ffmpeg/FFmpeg
1
0
Fork 0
mirror of https://git.ffmpeg.org/ffmpeg.git synced 2024-09-20 05:16:38 +00:00
Code Issues Packages Projects Releases Wiki Activity

simplify multiply table init

Browse Source 
Originally committed as revision 7503 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2007-01-14 21:30:54 +00:00
parent 86074ce341
commit 7200f5d054
1 changed files with 11 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
libavutil/aes.c
View File

@ -99,15 +99,25 @@ void av_aes_encrypt(AVAES *a){
crypt(a, 2, sbox, enc_multbl);
}
static void init_multbl3(uint8_t tbl[4][256][4]){
int i, j, k;
for(k=1; k<4; k++)
for(j=0; j<256; j++)
for(i=0; i<4; i++)
tbl[k][j][i]= tbl[k-1][j][(i-1)&3];
}
static void init_multbl2(uint8_t tbl[1024], int c[4], uint8_t *log8, uint8_t *alog8, uint8_t *sbox){
int i;
for(i=0; i<1024; i++){
int x= sbox[i/4];
if(x) tbl[i]= alog8[ log8[x] + log8[c[i&3]] ];
}
#ifndef CONFIG_SMALL
init_multbl3(tbl);
#endif
}
// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
AVAES *av_aes_init(uint8_t *key, int key_bits, int decrypt) {
AVAES *a;
@ -136,17 +146,7 @@ AVAES *av_aes_init(uint8_t *key, int key_bits, int decrypt) {
// av_log(NULL, AV_LOG_ERROR, "%d, ", log8[i]);
}
init_multbl2(dec_multbl[0], (int[4]){0xe, 0x9, 0xd, 0xb}, log8, alog8, inv_sbox);
#ifndef CONFIG_SMALL
init_multbl2(dec_multbl[1], (int[4]){0xb, 0xe, 0x9, 0xd}, log8, alog8, inv_sbox);
init_multbl2(dec_multbl[2], (int[4]){0xd, 0xb, 0xe, 0x9}, log8, alog8, inv_sbox);
init_multbl2(dec_multbl[3], (int[4]){0x9, 0xd, 0xb, 0xe}, log8, alog8, inv_sbox);
#endif
init_multbl2(enc_multbl[0], (int[4]){0x2, 0x1, 0x1, 0x3}, log8, alog8, sbox);
#ifndef CONFIG_SMALL
init_multbl2(enc_multbl[1], (int[4]){0x3, 0x2, 0x1, 0x1}, log8, alog8, sbox);
init_multbl2(enc_multbl[2], (int[4]){0x1, 0x3, 0x2, 0x1}, log8, alog8, sbox);
init_multbl2(enc_multbl[3], (int[4]){0x1, 0x1, 0x3, 0x2}, log8, alog8, sbox);
#endif
}
if(key_bits!=128 && key_bits!=192 && key_bits!=256)