Imported Debian version 2.5.2~trusty
[deb_ffmpeg.git] / ffmpeg / libavformat / rtmpdh.c
... / ...
CommitLineData
1/*
2 * RTMP Diffie-Hellmann utilities
3 * Copyright (c) 2009 Andrej Stepanchuk
4 * Copyright (c) 2009-2010 Howard Chu
5 * Copyright (c) 2012 Samuel Pitoiset
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24/**
25 * @file
26 * RTMP Diffie-Hellmann utilities
27 */
28
29#include "config.h"
30#include "rtmpdh.h"
31#include "libavutil/random_seed.h"
32
33#define P1024 \
34 "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
35 "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
36 "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
37 "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
38 "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \
39 "FFFFFFFFFFFFFFFF"
40
41#define Q1024 \
42 "7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \
43 "948127044533E63A0105DF531D89CD9128A5043CC71A026E" \
44 "F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \
45 "F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \
46 "F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \
47 "FFFFFFFFFFFFFFFF"
48
49#if CONFIG_NETTLE || CONFIG_GCRYPT
50#if CONFIG_NETTLE
51#define bn_new(bn) \
52 do { \
53 bn = av_malloc(sizeof(*bn)); \
54 if (bn) \
55 mpz_init2(bn, 1); \
56 } while (0)
57#define bn_free(bn) \
58 do { \
59 mpz_clear(bn); \
60 av_free(bn); \
61 } while (0)
62#define bn_set_word(bn, w) mpz_set_ui(bn, w)
63#define bn_cmp(a, b) mpz_cmp(a, b)
64#define bn_copy(to, from) mpz_set(to, from)
65#define bn_sub_word(bn, w) mpz_sub_ui(bn, bn, w)
66#define bn_cmp_1(bn) mpz_cmp_ui(bn, 1)
67#define bn_num_bytes(bn) (mpz_sizeinbase(bn, 2) + 7) / 8
68#define bn_bn2bin(bn, buf, len) nettle_mpz_get_str_256(len, buf, bn)
69#define bn_bin2bn(bn, buf, len) \
70 do { \
71 bn_new(bn); \
72 if (bn) \
73 nettle_mpz_set_str_256_u(bn, len, buf); \
74 } while (0)
75#define bn_hex2bn(bn, buf, ret) \
76 do { \
77 bn_new(bn); \
78 if (bn) \
79 ret = (mpz_set_str(bn, buf, 16) == 0); \
80 } while (0)
81#define bn_modexp(bn, y, q, p) mpz_powm(bn, y, q, p)
82#define bn_random(bn, num_bytes) \
83 do { \
84 gmp_randstate_t rs; \
85 gmp_randinit_mt(rs); \
86 gmp_randseed_ui(rs, av_get_random_seed()); \
87 mpz_urandomb(bn, rs, num_bytes); \
88 gmp_randclear(rs); \
89 } while (0)
90#elif CONFIG_GCRYPT
91#define bn_new(bn) bn = gcry_mpi_new(1)
92#define bn_free(bn) gcry_mpi_release(bn)
93#define bn_set_word(bn, w) gcry_mpi_set_ui(bn, w)
94#define bn_cmp(a, b) gcry_mpi_cmp(a, b)
95#define bn_copy(to, from) gcry_mpi_set(to, from)
96#define bn_sub_word(bn, w) gcry_mpi_sub_ui(bn, bn, w)
97#define bn_cmp_1(bn) gcry_mpi_cmp_ui(bn, 1)
98#define bn_num_bytes(bn) (gcry_mpi_get_nbits(bn) + 7) / 8
99#define bn_bn2bin(bn, buf, len) gcry_mpi_print(GCRYMPI_FMT_USG, buf, len, NULL, bn)
100#define bn_bin2bn(bn, buf, len) gcry_mpi_scan(&bn, GCRYMPI_FMT_USG, buf, len, NULL)
101#define bn_hex2bn(bn, buf, ret) ret = (gcry_mpi_scan(&bn, GCRYMPI_FMT_HEX, buf, 0, 0) == 0)
102#define bn_modexp(bn, y, q, p) gcry_mpi_powm(bn, y, q, p)
103#define bn_random(bn, num_bytes) gcry_mpi_randomize(bn, num_bytes, GCRY_WEAK_RANDOM)
104#endif
105
106#define MAX_BYTES 18000
107
108#define dh_new() av_malloc(sizeof(FF_DH))
109
110static FFBigNum dh_generate_key(FF_DH *dh)
111{
112 int num_bytes;
113
114 num_bytes = bn_num_bytes(dh->p) - 1;
115 if (num_bytes <= 0 || num_bytes > MAX_BYTES)
116 return NULL;
117
118 bn_new(dh->priv_key);
119 if (!dh->priv_key)
120 return NULL;
121 bn_random(dh->priv_key, num_bytes);
122
123 bn_new(dh->pub_key);
124 if (!dh->pub_key) {
125 bn_free(dh->priv_key);
126 return NULL;
127 }
128
129 bn_modexp(dh->pub_key, dh->g, dh->priv_key, dh->p);
130
131 return dh->pub_key;
132}
133
134static int dh_compute_key(FF_DH *dh, FFBigNum pub_key_bn,
135 uint32_t pub_key_len, uint8_t *secret_key)
136{
137 FFBigNum k;
138 int num_bytes;
139
140 num_bytes = bn_num_bytes(dh->p);
141 if (num_bytes <= 0 || num_bytes > MAX_BYTES)
142 return -1;
143
144 bn_new(k);
145 if (!k)
146 return -1;
147
148 bn_modexp(k, pub_key_bn, dh->priv_key, dh->p);
149 bn_bn2bin(k, secret_key, pub_key_len);
150 bn_free(k);
151
152 /* return the length of the shared secret key like DH_compute_key */
153 return pub_key_len;
154}
155
156void ff_dh_free(FF_DH *dh)
157{
158 bn_free(dh->p);
159 bn_free(dh->g);
160 bn_free(dh->pub_key);
161 bn_free(dh->priv_key);
162 av_free(dh);
163}
164#elif CONFIG_OPENSSL
165#define bn_new(bn) bn = BN_new()
166#define bn_free(bn) BN_free(bn)
167#define bn_set_word(bn, w) BN_set_word(bn, w)
168#define bn_cmp(a, b) BN_cmp(a, b)
169#define bn_copy(to, from) BN_copy(to, from)
170#define bn_sub_word(bn, w) BN_sub_word(bn, w)
171#define bn_cmp_1(bn) BN_cmp(bn, BN_value_one())
172#define bn_num_bytes(bn) BN_num_bytes(bn)
173#define bn_bn2bin(bn, buf, len) BN_bn2bin(bn, buf)
174#define bn_bin2bn(bn, buf, len) bn = BN_bin2bn(buf, len, 0)
175#define bn_hex2bn(bn, buf, ret) ret = BN_hex2bn(&bn, buf)
176#define bn_modexp(bn, y, q, p) \
177 do { \
178 BN_CTX *ctx = BN_CTX_new(); \
179 if (!ctx) \
180 return AVERROR(ENOMEM); \
181 if (!BN_mod_exp(bn, y, q, p, ctx)) { \
182 BN_CTX_free(ctx); \
183 return AVERROR(EINVAL); \
184 } \
185 BN_CTX_free(ctx); \
186 } while (0)
187
188#define dh_new() DH_new()
189#define dh_generate_key(dh) DH_generate_key(dh)
190#define dh_compute_key(dh, pub, len, secret) DH_compute_key(secret, pub, dh)
191
192void ff_dh_free(FF_DH *dh)
193{
194 DH_free(dh);
195}
196#endif
197
198static int dh_is_valid_public_key(FFBigNum y, FFBigNum p, FFBigNum q)
199{
200 FFBigNum bn = NULL;
201 int ret = AVERROR(EINVAL);
202
203 bn_new(bn);
204 if (!bn)
205 return AVERROR(ENOMEM);
206
207 /* y must lie in [2, p - 1] */
208 bn_set_word(bn, 1);
209 if (!bn_cmp(y, bn))
210 goto fail;
211
212 /* bn = p - 2 */
213 bn_copy(bn, p);
214 bn_sub_word(bn, 1);
215 if (!bn_cmp(y, bn))
216 goto fail;
217
218 /* Verify with Sophie-Germain prime
219 *
220 * This is a nice test to make sure the public key position is calculated
221 * correctly. This test will fail in about 50% of the cases if applied to
222 * random data.
223 */
224 /* y must fulfill y^q mod p = 1 */
225 bn_modexp(bn, y, q, p);
226
227 if (bn_cmp_1(bn))
228 goto fail;
229
230 ret = 0;
231fail:
232 bn_free(bn);
233
234 return ret;
235}
236
237av_cold FF_DH *ff_dh_init(int key_len)
238{
239 FF_DH *dh;
240 int ret;
241
242 if (!(dh = dh_new()))
243 return NULL;
244
245 bn_new(dh->g);
246 if (!dh->g)
247 goto fail;
248
249 bn_hex2bn(dh->p, P1024, ret);
250 if (!ret)
251 goto fail;
252
253 bn_set_word(dh->g, 2);
254 dh->length = key_len;
255
256 return dh;
257
258fail:
259 ff_dh_free(dh);
260
261 return NULL;
262}
263
264int ff_dh_generate_public_key(FF_DH *dh)
265{
266 int ret = 0;
267
268 while (!ret) {
269 FFBigNum q1 = NULL;
270
271 if (!dh_generate_key(dh))
272 return AVERROR(EINVAL);
273
274 bn_hex2bn(q1, Q1024, ret);
275 if (!ret)
276 return AVERROR(ENOMEM);
277
278 ret = dh_is_valid_public_key(dh->pub_key, dh->p, q1);
279 bn_free(q1);
280
281 if (!ret) {
282 /* the public key is valid */
283 break;
284 }
285 }
286
287 return ret;
288}
289
290int ff_dh_write_public_key(FF_DH *dh, uint8_t *pub_key, int pub_key_len)
291{
292 int len;
293
294 /* compute the length of the public key */
295 len = bn_num_bytes(dh->pub_key);
296 if (len <= 0 || len > pub_key_len)
297 return AVERROR(EINVAL);
298
299 /* convert the public key value into big-endian form */
300 memset(pub_key, 0, pub_key_len);
301 bn_bn2bin(dh->pub_key, pub_key + pub_key_len - len, len);
302
303 return 0;
304}
305
306int ff_dh_compute_shared_secret_key(FF_DH *dh, const uint8_t *pub_key,
307 int pub_key_len, uint8_t *secret_key)
308{
309 FFBigNum q1 = NULL, pub_key_bn = NULL;
310 int ret;
311
312 /* convert the big-endian form of the public key into a bignum */
313 bn_bin2bn(pub_key_bn, pub_key, pub_key_len);
314 if (!pub_key_bn)
315 return AVERROR(ENOMEM);
316
317 /* convert the string containing a hexadecimal number into a bignum */
318 bn_hex2bn(q1, Q1024, ret);
319 if (!ret) {
320 ret = AVERROR(ENOMEM);
321 goto fail;
322 }
323
324 /* when the public key is valid we have to compute the shared secret key */
325 if ((ret = dh_is_valid_public_key(pub_key_bn, dh->p, q1)) < 0) {
326 goto fail;
327 } else if ((ret = dh_compute_key(dh, pub_key_bn, pub_key_len,
328 secret_key)) < 0) {
329 ret = AVERROR(EINVAL);
330 goto fail;
331 }
332
333fail:
334 bn_free(pub_key_bn);
335 bn_free(q1);
336
337 return ret;
338}
339