libavutil/aes.c

   1 /*
   2  * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
   3  *
   4  * some optimization ideas from aes128.c by Reimar Doeffinger
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "common.h"
  24 #include "aes.h"
  25
  26 typedef struct AVAES{
  27     // Note: round_key[16] is accessed in the init code, but this only
  28     // overwrites state, which does not matter (see also r7471).
  29     uint8_t round_key[15][4][4];
  30     uint8_t state[2][4][4];
  31     int rounds;
  32 }AVAES;
  33
  34 const int av_aes_size= sizeof(AVAES);
  35
  36 static const uint8_t rcon[10] = {
  37   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
  38 };
  39
  40 static uint8_t     sbox[256];
  41 static uint8_t inv_sbox[256];
  42 #if CONFIG_SMALL
  43 static uint32_t enc_multbl[1][256];
  44 static uint32_t dec_multbl[1][256];
  45 #else
  46 static uint32_t enc_multbl[4][256];
  47 static uint32_t dec_multbl[4][256];
  48 #endif
  49
  50 static inline void addkey(uint64_t dst[2], const uint64_t src[2], const uint64_t round_key[2]){
  51     dst[0] = src[0] ^ round_key[0];
  52     dst[1] = src[1] ^ round_key[1];
  53 }
  54
  55 static void subshift(uint8_t s0[2][16], int s, const uint8_t *box){
  56     uint8_t (*s1)[16]= s0[0] - s;
  57     uint8_t (*s3)[16]= s0[0] + s;
  58     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]];
  59     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]];
  60     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]];
  61     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]];
  62 }
  63
  64 static inline int mix_core(uint32_t multbl[4][256], int a, int b, int c, int d){
  65 #if CONFIG_SMALL
  66 #define ROT(x,s) ((x<<s)|(x>>(32-s)))
  67     return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
  68 #else
  69     return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
  70 #endif
  71 }
  72
  73 static inline void mix(uint8_t state[2][4][4], uint32_t multbl[4][256], int s1, int s3){
  74     ((uint32_t *)(state))[0] = mix_core(multbl, state[1][0][0], state[1][s1  ][1], state[1][2][2], state[1][s3  ][3]);
  75     ((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]);
  76     ((uint32_t *)(state))[2] = mix_core(multbl, state[1][2][0], state[1][s3  ][1], state[1][0][2], state[1][s1  ][3]);
  77     ((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]);
  78 }
  79
  80 static inline void crypt(AVAES *a, int s, const uint8_t *sbox, const uint32_t *multbl){
  81     int r;
  82
  83     for(r=a->rounds-1; r>0; r--){
  84         mix(a->state, multbl, 3-s, 1+s);
  85         addkey(a->state[1], a->state[0], a->round_key[r]);
  86     }
  87     subshift(a->state[0][0], s, sbox);
  88 }
  89
  90 void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt){
  91     while(count--){
  92         addkey(a->state[1], src, a->round_key[a->rounds]);
  93         if(decrypt) {
  94             crypt(a, 0, inv_sbox, dec_multbl);
  95             if(iv){
  96                 addkey(a->state[0], a->state[0], iv);
  97                 memcpy(iv, src, 16);
  98             }
  99             addkey(dst, a->state[0], a->round_key[0]);
 100         }else{
 101             if(iv) addkey(a->state[1], a->state[1], iv);
 102             crypt(a, 2,     sbox, enc_multbl);
 103             addkey(dst, a->state[0], a->round_key[0]);
 104             if(iv) memcpy(iv, dst, 16);
 105         }
 106         src+=16;
 107         dst+=16;
 108     }
 109 }
 110
 111 static void init_multbl2(uint8_t tbl[1024], const int c[4], const uint8_t *log8, const uint8_t *alog8, const uint8_t *sbox){
 112     int i, j;
 113     for(i=0; i<1024; i++){
 114         int x= sbox[i>>2];
 115         if(x) tbl[i]= alog8[ log8[x] + log8[c[i&3]] ];
 116     }
 117 #if !CONFIG_SMALL
 118     for(j=256; j<1024; j++)
 119         for(i=0; i<4; i++)
 120             tbl[4*j+i]= tbl[4*j + ((i-1)&3) - 1024];
 121 #endif
 122 }
 123
 124 // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
 125 int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt) {
 126     int i, j, t, rconpointer = 0;
 127     uint8_t tk[8][4];
 128     int KC= key_bits>>5;
 129     int rounds= KC + 6;
 130     uint8_t  log8[256];
 131     uint8_t alog8[512];
 132
 133     if(!enc_multbl[0][sizeof(enc_multbl)/sizeof(enc_multbl[0][0])-1]){
 134         j=1;
 135         for(i=0; i<255; i++){
 136             alog8[i]=
 137             alog8[i+255]= j;
 138             log8[j]= i;
 139             j^= j+j;
 140             if(j>255) j^= 0x11B;
 141         }
 142         for(i=0; i<256; i++){
 143             j= i ? alog8[255-log8[i]] : 0;
 144             j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4);
 145             j = (j ^ (j>>8) ^ 99) & 255;
 146             inv_sbox[j]= i;
 147             sbox    [i]= j;
 148         }
 149         init_multbl2(dec_multbl[0], (const int[4]){0xe, 0x9, 0xd, 0xb}, log8, alog8, inv_sbox);
 150         init_multbl2(enc_multbl[0], (const int[4]){0x2, 0x1, 0x1, 0x3}, log8, alog8, sbox);
 151     }
 152
 153     if(key_bits!=128 && key_bits!=192 && key_bits!=256)
 154         return -1;
 155
 156     a->rounds= rounds;
 157
 158     memcpy(tk, key, KC*4);
 159
 160     for(t= 0; t < (rounds+1)*16;) {
 161         memcpy(a->round_key[0][0]+t, tk, KC*4);
 162         t+= KC*4;
 163
 164         for(i = 0; i < 4; i++)
 165             tk[0][i] ^= sbox[tk[KC-1][(i+1)&3]];
 166         tk[0][0] ^= rcon[rconpointer++];
 167
 168         for(j = 1; j < KC; j++){
 169             if(KC != 8 || j != KC>>1)
 170                 for(i = 0; i < 4; i++) tk[j][i] ^=      tk[j-1][i];
 171             else
 172                 for(i = 0; i < 4; i++) tk[j][i] ^= sbox[tk[j-1][i]];
 173         }
 174     }
 175
 176     if(decrypt){
 177         for(i=1; i<rounds; i++){
 178             uint8_t tmp[3][16];
 179             memcpy(tmp[2], a->round_key[i][0], 16);
 180             subshift(tmp[1], 0, sbox);
 181             mix(tmp, dec_multbl, 1, 3);
 182             memcpy(a->round_key[i][0], tmp[0], 16);
 183         }
 184     }else{
 185         for(i=0; i<(rounds+1)>>1; i++){
 186             for(j=0; j<16; j++)
 187                 FFSWAP(int, a->round_key[i][0][j], a->round_key[rounds-i][0][j]);
 188         }
 189     }
 190
 191     return 0;
 192 }
 193
 194 #ifdef TEST
 195 #include "lfg.h"
 196 #include "log.h"
 197
 198 int main(void){
 199     int i,j;
 200     AVAES ae, ad, b;
 201     uint8_t rkey[2][16]= {
 202         {0},
 203         {0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3, 0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59}};
 204     uint8_t pt[16], rpt[2][16]= {
 205         {0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad, 0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3},
 206         {0}};
 207     uint8_t rct[2][16]= {
 208         {0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7, 0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf},
 209         {0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0, 0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65}};
 210     uint8_t temp[16];
 211     AVLFG prn;
 212
 213     av_aes_init(&ae, "PI=3.141592654..", 128, 0);
 214     av_aes_init(&ad, "PI=3.141592654..", 128, 1);
 215     av_log_set_level(AV_LOG_DEBUG);
 216     av_lfg_init(&prn, 1);
 217
 218     for(i=0; i<2; i++){
 219         av_aes_init(&b, rkey[i], 128, 1);
 220         av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
 221         for(j=0; j<16; j++)
 222             if(rpt[i][j] != temp[j])
 223                 av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n", j, rpt[i][j], temp[j]);
 224     }
 225
 226     for(i=0; i<10000; i++){
 227         for(j=0; j<16; j++){
 228             pt[j] = av_lfg_get(&prn);
 229         }
 230 {START_TIMER
 231         av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
 232         if(!(i&(i-1)))
 233             av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n", temp[0], temp[5], temp[10], temp[15]);
 234         av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
 235 STOP_TIMER("aes")}
 236         for(j=0; j<16; j++){
 237             if(pt[j] != temp[j]){
 238                 av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n", i,j, pt[j], temp[j]);
 239             }
 240         }
 241     }
 242     return 0;
 243 }
 244 #endif