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FFmpeg/libavutil/aes.c
Reimar Döffinger dd025f25da 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
2010-06-30 04:50:35 +00:00

255 lines
8.6 KiB
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/*
* copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
*
* some optimization ideas from aes128.c by Reimar Doeffinger
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#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).
av_aes_block round_key[15];
av_aes_block state[2];
int rounds;
}AVAES;
const int av_aes_size= sizeof(AVAES);
static const uint8_t rcon[10] = {
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
};
static uint8_t sbox[256];
static uint8_t inv_sbox[256];
#if 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(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(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){
#if CONFIG_SMALL
#define ROT(x,s) ((x<<s)|(x>>(32-s)))
return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
#else
return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
#endif
}
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]){
int r;
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]);
}
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){
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]);
if(decrypt) {
crypt(a, 0, inv_sbox, dec_multbl);
if(iv){
addkey(&a->state[0], &a->state[0], iv);
memcpy(iv, src, 16);
}
addkey(dst, &a->state[0], &a->round_key[0]);
}else{
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]);
if(iv) memcpy(iv, dst, 16);
}
src++;
dst++;
}
}
static void init_multbl2(uint8_t tbl[1024], const int c[4], const uint8_t *log8, const uint8_t *alog8, const uint8_t *sbox){
int i, j;
for(i=0; i<1024; i++){
int x= sbox[i>>2];
if(x) tbl[i]= alog8[ log8[x] + log8[c[i&3]] ];
}
#if !CONFIG_SMALL
for(j=256; j<1024; j++)
for(i=0; i<4; i++)
tbl[4*j+i]= tbl[4*j + ((i-1)&3) - 1024];
#endif
}
// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt) {
int i, j, t, rconpointer = 0;
uint8_t tk[8][4];
int KC= key_bits>>5;
int rounds= KC + 6;
uint8_t log8[256];
uint8_t alog8[512];
if(!enc_multbl[0][sizeof(enc_multbl)/sizeof(enc_multbl[0][0])-1]){
j=1;
for(i=0; i<255; i++){
alog8[i]=
alog8[i+255]= j;
log8[j]= i;
j^= j+j;
if(j>255) j^= 0x11B;
}
for(i=0; i<256; i++){
j= i ? alog8[255-log8[i]] : 0;
j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4);
j = (j ^ (j>>8) ^ 99) & 255;
inv_sbox[j]= i;
sbox [i]= j;
}
init_multbl2(dec_multbl[0], (const int[4]){0xe, 0x9, 0xd, 0xb}, log8, alog8, inv_sbox);
init_multbl2(enc_multbl[0], (const int[4]){0x2, 0x1, 0x1, 0x3}, log8, alog8, sbox);
}
if(key_bits!=128 && key_bits!=192 && key_bits!=256)
return -1;
a->rounds= rounds;
memcpy(tk, key, KC*4);
for(t= 0; t < (rounds+1)*16;) {
memcpy(a->round_key[0].u8+t, tk, KC*4);
t+= KC*4;
for(i = 0; i < 4; i++)
tk[0][i] ^= sbox[tk[KC-1][(i+1)&3]];
tk[0][0] ^= rcon[rconpointer++];
for(j = 1; j < KC; j++){
if(KC != 8 || j != KC>>1)
for(i = 0; i < 4; i++) tk[j][i] ^= tk[j-1][i];
else
for(i = 0; i < 4; i++) tk[j][i] ^= sbox[tk[j-1][i]];
}
}
if(decrypt){
for(i=1; i<rounds; i++){
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], &tmp[0], 16);
}
}else{
for(i=0; i<(rounds+1)>>1; i++){
for(j=0; j<16; j++)
FFSWAP(int, a->round_key[i].u8[j], a->round_key[rounds-i].u8[j]);
}
}
return 0;
}
#ifdef TEST
#include "lfg.h"
#include "log.h"
int main(void){
int i,j;
AVAES ae, ad, b;
uint8_t rkey[2][16]= {
{0},
{0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3, 0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59}};
uint8_t pt[16], rpt[2][16]= {
{0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad, 0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3},
{0}};
uint8_t rct[2][16]= {
{0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7, 0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf},
{0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0, 0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65}};
uint8_t temp[16];
AVLFG prng;
av_aes_init(&ae, "PI=3.141592654..", 128, 0);
av_aes_init(&ad, "PI=3.141592654..", 128, 1);
av_log_set_level(AV_LOG_DEBUG);
av_lfg_init(&prng, 1);
for(i=0; i<2; i++){
av_aes_init(&b, rkey[i], 128, 1);
av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
for(j=0; j<16; j++)
if(rpt[i][j] != temp[j])
av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n", j, rpt[i][j], temp[j]);
}
for(i=0; i<10000; i++){
for(j=0; j<16; j++){
pt[j] = av_lfg_get(&prng);
}
{START_TIMER
av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
if(!(i&(i-1)))
av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n", temp[0], temp[5], temp[10], temp[15]);
av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
STOP_TIMER("aes")}
for(j=0; j<16; j++){
if(pt[j] != temp[j]){
av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n", i,j, pt[j], temp[j]);
}
}
}
return 0;
}
#endif
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