1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
59 #include "internal/cryptlib.h"
60 #include <openssl/rand.h>
61 #include <openssl/dh.h>
62 #include "internal/bn_int.h"
64 static int generate_key(DH *dh);
65 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
66 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
67 const BIGNUM *a, const BIGNUM *p,
68 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
69 static int dh_init(DH *dh);
70 static int dh_finish(DH *dh);
72 int DH_generate_key(DH *dh)
74 return dh->meth->generate_key(dh);
77 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
79 return dh->meth->compute_key(key, pub_key, dh);
82 int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
85 rv = dh->meth->compute_key(key, pub_key, dh);
88 pad = BN_num_bytes(dh->p) - rv;
90 memmove(key + pad, key, rv);
96 static DH_METHOD dh_ossl = {
108 const DH_METHOD *DH_OpenSSL(void)
113 static int generate_key(DH *dh)
116 int generate_new_key = 0;
119 BN_MONT_CTX *mont = NULL;
120 BIGNUM *pub_key = NULL, *priv_key = NULL;
126 if (dh->priv_key == NULL) {
127 priv_key = BN_secure_new();
128 if (priv_key == NULL)
130 generate_new_key = 1;
132 priv_key = dh->priv_key;
134 if (dh->pub_key == NULL) {
139 pub_key = dh->pub_key;
141 if (dh->flags & DH_FLAG_CACHE_MONT_P) {
142 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
143 CRYPTO_LOCK_DH, dh->p, ctx);
148 if (generate_new_key) {
151 if (!BN_rand_range(priv_key, dh->q))
154 while (BN_is_zero(priv_key) || BN_is_one(priv_key));
156 /* secret exponent length */
157 l = dh->length ? dh->length : BN_num_bits(dh->p) - 1;
158 if (!BN_rand(priv_key, l, 0, 0))
164 BIGNUM *local_prk = NULL;
167 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) {
168 local_prk = prk = BN_new();
169 if (local_prk == NULL)
171 BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
176 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) {
180 /* We MUST free local_prk before any further use of priv_key */
184 dh->pub_key = pub_key;
185 dh->priv_key = priv_key;
189 DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB);
191 if (pub_key != dh->pub_key)
193 if (priv_key != dh->priv_key)
199 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
202 BN_MONT_CTX *mont = NULL;
207 if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
208 DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE);
216 tmp = BN_CTX_get(ctx);
218 if (dh->priv_key == NULL) {
219 DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE);
223 if (dh->flags & DH_FLAG_CACHE_MONT_P) {
224 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
225 CRYPTO_LOCK_DH, dh->p, ctx);
226 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) {
228 BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
234 if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
235 DHerr(DH_F_COMPUTE_KEY, DH_R_INVALID_PUBKEY);
240 meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) {
241 DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
245 ret = BN_bn2bin(tmp, key);
254 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
255 const BIGNUM *a, const BIGNUM *p,
256 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
259 * If a is only one word long and constant time is false, use the faster
260 * exponenentiation function.
262 if (bn_get_top(a) == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0)) {
263 BN_ULONG A = bn_get_words(a)[0];
264 return BN_mod_exp_mont_word(r, A, p, m, ctx, m_ctx);
266 return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
269 static int dh_init(DH *dh)
271 dh->flags |= DH_FLAG_CACHE_MONT_P;
275 static int dh_finish(DH *dh)
277 BN_MONT_CTX_free(dh->method_mont_p);