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- Add more comments
- Adjust setkey_enc

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2023-02-22 14:37:11 +08:00
parent baae4012bf
commit 3304c204ba
1 changed files with 29 additions and 20 deletions
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49
library/aesce.c
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@ -82,6 +82,8 @@ static uint8x16_t aesce_encrypt_block(uint8x16_t block,
block = vaeseq_u8(block, vld1q_u8(keys + (rounds -1) * 16));
/* Final round: no MixColumns */
/* Final AddRoundKey */
block = veorq_u8(block, vld1q_u8(keys + rounds * 16));
return block;
@ -183,40 +185,47 @@ static void aesce_setkey_enc(unsigned char *rk,
const unsigned char *key,
const size_t key_bit_length)
{
uint32_t *rki;
uint32_t *rko;
uint32_t *rk_u32 = (uint32_t *) rk;
const uint32_t key_len_in_words = key_bit_length / 32;
const uint32_t key_len_in_bytes = key_bit_length / 8;
const size_t round_key_len_in_words = 4;
static uint8_t const rcon[] = { 0x01, 0x02, 0x04, 0x08, 0x10,
0x20, 0x40, 0x80, 0x1b, 0x36 };
const uint32_t rounds =
key_bit_length == 128 ? sizeof(rcon) : key_bit_length == 192 ? 8 : 7;
/* Require max(key_len_in_words, round_key_len_len_in_words) + 7 */
const size_t round_keys_needed = key_len_in_words + 7;
const size_t key_expansion_size_in_words =
round_keys_needed * round_key_len_in_words;
const uint32_t *rko_end = (uint32_t *) rk + key_expansion_size_in_words;
memcpy(rk, key, key_len_in_bytes);
memcpy(rk, key, key_len_in_words * 4);
for (size_t i = 0; i < rounds; i++) {
rki = rk_u32 + i * key_len_in_words;
for (uint32_t *rki = (uint32_t *) rk;
rki + key_len_in_words < rko_end;
rki += key_len_in_words) {
size_t iteration = (rki- (uint32_t *) rk)/key_len_in_words;
uint32_t *rko;
rko = rki + key_len_in_words;
rko[0] = aes_rot_word(aes_sub_word(rki[key_len_in_words - 1]));
rko[0] ^= rcon[i] ^ rki[0];
rko[0] ^= rcon[iteration] ^ rki[0];
rko[1] = rko[0] ^ rki[1];
rko[2] = rko[1] ^ rki[2];
rko[3] = rko[2] ^ rki[3];
if (rko+key_len_in_words > rko_end) {
/* Do not write overflow words.*/
continue;
}
switch (key_bit_length) {
case 128:
break;
case 192:
if (i < 7) {
rko[4] = rko[3] ^ rki[4];
rko[5] = rko[4] ^ rki[5];
}
rko[4] = rko[3] ^ rki[4];
rko[5] = rko[4] ^ rki[5];
break;
case 256:
if (i < 6) {
rko[4] = aes_sub_word(rko[3]) ^ rki[4];
rko[5] = rko[4] ^ rki[5];
rko[6] = rko[5] ^ rki[6];
rko[7] = rko[6] ^ rki[7];
}
rko[4] = aes_sub_word(rko[3]) ^ rki[4];
rko[5] = rko[4] ^ rki[5];
rko[6] = rko[5] ^ rki[6];
rko[7] = rko[6] ^ rki[7];
break;
}
}