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Improve comments for key expansion

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Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2023-03-01 11:18:20 +08:00
parent df87a12c81
commit 2c26651938
1 changed files with 5 additions and 5 deletions
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10
library/aesce.c
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@ -212,14 +212,14 @@ static void aesce_setkey_enc(unsigned char *rk,
0x20, 0x40, 0x80, 0x1b, 0x36 };
/* See https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.197.pdf
* - Section 5, Nr = Nk + 6
* - Section 5.2, the key expansion size is Nb*(Nr+1)
* - Section 5.2, the length of round keys is Nb*(Nr+1)
*/
const uint32_t key_len_in_words = key_bit_length / 32; /* Nk */
const size_t round_key_len_in_words = 4; /* Nb */
const size_t round_keys_needed = key_len_in_words + 6; /* Nr */
const size_t key_expansion_size_in_words =
round_key_len_in_words * (round_keys_needed + 1); /* Nb*(Nr+1) */
const uint32_t *rko_end = (uint32_t *) rk + key_expansion_size_in_words;
const size_t rounds_needed = key_len_in_words + 6; /* Nr */
const size_t round_keys_len_in_words =
round_key_len_in_words * (rounds_needed + 1); /* Nb*(Nr+1) */
const uint32_t *rko_end = (uint32_t *) rk + round_keys_len_in_words;
memcpy(rk, key, key_len_in_words * 4);