aes: use direct assignments instead of memcpy() or loops
[libav.git] / 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
26 typedef union {
27 uint64_t u64[2];
28 uint32_t u32[4];
29 uint8_t u8x4[4][4];
30 uint8_t u8[16];
31 } av_aes_block;
32
33 typedef struct AVAES {
34 // Note: round_key[16] is accessed in the init code, but this only
35 // overwrites state, which does not matter (see also r7471).
36 av_aes_block round_key[15];
37 av_aes_block state[2];
38 int rounds;
39 } AVAES;
40
41 const int av_aes_size= sizeof(AVAES);
42
43 static const uint8_t rcon[10] = {
44 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
45 };
46
47 static uint8_t sbox[256];
48 static uint8_t inv_sbox[256];
49 #if CONFIG_SMALL
50 static uint32_t enc_multbl[1][256];
51 static uint32_t dec_multbl[1][256];
52 #else
53 static uint32_t enc_multbl[4][256];
54 static uint32_t dec_multbl[4][256];
55 #endif
56
57 static inline void addkey(av_aes_block *dst, const av_aes_block *src,
58 const av_aes_block *round_key)
59 {
60 dst->u64[0] = src->u64[0] ^ round_key->u64[0];
61 dst->u64[1] = src->u64[1] ^ round_key->u64[1];
62 }
63
64 static void subshift(av_aes_block s0[2], int s, const uint8_t *box)
65 {
66 av_aes_block *s1 = (av_aes_block *) (s0[0].u8 - s);
67 av_aes_block *s3 = (av_aes_block *) (s0[0].u8 + s);
68
69 s0[0].u8[ 0] = box[s0[1].u8[ 0]];
70 s0[0].u8[ 4] = box[s0[1].u8[ 4]];
71 s0[0].u8[ 8] = box[s0[1].u8[ 8]];
72 s0[0].u8[12] = box[s0[1].u8[12]];
73 s1[0].u8[ 3] = box[s1[1].u8[ 7]];
74 s1[0].u8[ 7] = box[s1[1].u8[11]];
75 s1[0].u8[11] = box[s1[1].u8[15]];
76 s1[0].u8[15] = box[s1[1].u8[ 3]];
77 s0[0].u8[ 2] = box[s0[1].u8[10]];
78 s0[0].u8[10] = box[s0[1].u8[ 2]];
79 s0[0].u8[ 6] = box[s0[1].u8[14]];
80 s0[0].u8[14] = box[s0[1].u8[ 6]];
81 s3[0].u8[ 1] = box[s3[1].u8[13]];
82 s3[0].u8[13] = box[s3[1].u8[ 9]];
83 s3[0].u8[ 9] = box[s3[1].u8[ 5]];
84 s3[0].u8[ 5] = box[s3[1].u8[ 1]];
85 }
86
87 static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){
88 #if CONFIG_SMALL
89 #define ROT(x,s) ((x<<s)|(x>>(32-s)))
90 return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
91 #else
92 return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
93 #endif
94 }
95
96 static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3){
97 uint8_t (*src)[4] = state[1].u8x4;
98 state[0].u32[0] = mix_core(multbl, src[0][0], src[s1 ][1], src[2][2], src[s3 ][3]);
99 state[0].u32[1] = mix_core(multbl, src[1][0], src[s3-1][1], src[3][2], src[s1-1][3]);
100 state[0].u32[2] = mix_core(multbl, src[2][0], src[s3 ][1], src[0][2], src[s1 ][3]);
101 state[0].u32[3] = mix_core(multbl, src[3][0], src[s1-1][1], src[1][2], src[s3-1][3]);
102 }
103
104 static inline void crypt(AVAES *a, int s, const uint8_t *sbox,
105 uint32_t multbl[][256])
106 {
107 int r;
108
109 for (r = a->rounds - 1; r > 0; r--) {
110 mix(a->state, multbl, 3 - s, 1 + s);
111 addkey(&a->state[1], &a->state[0], &a->round_key[r]);
112 }
113
114 subshift(&a->state[0], s, sbox);
115 }
116
117 void av_aes_crypt(AVAES *a, uint8_t *dst_, const uint8_t *src_,
118 int count, uint8_t *iv_, int decrypt)
119 {
120 av_aes_block *dst = (av_aes_block *) dst_;
121 const av_aes_block *src = (const av_aes_block *) src_;
122 av_aes_block *iv = (av_aes_block *) iv_;
123
124 while (count--) {
125 addkey(&a->state[1], src, &a->round_key[a->rounds]);
126 if (decrypt) {
127 crypt(a, 0, inv_sbox, dec_multbl);
128 if (iv) {
129 addkey(&a->state[0], &a->state[0], iv);
130 *iv = *src;
131 }
132 addkey(dst, &a->state[0], &a->round_key[0]);
133 } else {
134 if (iv)
135 addkey(&a->state[1], &a->state[1], iv);
136 crypt(a, 2, sbox, enc_multbl);
137 addkey(dst, &a->state[0], &a->round_key[0]);
138 if (iv)
139 *iv = *dst;
140 }
141 src++;
142 dst++;
143 }
144 }
145
146 static void init_multbl2(uint8_t tbl[1024], const int c[4],
147 const uint8_t *log8, const uint8_t *alog8,
148 const uint8_t *sbox)
149 {
150 int i, j;
151
152 for (i = 0; i < 1024; i++) {
153 int x = sbox[i >> 2];
154 if (x)
155 tbl[i] = alog8[log8[x] + log8[c[i & 3]]];
156 }
157 #if !CONFIG_SMALL
158 for (j = 256; j < 1024; j++)
159 for (i = 0; i < 4; i++)
160 tbl[4*j + i] = tbl[4*j + ((i - 1) & 3) - 1024];
161 #endif
162 }
163
164 // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
165 int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
166 {
167 int i, j, t, rconpointer = 0;
168 uint8_t tk[8][4];
169 int KC = key_bits >> 5;
170 int rounds = KC + 6;
171 uint8_t log8[256];
172 uint8_t alog8[512];
173
174 if (!enc_multbl[FF_ARRAY_ELEMS(enc_multbl)-1][FF_ARRAY_ELEMS(enc_multbl[0])-1]) {
175 j = 1;
176 for (i = 0; i < 255; i++) {
177 alog8[i] = alog8[i + 255] = j;
178 log8[j] = i;
179 j ^= j + j;
180 if (j > 255)
181 j ^= 0x11B;
182 }
183 for (i = 0; i < 256; i++) {
184 j = i ? alog8[255 - log8[i]] : 0;
185 j ^= (j << 1) ^ (j << 2) ^ (j << 3) ^ (j << 4);
186 j = (j ^ (j >> 8) ^ 99) & 255;
187 inv_sbox[j] = i;
188 sbox[i] = j;
189 }
190 init_multbl2(dec_multbl[0], (const int[4]) { 0xe, 0x9, 0xd, 0xb },
191 log8, alog8, inv_sbox);
192 init_multbl2(enc_multbl[0], (const int[4]) { 0x2, 0x1, 0x1, 0x3 },
193 log8, alog8, sbox);
194 }
195
196 if (key_bits != 128 && key_bits != 192 && key_bits != 256)
197 return -1;
198
199 a->rounds = rounds;
200
201 memcpy(tk, key, KC * 4);
202
203 for (t = 0; t < (rounds + 1) * 16;) {
204 memcpy(a->round_key[0].u8 + t, tk, KC * 4);
205 t += KC * 4;
206
207 for (i = 0; i < 4; i++)
208 tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]];
209 tk[0][0] ^= rcon[rconpointer++];
210
211 for (j = 1; j < KC; j++) {
212 if (KC != 8 || j != KC >> 1)
213 for (i = 0; i < 4; i++)
214 tk[j][i] ^= tk[j - 1][i];
215 else
216 for (i = 0; i < 4; i++)
217 tk[j][i] ^= sbox[tk[j - 1][i]];
218 }
219 }
220
221 if (decrypt) {
222 for (i = 1; i < rounds; i++) {
223 av_aes_block tmp[3];
224 tmp[2] = a->round_key[i];
225 subshift(&tmp[1], 0, sbox);
226 mix(tmp, dec_multbl, 1, 3);
227 a->round_key[i] = tmp[0];
228 }
229 } else {
230 for (i = 0; i < (rounds + 1) >> 1; i++) {
231 FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds-i]);
232 }
233 }
234
235 return 0;
236 }
237
238 #ifdef TEST
239 #include <string.h>
240 #include "lfg.h"
241 #include "log.h"
242
243 int main(int argc, char **argv)
244 {
245 int i, j;
246 AVAES b;
247 uint8_t rkey[2][16] = {
248 { 0 },
249 { 0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3,
250 0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59 }
251 };
252 uint8_t pt[16], rpt[2][16]= {
253 { 0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad,
254 0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3 },
255 { 0 }
256 };
257 uint8_t rct[2][16]= {
258 { 0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7,
259 0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf },
260 { 0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0,
261 0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65 }
262 };
263 uint8_t temp[16];
264 int err = 0;
265
266 av_log_set_level(AV_LOG_DEBUG);
267
268 for (i = 0; i < 2; i++) {
269 av_aes_init(&b, rkey[i], 128, 1);
270 av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
271 for (j = 0; j < 16; j++) {
272 if (rpt[i][j] != temp[j]) {
273 av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n",
274 j, rpt[i][j], temp[j]);
275 err = 1;
276 }
277 }
278 }
279
280 if (argc > 1 && !strcmp(argv[1], "-t")) {
281 AVAES ae, ad;
282 AVLFG prng;
283
284 av_aes_init(&ae, "PI=3.141592654..", 128, 0);
285 av_aes_init(&ad, "PI=3.141592654..", 128, 1);
286 av_lfg_init(&prng, 1);
287
288 for (i = 0; i < 10000; i++) {
289 for (j = 0; j < 16; j++) {
290 pt[j] = av_lfg_get(&prng);
291 }
292 {
293 START_TIMER;
294 av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
295 if (!(i & (i - 1)))
296 av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n",
297 temp[0], temp[5], temp[10], temp[15]);
298 av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
299 STOP_TIMER("aes");
300 }
301 for (j = 0; j < 16; j++) {
302 if (pt[j] != temp[j]) {
303 av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n",
304 i, j, pt[j], temp[j]);
305 }
306 }
307 }
308 }
309 return err;
310 }
311 #endif