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stealing multbl trick from reimar 

Originally committed as revision 7466 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2007-01-14 13:15:26 +00:00
parent 8f36d4ba4d
commit cd0968c4ca
1 changed files with 25 additions and 16 deletions
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41
libavutil/aes.c
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@ -35,10 +35,15 @@ static const uint8_t rcon[30] = {
0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91
};
static uint8_t log8[256];
static uint8_t alog8[512];
static uint8_t sbox[256];
static uint8_t inv_sbox[256];
#ifdef CONFIG_SMALL
static uint32_t enc_multbl[1][256];
static uint32_t dec_multbl[1][256];
#else
static uint32_t enc_multbl[4][256];
static uint32_t dec_multbl[4][256];
#endif
static inline void addkey(uint64_t state[2], uint64_t round_key[2]){
state[0] ^= round_key[0];
@ -50,23 +55,24 @@ static inline void addkey(uint64_t state[2], uint64_t round_key[2]){
#define SUBSHIFT2(s, box) t=s[0]; s[0]=box[s[ 8]]; s[ 8]=box[ t]; t=s[ 4]; s[ 4]=box[s[12]]; s[12]=box[t];
#define SUBSHIFT3(s, box) t=s[0]; s[0]=box[s[12]]; s[12]=box[s[ 8]]; s[ 8]=box[s[ 4]]; s[ 4]=box[t];
static inline int mul(int a, int b){
static inline int mul(int a, int b, uint8_t alog8[256]){
if(a==255) return 0;
else return alog8[a+b];
}
static inline void mix(uint8_t state[4][4], int c0, int c1, int c2, int c3){
uint8_t tmp[4][4];
int i, j;
#define ROT(x,s) ((x>>s)|(x<<(32-s))
for(i=0; i<16; i++)
tmp[0][i]= log8[ state[0][i] ];
for(j=0; j<4; j++)
for(i=0; i<4; i++)
state[j][i]= mul( tmp[j][ i ], c0 )
^mul( tmp[j][(i+ 1)&3], c1 )
^mul( tmp[j][(i+ 2)&3], c2 )
^mul( tmp[j][(i+ 3)&3], c3 );
static inline void mix(uint8_t state[4][4], uint32_t multbl[4][256]){
int i;
for(i=0; i<4; i++)
#ifdef CONFIG_SMALL
((uint32_t *)(state))[i] = multbl[0][state[i][0]] ^ ROT(multbl[0][state[i][1]], 8)
^ROT(multbl[0][state[i][2]],16) ^ ROT(multbl[0][state[i][3]],24);
#else
((uint32_t *)(state))[i] = multbl[0][state[i][0]] ^ multbl[1][state[i][1]]
^multbl[2][state[i][2]] ^ multbl[3][state[i][3]];
#endif
}
@ -77,7 +83,7 @@ void av_aes_decrypt(AVAES *a){
if(r==a->rounds-1)
addkey(a->state, a->round_key[r+1]);
else
mix(a->state, log8[0xe], log8[0xb], log8[0xd], log8[9]); //FIXME replace log8 by const
mix(a->state, dec_multbl);
SUBSHIFT0((a->state[0]+0), inv_sbox)
SUBSHIFT3((a->state[0]+1), inv_sbox)
SUBSHIFT2((a->state[0]+2), inv_sbox)
@ -98,7 +104,7 @@ void av_aes_encrypt(AVAES *a){
if(r==a->rounds-1)
addkey(a->state, a->round_key[r+1]);
else
mix(a->state, log8[2], log8[3], 0, 0); //FIXME replace log8 by const / optimze mix as this can be simplified alot
mix(a->state, enc_multbl); //FIXME replace log8 by const / optimze mix as this can be simplified alot
}
}
@ -109,6 +115,8 @@ AVAES *av_aes_init(uint8_t *key, int key_bits) {
uint8_t tk[8][4];
int KC= key_bits/32;
int rounds= KC + 6;
uint8_t log8[256];
uint8_t alog8[512];
if(!sbox[255]){
j=1;
@ -127,6 +135,7 @@ AVAES *av_aes_init(uint8_t *key, int key_bits) {
inv_sbox[j]= i;
sbox [i]= j;
// av_log(NULL, AV_LOG_ERROR, "%d, ", log8[i]);
//FIXME multbl init
}
}