static void mix_columns(uint8_t *state, int mode) {
int i, j;
uint8_t column[4];
for(i = 0; i < NB; i++) {
for(j = 0; j < 4; j++)
column[j] = state[4 * j + i];
if(mode == FOR_MIX)
mix_column(column);
else
inv_mix_column(column);
for(j = 0; j < 4; j++)
state[4 * j + i] = column[j];
}
}
static
void aes_dec_round(aes_cipher_state_t* state, const aes_roundkey_t* k)
{
uint8_t tmp[16];
uint8_t i;
uint8_t t,u,v,w;
/// *** STEP 1: keyAdd ***
for(i=0; i<16; ++i)
{
tmp[i] = state->s[i] ^ k->ks[i];
}
#ifdef ENCRYPTION_DEBUG
beginSerial(115200, 0);
digitalWrite(23,0x01);
digitalWrite(11,0x00);
printString("\n\n*** STEP 1: keyAdd --> ", 0);
for(i=0; i<16; ++i)
{
puthex((char)tmp[i],0);
_delay_ms(3);
}
#endif
/// *** STEP 2: mixColums ***
inv_mix_column(&tmp[0]);
inv_mix_column(&tmp[4]);
inv_mix_column(&tmp[8]);
inv_mix_column(&tmp[12]);
// copy result
for(i=0; i<16; ++i)
{
state->s[i] = tmp[i];
}
#ifdef ENCRYPTION_DEBUG
printString("\n*** STEP 2: mixColums --> ", 0);
_delay_ms(3);
for(i=0; i<16; ++i)
{
puthex((char)state->s[i],0);
_delay_ms(3);
}
#endif
/// *** STEP 3: shiftRows ***
aes_invshiftcol(state->s+1, 1);
aes_invshiftcol(state->s+2, 2);
aes_invshiftcol(state->s+3, 3);
#ifdef ENCRYPTION_DEBUG
printString("\n*** STEP 3: shiftRows --> ", 0);
_delay_ms(3);
for(i=0; i<16; ++i)
{
puthex((char)state->s[i],0);
_delay_ms(3);
}
#endif
/// *** STEP 4: subBytes ***
for(i=0; i<16; ++i)
{
state->s[i] = pgm_read_byte(aes_invsbox+state->s[i]);
}
#ifdef ENCRYPTION_DEBUG
printString("\n*** STEP 4: subBytes --> ", 0);
_delay_ms(3);
for(i=0; i<16; ++i)
{
puthex((char)state->s[i],0);
_delay_ms(3);
}
printString("\n", 0);
#endif
}