Commit | Line | Data |
---|---|---|
2ba45a60 DM |
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 | ||
110 | static 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 | ||
134 | static 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 | ||
156 | void 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 | ||
192 | void ff_dh_free(FF_DH *dh) | |
193 | { | |
194 | DH_free(dh); | |
195 | } | |
196 | #endif | |
197 | ||
198 | static 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; | |
231 | fail: | |
232 | bn_free(bn); | |
233 | ||
234 | return ret; | |
235 | } | |
236 | ||
237 | av_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 | ||
258 | fail: | |
259 | ff_dh_free(dh); | |
260 | ||
261 | return NULL; | |
262 | } | |
263 | ||
264 | int 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 | ||
290 | int 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 | ||
306 | int 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 | ||
333 | fail: | |
334 | bn_free(pub_key_bn); | |
335 | bn_free(q1); | |
336 | ||
337 | return ret; | |
338 | } | |
339 |