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#include <stdint.h>
#include <string.h>
#include "constants.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(
tweakey_state *TK,
const uint8_t key[KEY_BYTES],
const uint8_t tweak[TWEAK_BYTES]
)
{
memcpy(TK->TK, tweak, TWEAK_BYTES);
memcpy(TK->TK+TWEAK_BYTES, key, KEY_BYTES);
}
void tweakey_state_extract(
const tweakey_state *TK,
uint8_t round_tweakey[ROUND_TWEAKEY_BYTES], /* output */
uint8_t i /* round constant */
)
{
memset(round_tweakey, 0, ROUND_TWEAKEY_BYTES);
for (const uint8_t *lane=TK->TK; lane<TK->TK+TWEAKEY_BYTES; lane+=LANE_BYTES)
{
for (size_t j=0; j<LANE_BYTES; j++)
{
round_tweakey[j] ^= lane[j];
}
}
round_tweakey[0] ^= i;
}
static void _permute_state(tweakey_state *TK)
{
uint8_t TK_old[TWEAKEY_BYTES];
memcpy(TK_old, TK->TK, sizeof(TK_old));
for (size_t j=0; j<TWEAKEY_BYTES; j+=LANE_BYTES)
{
for (size_t k=0; k<LANE_BYTES; k++)
{
TK->TK[j+h[k]] = TK_old[j+k];
}
}
}
static void _multiply_state(tweakey_state *TK)
{
/* Lane 0 is multiplied by Id; lane 1 by P_0, lane 2 by P_1... */
for (size_t j=1; j<LANES_NB; j++)
{
const uint8_t *P_lane = P[j-1];
for (size_t k=0; k<LANE_BYTES; k++)
{
size_t offset = j*LANE_BYTES + k;
TK->TK[offset] = P_lane[TK->TK[offset]];
}
}
}
void tweakey_state_update(tweakey_state *TK)
{
_permute_state(TK);
_multiply_state(TK);
}
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