From dd025f25daeaa81e1cb815fb86d307eeef821727 Mon Sep 17 00:00:00 2001 From: Reimar Döffinger Date: Wed, 30 Jun 2010 04:50:35 +0000 Subject: Change AES code to be strict-aliasing-safe. Makes it give correct results with e.g. gcc 4.4. For unknown reasons the generate asm code also changes on e.g. gcc 4.3, making the code a bit larger but also a bit faster. Originally committed as revision 23896 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavutil/aes.c | 74 ++++++++++++++++++++++++++++++++------------------------- 1 file changed, 42 insertions(+), 32 deletions(-) (limited to 'libavutil/aes.c') diff --git a/libavutil/aes.c b/libavutil/aes.c index da4ecbbd97..58654233d7 100644 --- a/libavutil/aes.c +++ b/libavutil/aes.c @@ -23,11 +23,18 @@ #include "common.h" #include "aes.h" +typedef union { + uint64_t u64[2]; + uint32_t u32[4]; + uint8_t u8x4[4][4]; + uint8_t u8[16]; +} av_aes_block; + typedef struct AVAES{ // Note: round_key[16] is accessed in the init code, but this only // overwrites state, which does not matter (see also r7471). - uint8_t round_key[15][4][4]; - uint8_t state[2][4][4]; + av_aes_block round_key[15]; + av_aes_block state[2]; int rounds; }AVAES; @@ -47,18 +54,18 @@ static uint32_t enc_multbl[4][256]; static uint32_t dec_multbl[4][256]; #endif -static inline void addkey(uint64_t dst[2], const uint64_t src[2], const uint64_t round_key[2]){ - dst[0] = src[0] ^ round_key[0]; - dst[1] = src[1] ^ round_key[1]; +static inline void addkey(av_aes_block *dst, const av_aes_block *src, const av_aes_block *round_key){ + dst->u64[0] = src->u64[0] ^ round_key->u64[0]; + dst->u64[1] = src->u64[1] ^ round_key->u64[1]; } -static void subshift(uint8_t s0[2][16], int s, const 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][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][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]]; +static void subshift(av_aes_block s0[2], int s, const uint8_t *box){ + av_aes_block *s1= (av_aes_block *)(s0[0].u8 - s); + av_aes_block *s3= (av_aes_block *)(s0[0].u8 + s); + s0[0].u8[0]=box[s0[1].u8[ 0]]; s0[0].u8[ 4]=box[s0[1].u8[ 4]]; s0[0].u8[ 8]=box[s0[1].u8[ 8]]; s0[0].u8[12]=box[s0[1].u8[12]]; + s1[0].u8[3]=box[s1[1].u8[ 7]]; s1[0].u8[ 7]=box[s1[1].u8[11]]; s1[0].u8[11]=box[s1[1].u8[15]]; s1[0].u8[15]=box[s1[1].u8[ 3]]; + s0[0].u8[2]=box[s0[1].u8[10]]; s0[0].u8[10]=box[s0[1].u8[ 2]]; s0[0].u8[ 6]=box[s0[1].u8[14]]; s0[0].u8[14]=box[s0[1].u8[ 6]]; + s3[0].u8[1]=box[s3[1].u8[13]]; s3[0].u8[13]=box[s3[1].u8[ 9]]; s3[0].u8[ 9]=box[s3[1].u8[ 5]]; s3[0].u8[ 5]=box[s3[1].u8[ 1]]; } static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){ @@ -70,11 +77,11 @@ static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){ #endif } -static inline void mix(uint8_t state[2][4][4], uint32_t multbl[][256], int s1, int s3){ - ((uint32_t *)(state))[0] = mix_core(multbl, state[1][0][0], state[1][s1 ][1], state[1][2][2], state[1][s3 ][3]); - ((uint32_t *)(state))[1] = mix_core(multbl, state[1][1][0], state[1][s3-1][1], state[1][3][2], state[1][s1-1][3]); - ((uint32_t *)(state))[2] = mix_core(multbl, state[1][2][0], state[1][s3 ][1], state[1][0][2], state[1][s1 ][3]); - ((uint32_t *)(state))[3] = mix_core(multbl, state[1][3][0], state[1][s1-1][1], state[1][1][2], state[1][s3-1][3]); +static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3){ + state[0].u32[0] = mix_core(multbl, state[1].u8x4[0][0], state[1].u8x4[s1 ][1], state[1].u8x4[2][2], state[1].u8x4[s3 ][3]); + state[0].u32[1] = mix_core(multbl, state[1].u8x4[1][0], state[1].u8x4[s3-1][1], state[1].u8x4[3][2], state[1].u8x4[s1-1][3]); + state[0].u32[2] = mix_core(multbl, state[1].u8x4[2][0], state[1].u8x4[s3 ][1], state[1].u8x4[0][2], state[1].u8x4[s1 ][3]); + state[0].u32[3] = mix_core(multbl, state[1].u8x4[3][0], state[1].u8x4[s1-1][1], state[1].u8x4[1][2], state[1].u8x4[s3-1][3]); } static inline void crypt(AVAES *a, int s, const uint8_t *sbox, uint32_t multbl[][256]){ @@ -82,29 +89,32 @@ static inline void crypt(AVAES *a, int s, const uint8_t *sbox, uint32_t multbl[] for(r=a->rounds-1; r>0; r--){ mix(a->state, multbl, 3-s, 1+s); - addkey(a->state[1], a->state[0], a->round_key[r]); + addkey(&a->state[1], &a->state[0], &a->round_key[r]); } - subshift(a->state[0][0], s, sbox); + subshift(&a->state[0], s, sbox); } -void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt){ +void av_aes_crypt(AVAES *a, uint8_t *dst_, const uint8_t *src_, int count, uint8_t *iv_, int decrypt){ + av_aes_block *dst = (av_aes_block *)dst_; + const av_aes_block *src = (const av_aes_block *)src_; + av_aes_block *iv = (av_aes_block *)iv_; while(count--){ - addkey(a->state[1], src, a->round_key[a->rounds]); + addkey(&a->state[1], src, &a->round_key[a->rounds]); if(decrypt) { crypt(a, 0, inv_sbox, dec_multbl); if(iv){ - addkey(a->state[0], a->state[0], iv); + addkey(&a->state[0], &a->state[0], iv); memcpy(iv, src, 16); } - addkey(dst, a->state[0], a->round_key[0]); + addkey(dst, &a->state[0], &a->round_key[0]); }else{ - if(iv) addkey(a->state[1], a->state[1], iv); + if(iv) addkey(&a->state[1], &a->state[1], iv); crypt(a, 2, sbox, enc_multbl); - addkey(dst, a->state[0], a->round_key[0]); + addkey(dst, &a->state[0], &a->round_key[0]); if(iv) memcpy(iv, dst, 16); } - src+=16; - dst+=16; + src++; + dst++; } } @@ -158,7 +168,7 @@ int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt) { memcpy(tk, key, KC*4); for(t= 0; t < (rounds+1)*16;) { - memcpy(a->round_key[0][0]+t, tk, KC*4); + memcpy(a->round_key[0].u8+t, tk, KC*4); t+= KC*4; for(i = 0; i < 4; i++) @@ -175,16 +185,16 @@ int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt) { if(decrypt){ for(i=1; iround_key[i][0], 16); + av_aes_block tmp[3]; + memcpy(&tmp[2], &a->round_key[i], 16); subshift(&tmp[1], 0, sbox); mix(tmp, dec_multbl, 1, 3); - memcpy(a->round_key[i][0], tmp[0], 16); + memcpy(&a->round_key[i], &tmp[0], 16); } }else{ for(i=0; i<(rounds+1)>>1; i++){ for(j=0; j<16; j++) - FFSWAP(int, a->round_key[i][0][j], a->round_key[rounds-i][0][j]); + FFSWAP(int, a->round_key[i].u8[j], a->round_key[rounds-i].u8[j]); } } -- cgit v1.2.3