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
27typedef 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
34typedef 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
42const int av_aes_size= sizeof(AVAES);
43
44static const uint8_t rcon[10] = {
45  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
46};
47
48static uint8_t     sbox[256];
49static uint8_t inv_sbox[256];
50#if CONFIG_SMALL
51static uint32_t enc_multbl[1][256];
52static uint32_t dec_multbl[1][256];
53#else
54static uint32_t enc_multbl[4][256];
55static 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
64static 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
71static 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
78static 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
85static 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
108static 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
116static 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
124static 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
137void 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
162static 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
188int 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
266int 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
335