fips_dh_key.c revision 296465 
1/* crypto/dh/dh_key.c */
2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
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.
8 *
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).
15 *
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.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
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)"
40 *
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
51 * SUCH DAMAGE.
52 *
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.]
57 */
58
59#include <stdio.h>
60#include <openssl/err.h>
61#include <openssl/bn.h>
62#ifndef OPENSSL_NO_RAND
63# include <openssl/rand.h>
64#endif
65#ifndef OPENSSL_NO_DH
66# include <openssl/dh.h>
67# include <openssl/fips.h>
68
69# ifdef OPENSSL_FIPS
70
71static int generate_key(DH *dh);
72static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
73static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
74                         const BIGNUM *a, const BIGNUM *p,
75                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
76static int dh_init(DH *dh);
77static int dh_finish(DH *dh);
78
79int DH_generate_key(DH *dh)
80{
81    return dh->meth->generate_key(dh);
82}
83
84int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
85{
86    return dh->meth->compute_key(key, pub_key, dh);
87}
88
89static const DH_METHOD dh_ossl = {
90    "OpenSSL DH Method",
91    generate_key,
92    compute_key,
93    dh_bn_mod_exp,
94    dh_init,
95    dh_finish,
96    0,
97    NULL
98};
99
100const DH_METHOD *DH_OpenSSL(void)
101{
102    return &dh_ossl;
103}
104
105static int generate_key(DH *dh)
106{
107    int ok = 0;
108    int generate_new_key = 0;
109    unsigned l;
110    BN_CTX *ctx;
111    BN_MONT_CTX *mont = NULL;
112    BIGNUM *pub_key = NULL, *priv_key = NULL;
113
114    if (FIPS_mode()
115        && (BN_num_bits(dh->p) < OPENSSL_DH_FIPS_MIN_MODULUS_BITS)) {
116        DHerr(DH_F_GENERATE_KEY, DH_R_KEY_SIZE_TOO_SMALL);
117        return 0;
118    }
119
120    ctx = BN_CTX_new();
121    if (ctx == NULL)
122        goto err;
123
124    if (dh->priv_key == NULL) {
125        priv_key = BN_new();
126        if (priv_key == NULL)
127            goto err;
128        generate_new_key = 1;
129    } else
130        priv_key = dh->priv_key;
131
132    if (dh->pub_key == NULL) {
133        pub_key = BN_new();
134        if (pub_key == NULL)
135            goto err;
136    } else
137        pub_key = dh->pub_key;
138
139    if (dh->flags & DH_FLAG_CACHE_MONT_P) {
140        mont = BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dh->method_mont_p,
141                                      CRYPTO_LOCK_DH, dh->p, ctx);
142        if (!mont)
143            goto err;
144    }
145
146    if (generate_new_key) {
147        l = dh->length ? dh->length : BN_num_bits(dh->p) - 1; /* secret
148                                                               * exponent
149                                                               * length */
150        if (!BN_rand(priv_key, l, 0, 0))
151            goto err;
152    }
153
154    {
155        BIGNUM local_prk;
156        BIGNUM *prk;
157
158        if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) {
159            BN_init(&local_prk);
160            prk = &local_prk;
161            BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
162        } else
163            prk = priv_key;
164
165        if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont))
166            goto err;
167    }
168
169    dh->pub_key = pub_key;
170    dh->priv_key = priv_key;
171    ok = 1;
172 err:
173    if (ok != 1)
174        DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB);
175
176    if ((pub_key != NULL) && (dh->pub_key == NULL))
177        BN_free(pub_key);
178    if ((priv_key != NULL) && (dh->priv_key == NULL))
179        BN_free(priv_key);
180    BN_CTX_free(ctx);
181    return (ok);
182}
183
184static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
185{
186    BN_CTX *ctx;
187    BN_MONT_CTX *mont = NULL;
188    BIGNUM *tmp;
189    int ret = -1;
190
191    ctx = BN_CTX_new();
192    if (ctx == NULL)
193        goto err;
194    BN_CTX_start(ctx);
195    tmp = BN_CTX_get(ctx);
196
197    if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
198        DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE);
199        goto err;
200    }
201
202    if (FIPS_mode()
203        && (BN_num_bits(dh->p) < OPENSSL_DH_FIPS_MIN_MODULUS_BITS)) {
204        DHerr(DH_F_COMPUTE_KEY, DH_R_KEY_SIZE_TOO_SMALL);
205        goto err;
206    }
207
208    if (dh->priv_key == NULL) {
209        DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE);
210        goto err;
211    }
212
213    if (dh->flags & DH_FLAG_CACHE_MONT_P) {
214        mont = BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dh->method_mont_p,
215                                      CRYPTO_LOCK_DH, dh->p, ctx);
216        if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) {
217            /* XXX */
218            BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
219        }
220        if (!mont)
221            goto err;
222    }
223
224    if (!dh->
225        meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) {
226        DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
227        goto err;
228    }
229
230    ret = BN_bn2bin(tmp, key);
231 err:
232    BN_CTX_end(ctx);
233    BN_CTX_free(ctx);
234    return (ret);
235}
236
237static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
238                         const BIGNUM *a, const BIGNUM *p,
239                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
240{
241    /*
242     * If a is only one word long and constant time is false, use the faster
243     * exponenentiation function.
244     */
245    if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0)) {
246        BN_ULONG A = a->d[0];
247        return BN_mod_exp_mont_word(r, A, p, m, ctx, m_ctx);
248    } else
249        return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
250}
251
252static int dh_init(DH *dh)
253{
254    FIPS_selftest_check();
255    dh->flags |= DH_FLAG_CACHE_MONT_P;
256    return (1);
257}
258
259static int dh_finish(DH *dh)
260{
261    if (dh->method_mont_p)
262        BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p);
263    return (1);
264}
265
266# endif
267#endif
268