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#include <stdint.h>
#include <string.h>
#include "parameters.h"
#include "tweakey.h"
#define LANE_BITS 64
#define LANE_BYTES (LANE_BITS/8)
#define LANES_NB (TWEAKEY_BYTES/LANE_BYTES)
void tweakey_state_init(
uint8_t TK[TWEAKEY_BYTES],
const uint8_t key[KEY_BYTES],
const uint8_t tweak[TWEAK_BYTES]
)
{
memcpy(TK, tweak, TWEAK_BYTES);
memcpy(TK+TWEAK_BYTES, key, KEY_BYTES);
}
void tweakey_state_extract(
const uint8_t TK[TWEAKEY_BYTES],
uint8_t round_constant,
uint8_t round_tweakey[ROUND_TWEAKEY_BYTES]
)
{
memset(round_tweakey, 0, ROUND_TWEAKEY_BYTES);
for (size_t j=0; j<LANES_NB; j++)
{
const uint8_t *TKj = TK + j*LANE_BYTES;
for (size_t k=0; k<LANE_BYTES; k++)
{
round_tweakey[k] ^= TKj[k];
}
}
round_tweakey[0] ^= round_constant;
}
static uint8_t _M1(uint8_t x)
{
return x<<3 ^ x>>3;
}
static uint8_t _M2(uint8_t x)
{
return x<<6 ^ (x & 0xf8) ^ x>>6;
}
static uint8_t _M3(uint8_t x)
{
return x & 0x1f;
}
static uint8_t _M4(uint8_t x)
{
/* (x<<2)>>3 would keep bit x6 due to integer promotion.
* Side-step this by writing each shift on its own statement. */
x <<= 2;
return x>>3;
}
static void _multiply_M(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
{
Y[7] = X[6];
Y[6] = X[5];
Y[5] = X[5]<<3 ^ X[4];
Y[4] = X[4]>>3 ^ X[3];
Y[3] = X[2];
Y[2] = X[6]<<2 ^ X[1];
Y[1] = X[0];
Y[0] = X[7];
}
static void _multiply_M2(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
{
Y[7] = X[5];
Y[6] = X[5]<<3 ^ X[4];
Y[5] = X[5]<<6 ^ _M1(X[4]) ^ X[3];
Y[4] = X[4]>>6 ^ X[3]>>3 ^ X[2];
Y[3] = X[6]<<2 ^ X[1];
Y[2] = X[5]<<2 ^ X[0];
Y[1] = X[7];
Y[0] = X[6];
}
static void _multiply_M3(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
{
Y[7] = X[5]<<3 ^ X[4];
Y[6] = X[5]<<6 ^ _M1(X[4]) ^ X[3];
Y[5] = _M2(X[4]) ^ _M1(X[3]) ^ X[2];
Y[4] = X[6]<<2 ^ X[3]>>6 ^ X[2]>>3 ^ X[1];
Y[3] = X[5]<<2 ^ X[0];
Y[2] = X[7] ^ X[5]<<5 ^ X[4]<<2;
Y[1] = X[6];
Y[0] = X[5];
}
static void _multiply_MR(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
{
Y[0] = X[1];
Y[1] = X[2];
Y[2] = X[3] ^ X[4]>>3;
Y[3] = X[4];
Y[4] = X[5] ^ X[6]<<3;
Y[5] = X[3]<<2 ^ X[6];
Y[6] = X[7];
Y[7] = X[0];
}
static void _multiply_MR2(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
{
Y[0] = X[2];
Y[1] = X[3] ^ X[4]>>3;
Y[2] = X[4] ^ X[5]>>3 ^ _M3(X[6]);
Y[3] = X[5] ^ X[6]<<3;
Y[4] = X[3]<<2 ^ X[6] ^ X[7]<<3;
Y[5] = X[4]<<2 ^ X[7];
Y[6] = X[0];
Y[7] = X[1];
}
static void _multiply_MR3(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES])
{
Y[0] = X[3] ^ X[4]>>3;
Y[1] = X[4] ^ X[5]>>3 ^ _M3(X[6]);
Y[2] = _M4(X[3]) ^ X[5] ^ _M1(X[6]) ^ _M3(X[7]);
Y[3] = X[3]<<2 ^ X[6] ^ X[7]<<3;
Y[4] = X[0]<<3 ^ X[4]<<2 ^ X[7];
Y[5] = X[0] ^ X[5]<<2 ^ X[6]<<5;
Y[6] = X[1];
Y[7] = X[2];
}
typedef void (*matrix_multiplication)(const uint8_t X[LANE_BYTES], uint8_t Y[LANE_BYTES]);
static const matrix_multiplication ALPHAS[6] = {
_multiply_M,
_multiply_M2,
_multiply_M3,
_multiply_MR,
_multiply_MR2,
_multiply_MR3
};
void tweakey_state_update(uint8_t TK[TWEAKEY_BYTES])
{
/* Skip lane 0, as it is multiplied by the identity matrix. */
for (size_t j=1; j<LANES_NB; j++)
{
uint8_t *TKj = TK + j*LANE_BYTES;
uint8_t TKj_old[LANE_BYTES];
memcpy(TKj_old, TKj, LANE_BYTES);
ALPHAS[j-1](TKj_old, TKj);
}
}
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