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dont use encode tables for decoding

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Originally committed as revision 7490 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2007-01-14 19:01:17 +00:00
parent 73374bf4d0
commit cc85897055
1 changed files with 7 additions and 5 deletions
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12
libavutil/aes.c
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@ -75,7 +75,7 @@ static inline void mix(uint8_t state[4][4], uint32_t multbl[4][256]){
void av_aes_decrypt(AVAES *a){ void av_aes_decrypt(AVAES *a){
int t, r; int t, r;
addkey(a->state, a->round_enc_key[a->rounds]); addkey(a->state, a->round_dec_key[a->rounds]);
for(r=a->rounds-2; r>=0; r--){ for(r=a->rounds-2; r>=0; r--){
SUBSHIFT3x((a->state[0]+1)) SUBSHIFT3x((a->state[0]+1))
SUBSHIFT2x((a->state[0]+2)) SUBSHIFT2x((a->state[0]+2))
@ -87,7 +87,7 @@ void av_aes_decrypt(AVAES *a){
SUBSHIFT3((a->state[0]+1), inv_sbox) SUBSHIFT3((a->state[0]+1), inv_sbox)
SUBSHIFT2((a->state[0]+2), inv_sbox) SUBSHIFT2((a->state[0]+2), inv_sbox)
SUBSHIFT1((a->state[0]+3), inv_sbox) SUBSHIFT1((a->state[0]+3), inv_sbox)
addkey(a->state, a->round_enc_key[0]); addkey(a->state, a->round_dec_key[0]);
} }
void av_aes_encrypt(AVAES *a){ void av_aes_encrypt(AVAES *a){
@ -183,10 +183,12 @@ AVAES *av_aes_init(uint8_t *key, int key_bits) {
} }
} }
for(i=0; i<sizeof(a->round_enc_key); i++) memcpy(a->round_dec_key, a->round_enc_key, sizeof(a->round_enc_key));
a->round_dec_key[0][0][i]= sbox[a->round_enc_key[0][0][i]]; for(i=1; i<rounds; i++){
for(i=1; i<rounds; i++) for(j=0; j<16; j++)
a->round_dec_key[i][0][j]= sbox[a->round_enc_key[i][0][j]];
mix(a->round_dec_key[i], dec_multbl); mix(a->round_dec_key[i], dec_multbl);
}
return a; return a;
} }