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.]
61 #include <openssl/rand.h>
62 #include <openssl/dh.h>
63 #include "internal/bn_int.h"
65 static int generate_key(DH
*dh
);
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
,
68 const BIGNUM
*a
, const BIGNUM
*p
,
69 const BIGNUM
*m
, BN_CTX
*ctx
, BN_MONT_CTX
*m_ctx
);
70 static int dh_init(DH
*dh
);
71 static int dh_finish(DH
*dh
);
73 int DH_generate_key(DH
*dh
)
75 return dh
->meth
->generate_key(dh
);
78 int DH_compute_key(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
80 return dh
->meth
->compute_key(key
, pub_key
, dh
);
83 int DH_compute_key_padded(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
86 rv
= dh
->meth
->compute_key(key
, pub_key
, dh
);
89 pad
= BN_num_bytes(dh
->p
) - rv
;
91 memmove(key
+ pad
, key
, rv
);
97 static DH_METHOD dh_ossl
= {
109 const DH_METHOD
*DH_OpenSSL(void)
114 static int generate_key(DH
*dh
)
117 int generate_new_key
= 0;
120 BN_MONT_CTX
*mont
= NULL
;
121 BIGNUM
*pub_key
= NULL
, *priv_key
= NULL
;
127 if (dh
->priv_key
== NULL
) {
129 if (priv_key
== NULL
)
131 generate_new_key
= 1;
133 priv_key
= dh
->priv_key
;
135 if (dh
->pub_key
== NULL
) {
140 pub_key
= dh
->pub_key
;
142 if (dh
->flags
& DH_FLAG_CACHE_MONT_P
) {
143 mont
= BN_MONT_CTX_set_locked(&dh
->method_mont_p
,
144 CRYPTO_LOCK_DH
, dh
->p
, ctx
);
149 if (generate_new_key
) {
152 if (!BN_rand_range(priv_key
, dh
->q
))
155 while (BN_is_zero(priv_key
) || BN_is_one(priv_key
));
157 /* secret exponent length */
158 l
= dh
->length
? dh
->length
: BN_num_bits(dh
->p
) - 1;
159 if (!BN_rand(priv_key
, l
, 0, 0))
165 BIGNUM
*local_prk
= NULL
;
168 if ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) == 0) {
169 local_prk
= prk
= BN_new();
170 BN_with_flags(prk
, priv_key
, BN_FLG_CONSTTIME
);
174 if (!dh
->meth
->bn_mod_exp(dh
, pub_key
, dh
->g
, prk
, dh
->p
, ctx
, mont
)) {
181 dh
->pub_key
= pub_key
;
182 dh
->priv_key
= priv_key
;
186 DHerr(DH_F_GENERATE_KEY
, ERR_R_BN_LIB
);
188 if (pub_key
!= dh
->pub_key
)
190 if (priv_key
!= dh
->priv_key
)
196 static int compute_key(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
199 BN_MONT_CTX
*mont
= NULL
;
204 if (BN_num_bits(dh
->p
) > OPENSSL_DH_MAX_MODULUS_BITS
) {
205 DHerr(DH_F_COMPUTE_KEY
, DH_R_MODULUS_TOO_LARGE
);
213 tmp
= BN_CTX_get(ctx
);
215 if (dh
->priv_key
== NULL
) {
216 DHerr(DH_F_COMPUTE_KEY
, DH_R_NO_PRIVATE_VALUE
);
220 if (dh
->flags
& DH_FLAG_CACHE_MONT_P
) {
221 mont
= BN_MONT_CTX_set_locked(&dh
->method_mont_p
,
222 CRYPTO_LOCK_DH
, dh
->p
, ctx
);
223 if ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) == 0) {
225 BN_set_flags(dh
->priv_key
, BN_FLG_CONSTTIME
);
231 if (!DH_check_pub_key(dh
, pub_key
, &check_result
) || check_result
) {
232 DHerr(DH_F_COMPUTE_KEY
, DH_R_INVALID_PUBKEY
);
237 meth
->bn_mod_exp(dh
, tmp
, pub_key
, dh
->priv_key
, dh
->p
, ctx
, mont
)) {
238 DHerr(DH_F_COMPUTE_KEY
, ERR_R_BN_LIB
);
242 ret
= BN_bn2bin(tmp
, key
);
251 static int dh_bn_mod_exp(const DH
*dh
, BIGNUM
*r
,
252 const BIGNUM
*a
, const BIGNUM
*p
,
253 const BIGNUM
*m
, BN_CTX
*ctx
, BN_MONT_CTX
*m_ctx
)
256 * If a is only one word long and constant time is false, use the faster
257 * exponenentiation function.
259 if (bn_get_top(a
) == 1 && ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) != 0)) {
260 BN_ULONG A
= bn_get_words(a
)[0];
261 return BN_mod_exp_mont_word(r
, A
, p
, m
, ctx
, m_ctx
);
263 return BN_mod_exp_mont(r
, a
, p
, m
, ctx
, m_ctx
);
266 static int dh_init(DH
*dh
)
268 dh
->flags
|= DH_FLAG_CACHE_MONT_P
;
272 static int dh_finish(DH
*dh
)
274 BN_MONT_CTX_free(dh
->method_mont_p
);