skinny
AddConstants
A 6-bit affine LFSR, whose state is denoted (rc5, rc4, rc3, rc2, rc1, rc0)
(with rc0 being the least significant bit), is used to generate round constants. Its update
function is defined as
The six bits are initialized 0 and are updated before use in a given round
Table for round constants for each round
you can verify the round constants with calculationg through lfsr
| Rounds | Constants |
|---|---|
| 1 -16 | 01,03,07,0F,1F,3E,3D,3B,37,2F,1E,3C,39,33,27,0E |
| 17 - 32 | 1D,3A,35,2B,16,2C,18,30,21,02,05,0B,17,2E,1C,38 |
| 33 - 48 | 31,23,06,0D,1B,36,2D,1A,34,29,12,24,08,11,22,04 |
| 49 - 62 | 09,13,26,0C,19,32,25,0A,15,2A,14,28,10,20 |
Then bits are arranged in a array of 4x4. depending on the size of bits in a cell of state matrix as shown in the below diagrams.
For s = 4
For s = 8
The round constants are combined with the state, respecting array positioning, using bitwise exclusive-or
