1 /* crypto/dh/dh_key.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
63 #include <openssl/rand.h>
64 #include <openssl/dh.h>
65 #include "internal/bn_int.h"
67 static int generate_key(DH *dh);
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,
71 const BIGNUM *m, BN_CTX *ctx,
73 static int dh_init(DH *dh);
74 static int dh_finish(DH *dh);
76 int DH_generate_key(DH *dh)
78 return dh->meth->generate_key(dh);
81 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
83 return dh->meth->compute_key(key, pub_key, dh);
86 int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
89 rv = dh->meth->compute_key(key, pub_key, dh);
92 pad = BN_num_bytes(dh->p) - rv;
95 memmove(key + pad, key, rv);
101 static DH_METHOD dh_ossl = {
113 const DH_METHOD *DH_OpenSSL(void)
118 static int generate_key(DH *dh)
121 int generate_new_key=0;
124 BN_MONT_CTX *mont=NULL;
125 BIGNUM *pub_key=NULL,*priv_key=NULL;
128 if (ctx == NULL) goto err;
130 if (dh->priv_key == NULL)
133 if (priv_key == NULL) goto err;
137 priv_key=dh->priv_key;
139 if (dh->pub_key == NULL)
142 if (pub_key == NULL) goto err;
148 if (dh->flags & DH_FLAG_CACHE_MONT_P)
150 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
151 CRYPTO_LOCK_DH, dh->p, ctx);
156 if (generate_new_key)
162 if (!BN_rand_range(priv_key, dh->q))
165 while (BN_is_zero(priv_key) || BN_is_one(priv_key));
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;
176 BIGNUM *local_prk = NULL;
179 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
181 local_prk = prk = BN_new();
182 BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
187 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont))
189 if(local_prk) BN_free(local_prk);
192 if(local_prk) BN_free(local_prk);
196 dh->priv_key=priv_key;
200 DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB);
202 if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key);
203 if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);
208 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
211 BN_MONT_CTX *mont=NULL;
216 if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS)
218 DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE);
223 if (ctx == NULL) goto err;
225 tmp = BN_CTX_get(ctx);
227 if (dh->priv_key == NULL)
229 DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
233 if (dh->flags & DH_FLAG_CACHE_MONT_P)
235 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
236 CRYPTO_LOCK_DH, dh->p, ctx);
237 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
240 BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
246 if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)
248 DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY);
252 if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont))
254 DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB);
258 ret=BN_bn2bin(tmp,key);
268 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
269 const BIGNUM *a, const BIGNUM *p,
270 const BIGNUM *m, BN_CTX *ctx,
273 /* If a is only one word long and constant time is false, use the faster
274 * exponenentiation function.
276 if (bn_get_top(a) == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0))
278 BN_ULONG A = bn_get_words(a)[0];
279 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);
282 return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);
286 static int dh_init(DH *dh)
288 dh->flags |= DH_FLAG_CACHE_MONT_P;
292 static int dh_finish(DH *dh)
294 if(dh->method_mont_p)
295 BN_MONT_CTX_free(dh->method_mont_p);