From b0642c74090f2ee58b452fca3c484ed83d9dd2f1 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Tue, 16 Jan 2007 17:40:40 +0000 Subject: change subshift a little, this reduces the object size a litlle Originally committed as revision 7546 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavutil/aes.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'libavutil/aes.c') diff --git a/libavutil/aes.c b/libavutil/aes.c index c2ba0d2db7..b338663986 100644 --- a/libavutil/aes.c +++ b/libavutil/aes.c @@ -50,11 +50,13 @@ static inline void addkey(uint64_t state[2], uint64_t round_key[2]){ state[3] = state[1] ^ round_key[1]; } -static void subshift(uint8_t s0[2][16], uint8_t s1[2][16], uint8_t s3[2][16], uint8_t *box){ +static void subshift(uint8_t s0[2][16], int s, uint8_t *box){ + uint8_t (*s1)[16]= s0[0] - s; + uint8_t (*s3)[16]= s0[0] + s; s0[0][0]=box[s0[1][ 0]]; s0[0][ 4]=box[s0[1][ 4]]; s0[0][ 8]=box[s0[1][ 8]]; s0[0][12]=box[s0[1][12]]; - s1[0][0]=box[s1[1][ 4]]; s1[0][ 4]=box[s1[1][ 8]]; s1[0][ 8]=box[s1[1][12]]; s1[0][12]=box[s1[1][ 0]]; + s1[0][3]=box[s1[1][ 7]]; s1[0][ 7]=box[s1[1][11]]; s1[0][11]=box[s1[1][15]]; s1[0][15]=box[s1[1][ 3]]; s0[0][2]=box[s0[1][10]]; s0[0][10]=box[s0[1][ 2]]; s0[0][ 6]=box[s0[1][14]]; s0[0][14]=box[s0[1][ 6]]; - s3[0][0]=box[s3[1][12]]; s3[0][12]=box[s3[1][ 8]]; s3[0][ 8]=box[s3[1][ 4]]; s3[0][ 4]=box[s3[1][ 0]]; + s3[0][1]=box[s3[1][13]]; s3[0][13]=box[s3[1][ 9]]; s3[0][ 9]=box[s3[1][ 5]]; s3[0][ 5]=box[s3[1][ 1]]; } #define ROT(x,s) ((x<>(32-s))) @@ -91,7 +93,7 @@ static inline void crypt(AVAES *a, int s, uint8_t *sbox, uint32_t *multbl){ mix(a->state, multbl, 3-s, 1+s); } addkey(a->state, a->round_key[1]); - subshift(a->state[0][0], a->state[0][0]+3-s, a->state[0][0]+1+s, sbox); + subshift(a->state[0][0], s, sbox); addkey(a->state, a->round_key[0]); } @@ -172,7 +174,7 @@ int av_aes_init(AVAES *a, uint8_t *key, int key_bits, int decrypt) { for(i=1; iround_key[i][0], 16); - subshift(tmp[0], tmp[0]+3, tmp[0]+1, sbox); + subshift(tmp[0], 0, sbox); memcpy(tmp[1], tmp[0], 16); mix(tmp, dec_multbl, 1, 3); memcpy(a->round_key[i][0], tmp[0], 16); -- cgit v1.2.3