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
);