merge setkey_enc* functions
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/aesce.c b/library/aesce.c
index 29a4ce0..b4ebdad 100644
--- a/library/aesce.c
+++ b/library/aesce.c
@@ -160,9 +160,6 @@
}
-static uint8_t const rcon[] = { 0x01, 0x02, 0x04, 0x08, 0x10,
- 0x20, 0x40, 0x80, 0x1b, 0x36 };
-
static inline uint32_t aes_rot_word(uint32_t word)
{
return (word << (32 - 8)) | (word >> 8);
@@ -180,75 +177,47 @@
}
/*
- * Key expansion, 128-bit case
+ * Key expansion function
*/
-static void aesce_setkey_enc_128(unsigned char *rk,
- const unsigned char *key)
+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;
+ 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;
- memcpy(rk, key, (128 / 8));
+ memcpy(rk, key, key_len_in_bytes);
- for (size_t i = 0; i < sizeof(rcon); i++) {
- rki = rk_u32 + i * (128 / 32);
- rko = rki + (128 / 32);
- rko[0] = aes_rot_word(aes_sub_word(rki[(128 / 32) - 1])) ^ rcon[i] ^ rki[0];
+ for (size_t i = 0; i < rounds; i++) {
+ rki = rk_u32 + i * key_len_in_words;
+ 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[1] = rko[0] ^ rki[1];
rko[2] = rko[1] ^ rki[2];
rko[3] = rko[2] ^ rki[3];
- }
-}
-
-/*
- * Key expansion, 192-bit case
- */
-static void aesce_setkey_enc_192(unsigned char *rk,
- const unsigned char *key)
-{
- uint32_t *rki;
- uint32_t *rko;
- uint32_t *rk_u32 = (uint32_t *) rk;
- memcpy(rk, key, (192 / 8));
-
- for (size_t i = 0; i < 8; i++) {
- rki = rk_u32 + i * (192 / 32);
- rko = rki + (192 / 32);
- rko[0] = aes_rot_word(aes_sub_word(rki[(192 / 32) - 1])) ^ rcon[i] ^ rki[0];
- rko[1] = rko[0] ^ rki[1];
- rko[2] = rko[1] ^ rki[2];
- rko[3] = rko[2] ^ rki[3];
- if (i < 7) {
- rko[4] = rko[3] ^ rki[4];
- rko[5] = rko[4] ^ rki[5];
- }
- }
-}
-
-/*
- * Key expansion, 256-bit case
- */
-static void aesce_setkey_enc_256(unsigned char *rk,
- const unsigned char *key)
-{
- uint32_t *rki;
- uint32_t *rko;
- uint32_t *rk_u32 = (uint32_t *) rk;
- memcpy(rk, key, (256 / 8));
-
- for (size_t i = 0; i < 7; i++) {
- rki = rk_u32 + i * (256 / 32);
- rko = rki + (256 / 32);
- rko[0] = aes_rot_word(aes_sub_word(rki[(256 / 32) - 1])) ^ rcon[i] ^ rki[0];
- rko[1] = rko[0] ^ rki[1];
- rko[2] = rko[1] ^ rki[2];
- rko[3] = rko[2] ^ rki[3];
- 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];
+ switch (key_bit_length) {
+ case 192:
+ if (i < 7) {
+ 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];
+ }
+ break;
}
}
}
@@ -261,9 +230,10 @@
size_t bits)
{
switch (bits) {
- case 128: aesce_setkey_enc_128(rk, key); break;
- case 192: aesce_setkey_enc_192(rk, key); break;
- case 256: aesce_setkey_enc_256(rk, key); break;
+ case 128:
+ case 192:
+ case 256:
+ aesce_setkey_enc(rk, key, bits); break;
default: return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}