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d02b48c6 | 1 | /* crypto/dh/dh_key.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
3 | * All rights reserved. |
4 | * | |
5 | * This package is an SSL implementation written | |
6 | * by Eric Young (eay@cryptsoft.com). | |
7 | * The implementation was written so as to conform with Netscapes SSL. | |
ae5c8664 | 8 | * |
d02b48c6 RE |
9 | * This library is free for commercial and non-commercial use as long as |
10 | * the following conditions are aheared to. The following conditions | |
11 | * apply to all code found in this distribution, be it the RC4, RSA, | |
12 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation | |
13 | * included with this distribution is covered by the same copyright terms | |
14 | * except that the holder is Tim Hudson (tjh@cryptsoft.com). | |
ae5c8664 | 15 | * |
d02b48c6 RE |
16 | * Copyright remains Eric Young's, and as such any Copyright notices in |
17 | * the code are not to be removed. | |
18 | * If this package is used in a product, Eric Young should be given attribution | |
19 | * as the author of the parts of the library used. | |
20 | * This can be in the form of a textual message at program startup or | |
21 | * in documentation (online or textual) provided with the package. | |
ae5c8664 | 22 | * |
d02b48c6 RE |
23 | * Redistribution and use in source and binary forms, with or without |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
26 | * 1. Redistributions of source code must retain the copyright | |
27 | * notice, this list of conditions and the following disclaimer. | |
28 | * 2. Redistributions in binary form must reproduce the above copyright | |
29 | * notice, this list of conditions and the following disclaimer in the | |
30 | * documentation and/or other materials provided with the distribution. | |
31 | * 3. All advertising materials mentioning features or use of this software | |
32 | * must display the following acknowledgement: | |
33 | * "This product includes cryptographic software written by | |
34 | * Eric Young (eay@cryptsoft.com)" | |
35 | * The word 'cryptographic' can be left out if the rouines from the library | |
36 | * being used are not cryptographic related :-). | |
ae5c8664 | 37 | * 4. If you include any Windows specific code (or a derivative thereof) from |
d02b48c6 RE |
38 | * the apps directory (application code) you must include an acknowledgement: |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
ae5c8664 | 40 | * |
d02b48c6 RE |
41 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
42 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
43 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
44 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
45 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
46 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
47 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
48 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
49 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
50 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
51 | * SUCH DAMAGE. | |
ae5c8664 | 52 | * |
d02b48c6 RE |
53 | * The licence and distribution terms for any publically available version or |
54 | * derivative of this code cannot be changed. i.e. this code cannot simply be | |
55 | * copied and put under another distribution licence | |
56 | * [including the GNU Public Licence.] | |
57 | */ | |
58 | ||
59 | #include <stdio.h> | |
60 | #include "cryptlib.h" | |
ec577822 BM |
61 | #include <openssl/bn.h> |
62 | #include <openssl/rand.h> | |
63 | #include <openssl/dh.h> | |
d02b48c6 | 64 | |
13066cee | 65 | static int generate_key(DH *dh); |
f971ccb2 RL |
66 | static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); |
67 | static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, | |
ae5c8664 MC |
68 | const BIGNUM *a, const BIGNUM *p, |
69 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); | |
13066cee DSH |
70 | static int dh_init(DH *dh); |
71 | static int dh_finish(DH *dh); | |
72 | ||
6b691a5c | 73 | int DH_generate_key(DH *dh) |
ae5c8664 | 74 | { |
03e16611 | 75 | #ifdef OPENSSL_FIPS |
ae5c8664 MC |
76 | if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD) |
77 | && !(dh->flags & DH_FLAG_NON_FIPS_ALLOW)) { | |
78 | DHerr(DH_F_DH_GENERATE_KEY, DH_R_NON_FIPS_METHOD); | |
79 | return 0; | |
80 | } | |
03e16611 | 81 | #endif |
ae5c8664 MC |
82 | return dh->meth->generate_key(dh); |
83 | } | |
13066cee | 84 | |
f971ccb2 | 85 | int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
ae5c8664 | 86 | { |
03e16611 | 87 | #ifdef OPENSSL_FIPS |
ae5c8664 MC |
88 | if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD) |
89 | && !(dh->flags & DH_FLAG_NON_FIPS_ALLOW)) { | |
90 | DHerr(DH_F_DH_COMPUTE_KEY, DH_R_NON_FIPS_METHOD); | |
91 | return 0; | |
92 | } | |
03e16611 | 93 | #endif |
ae5c8664 MC |
94 | return dh->meth->compute_key(key, pub_key, dh); |
95 | } | |
13066cee | 96 | |
6c4b3514 | 97 | int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
ae5c8664 MC |
98 | { |
99 | int rv, pad; | |
100 | rv = dh->meth->compute_key(key, pub_key, dh); | |
101 | if (rv <= 0) | |
102 | return rv; | |
103 | pad = BN_num_bytes(dh->p) - rv; | |
104 | if (pad > 0) { | |
105 | memmove(key + pad, key, rv); | |
106 | memset(key, 0, pad); | |
107 | } | |
108 | return rv + pad; | |
109 | } | |
6c4b3514 | 110 | |
13066cee | 111 | static DH_METHOD dh_ossl = { |
ae5c8664 MC |
112 | "OpenSSL DH Method", |
113 | generate_key, | |
114 | compute_key, | |
115 | dh_bn_mod_exp, | |
116 | dh_init, | |
117 | dh_finish, | |
118 | 0, | |
119 | NULL, | |
120 | NULL | |
13066cee DSH |
121 | }; |
122 | ||
f971ccb2 | 123 | const DH_METHOD *DH_OpenSSL(void) |
13066cee | 124 | { |
ae5c8664 | 125 | return &dh_ossl; |
13066cee DSH |
126 | } |
127 | ||
128 | static int generate_key(DH *dh) | |
ae5c8664 MC |
129 | { |
130 | int ok = 0; | |
131 | int generate_new_key = 0; | |
132 | unsigned l; | |
133 | BN_CTX *ctx; | |
134 | BN_MONT_CTX *mont = NULL; | |
135 | BIGNUM *pub_key = NULL, *priv_key = NULL; | |
d02b48c6 | 136 | |
ae5c8664 MC |
137 | ctx = BN_CTX_new(); |
138 | if (ctx == NULL) | |
139 | goto err; | |
d02b48c6 | 140 | |
ae5c8664 MC |
141 | if (dh->priv_key == NULL) { |
142 | priv_key = BN_new(); | |
143 | if (priv_key == NULL) | |
144 | goto err; | |
145 | generate_new_key = 1; | |
146 | } else | |
147 | priv_key = dh->priv_key; | |
d02b48c6 | 148 | |
ae5c8664 MC |
149 | if (dh->pub_key == NULL) { |
150 | pub_key = BN_new(); | |
151 | if (pub_key == NULL) | |
152 | goto err; | |
153 | } else | |
154 | pub_key = dh->pub_key; | |
d02b48c6 | 155 | |
ae5c8664 MC |
156 | if (dh->flags & DH_FLAG_CACHE_MONT_P) { |
157 | mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, | |
158 | CRYPTO_LOCK_DH, dh->p, ctx); | |
159 | if (!mont) | |
160 | goto err; | |
161 | } | |
6ec8e63a | 162 | |
ae5c8664 MC |
163 | if (generate_new_key) { |
164 | if (dh->q) { | |
165 | do { | |
166 | if (!BN_rand_range(priv_key, dh->q)) | |
167 | goto err; | |
168 | } | |
169 | while (BN_is_zero(priv_key) || BN_is_one(priv_key)); | |
170 | } else { | |
171 | /* secret exponent length */ | |
172 | l = dh->length ? dh->length : BN_num_bits(dh->p) - 1; | |
173 | if (!BN_rand(priv_key, l, 0, 0)) | |
174 | goto err; | |
175 | } | |
176 | } | |
dfeab068 | 177 | |
ae5c8664 MC |
178 | { |
179 | BIGNUM local_prk; | |
180 | BIGNUM *prk; | |
46a64376 | 181 | |
ae5c8664 MC |
182 | if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) { |
183 | BN_init(&local_prk); | |
184 | prk = &local_prk; | |
185 | BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME); | |
186 | } else | |
187 | prk = priv_key; | |
46a64376 | 188 | |
ae5c8664 MC |
189 | if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) |
190 | goto err; | |
191 | } | |
46a64376 | 192 | |
ae5c8664 MC |
193 | dh->pub_key = pub_key; |
194 | dh->priv_key = priv_key; | |
195 | ok = 1; | |
196 | err: | |
197 | if (ok != 1) | |
198 | DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB); | |
d02b48c6 | 199 | |
ae5c8664 MC |
200 | if ((pub_key != NULL) && (dh->pub_key == NULL)) |
201 | BN_free(pub_key); | |
202 | if ((priv_key != NULL) && (dh->priv_key == NULL)) | |
203 | BN_free(priv_key); | |
204 | BN_CTX_free(ctx); | |
205 | return (ok); | |
206 | } | |
d02b48c6 | 207 | |
f971ccb2 | 208 | static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
ae5c8664 MC |
209 | { |
210 | BN_CTX *ctx = NULL; | |
211 | BN_MONT_CTX *mont = NULL; | |
212 | BIGNUM *tmp; | |
213 | int ret = -1; | |
214 | int check_result; | |
d02b48c6 | 215 | |
ae5c8664 MC |
216 | if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) { |
217 | DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE); | |
218 | goto err; | |
219 | } | |
5e3225cc | 220 | |
ae5c8664 MC |
221 | ctx = BN_CTX_new(); |
222 | if (ctx == NULL) | |
223 | goto err; | |
224 | BN_CTX_start(ctx); | |
225 | tmp = BN_CTX_get(ctx); | |
6ec8e63a | 226 | |
ae5c8664 MC |
227 | if (dh->priv_key == NULL) { |
228 | DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE); | |
229 | goto err; | |
230 | } | |
dfeab068 | 231 | |
ae5c8664 MC |
232 | if (dh->flags & DH_FLAG_CACHE_MONT_P) { |
233 | mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, | |
234 | CRYPTO_LOCK_DH, dh->p, ctx); | |
235 | if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) { | |
236 | /* XXX */ | |
237 | BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME); | |
238 | } | |
239 | if (!mont) | |
240 | goto err; | |
241 | } | |
bf3d6c0c | 242 | |
ae5c8664 MC |
243 | if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) { |
244 | DHerr(DH_F_COMPUTE_KEY, DH_R_INVALID_PUBKEY); | |
245 | goto err; | |
246 | } | |
d02b48c6 | 247 | |
ae5c8664 MC |
248 | if (!dh-> |
249 | meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) { | |
250 | DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB); | |
251 | goto err; | |
252 | } | |
13066cee | 253 | |
ae5c8664 MC |
254 | ret = BN_bn2bin(tmp, key); |
255 | err: | |
256 | if (ctx != NULL) { | |
257 | BN_CTX_end(ctx); | |
258 | BN_CTX_free(ctx); | |
259 | } | |
260 | return (ret); | |
261 | } | |
6dad7bd6 | 262 | |
ae5c8664 MC |
263 | static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, |
264 | const BIGNUM *a, const BIGNUM *p, | |
265 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx) | |
266 | { | |
267 | /* | |
268 | * If a is only one word long and constant time is false, use the faster | |
269 | * exponenentiation function. | |
270 | */ | |
271 | if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0)) { | |
272 | BN_ULONG A = a->d[0]; | |
273 | return BN_mod_exp_mont_word(r, A, p, m, ctx, m_ctx); | |
274 | } else | |
275 | return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx); | |
276 | } | |
13066cee DSH |
277 | |
278 | static int dh_init(DH *dh) | |
ae5c8664 MC |
279 | { |
280 | dh->flags |= DH_FLAG_CACHE_MONT_P; | |
281 | return (1); | |
282 | } | |
13066cee DSH |
283 | |
284 | static int dh_finish(DH *dh) | |
ae5c8664 MC |
285 | { |
286 | if (dh->method_mont_p) | |
287 | BN_MONT_CTX_free(dh->method_mont_p); | |
288 | return (1); | |
289 | } |