diff options
Diffstat (limited to 'src/ae-common.h')
| -rw-r--r-- | src/ae-common.h | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/src/ae-common.h b/src/ae-common.h index da5d04d..561854e 100644 --- a/src/ae-common.h +++ b/src/ae-common.h @@ -65,26 +65,23 @@ static inline void pad10(size_t X_len, const uint8_t X[X_len], uint8_t padded[BL } } -static inline void _fill_ad_tweak( +static inline void fill_index_tweak( uint8_t prefix, - uint64_t block_nb, + uint64_t block_index, uint8_t tweak[TWEAK_BYTES] ) { /* The t-bit tweak is filled as follows: * - * - bits [ 1, t-4]: block number - * [ 1, 64]: actual 64-bit block number + * - bits [ 1, t-4]: block index + * [ 1, 64]: actual 64-bit block index * [ 65, t-4]: 0-padding * - bits [t-3, t]: constant 4-bit prefix */ - for (size_t i=0; i<sizeof(block_nb); i++) + for (size_t i=0; i<sizeof(block_index); i++) { - uint64_t mask = (uint64_t)0xff << 8*i; - uint8_t b = (mask & block_nb) >> 8*i; - - tweak[i] = b; + tweak[i] = block_index >> 8*i & 0xff; } /* Assume padding bytes have already been memset to 0. */ @@ -110,7 +107,7 @@ static void process_associated_data( for (size_t i=0; i<l_a; i++) { - _fill_ad_tweak(0x2, i, tweak); + fill_index_tweak(0x2, i, tweak); encrypt(key, tweak, &A[i*BLOCK_BYTES], Ek_Ai); xor_into(Auth, Ek_Ai); } @@ -119,7 +116,7 @@ static void process_associated_data( { uint8_t A_rest[BLOCK_BYTES]; pad10(rest, &A[l_a*BLOCK_BYTES], A_rest); - _fill_ad_tweak(0x6, l_a, tweak); + fill_index_tweak(0x6, l_a, tweak); encrypt(key, tweak, A_rest, Ek_Ai); xor_into(Auth, Ek_Ai); } |