7e47643de50c2af3e8c9

round[10].s_box
d61352d1a6f3f3a04327d9fee50d9bdd

round[10].s_row
d6f3d9dda6279bd1430d52a0e513f3fe

round[10].m_col
bd86f0ea748fc4f4630f11c1e9331233

round[10].k_sch
7ccff71cbeb4fe5413e6bbf0d261a7df

round[11].start
c14907f6ca3b3aa070e9aa313b52b5ec

round[11].s_box
783bc54274e280e0511eacc7e200d5ce

round[11].s_row
78e2acce741ed5425100c5e0e23b80c7

round[11].m_col
af8690415d6e1dd387e5fbedd5c89013

round[11].k_sch
f01afafee7a82979d7a5644ab3afe640

round[12].start
5f9c6abfbac634aa50409fa766677653

round[12].s_box
cfde0208f4b418ac5309db5c338538ed

round[12].s_row
cfb4dbedf4093808538502ac33de185c

round[12].m_col
7427fae4d8a695269ce83d315be0392b

round[12].k_sch
2541fe719bf500258813bbd55a721c0a

round[13].start
516604954353950314fb86e401922521

round[13].s_box
d133f22a1aed2a7bfa0f44697c4f3ffd

round[13].s_row
d1ed44fd1a0f3f2afa4ff27b7c332a69

round[13].m_col
2c21a820306f154ab712c75eee0da04f

round[13].k_sch
4e5a6699a9f24fe07e572baacdf8cdea

round[14].start
627bceb9999d5aaac945ecf423f56da5

round[14].s_box
aa218b56ee5ebeacdd6ecebf26e63c06

round[14].s_row
aa5ece06ee6e3c56dde68bac2621bebf

round[14].k_sch
24fc79ccbf0979e9371ac23c6d68de36

round[14].output 8ea2b7ca516745bfeafc49904b496089

INVERSE CIPHER (DECRYPT):

round[ 0].iinput 8ea2b7ca516745bfeafc49904b496089

round[ 0].ik_sch 24fc79ccbf0979e9371ac23c6d68de36

round[ 1].istart aa5ece06ee6e3c56dde68bac2621bebf

round[ 1].is_row aa218b56ee5ebeacdd6ecebf26e63c06

round[ 1].is_box 627bceb9999d5aaac945ecf423f56da5

round[ 1].ik_sch 4e5a6699a9f24fe07e572baacdf8cdea

round[ 1].ik_add 2c21a820306f154ab712c75eee0da04f

round[ 2].istart d1ed44fd1a0f3f2afa4ff27b7c332a69

round[ 2].is_row d133f22a1aed2a7bfa0f44697c4f3ffd

round[ 2].is_box 516604954353950314fb86e401922521

round[ 2].ik_sch 2541fe719bf500258813bbd55a721c0a

round[ 2].ik_add 7427fae4d8a695269ce83d315be0392b

round[ 3].istart cfb4dbedf4093808538502ac33de185c

round[ 3].is_row cfde0208f4b418ac5309db5c338538ed

round[ 3].is_box 5f9c6abfbac634aa50409fa766677653

round[ 3].ik_sch f01afafee7a82979d7a5644ab3afe640

round[ 3].ik_add af8690415d6e1dd387e5fbedd5c89013

43























































round[ 4].istart 78e2acce741ed5425100c5e0e23b80c7

round[ 4].is_row 783bc54274e280e0511eacc7e200d5ce

round[ 4].is_box c14907f6ca3b3aa070e9aa313b52b5ec

round[ 4].ik_sch 7ccff71cbeb4fe5413e6bbf0d261a7df

round[ 4].ik_add bd86f0ea748fc4f4630f11c1e9331233

round[ 5].istart d6f3d9dda6279bd1430d52a0e513f3fe

round[ 5].is_row d61352d1a6f3f3a04327d9fee50d9bdd

round[ 5].is_box 4a824851c57e7e47643de50c2af3e8c9

round[ 5].ik_sch 45f5a66017b2d387300d4d33640a820a

round[ 5].ik_add 0f77ee31d2ccadc05430a83f4ef96ac3

round[ 6].istart beb50aa6cff856126b0d6aff45c25dc4

round[ 6].is_row bec26a12cfb55dff6bf80ac4450d56a6

round[ 6].is_box 5aa858395fd28d7d05e1a38868f3b9c5

round[ 6].ik_sch 0bdc905fc27b0948ad5245a4c1871c2f

round[ 6].ik_add 5174c8669da98435a8b3e62ca974a5ea

round[ 7].istart f6e062ff507458f9be50497656ed654c

round[ 7].is_row f6ed49f950e06576be74624c565058ff

round[ 7].is_box d653a4696ca0bc0f5acaab5db96c5e7d

round[ 7].ik_sch 3de23a75524775e727bf9eb45407cf39

round[ 7].ik_add ebb19e1c3ee7c9e87d7535e9ed6b9144

round[ 8].istart d22f0c291ffe031a789d83b2ecc5364c

round[ 8].is_row d2c5831a1f2f36b278fe0c4cec9d0329

round[ 8].is_box 7f074143cb4e243ec10c815d8375d54c

round[ 8].ik_sch c656827fc9a799176f294cec6cd5598b

round[ 8].ik_add b951c33c02e9bd29ae25cdb1efa08cc7

round[ 9].istart 2e6e7a2dafc6eef83a86ace7c25ba934

round[ 9].is_row 2e5bacf8af6ea9e73ac67a34c286ee2d

round[ 9].is_box c357aae11b45b7b0a2c7bd28a8dc99fa

round[ 9].ik_sch 6de1f1486fa54f9275f8eb5373b8518d

round[ 9].ik_add aeb65ba974e0f822d73f567bdb64c877

round[10].istart 9cf0a62049fd59a399518984f26be178

round[10].is_row 9c6b89a349f0e18499fda678f2515920

round[10].is_box 1c05f271a417e04ff921c5c104701554

round[10].ik_sch ae87dff00ff11b68a68ed5fb03fc1567

round[10].ik_add b2822d81abe6fb275faf103a078c0033

round[11].istart 88db34fb1f807678d3f833c2194a759e

round[11].is_row 884a33781fdb75c2d380349e19f876fb

round[11].is_box 975c66c1cb9f3fa8a93a28df8ee10f63

round[11].ik_sch 1651a8cd0244beda1a5da4c10640bade

round[11].ik_add 810dce0cc9db8172b3678c1e88a1b5bd

round[12].istart ad9c7e017e55ef25bc150fe01ccb6395

round[12].is_row adcb0f257e9c63e0bc557e951c15ef01

round[12].is_box 1859fbc28a1c00a078ed8aadc42f6109

round[12].ik_sch a573c29fa176c498a97fce93a572c09c

round[12].ik_add bd2a395d2b6ac438d192443e615da195

round[13].istart 84e1fd6b1a5c946fdf4938977cfbac23

round[13].is_row 84fb386f1ae1ac97df5cfd237c49946b

round[13].is_box 4f63760643e0aa85efa7213201a4e705

round[13].ik_sch 101112131415161718191a1b1c1d1e1f

round[13].ik_add 5f72641557f5bc92f7be3b291db9f91a

round[14].istart 6353e08c0960e104cd70b751bacad0e7

round[14].is_row 63cab7040953d051cd60e0e7ba70e18c

round[14].is_box 00102030405060708090a0b0c0d0e0f0

round[14].ik_sch 000102030405060708090a0b0c0d0e0f

round[14].ioutput 00112233445566778899aabbccddeeff

EQUIVALENT INVERSE CIPHER (DECRYPT):

44


























































round[ 0].iinput 8ea2b7ca516745bfeafc49904b496089

round[ 0].ik_sch 24fc79ccbf0979e9371ac23c6d68de36

round[ 1].istart aa5ece06ee6e3c56dde68bac2621bebf

round[ 1].is_box 629deca599456db9c9f5ceaa237b5af4

round[ 1].is_row 627bceb9999d5aaac945ecf423f56da5

round[ 1].im_col e51c9502a5c1950506a61024596b2b07

round[ 1].ik_sch 34f1d1ffbfceaa2ffce9e25f2558016e

round[ 2].istart d1ed44fd1a0f3f2afa4ff27b7c332a69

round[ 2].is_box 5153862143fb259514920403016695e4

round[ 2].is_row 516604954353950314fb86e401922521

round[ 2].im_col 91a29306cc450d0226f4b5eaef5efed8

round[ 2].ik_sch 5e1648eb384c350a7571b746dc80e684

round[ 3].istart cfb4dbedf4093808538502ac33de185c

round[ 3].is_box 5fc69f53ba4076bf50676aaa669c34a7

round[ 3].is_row 5f9c6abfbac634aa50409fa766677653

round[ 3].im_col b041a94eff21ae9212278d903b8a63f6

round[ 3].ik_sch c8a305808b3f7bd043274870d9b1e331

round[ 4].istart 78e2acce741ed5425100c5e0e23b80c7

round[ 4].is_box c13baaeccae9b5f6705207a03b493a31

round[ 4].is_row c14907f6ca3b3aa070e9aa313b52b5ec

round[ 4].im_col 638357cec07de6300e30d0ec4ce2a23c

round[ 4].ik_sch b5708e13665a7de14d3d824ca9f151c2

round[ 5].istart d6f3d9dda6279bd1430d52a0e513f3fe

round[ 5].is_box 4a7ee5c9c53de85164f348472a827e0c

round[ 5].is_row 4a824851c57e7e47643de50c2af3e8c9

round[ 5].im_col ca6f71058c642842a315595fdf54f685

round[ 5].ik_sch 74da7ba3439c7e50c81833a09a96ab41

round[ 6].istart beb50aa6cff856126b0d6aff45c25dc4

round[ 6].is_box 5ad2a3c55fe1b93905f3587d68a88d88

round[ 6].is_row 5aa858395fd28d7d05e1a38868f3b9c5

round[ 6].im_col ca46f5ea835eab0b9537b6dbb221b6c2

round[ 6].ik_sch 3ca69715d32af3f22b67ffade4ccd38e

round[ 7].istart f6e062ff507458f9be50497656ed654c

round[ 7].is_box d6a0ab7d6cca5e695a6ca40fb953bc5d

round[ 7].is_row d653a4696ca0bc0f5acaab5db96c5e7d

round[ 7].im_col 2a70c8da28b806e9f319ce42be4baead

round[ 7].ik_sch f85fc4f3374605f38b844df0528e98e1

round[ 8].istart d22f0c291ffe031a789d83b2ecc5364c

round[ 8].is_box 7f4e814ccb0cd543c175413e8307245d

round[ 8].is_row 7f074143cb4e243ec10c815d8375d54c

round[ 8].im_col f0073ab7404a8a1fc2cba0b80df08517

round[ 8].ik_sch de69409aef8c64e7f84d0c5fcfab2c23

round[ 9].istart 2e6e7a2dafc6eef83a86ace7c25ba934

round[ 9].is_box c345bdfa1bc799e1a2dcaab0a857b728

round[ 9].is_row c357aae11b45b7b0a2c7bd28a8dc99fa

round[ 9].im_col 3225fe3686e498a32593c1872b613469

round[ 9].ik_sch aed55816cf19c100bcc24803d90ad511

round[10].istart 9cf0a62049fd59a399518984f26be178

round[10].is_box 1c17c554a4211571f970f24f0405e0c1

round[10].is_row 1c05f271a417e04ff921c5c104701554

round[10].im_col 9d1d5c462e655205c4395b7a2eac55e2

round[10].ik_sch 15c668bd31e5247d17c168b837e6207c

round[11].istart 88db34fb1f807678d3f833c2194a759e

round[11].is_box 979f2863cb3a0fc1a9e166a88e5c3fdf

round[11].is_row 975c66c1cb9f3fa8a93a28df8ee10f63

round[11].im_col d24bfb0e1f997633cfce86e37903fe87

round[11].ik_sch 7fd7850f61cc991673db890365c89d12

45