Line data Source code
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 "cryptlib.h"
61 : #include <openssl/bn.h>
62 : #include <openssl/dh.h>
63 :
64 : /*-
65 : * Check that p is a safe prime and
66 : * if g is 2, 3 or 5, check that it is a suitable generator
67 : * where
68 : * for 2, p mod 24 == 11
69 : * for 3, p mod 12 == 5
70 : * for 5, p mod 10 == 3 or 7
71 : * should hold.
72 : */
73 :
74 0 : int DH_check(const DH *dh, int *ret)
75 : {
76 : int ok = 0;
77 : BN_CTX *ctx = NULL;
78 : BN_ULONG l;
79 : BIGNUM *t1 = NULL, *t2 = NULL;
80 :
81 0 : *ret = 0;
82 0 : ctx = BN_CTX_new();
83 0 : if (ctx == NULL)
84 : goto err;
85 0 : BN_CTX_start(ctx);
86 0 : t1 = BN_CTX_get(ctx);
87 0 : if (t1 == NULL)
88 : goto err;
89 0 : t2 = BN_CTX_get(ctx);
90 0 : if (t2 == NULL)
91 : goto err;
92 :
93 0 : if (dh->q) {
94 0 : if (BN_cmp(dh->g, BN_value_one()) <= 0)
95 0 : *ret |= DH_NOT_SUITABLE_GENERATOR;
96 0 : else if (BN_cmp(dh->g, dh->p) >= 0)
97 0 : *ret |= DH_NOT_SUITABLE_GENERATOR;
98 : else {
99 : /* Check g^q == 1 mod p */
100 0 : if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
101 : goto err;
102 0 : if (!BN_is_one(t1))
103 0 : *ret |= DH_NOT_SUITABLE_GENERATOR;
104 : }
105 0 : if (!BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL))
106 0 : *ret |= DH_CHECK_Q_NOT_PRIME;
107 : /* Check p == 1 mod q i.e. q divides p - 1 */
108 0 : if (!BN_div(t1, t2, dh->p, dh->q, ctx))
109 : goto err;
110 0 : if (!BN_is_one(t2))
111 0 : *ret |= DH_CHECK_INVALID_Q_VALUE;
112 0 : if (dh->j && BN_cmp(dh->j, t1))
113 0 : *ret |= DH_CHECK_INVALID_J_VALUE;
114 :
115 0 : } else if (BN_is_word(dh->g, DH_GENERATOR_2)) {
116 0 : l = BN_mod_word(dh->p, 24);
117 0 : if (l != 11)
118 0 : *ret |= DH_NOT_SUITABLE_GENERATOR;
119 : }
120 : #if 0
121 : else if (BN_is_word(dh->g, DH_GENERATOR_3)) {
122 : l = BN_mod_word(dh->p, 12);
123 : if (l != 5)
124 : *ret |= DH_NOT_SUITABLE_GENERATOR;
125 : }
126 : #endif
127 0 : else if (BN_is_word(dh->g, DH_GENERATOR_5)) {
128 0 : l = BN_mod_word(dh->p, 10);
129 0 : if ((l != 3) && (l != 7))
130 0 : *ret |= DH_NOT_SUITABLE_GENERATOR;
131 : } else
132 0 : *ret |= DH_UNABLE_TO_CHECK_GENERATOR;
133 :
134 0 : if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL))
135 0 : *ret |= DH_CHECK_P_NOT_PRIME;
136 0 : else if (!dh->q) {
137 0 : if (!BN_rshift1(t1, dh->p))
138 : goto err;
139 0 : if (!BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL))
140 0 : *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
141 : }
142 : ok = 1;
143 : err:
144 0 : if (ctx != NULL) {
145 0 : BN_CTX_end(ctx);
146 0 : BN_CTX_free(ctx);
147 : }
148 0 : return (ok);
149 : }
150 :
151 0 : int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
152 : {
153 : int ok = 0;
154 : BIGNUM *q = NULL;
155 :
156 0 : *ret = 0;
157 0 : q = BN_new();
158 0 : if (q == NULL)
159 : goto err;
160 0 : BN_set_word(q, 1);
161 0 : if (BN_cmp(pub_key, q) <= 0)
162 0 : *ret |= DH_CHECK_PUBKEY_TOO_SMALL;
163 0 : BN_copy(q, dh->p);
164 0 : BN_sub_word(q, 1);
165 0 : if (BN_cmp(pub_key, q) >= 0)
166 0 : *ret |= DH_CHECK_PUBKEY_TOO_LARGE;
167 :
168 : ok = 1;
169 : err:
170 0 : if (q != NULL)
171 0 : BN_free(q);
172 0 : return (ok);
173 : }
|
