aes.c 10.1 KB
Newer Older
1
/*
2
 * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
3
 *
4 5
 * some optimization ideas from aes128.c by Reimar Doeffinger
 *
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
 * 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"
25
#include "intreadwrite.h"
26

27 28 29 30 31 32 33
typedef union {
    uint64_t u64[2];
    uint32_t u32[4];
    uint8_t u8x4[4][4];
    uint8_t u8[16];
} av_aes_block;

34
typedef struct AVAES {
35 36
    // Note: round_key[16] is accessed in the init code, but this only
    // overwrites state, which does not matter (see also r7471).
37 38
    av_aes_block round_key[15];
    av_aes_block state[2];
39
    int rounds;
40
} AVAES;
41

42 43
const int av_aes_size= sizeof(AVAES);

Michael Niedermayer's avatar
Michael Niedermayer committed
44 45
static const uint8_t rcon[10] = {
  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
46 47 48 49
};

static uint8_t     sbox[256];
static uint8_t inv_sbox[256];
50
#if CONFIG_SMALL
51 52 53 54 55 56
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
57

58 59 60 61 62
#if HAVE_BIGENDIAN
#   define ROT(x, s) ((x >> s) | (x << (32-s)))
#else
#   define ROT(x, s) ((x << s) | (x >> (32-s)))
#endif
63

64 65 66
static inline void addkey(av_aes_block *dst, const av_aes_block *src,
                          const av_aes_block *round_key)
{
67 68
    dst->u64[0] = src->u64[0] ^ round_key->u64[0];
    dst->u64[1] = src->u64[1] ^ round_key->u64[1];
69 70
}

71 72 73 74 75 76 77 78 79 80 81 82 83 84
static inline void addkey_s(av_aes_block *dst, const uint8_t *src,
                            const av_aes_block *round_key)
{
    dst->u64[0] = AV_RN64(src)     ^ round_key->u64[0];
    dst->u64[1] = AV_RN64(src + 8) ^ round_key->u64[1];
}

static inline void addkey_d(uint8_t *dst, const av_aes_block *src,
                            const av_aes_block *round_key)
{
    AV_WN64(dst,     src->u64[0] ^ round_key->u64[0]);
    AV_WN64(dst + 8, src->u64[1] ^ round_key->u64[1]);
}

85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105
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]];
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){
117 118 119 120 121
    uint8_t (*src)[4] = state[1].u8x4;
    state[0].u32[0] = mix_core(multbl, src[0][0], src[s1  ][1], src[2][2], src[s3  ][3]);
    state[0].u32[1] = mix_core(multbl, src[1][0], src[s3-1][1], src[3][2], src[s1-1][3]);
    state[0].u32[2] = mix_core(multbl, src[2][0], src[s3  ][1], src[0][2], src[s1  ][3]);
    state[0].u32[3] = mix_core(multbl, src[3][0], src[s1-1][1], src[1][2], src[s3-1][3]);
122
}
123

124 125 126
static inline void crypt(AVAES *a, int s, const uint8_t *sbox,
                         uint32_t multbl[][256])
{
Michael Niedermayer's avatar
Michael Niedermayer committed
127
    int r;
128

129 130
    for (r = a->rounds - 1; r > 0; r--) {
        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
}

137 138
void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src,
                  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) {
Michael Niedermayer's avatar
Michael Niedermayer committed
143
            crypt(a, 0, inv_sbox, dec_multbl);
144
            if (iv) {
145 146
                addkey_s(&a->state[0], iv, &a->state[0]);
                memcpy(iv, src, 16);
Michael Niedermayer's avatar
Michael Niedermayer committed
147
            }
148
            addkey_d(dst, &a->state[0], &a->round_key[0]);
149 150
        } else {
            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);
Michael Niedermayer's avatar
Michael Niedermayer committed
156
        }
157 158
        src += 16;
        dst += 16;
Michael Niedermayer's avatar
Michael Niedermayer committed
159
    }
Michael Niedermayer's avatar
Michael Niedermayer committed
160 161
}

162
static void init_multbl2(uint32_t tbl[][256], const int c[4],
163 164 165
                         const uint8_t *log8, const uint8_t *alog8,
                         const uint8_t *sbox)
{
166
    int i;
167

168 169 170 171 172 173 174 175 176 177
    for (i = 0; i < 256; i++) {
        int x = sbox[i];
        if (x) {
            int k, l, m, n;
            x = log8[x];
            k = alog8[x + log8[c[0]]];
            l = alog8[x + log8[c[1]]];
            m = alog8[x + log8[c[2]]];
            n = alog8[x + log8[c[3]]];
            tbl[0][i] = AV_NE(MKBETAG(k,l,m,n), MKTAG(k,l,m,n));
178
#if !CONFIG_SMALL
179 180 181
            tbl[1][i] = ROT(tbl[0][i], 8);
            tbl[2][i] = ROT(tbl[0][i], 16);
            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
188 189
int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
{
190 191
    int i, j, t, rconpointer = 0;
    uint8_t tk[8][4];
192 193 194
    int KC = key_bits >> 5;
    int rounds = KC + 6;
    uint8_t log8[256];
195
    uint8_t alog8[512];
196

197 198 199 200 201 202 203 204
    if (!enc_multbl[FF_ARRAY_ELEMS(enc_multbl)-1][FF_ARRAY_ELEMS(enc_multbl[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;
205
        }
206 207 208 209 210 211
        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;
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;
Michael Niedermayer's avatar
Michael Niedermayer committed
223

224
    memcpy(tk, key, KC * 4);
225

226 227 228
    for (t = 0; t < (rounds + 1) * 16;) {
        memcpy(a->round_key[0].u8 + t, tk, KC * 4);
        t += KC * 4;
229

230 231
        for (i = 0; i < 4; i++)
            tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]];
232 233
        tk[0][0] ^= rcon[rconpointer++];

234 235 236 237
        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];
238
            else
239 240
                for (i = 0; i < 4; i++)
                    tk[j][i] ^= sbox[tk[j - 1][i]];
241 242
        }
    }
243

244 245
    if (decrypt) {
        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];
Michael Niedermayer's avatar
Michael Niedermayer committed
251
        }
252 253
    } else {
        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

266 267
int main(int argc, char **argv)
{
268
    int i, j;
269
    AVAES b;
270 271 272 273 274
    uint8_t rkey[2][16] = {
        { 0 },
        { 0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3,
          0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59 }
    };
Michael Niedermayer's avatar
Michael Niedermayer committed
275
    uint8_t pt[16], rpt[2][16]= {
276 277 278 279
        { 0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad,
          0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3 },
        { 0 }
    };
Michael Niedermayer's avatar
Michael Niedermayer committed
280
    uint8_t rct[2][16]= {
281 282 283 284 285
        { 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 }
    };
286
    uint8_t temp[16];
287
    int err = 0;
288

289
    av_log_set_level(AV_LOG_DEBUG);
Michael Niedermayer's avatar
Michael Niedermayer committed
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);
294 295 296 297
        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]);
298 299
                err = 1;
            }
300
        }
Michael Niedermayer's avatar
Michael Niedermayer committed
301
    }
302

303 304 305 306 307 308 309 310
    if (argc > 1 && !strcmp(argv[1], "-t")) {
        AVAES ae, ad;
        AVLFG prng;

        av_aes_init(&ae, "PI=3.141592654..", 128, 0);
        av_aes_init(&ad, "PI=3.141592654..", 128, 1);
        av_lfg_init(&prng, 1);

311 312
        for (i = 0; i < 10000; i++) {
            for (j = 0; j < 16; j++) {
313 314 315 316 317
                pt[j] = av_lfg_get(&prng);
            }
            {
                START_TIMER;
                av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
318 319 320
                if (!(i & (i - 1)))
                    av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n",
                           temp[0], temp[5], temp[10], temp[15]);
321 322 323
                av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
                STOP_TIMER("aes");
            }
324 325 326 327
            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]);
328
                }
Michael Niedermayer's avatar
Michael Niedermayer committed
329 330
            }
        }
331
    }
332
    return err;
333 334
}
#endif