Libav
aes.c
Go to the documentation of this file.
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 #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).
40  int rounds;
41 } AVAES;
42 
43 #if FF_API_CONTEXT_SIZE
44 const int av_aes_size= sizeof(AVAES);
45 #endif
46 
47 struct AVAES *av_aes_alloc(void)
48 {
49  return av_mallocz(sizeof(struct AVAES));
50 }
51 
52 static const uint8_t rcon[10] = {
53  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
54 };
55 
56 static uint8_t sbox[256];
57 static uint8_t inv_sbox[256];
58 #if CONFIG_SMALL
59 static uint32_t enc_multbl[1][256];
60 static uint32_t dec_multbl[1][256];
61 #else
62 static uint32_t enc_multbl[4][256];
63 static uint32_t dec_multbl[4][256];
64 #endif
65 
66 #if HAVE_BIGENDIAN
67 # define ROT(x, s) ((x >> s) | (x << (32-s)))
68 #else
69 # define ROT(x, s) ((x << s) | (x >> (32-s)))
70 #endif
71 
72 static inline void addkey(av_aes_block *dst, const av_aes_block *src,
73  const av_aes_block *round_key)
74 {
75  dst->u64[0] = src->u64[0] ^ round_key->u64[0];
76  dst->u64[1] = src->u64[1] ^ round_key->u64[1];
77 }
78 
79 static inline void addkey_s(av_aes_block *dst, const uint8_t *src,
80  const av_aes_block *round_key)
81 {
82  dst->u64[0] = AV_RN64(src) ^ round_key->u64[0];
83  dst->u64[1] = AV_RN64(src + 8) ^ round_key->u64[1];
84 }
85 
86 static inline void addkey_d(uint8_t *dst, const av_aes_block *src,
87  const av_aes_block *round_key)
88 {
89  AV_WN64(dst, src->u64[0] ^ round_key->u64[0]);
90  AV_WN64(dst + 8, src->u64[1] ^ round_key->u64[1]);
91 }
92 
93 static void subshift(av_aes_block s0[2], int s, const uint8_t *box)
94 {
95  av_aes_block *s1 = (av_aes_block *) (s0[0].u8 - s);
96  av_aes_block *s3 = (av_aes_block *) (s0[0].u8 + s);
97 
98  s0[0].u8[ 0] = box[s0[1].u8[ 0]];
99  s0[0].u8[ 4] = box[s0[1].u8[ 4]];
100  s0[0].u8[ 8] = box[s0[1].u8[ 8]];
101  s0[0].u8[12] = box[s0[1].u8[12]];
102  s1[0].u8[ 3] = box[s1[1].u8[ 7]];
103  s1[0].u8[ 7] = box[s1[1].u8[11]];
104  s1[0].u8[11] = box[s1[1].u8[15]];
105  s1[0].u8[15] = box[s1[1].u8[ 3]];
106  s0[0].u8[ 2] = box[s0[1].u8[10]];
107  s0[0].u8[10] = box[s0[1].u8[ 2]];
108  s0[0].u8[ 6] = box[s0[1].u8[14]];
109  s0[0].u8[14] = box[s0[1].u8[ 6]];
110  s3[0].u8[ 1] = box[s3[1].u8[13]];
111  s3[0].u8[13] = box[s3[1].u8[ 9]];
112  s3[0].u8[ 9] = box[s3[1].u8[ 5]];
113  s3[0].u8[ 5] = box[s3[1].u8[ 1]];
114 }
115 
116 static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d){
117 #if CONFIG_SMALL
118  return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);
119 #else
120  return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];
121 #endif
122 }
123 
124 static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3){
125  uint8_t (*src)[4] = state[1].u8x4;
126  state[0].u32[0] = mix_core(multbl, src[0][0], src[s1 ][1], src[2][2], src[s3 ][3]);
127  state[0].u32[1] = mix_core(multbl, src[1][0], src[s3-1][1], src[3][2], src[s1-1][3]);
128  state[0].u32[2] = mix_core(multbl, src[2][0], src[s3 ][1], src[0][2], src[s1 ][3]);
129  state[0].u32[3] = mix_core(multbl, src[3][0], src[s1-1][1], src[1][2], src[s3-1][3]);
130 }
131 
132 static inline void crypt(AVAES *a, int s, const uint8_t *sbox,
133  uint32_t multbl[][256])
134 {
135  int r;
136 
137  for (r = a->rounds - 1; r > 0; r--) {
138  mix(a->state, multbl, 3 - s, 1 + s);
139  addkey(&a->state[1], &a->state[0], &a->round_key[r]);
140  }
141 
142  subshift(&a->state[0], s, sbox);
143 }
144 
145 void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src,
146  int count, uint8_t *iv, int decrypt)
147 {
148  while (count--) {
149  addkey_s(&a->state[1], src, &a->round_key[a->rounds]);
150  if (decrypt) {
151  crypt(a, 0, inv_sbox, dec_multbl);
152  if (iv) {
153  addkey_s(&a->state[0], iv, &a->state[0]);
154  memcpy(iv, src, 16);
155  }
156  addkey_d(dst, &a->state[0], &a->round_key[0]);
157  } else {
158  if (iv)
159  addkey_s(&a->state[1], iv, &a->state[1]);
160  crypt(a, 2, sbox, enc_multbl);
161  addkey_d(dst, &a->state[0], &a->round_key[0]);
162  if (iv)
163  memcpy(iv, dst, 16);
164  }
165  src += 16;
166  dst += 16;
167  }
168 }
169 
170 static void init_multbl2(uint32_t tbl[][256], const int c[4],
171  const uint8_t *log8, const uint8_t *alog8,
172  const uint8_t *sbox)
173 {
174  int i;
175 
176  for (i = 0; i < 256; i++) {
177  int x = sbox[i];
178  if (x) {
179  int k, l, m, n;
180  x = log8[x];
181  k = alog8[x + log8[c[0]]];
182  l = alog8[x + log8[c[1]]];
183  m = alog8[x + log8[c[2]]];
184  n = alog8[x + log8[c[3]]];
185  tbl[0][i] = AV_NE(MKBETAG(k,l,m,n), MKTAG(k,l,m,n));
186 #if !CONFIG_SMALL
187  tbl[1][i] = ROT(tbl[0][i], 8);
188  tbl[2][i] = ROT(tbl[0][i], 16);
189  tbl[3][i] = ROT(tbl[0][i], 24);
190 #endif
191  }
192  }
193 }
194 
195 // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
196 int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
197 {
198  int i, j, t, rconpointer = 0;
199  uint8_t tk[8][4];
200  int KC = key_bits >> 5;
201  int rounds = KC + 6;
202  uint8_t log8[256];
203  uint8_t alog8[512];
204 
206  j = 1;
207  for (i = 0; i < 255; i++) {
208  alog8[i] = alog8[i + 255] = j;
209  log8[j] = i;
210  j ^= j + j;
211  if (j > 255)
212  j ^= 0x11B;
213  }
214  for (i = 0; i < 256; i++) {
215  j = i ? alog8[255 - log8[i]] : 0;
216  j ^= (j << 1) ^ (j << 2) ^ (j << 3) ^ (j << 4);
217  j = (j ^ (j >> 8) ^ 99) & 255;
218  inv_sbox[j] = i;
219  sbox[i] = j;
220  }
221  init_multbl2(dec_multbl, (const int[4]) { 0xe, 0x9, 0xd, 0xb },
222  log8, alog8, inv_sbox);
223  init_multbl2(enc_multbl, (const int[4]) { 0x2, 0x1, 0x1, 0x3 },
224  log8, alog8, sbox);
225  }
226 
227  if (key_bits != 128 && key_bits != 192 && key_bits != 256)
228  return -1;
229 
230  a->rounds = rounds;
231 
232  memcpy(tk, key, KC * 4);
233  memcpy(a->round_key[0].u8, key, KC * 4);
234 
235  for (t = KC * 4; t < (rounds + 1) * 16; t += KC * 4) {
236  for (i = 0; i < 4; i++)
237  tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]];
238  tk[0][0] ^= rcon[rconpointer++];
239 
240  for (j = 1; j < KC; j++) {
241  if (KC != 8 || j != KC >> 1)
242  for (i = 0; i < 4; i++)
243  tk[j][i] ^= tk[j - 1][i];
244  else
245  for (i = 0; i < 4; i++)
246  tk[j][i] ^= sbox[tk[j - 1][i]];
247  }
248 
249  memcpy(a->round_key[0].u8 + t, tk, KC * 4);
250  }
251 
252  if (decrypt) {
253  for (i = 1; i < rounds; i++) {
254  av_aes_block tmp[3];
255  tmp[2] = a->round_key[i];
256  subshift(&tmp[1], 0, sbox);
257  mix(tmp, dec_multbl, 1, 3);
258  a->round_key[i] = tmp[0];
259  }
260  } else {
261  for (i = 0; i < (rounds + 1) >> 1; i++) {
262  FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds-i]);
263  }
264  }
265 
266  return 0;
267 }
268 
269 #ifdef TEST
270 #include <string.h>
271 #include "lfg.h"
272 #include "log.h"
273 
274 int main(int argc, char **argv)
275 {
276  int i, j;
277  AVAES b;
278  uint8_t rkey[2][16] = {
279  { 0 },
280  { 0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3,
281  0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59 }
282  };
283  uint8_t pt[16], rpt[2][16]= {
284  { 0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad,
285  0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3 },
286  { 0 }
287  };
288  uint8_t rct[2][16]= {
289  { 0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7,
290  0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf },
291  { 0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0,
292  0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65 }
293  };
294  uint8_t temp[16];
295  int err = 0;
296 
298 
299  for (i = 0; i < 2; i++) {
300  av_aes_init(&b, rkey[i], 128, 1);
301  av_aes_crypt(&b, temp, rct[i], 1, NULL, 1);
302  for (j = 0; j < 16; j++) {
303  if (rpt[i][j] != temp[j]) {
304  av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n",
305  j, rpt[i][j], temp[j]);
306  err = 1;
307  }
308  }
309  }
310 
311  if (argc > 1 && !strcmp(argv[1], "-t")) {
312  AVAES ae, ad;
313  AVLFG prng;
314 
315  av_aes_init(&ae, "PI=3.141592654..", 128, 0);
316  av_aes_init(&ad, "PI=3.141592654..", 128, 1);
317  av_lfg_init(&prng, 1);
318 
319  for (i = 0; i < 10000; i++) {
320  for (j = 0; j < 16; j++) {
321  pt[j] = av_lfg_get(&prng);
322  }
323  {
324  START_TIMER;
325  av_aes_crypt(&ae, temp, pt, 1, NULL, 0);
326  if (!(i & (i - 1)))
327  av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n",
328  temp[0], temp[5], temp[10], temp[15]);
329  av_aes_crypt(&ad, temp, temp, 1, NULL, 1);
330  STOP_TIMER("aes");
331  }
332  for (j = 0; j < 16; j++) {
333  if (pt[j] != temp[j]) {
334  av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n",
335  i, j, pt[j], temp[j]);
336  }
337  }
338  }
339  }
340  return err;
341 }
342 #endif
Definition: lfg.h:25
static uint8_t inv_sbox[256]
Definition: aes.c:57
void av_log_set_level(int level)
Set the log level.
Definition: log.c:191
#define ROT(x, s)
Definition: aes.c:69
av_aes_block round_key[15]
Definition: aes.c:38
void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt)
Encrypt or decrypt a buffer using a previously initialized context.
Definition: aes.c:145
#define FF_ARRAY_ELEMS(a)
static void addkey(av_aes_block *dst, const av_aes_block *src, const av_aes_block *round_key)
Definition: aes.c:72
static void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3)
Definition: aes.c:124
static uint32_t enc_multbl[4][256]
Definition: aes.c:62
uint32_t u32[4]
Definition: aes.c:30
uint8_t
static uint8_t sbox[256]
Definition: aes.c:56
#define b
Definition: input.c:52
#define AV_NE(be, le)
Definition: common.h:45
int pt
Definition: rtp.c:34
high precision timer, useful to profile code
#define r
Definition: input.c:51
uint64_t u64[2]
Definition: aes.c:29
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:123
static void subshift(av_aes_block s0[2], int s, const uint8_t *box)
Definition: aes.c:93
static void crypt(AVAES *a, int s, const uint8_t *sbox, uint32_t multbl[][256])
Definition: aes.c:132
static const uint8_t rcon[10]
Definition: aes.c:52
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:144
void av_log(void *avcl, int level, const char *fmt,...)
Definition: log.c:169
const int av_aes_size
Definition: aes.c:44
int main(int argc, char **argv)
Definition: avconv.c:2609
struct AVAES * av_aes_alloc(void)
Allocate an AVAES context.
Definition: aes.c:47
static void addkey_d(uint8_t *dst, const av_aes_block *src, const av_aes_block *round_key)
Definition: aes.c:86
static int mix_core(uint32_t multbl[][256], int a, int b, int c, int d)
Definition: aes.c:116
static void addkey_s(av_aes_block *dst, const uint8_t *src, const av_aes_block *round_key)
Definition: aes.c:79
uint8_t u8[16]
Definition: aes.c:32
int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)
Initialize an AVAES context.
Definition: aes.c:196
NULL
Definition: eval.c:55
static void init_multbl2(uint32_t tbl[][256], const int c[4], const uint8_t *log8, const uint8_t *alog8, const uint8_t *sbox)
Definition: aes.c:170
#define START_TIMER
Definition: timer.h:84
av_aes_block state[2]
Definition: aes.c:39
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:38
int rounds
Definition: aes.c:40
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:30
static uint32_t dec_multbl[4][256]
Definition: aes.c:63
uint8_t u8x4[4][4]
Definition: aes.c:31
common internal and external API header
#define MKBETAG(a, b, c, d)
Definition: common.h:239
#define STOP_TIMER(id)
Definition: timer.h:85
#define AV_RN64(p)
Definition: intreadwrite.h:330
#define FFSWAP(type, a, b)
Definition: common.h:60
Definition: aes.c:35
#define MKTAG(a, b, c, d)
Definition: common.h:238
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:205
#define AV_WN64(p, v)
Definition: intreadwrite.h:342