ffmpeg/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 #include "intreadwrite.h"
  26 #include "timer.h"
  27
  28 typedef union {
  29     uint64_t u64[2];
  30     uint32_t u32[4];
  31     uint8_t u8x4[4][4];
  32     uint8_t u8[16];
  33 } av_aes_block;
  34
  35 typedef struct AVAES {
  36     // Note: round_key[16] is accessed in the init code, but this only
  37     // overwrites state, which does not matter (see also commit ba554c0).
  38     av_aes_block round_key[15];
  39     av_aes_block state[2];
  40     int rounds;
  41 } AVAES;
  42
  43 const int av_aes_size= sizeof(AVAES);
  44
  45 struct AVAES *av_aes_alloc(void)
  46 {
  47     return av_mallocz(sizeof(struct AVAES));
  48 }
  49
  50 static const uint8_t rcon[10] = {
  51   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
  52 };
  53
  54 static uint8_t     sbox[256];
  55 static uint8_t inv_sbox[256];
  56 #if CONFIG_SMALL
  57 static uint32_t enc_multbl[1][256];
  58 static uint32_t dec_multbl[1][256];
  59 #else
  60 static uint32_t enc_multbl[4][256];
  61 static uint32_t dec_multbl[4][256];
  62 #endif
  63
  64 #if HAVE_BIGENDIAN
  65 #   define ROT(x, s) ((x >> s) | (x << (32-s)))
  66 #else
  67 #   define ROT(x, s) ((x << s) | (x >> (32-s)))
  68 #endif
  69
  70 static inline void addkey(av_aes_block *dst, const av_aes_block *src,
  71                           const av_aes_block *round_key)
  72 {
  73     dst->u64[0] = src->u64[0] ^ round_key->u64[0];
  74     dst->u64[1] = src->u64[1] ^ round_key->u64[1];
  75 }
  76
  77 static inline void addkey_s(av_aes_block *dst, const uint8_t *src,
  78                             const av_aes_block *round_key)
  79 {
  80     dst->u64[0] = AV_RN64(src)     ^ round_key->u64[0];
  81     dst->u64[1] = AV_RN64(src + 8) ^ round_key->u64[1];
  82 }
  83
  84 static inline void addkey_d(uint8_t *dst, const av_aes_block *src,
  85                             const av_aes_block *round_key)
  86 {
  87     AV_WN64(dst,     src->u64[0] ^ round_key->u64[0]);
  88     AV_WN64(dst + 8, src->u64[1] ^ round_key->u64[1]);
  89 }
  90
  91 static void subshift(av_aes_block s0[2], int s, const uint8_t *box)
  92 {
  93     av_aes_block *s1 = (av_aes_block *) (s0[0].u8 - s);
  94     av_aes_block *s3 = (av_aes_block *) (s0[0].u8 + s);
  95
  96     s0[0].u8[ 0] = box[s0[1].u8[ 0]];
  97     s0[0].u8[ 4] = box[s0[1].u8[ 4]];
  98     s0[0].u8[ 8] = box[s0[1].u8[ 8]];
  99     s0[0].u8[12] = box[s0[1].u8[12]];
 100     s1[0].u8[ 3] = box[s1[1].u8[ 7]];
 101     s1[0].u8[ 7] = box[s1[1].u8[11]];
 102     s1[0].u8[11] = box[s1[1].u8[15]];
 103     s1[0].u8[15] = box[s1[1].u8[ 3]];
 104     s0[0].u8[ 2] = box[s0[1].u8[10]];
 105     s0[0].u8[10] = box[s0[1].u8[ 2]];
 106     s0[0].u8[ 6] = box[s0[1].u8[14]];
 107     s0[0].u8[14] = box[s0[1].u8[ 6]];
 108     s3[0].u8[ 1] = box[s3[1].u8[13]];
 109     s3[0].u8[13] = box[s3[1].u8[ 9]];
 110     s3[0].u8[ 9] = box[s3[1].u8[ 5]];
 111     s3[0].u8[ 5] = box[s3[1].u8[ 1]];
 112 }
 113
 114 static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){
 115 #if CONFIG_SMALL
 116     return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
 117 #else
 118     return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
 119 #endif
 120 }
 121
 122 static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3){
 123     uint8_t (*src)[4] = state[1].u8x4;
 124     state[0].u32[0] = mix_core(multbl, src[0][0], src[s1  ][1], src[2][2], src[s3  ][3]);
 125     state[0].u32[1] = mix_core(multbl, src[1][0], src[s3-1][1], src[3][2], src[s1-1][3]);
 126     state[0].u32[2] = mix_core(multbl, src[2][0], src[s3  ][1], src[0][2], src[s1  ][3]);
 127     state[0].u32[3] = mix_core(multbl, src[3][0], src[s1-1][1], src[1][2], src[s3-1][3]);
 128 }
 129
 130 static inline void crypt(AVAES *a, int s, const uint8_t *sbox,
 131                          uint32_t multbl[][256])
 132 {
 133     int r;
 134
 135     for (r = a->rounds - 1; r > 0; r--) {
 136         mix(a->state, multbl, 3 - s, 1 + s);
 137         addkey(&a->state[1], &a->state[0], &a->round_key[r]);
 138     }
 139
 140     subshift(&a->state[0], s, sbox);
 141 }
 142
 143 void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src,
 144                   int count, uint8_t *iv, int decrypt)
 145 {
 146     while (count--) {
 147         addkey_s(&a->state[1], src, &a->round_key[a->rounds]);
 148         if (decrypt) {
 149             crypt(a, 0, inv_sbox, dec_multbl);
 150             if (iv) {
 151                 addkey_s(&a->state[0], iv, &a->state[0]);
 152                 memcpy(iv, src, 16);
 153             }
 154             addkey_d(dst, &a->state[0], &a->round_key[0]);
 155         } else {
 156             if (iv)
 157                 addkey_s(&a->state[1], iv, &a->state[1]);
 158             crypt(a, 2, sbox, enc_multbl);
 159             addkey_d(dst, &a->state[0], &a->round_key[0]);
 160             if (iv)
 161                 memcpy(iv, dst, 16);
 162         }
 163         src += 16;
 164         dst += 16;
 165     }
 166 }
 167
 168 static void init_multbl2(uint32_t tbl[][256], const int c[4],
 169                          const uint8_t *log8, const uint8_t *alog8,
 170                          const uint8_t *sbox)
 171 {
 172     int i;
 173
 174     for (i = 0; i < 256; i++) {
 175         int x = sbox[i];
 176         if (x) {
 177             int k, l, m, n;
 178             x = log8[x];
 179             k = alog8[x + log8[c[0]]];
 180             l = alog8[x + log8[c[1]]];
 181             m = alog8[x + log8[c[2]]];
 182             n = alog8[x + log8[c[3]]];
 183             tbl[0][i] = AV_NE(MKBETAG(k,l,m,n), MKTAG(k,l,m,n));
 184 #if !CONFIG_SMALL
 185             tbl[1][i] = ROT(tbl[0][i], 8);
 186             tbl[2][i] = ROT(tbl[0][i], 16);
 187             tbl[3][i] = ROT(tbl[0][i], 24);
 188 #endif
 189         }
 190     }
 191 }
 192
 193 // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
 194 int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
 195 {
 196     int i, j, t, rconpointer = 0;
 197     uint8_t tk[8][4];
 198     int KC = key_bits >> 5;
 199     int rounds = KC + 6;
 200     uint8_t log8[256];
 201     uint8_t alog8[512];
 202
 203     if (!enc_multbl[FF_ARRAY_ELEMS(enc_multbl)-1][FF_ARRAY_ELEMS(enc_multbl[0])-1]) {
 204         j = 1;
 205         for (i = 0; i < 255; i++) {
 206             alog8[i] = alog8[i + 255] = j;
 207             log8[j] = i;
 208             j ^= j + j;
 209             if (j > 255)
 210                 j ^= 0x11B;
 211         }
 212         for (i = 0; i < 256; i++) {
 213             j = i ? alog8[255 - log8[i]] : 0;
 214             j ^= (j << 1) ^ (j << 2) ^ (j << 3) ^ (j << 4);
 215             j = (j ^ (j >> 8) ^ 99) & 255;
 216             inv_sbox[j] = i;
 217             sbox[i] = j;
 218         }
 219         init_multbl2(dec_multbl, (const int[4]) { 0xe, 0x9, 0xd, 0xb },
 220                      log8, alog8, inv_sbox);
 221         init_multbl2(enc_multbl, (const int[4]) { 0x2, 0x1, 0x1, 0x3 },
 222                      log8, alog8, sbox);
 223     }
 224
 225     if (key_bits != 128 && key_bits != 192 && key_bits != 256)
 226         return -1;
 227
 228     a->rounds = rounds;
 229
 230     memcpy(tk, key, KC * 4);
 231     memcpy(a->round_key[0].u8, key, KC * 4);
 232
 233     for (t = KC * 4; t < (rounds + 1) * 16; t += KC * 4) {
 234         for (i = 0; i < 4; i++)
 235             tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]];
 236         tk[0][0] ^= rcon[rconpointer++];
 237
 238         for (j = 1; j < KC; j++) {
 239             if (KC != 8 || j != KC >> 1)
 240                 for (i = 0; i < 4; i++)
 241                     tk[j][i] ^= tk[j - 1][i];
 242             else
 243                 for (i = 0; i < 4; i++)
 244                     tk[j][i] ^= sbox[tk[j - 1][i]];
 245         }
 246
 247         memcpy(a->round_key[0].u8 + t, tk, KC * 4);
 248     }
 249
 250     if (decrypt) {
 251         for (i = 1; i < rounds; i++) {
 252             av_aes_block tmp[3];
 253             tmp[2] = a->round_key[i];
 254             subshift(&tmp[1], 0, sbox);
 255             mix(tmp, dec_multbl, 1, 3);
 256             a->round_key[i] = tmp[0];
 257         }
 258     } else {
 259         for (i = 0; i < (rounds + 1) >> 1; i++) {
 260             FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds-i]);
 261         }
 262     }
 263
 264     return 0;
 265 }
 266
 267 #ifdef TEST
 268 // LCOV_EXCL_START
 269 #include <string.h>
 270 #include "lfg.h"
 271 #include "log.h"
 272
 273 int main(int argc, char **argv)
 274 {
 275     int i, j;
 276     AVAES b;
 277     uint8_t rkey[2][16] = {
 278         { 0 },
 279         { 0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3,
 280           0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59 }
 281     };
 282     uint8_t pt[16], rpt[2][16]= {
 283         { 0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad,
 284           0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3 },
 285         { 0 }
 286     };
 287     uint8_t rct[2][16]= {
 288         { 0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7,
 289           0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf },
 290         { 0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0,
 291           0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65 }
 292     };
 293     uint8_t temp[16];
 294     int err = 0;
 295
 296     av_log_set_level(AV_LOG_DEBUG);
 297
 298     for (i = 0; i < 2; i++) {
 299         av_aes_init(&b, rkey[i], 128, 1);
 300         av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
 301         for (j = 0; j < 16; j++) {
 302             if (rpt[i][j] != temp[j]) {
 303                 av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n",
 304                        j, rpt[i][j], temp[j]);
 305                 err = 1;
 306             }
 307         }
 308     }
 309
 310     if (argc > 1 && !strcmp(argv[1], "-t")) {
 311         AVAES ae, ad;
 312         AVLFG prng;
 313
 314         av_aes_init(&ae, "PI=3.141592654..", 128, 0);
 315         av_aes_init(&ad, "PI=3.141592654..", 128, 1);
 316         av_lfg_init(&prng, 1);
 317
 318         for (i = 0; i < 10000; i++) {
 319             for (j = 0; j < 16; j++) {
 320                 pt[j] = av_lfg_get(&prng);
 321             }
 322             {
 323                 START_TIMER;
 324                 av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
 325                 if (!(i & (i - 1)))
 326                     av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n",
 327                            temp[0], temp[5], temp[10], temp[15]);
 328                 av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
 329                 STOP_TIMER("aes");
 330             }
 331             for (j = 0; j < 16; j++) {
 332                 if (pt[j] != temp[j]) {
 333                     av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n",
 334                            i, j, pt[j], temp[j]);
 335                 }
 336             }
 337         }
 338     }
 339     return err;
 340 }
 341 // LCOV_EXCL_STOP
 342 #endif