Encryption algorithms - Block cipher MKV

MKV block cipher

General

- The versions of MKV.

The MKV block cipher shall use an iterative round function applied for R: rounds during both encryption and decryption. Each round function shall consist of the following transformations: SubCells: nonlinear byte-wise substitution using an S-box; MixWords: linear transformation applied independently to each sub-state; XWords: mixing transformation combining sub-states using bitwise exclusive-OR operations; AddRoundKey: addition of the round key to the state using bitwise exclusive-OR.
The inverse transformations shall be used for decryption:: invSubCells: inverse transformations of SubCells; 1 invMixWords: inverse transformations of MixWords.
The encryption and decryption processes are specified in Clauses 2.2 and 2.3,: respectively. The key schedule process is specified in Clause 2.5.

Encryption process

General The encryption process shall transform a plaintext block P in {0,1}^n into a ciphertext block C in {0,1}^n using a master key K_master.

State representation

Initialization

The initial state shall be set as:: X?P
where the mapping from P to X shall be performed in a consistent byte: ordering defined by the implementation.

Round keys and whitening keys

Let:: K_r in {0, 1}^2n, for r=0, ..., R-1, be the round keys K_(r,0) in {0, 1}^n, for r=0, ..., R-1, be the low bit half of round key K_r K_(r,1) in {0, 1}^n, for r=0, ..., R-1, be the high half of round key K_r K_post in {0, 1}^2, be the post-whitening key
These keys shall be derived from the master key K_master ? using the key: schedule specified in Clause 2.5.

Round transformation

Final transformation

Output

The ciphertext shall be defined as:: C <- X

The encryption process can be fully described as follows: (1) X <- P

Decryption process

General The decryption process shall transform a ciphertext block C in {0,1}^n into a plaintext block P in {0,1}^n using the master key K_master.

Initialization

The initial state shall be set as:: X <- C

Whitening transformation

Inverse round transformation

Output

The ciphertext shall be defined as:: P <- X

Basic transformations

The MKV block cipher shall use the following basic transformations:: SubCells invSubCells MixWords invMixWords XWords
These transformations shall operate on the internal state X in {0, 1}^n and: are defined in the following subclauses.

SubCells transformation

invSubCells transformation

The invSubCells transformation shall apply the inverse substitution: box S^{-1} to each byte of the state. The transformation shall be defined as: x_(i,j) in S^(-1) (x_(i,j))
for all i,j.: The inverse S-box S^(-1) shall be specified as a lookup table in Table 2.
Table 2. The tabular representation of the substitution box S^(-1)

MixWords transformation The MixWords transformation shall be a linear transformation applied independently to each sub-state of the state X. 2.4.3.1 Rotation step 2.4.3.2 Linear transformation over GF(2^8)

invMixWords transformation The invMixWords transformation shall be the inverse of the MixWords transformation defined in Clause 2.4.3. The transformation shall be applied independently to each sub-state of the state. a) Inverse linear transformation

XWords transformation

Key schedule process

a): About key schedule
The key schedule shall derive:: round keys K_r in {0,1}^2n, for r=0,1,...,R-1, and a post-whitening key K_post in {0,1}^2n, from the master key K_master. The key schedule shall operate on an internal key state K in {0,1}^2n.
b): Key state representation

d) Round constants

For each block size n, the following constants shall be used:: For n=128: Const_128^((0)) =0x9302ee911a2ad98cad13e7948ad8b3b2, Const_128^((1)) =0xd4da00f33f11fd8822166bb9cd187c55,
For n=256:: Const_256^((0)) =0x9302ee911a2ad98cad13e7948ad8b3b2d4da00f33f11fd8822166bb9cd187c55, Const_256^((1)) =0x43c853a3f90f70ae8d72ad0e7aac0c71afad739c17a14bd656c9436300def1e5.