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 Libav.
   7  *
   8  * Libav 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  * Libav 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 Libav; 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 #include "intreadwrite.h"
  26
  27 typedef union {
  28     uint64_t u64[2];
  29     uint32_t u32[4];
  30     uint8_t u8x4[4][4];
  31     uint8_t u8[16];
  32 } av_aes_block;
  33
  34 typedef struct AVAES {
  35     // Note: round_key[16] is accessed in the init code, but this only
  36     // overwrites state, which does not matter (see also commit ba554c0).
  37     av_aes_block round_key[15];
  38     av_aes_block state[2];
  39     int rounds;
  40 } AVAES;
  41
  42 const int av_aes_size= sizeof(AVAES);
  43
  44 static const uint8_t rcon[10] = {
  45   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
  46 };
  47
  48 static uint8_t     sbox[256];
  49 static uint8_t inv_sbox[256];
  50 #if CONFIG_SMALL
  51 static uint32_t enc_multbl[1][256];
  52 static uint32_t dec_multbl[1][256];
  53 #else
  54 static uint32_t enc_multbl[4][256];
  55 static uint32_t dec_multbl[4][256];
  56 #endif
  57
  58 #if HAVE_BIGENDIAN
  59 #   define ROT(x, s) ((x >> s) | (x << (32-s)))
  60 #else
  61 #   define ROT(x, s) ((x << s) | (x >> (32-s)))
  62 #endif
  63
  64 static inline void addkey(av_aes_block *dst, const av_aes_block *src,
  65                           const av_aes_block *round_key)
  66 {
  67     dst->u64[0] = src->u64[0] ^ round_key->u64[0];
  68     dst->u64[1] = src->u64[1] ^ round_key->u64[1];
  69 }
  70
  71 static inline void addkey_s(av_aes_block *dst, const uint8_t *src,
  72                             const av_aes_block *round_key)
  73 {
  74     dst->u64[0] = AV_RN64(src)     ^ round_key->u64[0];
  75     dst->u64[1] = AV_RN64(src + 8) ^ round_key->u64[1];
  76 }
  77
  78 static inline void addkey_d(uint8_t *dst, const av_aes_block *src,
  79                             const av_aes_block *round_key)
  80 {
  81     AV_WN64(dst,     src->u64[0] ^ round_key->u64[0]);
  82     AV_WN64(dst + 8, src->u64[1] ^ round_key->u64[1]);
  83 }
  84
  85 static void subshift(av_aes_block s0[2], int s, const uint8_t *box)
  86 {
  87     av_aes_block *s1 = (av_aes_block *) (s0[0].u8 - s);
  88     av_aes_block *s3 = (av_aes_block *) (s0[0].u8 + s);
  89
  90     s0[0].u8[ 0] = box[s0[1].u8[ 0]];
  91     s0[0].u8[ 4] = box[s0[1].u8[ 4]];
  92     s0[0].u8[ 8] = box[s0[1].u8[ 8]];
  93     s0[0].u8[12] = box[s0[1].u8[12]];
  94     s1[0].u8[ 3] = box[s1[1].u8[ 7]];
  95     s1[0].u8[ 7] = box[s1[1].u8[11]];
  96     s1[0].u8[11] = box[s1[1].u8[15]];
  97     s1[0].u8[15] = box[s1[1].u8[ 3]];
  98     s0[0].u8[ 2] = box[s0[1].u8[10]];
  99     s0[0].u8[10] = box[s0[1].u8[ 2]];
 100     s0[0].u8[ 6] = box[s0[1].u8[14]];
 101     s0[0].u8[14] = box[s0[1].u8[ 6]];
 102     s3[0].u8[ 1] = box[s3[1].u8[13]];
 103     s3[0].u8[13] = box[s3[1].u8[ 9]];
 104     s3[0].u8[ 9] = box[s3[1].u8[ 5]];
 105     s3[0].u8[ 5] = box[s3[1].u8[ 1]];
 106 }
 107
 108 static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){
 109 #if CONFIG_SMALL
 110     return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
 111 #else
 112     return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
 113 #endif
 114 }
 115
 116 static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3){
 117     uint8_t (*src)[4] = state[1].u8x4;
 118     state[0].u32[0] = mix_core(multbl, src[0][0], src[s1  ][1], src[2][2], src[s3  ][3]);
 119     state[0].u32[1] = mix_core(multbl, src[1][0], src[s3-1][1], src[3][2], src[s1-1][3]);
 120     state[0].u32[2] = mix_core(multbl, src[2][0], src[s3  ][1], src[0][2], src[s1  ][3]);
 121     state[0].u32[3] = mix_core(multbl, src[3][0], src[s1-1][1], src[1][2], src[s3-1][3]);
 122 }
 123
 124 static inline void crypt(AVAES *a, int s, const uint8_t *sbox,
 125                          uint32_t multbl[][256])
 126 {
 127     int r;
 128
 129     for (r = a->rounds - 1; r > 0; r--) {
 130         mix(a->state, multbl, 3 - s, 1 + s);
 131         addkey(&a->state[1], &a->state[0], &a->round_key[r]);
 132     }
 133
 134     subshift(&a->state[0], s, sbox);
 135 }
 136
 137 void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src,
 138                   int count, uint8_t *iv, int decrypt)
 139 {
 140     while (count--) {
 141         addkey_s(&a->state[1], src, &a->round_key[a->rounds]);
 142         if (decrypt) {
 143             crypt(a, 0, inv_sbox, dec_multbl);
 144             if (iv) {
 145                 addkey_s(&a->state[0], iv, &a->state[0]);
 146                 memcpy(iv, src, 16);
 147             }
 148             addkey_d(dst, &a->state[0], &a->round_key[0]);
 149         } else {
 150             if (iv)
 151                 addkey_s(&a->state[1], iv, &a->state[1]);
 152             crypt(a, 2, sbox, enc_multbl);
 153             addkey_d(dst, &a->state[0], &a->round_key[0]);
 154             if (iv)
 155                 memcpy(iv, dst, 16);
 156         }
 157         src += 16;
 158         dst += 16;
 159     }
 160 }
 161
 162 static void init_multbl2(uint32_t tbl[][256], const int c[4],
 163                          const uint8_t *log8, const uint8_t *alog8,
 164                          const uint8_t *sbox)
 165 {
 166     int i;
 167
 168     for (i = 0; i < 256; i++) {
 169         int x = sbox[i];
 170         if (x) {
 171             int k, l, m, n;
 172             x = log8[x];
 173             k = alog8[x + log8[c[0]]];
 174             l = alog8[x + log8[c[1]]];
 175             m = alog8[x + log8[c[2]]];
 176             n = alog8[x + log8[c[3]]];
 177             tbl[0][i] = AV_NE(MKBETAG(k,l,m,n), MKTAG(k,l,m,n));
 178 #if !CONFIG_SMALL
 179             tbl[1][i] = ROT(tbl[0][i], 8);
 180             tbl[2][i] = ROT(tbl[0][i], 16);
 181             tbl[3][i] = ROT(tbl[0][i], 24);
 182 #endif
 183         }
 184     }
 185 }
 186
 187 // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
 188 int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
 189 {
 190     int i, j, t, rconpointer = 0;
 191     uint8_t tk[8][4];
 192     int KC = key_bits >> 5;
 193     int rounds = KC + 6;
 194     uint8_t log8[256];
 195     uint8_t alog8[512];
 196
 197     if (!enc_multbl[FF_ARRAY_ELEMS(enc_multbl)-1][FF_ARRAY_ELEMS(enc_multbl[0])-1]) {
 198         j = 1;
 199         for (i = 0; i < 255; i++) {
 200             alog8[i] = alog8[i + 255] = j;
 201             log8[j] = i;
 202             j ^= j + j;
 203             if (j > 255)
 204                 j ^= 0x11B;
 205         }
 206         for (i = 0; i < 256; i++) {
 207             j = i ? alog8[255 - log8[i]] : 0;
 208             j ^= (j << 1) ^ (j << 2) ^ (j << 3) ^ (j << 4);
 209             j = (j ^ (j >> 8) ^ 99) & 255;
 210             inv_sbox[j] = i;
 211             sbox[i] = j;
 212         }
 213         init_multbl2(dec_multbl, (const int[4]) { 0xe, 0x9, 0xd, 0xb },
 214                      log8, alog8, inv_sbox);
 215         init_multbl2(enc_multbl, (const int[4]) { 0x2, 0x1, 0x1, 0x3 },
 216                      log8, alog8, sbox);
 217     }
 218
 219     if (key_bits != 128 && key_bits != 192 && key_bits != 256)
 220         return -1;
 221
 222     a->rounds = rounds;
 223
 224     memcpy(tk, key, KC * 4);
 225     memcpy(a->round_key[0].u8, key, KC * 4);
 226
 227     for (t = KC * 4; t < (rounds + 1) * 16; t += KC * 4) {
 228         for (i = 0; i < 4; i++)
 229             tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]];
 230         tk[0][0] ^= rcon[rconpointer++];
 231
 232         for (j = 1; j < KC; j++) {
 233             if (KC != 8 || j != KC >> 1)
 234                 for (i = 0; i < 4; i++)
 235                     tk[j][i] ^= tk[j - 1][i];
 236             else
 237                 for (i = 0; i < 4; i++)
 238                     tk[j][i] ^= sbox[tk[j - 1][i]];
 239         }
 240
 241         memcpy(a->round_key[0].u8 + t, tk, KC * 4);
 242     }
 243
 244     if (decrypt) {
 245         for (i = 1; i < rounds; i++) {
 246             av_aes_block tmp[3];
 247             tmp[2] = a->round_key[i];
 248             subshift(&tmp[1], 0, sbox);
 249             mix(tmp, dec_multbl, 1, 3);
 250             a->round_key[i] = tmp[0];
 251         }
 252     } else {
 253         for (i = 0; i < (rounds + 1) >> 1; i++) {
 254             FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds-i]);
 255         }
 256     }
 257
 258     return 0;
 259 }
 260
 261 #ifdef TEST
 262 #include <string.h>
 263 #include "lfg.h"
 264 #include "log.h"
 265
 266 int main(int argc, char **argv)
 267 {
 268     int i, j;
 269     AVAES b;
 270     uint8_t rkey[2][16] = {
 271         { 0 },
 272         { 0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3,
 273           0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59 }
 274     };
 275     uint8_t pt[16], rpt[2][16]= {
 276         { 0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad,
 277           0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3 },
 278         { 0 }
 279     };
 280     uint8_t rct[2][16]= {
 281         { 0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7,
 282           0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf },
 283         { 0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0,
 284           0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65 }
 285     };
 286     uint8_t temp[16];
 287     int err = 0;
 288
 289     av_log_set_level(AV_LOG_DEBUG);
 290
 291     for (i = 0; i < 2; i++) {
 292         av_aes_init(&b, rkey[i], 128, 1);
 293         av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
 294         for (j = 0; j < 16; j++) {
 295             if (rpt[i][j] != temp[j]) {
 296                 av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n",
 297                        j, rpt[i][j], temp[j]);
 298                 err = 1;
 299             }
 300         }
 301     }
 302
 303     if (argc > 1 && !strcmp(argv[1], "-t")) {
 304         AVAES ae, ad;
 305         AVLFG prng;
 306
 307         av_aes_init(&ae, "PI=3.141592654..", 128, 0);
 308         av_aes_init(&ad, "PI=3.141592654..", 128, 1);
 309         av_lfg_init(&prng, 1);
 310
 311         for (i = 0; i < 10000; i++) {
 312             for (j = 0; j < 16; j++) {
 313                 pt[j] = av_lfg_get(&prng);
 314             }
 315             {
 316                 START_TIMER;
 317                 av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
 318                 if (!(i & (i - 1)))
 319                     av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n",
 320                            temp[0], temp[5], temp[10], temp[15]);
 321                 av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
 322                 STOP_TIMER("aes");
 323             }
 324             for (j = 0; j < 16; j++) {
 325                 if (pt[j] != temp[j]) {
 326                     av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n",
 327                            i, j, pt[j], temp[j]);
 328                 }
 329             }
 330         }
 331     }
 332     return err;
 333 }
 334 #endif