Improve readabilities
- Add more comments
- Adjust setkey_enc
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/aesce.c b/library/aesce.c
index b4ebdad..6481122 100644
--- a/library/aesce.c
+++ b/library/aesce.c
@@ -82,6 +82,8 @@
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 @@
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;
}
}