dsa_key.c revision 296341 
1/* crypto/dsa/dsa_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 <time.h>
61#include "cryptlib.h"
62#ifndef OPENSSL_NO_SHA
63# include <openssl/bn.h>
64# include <openssl/dsa.h>
65# include <openssl/rand.h>
66
67# ifdef OPENSSL_FIPS
68#  include <openssl/fips.h>
69# endif
70
71static int dsa_builtin_keygen(DSA *dsa);
72
73int DSA_generate_key(DSA *dsa)
74{
75# ifdef OPENSSL_FIPS
76    if (FIPS_mode() && !(dsa->meth->flags & DSA_FLAG_FIPS_METHOD)
77        && !(dsa->flags & DSA_FLAG_NON_FIPS_ALLOW)) {
78        DSAerr(DSA_F_DSA_GENERATE_KEY, DSA_R_NON_FIPS_DSA_METHOD);
79        return 0;
80    }
81# endif
82    if (dsa->meth->dsa_keygen)
83        return dsa->meth->dsa_keygen(dsa);
84# ifdef OPENSSL_FIPS
85    if (FIPS_mode())
86        return FIPS_dsa_generate_key(dsa);
87# endif
88    return dsa_builtin_keygen(dsa);
89}
90
91static int dsa_builtin_keygen(DSA *dsa)
92{
93    int ok = 0;
94    BN_CTX *ctx = NULL;
95    BIGNUM *pub_key = NULL, *priv_key = NULL;
96
97    if ((ctx = BN_CTX_new()) == NULL)
98        goto err;
99
100    if (dsa->priv_key == NULL) {
101        if ((priv_key = BN_new()) == NULL)
102            goto err;
103    } else
104        priv_key = dsa->priv_key;
105
106    do
107        if (!BN_rand_range(priv_key, dsa->q))
108            goto err;
109    while (BN_is_zero(priv_key)) ;
110
111    if (dsa->pub_key == NULL) {
112        if ((pub_key = BN_new()) == NULL)
113            goto err;
114    } else
115        pub_key = dsa->pub_key;
116
117    {
118        BIGNUM local_prk;
119        BIGNUM *prk;
120
121        if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
122            BN_init(&local_prk);
123            prk = &local_prk;
124            BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
125        } else
126            prk = priv_key;
127
128        if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx))
129            goto err;
130    }
131
132    dsa->priv_key = priv_key;
133    dsa->pub_key = pub_key;
134    ok = 1;
135
136 err:
137    if ((pub_key != NULL) && (dsa->pub_key == NULL))
138        BN_free(pub_key);
139    if ((priv_key != NULL) && (dsa->priv_key == NULL))
140        BN_free(priv_key);
141    if (ctx != NULL)
142        BN_CTX_free(ctx);
143    return (ok);
144}
145#endif
146