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/bn.h>
62 #include <openssl/rand.h>
63 #include <openssl/dh.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
)
76 if (FIPS_mode() && !(dh
->meth
->flags
& DH_FLAG_FIPS_METHOD
)
77 && !(dh
->flags
& DH_FLAG_NON_FIPS_ALLOW
)) {
78 DHerr(DH_F_DH_GENERATE_KEY
, DH_R_NON_FIPS_METHOD
);
82 return dh
->meth
->generate_key(dh
);
85 int DH_compute_key(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
88 if (FIPS_mode() && !(dh
->meth
->flags
& DH_FLAG_FIPS_METHOD
)
89 && !(dh
->flags
& DH_FLAG_NON_FIPS_ALLOW
)) {
90 DHerr(DH_F_DH_COMPUTE_KEY
, DH_R_NON_FIPS_METHOD
);
94 return dh
->meth
->compute_key(key
, pub_key
, dh
);
97 int DH_compute_key_padded(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
100 rv
= dh
->meth
->compute_key(key
, pub_key
, dh
);
103 pad
= BN_num_bytes(dh
->p
) - rv
;
105 memmove(key
+ pad
, key
, rv
);
111 static DH_METHOD dh_ossl
= {
123 const DH_METHOD
*DH_OpenSSL(void)
128 static int generate_key(DH
*dh
)
131 int generate_new_key
= 0;
134 BN_MONT_CTX
*mont
= NULL
;
135 BIGNUM
*pub_key
= NULL
, *priv_key
= NULL
;
141 if (dh
->priv_key
== NULL
) {
143 if (priv_key
== NULL
)
145 generate_new_key
= 1;
147 priv_key
= dh
->priv_key
;
149 if (dh
->pub_key
== NULL
) {
154 pub_key
= dh
->pub_key
;
156 if (dh
->flags
& DH_FLAG_CACHE_MONT_P
) {
157 mont
= BN_MONT_CTX_set_locked(&dh
->method_mont_p
,
158 CRYPTO_LOCK_DH
, dh
->p
, ctx
);
163 if (generate_new_key
) {
166 if (!BN_rand_range(priv_key
, dh
->q
))
169 while (BN_is_zero(priv_key
) || BN_is_one(priv_key
));
171 /* secret exponent length */
172 l
= dh
->length
? dh
->length
: BN_num_bits(dh
->p
) - 1;
173 if (!BN_rand(priv_key
, l
, 0, 0))
182 if ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) == 0) {
185 BN_with_flags(prk
, priv_key
, BN_FLG_CONSTTIME
);
189 if (!dh
->meth
->bn_mod_exp(dh
, pub_key
, dh
->g
, prk
, dh
->p
, ctx
, mont
))
193 dh
->pub_key
= pub_key
;
194 dh
->priv_key
= priv_key
;
198 DHerr(DH_F_GENERATE_KEY
, ERR_R_BN_LIB
);
200 if ((pub_key
!= NULL
) && (dh
->pub_key
== NULL
))
202 if ((priv_key
!= NULL
) && (dh
->priv_key
== NULL
))
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
) {
217 DHerr(DH_F_COMPUTE_KEY
, DH_R_MODULUS_TOO_LARGE
);
225 tmp
= BN_CTX_get(ctx
);
229 if (dh
->priv_key
== NULL
) {
230 DHerr(DH_F_COMPUTE_KEY
, DH_R_NO_PRIVATE_VALUE
);
234 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) {
239 BN_set_flags(dh
->priv_key
, BN_FLG_CONSTTIME
);
245 if (!DH_check_pub_key(dh
, pub_key
, &check_result
) || check_result
) {
246 DHerr(DH_F_COMPUTE_KEY
, DH_R_INVALID_PUBKEY
);
251 meth
->bn_mod_exp(dh
, tmp
, pub_key
, dh
->priv_key
, dh
->p
, ctx
, mont
)) {
252 DHerr(DH_F_COMPUTE_KEY
, ERR_R_BN_LIB
);
256 ret
= BN_bn2bin(tmp
, key
);
265 static int dh_bn_mod_exp(const DH
*dh
, BIGNUM
*r
,
266 const BIGNUM
*a
, const BIGNUM
*p
,
267 const BIGNUM
*m
, BN_CTX
*ctx
, BN_MONT_CTX
*m_ctx
)
270 * If a is only one word long and constant time is false, use the faster
271 * exponenentiation function.
273 if (a
->top
== 1 && ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) != 0)) {
274 BN_ULONG A
= a
->d
[0];
275 return BN_mod_exp_mont_word(r
, A
, p
, m
, ctx
, m_ctx
);
277 return BN_mod_exp_mont(r
, a
, p
, m
, ctx
, m_ctx
);
280 static int dh_init(DH
*dh
)
282 dh
->flags
|= DH_FLAG_CACHE_MONT_P
;
286 static int dh_finish(DH
*dh
)
288 if (dh
->method_mont_p
)
289 BN_MONT_CTX_free(dh
->method_mont_p
);