fips_dh_check.c revision 296465 
1/* crypto/dh/dh_check.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/bn.h>
61#include <openssl/dh.h>
62#include <openssl/err.h>
63#include <openssl/fips.h>
64
65/*-
66 * Check that p is a safe prime and
67 * if g is 2, 3 or 5, check that is is a suitable generator
68 * where
69 * for 2, p mod 24 == 11
70 * for 3, p mod 12 == 5
71 * for 5, p mod 10 == 3 or 7
72 * should hold.
73 */
74
75#ifdef OPENSSL_FIPS
76
77int DH_check(const DH *dh, int *ret)
78{
79    int ok = 0;
80    BN_CTX *ctx = NULL;
81    BN_ULONG l;
82    BIGNUM *q = NULL;
83
84    *ret = 0;
85    ctx = BN_CTX_new();
86    if (ctx == NULL)
87        goto err;
88    q = BN_new();
89    if (q == NULL)
90        goto err;
91
92    if (BN_is_word(dh->g, DH_GENERATOR_2)) {
93        l = BN_mod_word(dh->p, 24);
94        if (l != 11)
95            *ret |= DH_NOT_SUITABLE_GENERATOR;
96    }
97# if 0
98    else if (BN_is_word(dh->g, DH_GENERATOR_3)) {
99        l = BN_mod_word(dh->p, 12);
100        if (l != 5)
101            *ret |= DH_NOT_SUITABLE_GENERATOR;
102    }
103# endif
104    else if (BN_is_word(dh->g, DH_GENERATOR_5)) {
105        l = BN_mod_word(dh->p, 10);
106        if ((l != 3) && (l != 7))
107            *ret |= DH_NOT_SUITABLE_GENERATOR;
108    } else
109        *ret |= DH_UNABLE_TO_CHECK_GENERATOR;
110
111    if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL))
112        *ret |= DH_CHECK_P_NOT_PRIME;
113    else {
114        if (!BN_rshift1(q, dh->p))
115            goto err;
116        if (!BN_is_prime_ex(q, BN_prime_checks, ctx, NULL))
117            *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
118    }
119    ok = 1;
120 err:
121    if (ctx != NULL)
122        BN_CTX_free(ctx);
123    if (q != NULL)
124        BN_free(q);
125    return (ok);
126}
127
128int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
129{
130    int ok = 0;
131    BIGNUM *q = NULL;
132
133    *ret = 0;
134    q = BN_new();
135    if (q == NULL)
136        goto err;
137    BN_set_word(q, 1);
138    if (BN_cmp(pub_key, q) <= 0)
139        *ret |= DH_CHECK_PUBKEY_TOO_SMALL;
140    BN_copy(q, dh->p);
141    BN_sub_word(q, 1);
142    if (BN_cmp(pub_key, q) >= 0)
143        *ret |= DH_CHECK_PUBKEY_TOO_LARGE;
144
145    ok = 1;
146 err:
147    if (q != NULL)
148        BN_free(q);
149    return (ok);
150}
151
152#endif
153