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aes.c
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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
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