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libavutil/aes.c

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00001 /*
00002  * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
00003  *
00004  * some optimization ideas from aes128.c by Reimar Doeffinger
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #include "common.h"
00024 #include "aes.h"
00025 
00026 typedef union {
00027     uint64_t u64[2];
00028     uint32_t u32[4];
00029     uint8_t u8x4[4][4];
00030     uint8_t u8[16];
00031 } av_aes_block;
00032 
00033 typedef struct AVAES{
00034     // Note: round_key[16] is accessed in the init code, but this only
00035     // overwrites state, which does not matter (see also r7471).
00036     av_aes_block round_key[15];
00037     av_aes_block state[2];
00038     int rounds;
00039 }AVAES;
00040 
00041 const int av_aes_size= sizeof(AVAES);
00042 
00043 static const uint8_t rcon[10] = {
00044   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
00045 };
00046 
00047 static uint8_t     sbox[256];
00048 static uint8_t inv_sbox[256];
00049 #if CONFIG_SMALL
00050 static uint32_t enc_multbl[1][256];
00051 static uint32_t dec_multbl[1][256];
00052 #else
00053 static uint32_t enc_multbl[4][256];
00054 static uint32_t dec_multbl[4][256];
00055 #endif
00056 
00057 static inline void addkey(av_aes_block *dst, const av_aes_block *src, const av_aes_block *round_key){
00058     dst->u64[0] = src->u64[0] ^ round_key->u64[0];
00059     dst->u64[1] = src->u64[1] ^ round_key->u64[1];
00060 }
00061 
00062 static void subshift(av_aes_block s0[2], int s, const uint8_t *box){
00063     av_aes_block *s1= (av_aes_block *)(s0[0].u8 - s);
00064     av_aes_block *s3= (av_aes_block *)(s0[0].u8 + s);
00065     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]];
00066     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]];
00067     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]];
00068     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]];
00069 }
00070 
00071 static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){
00072 #if CONFIG_SMALL
00073 #define ROT(x,s) ((x<<s)|(x>>(32-s)))
00074     return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
00075 #else
00076     return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
00077 #endif
00078 }
00079 
00080 static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3){
00081     uint8_t (*src)[4] = state[1].u8x4;
00082     state[0].u32[0] = mix_core(multbl, src[0][0], src[s1  ][1], src[2][2], src[s3  ][3]);
00083     state[0].u32[1] = mix_core(multbl, src[1][0], src[s3-1][1], src[3][2], src[s1-1][3]);
00084     state[0].u32[2] = mix_core(multbl, src[2][0], src[s3  ][1], src[0][2], src[s1  ][3]);
00085     state[0].u32[3] = mix_core(multbl, src[3][0], src[s1-1][1], src[1][2], src[s3-1][3]);
00086 }
00087 
00088 static inline void crypt(AVAES *a, int s, const uint8_t *sbox, uint32_t multbl[][256]){
00089     int r;
00090 
00091     for(r=a->rounds-1; r>0; r--){
00092         mix(a->state, multbl, 3-s, 1+s);
00093         addkey(&a->state[1], &a->state[0], &a->round_key[r]);
00094     }
00095     subshift(&a->state[0], s, sbox);
00096 }
00097 
00098 void av_aes_crypt(AVAES *a, uint8_t *dst_, const uint8_t *src_, int count, uint8_t *iv_, int decrypt){
00099     av_aes_block *dst = (av_aes_block *)dst_;
00100     const av_aes_block *src = (const av_aes_block *)src_;
00101     av_aes_block *iv = (av_aes_block *)iv_;
00102     while(count--){
00103         addkey(&a->state[1], src, &a->round_key[a->rounds]);
00104         if(decrypt) {
00105             crypt(a, 0, inv_sbox, dec_multbl);
00106             if(iv){
00107                 addkey(&a->state[0], &a->state[0], iv);
00108                 memcpy(iv, src, 16);
00109             }
00110             addkey(dst, &a->state[0], &a->round_key[0]);
00111         }else{
00112             if(iv) addkey(&a->state[1], &a->state[1], iv);
00113             crypt(a, 2,     sbox, enc_multbl);
00114             addkey(dst, &a->state[0], &a->round_key[0]);
00115             if(iv) memcpy(iv, dst, 16);
00116         }
00117         src++;
00118         dst++;
00119     }
00120 }
00121 
00122 static void init_multbl2(uint8_t tbl[1024], const int c[4], const uint8_t *log8, const uint8_t *alog8, const uint8_t *sbox){
00123     int i, j;
00124     for(i=0; i<1024; i++){
00125         int x= sbox[i>>2];
00126         if(x) tbl[i]= alog8[ log8[x] + log8[c[i&3]] ];
00127     }
00128 #if !CONFIG_SMALL
00129     for(j=256; j<1024; j++)
00130         for(i=0; i<4; i++)
00131             tbl[4*j+i]= tbl[4*j + ((i-1)&3) - 1024];
00132 #endif
00133 }
00134 
00135 // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
00136 int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt) {
00137     int i, j, t, rconpointer = 0;
00138     uint8_t tk[8][4];
00139     int KC= key_bits>>5;
00140     int rounds= KC + 6;
00141     uint8_t  log8[256];
00142     uint8_t alog8[512];
00143 
00144     if(!enc_multbl[FF_ARRAY_ELEMS(enc_multbl)-1][FF_ARRAY_ELEMS(enc_multbl[0])-1]){
00145         j=1;
00146         for(i=0; i<255; i++){
00147             alog8[i]=
00148             alog8[i+255]= j;
00149             log8[j]= i;
00150             j^= j+j;
00151             if(j>255) j^= 0x11B;
00152         }
00153         for(i=0; i<256; i++){
00154             j= i ? alog8[255-log8[i]] : 0;
00155             j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4);
00156             j = (j ^ (j>>8) ^ 99) & 255;
00157             inv_sbox[j]= i;
00158             sbox    [i]= j;
00159         }
00160         init_multbl2(dec_multbl[0], (const int[4]){0xe, 0x9, 0xd, 0xb}, log8, alog8, inv_sbox);
00161         init_multbl2(enc_multbl[0], (const int[4]){0x2, 0x1, 0x1, 0x3}, log8, alog8, sbox);
00162     }
00163 
00164     if(key_bits!=128 && key_bits!=192 && key_bits!=256)
00165         return -1;
00166 
00167     a->rounds= rounds;
00168 
00169     memcpy(tk, key, KC*4);
00170 
00171     for(t= 0; t < (rounds+1)*16;) {
00172         memcpy(a->round_key[0].u8+t, tk, KC*4);
00173         t+= KC*4;
00174 
00175         for(i = 0; i < 4; i++)
00176             tk[0][i] ^= sbox[tk[KC-1][(i+1)&3]];
00177         tk[0][0] ^= rcon[rconpointer++];
00178 
00179         for(j = 1; j < KC; j++){
00180             if(KC != 8 || j != KC>>1)
00181                 for(i = 0; i < 4; i++) tk[j][i] ^=      tk[j-1][i];
00182             else
00183                 for(i = 0; i < 4; i++) tk[j][i] ^= sbox[tk[j-1][i]];
00184         }
00185     }
00186 
00187     if(decrypt){
00188         for(i=1; i<rounds; i++){
00189             av_aes_block tmp[3];
00190             memcpy(&tmp[2], &a->round_key[i], 16);
00191             subshift(&tmp[1], 0, sbox);
00192             mix(tmp, dec_multbl, 1, 3);
00193             memcpy(&a->round_key[i], &tmp[0], 16);
00194         }
00195     }else{
00196         for(i=0; i<(rounds+1)>>1; i++){
00197             for(j=0; j<16; j++)
00198                 FFSWAP(int, a->round_key[i].u8[j], a->round_key[rounds-i].u8[j]);
00199         }
00200     }
00201 
00202     return 0;
00203 }
00204 
00205 #ifdef TEST
00206 #include "lfg.h"
00207 #include "log.h"
00208 
00209 int main(void){
00210     int i,j;
00211     AVAES ae, ad, b;
00212     uint8_t rkey[2][16]= {
00213         {0},
00214         {0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3, 0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59}};
00215     uint8_t pt[16], rpt[2][16]= {
00216         {0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad, 0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3},
00217         {0}};
00218     uint8_t rct[2][16]= {
00219         {0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7, 0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf},
00220         {0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0, 0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65}};
00221     uint8_t temp[16];
00222     AVLFG prng;
00223 
00224     av_aes_init(&ae, "PI=3.141592654..", 128, 0);
00225     av_aes_init(&ad, "PI=3.141592654..", 128, 1);
00226     av_log_set_level(AV_LOG_DEBUG);
00227     av_lfg_init(&prng, 1);
00228 
00229     for(i=0; i<2; i++){
00230         av_aes_init(&b, rkey[i], 128, 1);
00231         av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
00232         for(j=0; j<16; j++)
00233             if(rpt[i][j] != temp[j])
00234                 av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n", j, rpt[i][j], temp[j]);
00235     }
00236 
00237     for(i=0; i<10000; i++){
00238         for(j=0; j<16; j++){
00239             pt[j] = av_lfg_get(&prng);
00240         }
00241 {START_TIMER
00242         av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
00243         if(!(i&(i-1)))
00244             av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n", temp[0], temp[5], temp[10], temp[15]);
00245         av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
00246 STOP_TIMER("aes")}
00247         for(j=0; j<16; j++){
00248             if(pt[j] != temp[j]){
00249                 av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n", i,j, pt[j], temp[j]);
00250             }
00251         }
00252     }
00253     return 0;
00254 }
00255 #endif

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