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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. | |
8 | * | |
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). | |
15 | * | |
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. | |
22 | * | |
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 :-). | |
37 | * 4. If you include any Windows specific code (or a derivative thereof) from | |
38 | * the apps directory (application code) you must include an acknowledgement: | |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
40 | * | |
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. | |
52 | * | |
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 | ||
73e45b2d | 59 | |
14ae26f2 | 60 | |
d02b48c6 RE |
61 | #include <stdio.h> |
62 | #include "cryptlib.h" | |
ec577822 BM |
63 | #include <openssl/bn.h> |
64 | #include <openssl/rand.h> | |
65 | #include <openssl/dh.h> | |
d02b48c6 | 66 | |
13066cee | 67 | static int generate_key(DH *dh); |
f971ccb2 RL |
68 | static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); |
69 | static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, | |
70 | const BIGNUM *a, const BIGNUM *p, | |
13066cee DSH |
71 | const BIGNUM *m, BN_CTX *ctx, |
72 | BN_MONT_CTX *m_ctx); | |
73 | static int dh_init(DH *dh); | |
74 | static int dh_finish(DH *dh); | |
75 | ||
6b691a5c | 76 | int DH_generate_key(DH *dh) |
13066cee | 77 | { |
cb78486d | 78 | return dh->meth->generate_key(dh); |
13066cee DSH |
79 | } |
80 | ||
f971ccb2 | 81 | int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
13066cee | 82 | { |
cb78486d | 83 | return dh->meth->compute_key(key, pub_key, dh); |
13066cee DSH |
84 | } |
85 | ||
bc91494e DSH |
86 | int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
87 | { | |
88 | int rv, pad; | |
89 | rv = dh->meth->compute_key(key, pub_key, dh); | |
90 | if (rv <= 0) | |
91 | return rv; | |
92 | pad = BN_num_bytes(dh->p) - rv; | |
93 | if (pad > 0) | |
94 | { | |
95 | memmove(key + pad, key, rv); | |
96 | memset(key, 0, pad); | |
97 | } | |
98 | return rv + pad; | |
99 | } | |
100 | ||
13066cee DSH |
101 | static DH_METHOD dh_ossl = { |
102 | "OpenSSL DH Method", | |
103 | generate_key, | |
104 | compute_key, | |
105 | dh_bn_mod_exp, | |
106 | dh_init, | |
107 | dh_finish, | |
4960411e | 108 | DH_FLAG_FIPS_METHOD, |
0e4aa0d2 | 109 | NULL, |
13066cee DSH |
110 | NULL |
111 | }; | |
112 | ||
f971ccb2 | 113 | const DH_METHOD *DH_OpenSSL(void) |
13066cee DSH |
114 | { |
115 | return &dh_ossl; | |
116 | } | |
117 | ||
118 | static int generate_key(DH *dh) | |
d02b48c6 RE |
119 | { |
120 | int ok=0; | |
924875e5 | 121 | int generate_new_key=0; |
6aecef81 | 122 | unsigned l; |
c62b26fd | 123 | BN_CTX *ctx; |
3cc54008 | 124 | BN_MONT_CTX *mont=NULL; |
d02b48c6 RE |
125 | BIGNUM *pub_key=NULL,*priv_key=NULL; |
126 | ||
c62b26fd BM |
127 | ctx = BN_CTX_new(); |
128 | if (ctx == NULL) goto err; | |
d02b48c6 RE |
129 | |
130 | if (dh->priv_key == NULL) | |
131 | { | |
d02b48c6 RE |
132 | priv_key=BN_new(); |
133 | if (priv_key == NULL) goto err; | |
924875e5 | 134 | generate_new_key=1; |
d02b48c6 RE |
135 | } |
136 | else | |
137 | priv_key=dh->priv_key; | |
138 | ||
139 | if (dh->pub_key == NULL) | |
140 | { | |
141 | pub_key=BN_new(); | |
142 | if (pub_key == NULL) goto err; | |
143 | } | |
144 | else | |
145 | pub_key=dh->pub_key; | |
146 | ||
6ec8e63a DSH |
147 | |
148 | if (dh->flags & DH_FLAG_CACHE_MONT_P) | |
dfeab068 | 149 | { |
879b1980 | 150 | mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, |
6ec8e63a DSH |
151 | CRYPTO_LOCK_DH, dh->p, ctx); |
152 | if (!mont) | |
153 | goto err; | |
dfeab068 | 154 | } |
dfeab068 | 155 | |
924875e5 BM |
156 | if (generate_new_key) |
157 | { | |
31360957 DSH |
158 | if (dh->q) |
159 | { | |
160 | do | |
161 | { | |
162 | if (!BN_rand_range(priv_key, dh->q)) | |
163 | goto err; | |
164 | } | |
165 | while (BN_is_zero(priv_key) || BN_is_one(priv_key)); | |
166 | } | |
167 | else | |
168 | { | |
169 | /* secret exponent length */ | |
170 | l = dh->length ? dh->length : BN_num_bits(dh->p)-1; | |
171 | if (!BN_rand(priv_key, l, 0, 0)) goto err; | |
172 | } | |
924875e5 | 173 | } |
46a64376 BM |
174 | |
175 | { | |
176 | BIGNUM local_prk; | |
177 | BIGNUM *prk; | |
178 | ||
179 | if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) | |
180 | { | |
a28a5d9c | 181 | BN_init(&local_prk); |
46a64376 | 182 | prk = &local_prk; |
bd31fb21 | 183 | BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME); |
46a64376 BM |
184 | } |
185 | else | |
186 | prk = priv_key; | |
187 | ||
188 | if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err; | |
189 | } | |
d02b48c6 RE |
190 | |
191 | dh->pub_key=pub_key; | |
192 | dh->priv_key=priv_key; | |
193 | ok=1; | |
194 | err: | |
195 | if (ok != 1) | |
aa4ce731 | 196 | DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB); |
d02b48c6 RE |
197 | |
198 | if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); | |
199 | if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); | |
c62b26fd | 200 | BN_CTX_free(ctx); |
d02b48c6 RE |
201 | return(ok); |
202 | } | |
203 | ||
f971ccb2 | 204 | static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
d02b48c6 | 205 | { |
c2cccfc5 | 206 | BN_CTX *ctx=NULL; |
3cc54008 | 207 | BN_MONT_CTX *mont=NULL; |
d02b48c6 RE |
208 | BIGNUM *tmp; |
209 | int ret= -1; | |
bf3d6c0c | 210 | int check_result; |
d02b48c6 | 211 | |
5e3225cc BM |
212 | if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) |
213 | { | |
214 | DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE); | |
215 | goto err; | |
216 | } | |
217 | ||
c62b26fd BM |
218 | ctx = BN_CTX_new(); |
219 | if (ctx == NULL) goto err; | |
220 | BN_CTX_start(ctx); | |
221 | tmp = BN_CTX_get(ctx); | |
d02b48c6 RE |
222 | |
223 | if (dh->priv_key == NULL) | |
224 | { | |
aa4ce731 | 225 | DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); |
d02b48c6 RE |
226 | goto err; |
227 | } | |
6ec8e63a DSH |
228 | |
229 | if (dh->flags & DH_FLAG_CACHE_MONT_P) | |
dfeab068 | 230 | { |
879b1980 | 231 | mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, |
6ec8e63a | 232 | CRYPTO_LOCK_DH, dh->p, ctx); |
46a64376 BM |
233 | if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) |
234 | { | |
235 | /* XXX */ | |
bd31fb21 | 236 | BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME); |
46a64376 | 237 | } |
6ec8e63a DSH |
238 | if (!mont) |
239 | goto err; | |
dfeab068 RE |
240 | } |
241 | ||
bf3d6c0c BL |
242 | if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) |
243 | { | |
244 | DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY); | |
245 | goto err; | |
246 | } | |
247 | ||
cb78486d | 248 | if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont)) |
d02b48c6 | 249 | { |
aa4ce731 | 250 | DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB); |
d02b48c6 RE |
251 | goto err; |
252 | } | |
253 | ||
254 | ret=BN_bn2bin(tmp,key); | |
255 | err: | |
47d55666 NL |
256 | if (ctx != NULL) |
257 | { | |
258 | BN_CTX_end(ctx); | |
259 | BN_CTX_free(ctx); | |
260 | } | |
d02b48c6 RE |
261 | return(ret); |
262 | } | |
13066cee | 263 | |
f971ccb2 RL |
264 | static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, |
265 | const BIGNUM *a, const BIGNUM *p, | |
13066cee DSH |
266 | const BIGNUM *m, BN_CTX *ctx, |
267 | BN_MONT_CTX *m_ctx) | |
6dad7bd6 | 268 | { |
46a64376 BM |
269 | /* If a is only one word long and constant time is false, use the faster |
270 | * exponenentiation function. | |
271 | */ | |
272 | if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0)) | |
6dad7bd6 BM |
273 | { |
274 | BN_ULONG A = a->d[0]; | |
275 | return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx); | |
276 | } | |
277 | else | |
278 | return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx); | |
279 | } | |
280 | ||
13066cee DSH |
281 | |
282 | static int dh_init(DH *dh) | |
6dad7bd6 | 283 | { |
13066cee DSH |
284 | dh->flags |= DH_FLAG_CACHE_MONT_P; |
285 | return(1); | |
6dad7bd6 | 286 | } |
13066cee DSH |
287 | |
288 | static int dh_finish(DH *dh) | |
6dad7bd6 | 289 | { |
13066cee | 290 | if(dh->method_mont_p) |
879b1980 | 291 | BN_MONT_CTX_free(dh->method_mont_p); |
13066cee | 292 | return(1); |
6dad7bd6 | 293 | } |