Branch data 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 : : /* Check that p is a safe prime and
65 : : * if g is 2, 3 or 5, check that it is a suitable generator
66 : : * where
67 : : * for 2, p mod 24 == 11
68 : : * for 3, p mod 12 == 5
69 : : * for 5, p mod 10 == 3 or 7
70 : : * should hold.
71 : : */
72 : :
73 : 1 : int DH_check(const DH *dh, int *ret)
74 : : {
75 : 1 : int ok=0;
76 : 1 : BN_CTX *ctx=NULL;
77 : : BN_ULONG l;
78 : 1 : BIGNUM *t1=NULL, *t2 = NULL;
79 : :
80 : 1 : *ret=0;
81 : 1 : ctx=BN_CTX_new();
82 [ + - ]: 1 : if (ctx == NULL) goto err;
83 : 1 : BN_CTX_start(ctx);
84 : 1 : t1=BN_CTX_get(ctx);
85 [ + - ]: 1 : if (t1 == NULL) goto err;
86 : 1 : t2=BN_CTX_get(ctx);
87 [ + - ]: 1 : if (t2 == NULL) goto err;
88 : :
89 [ - + ]: 1 : if (dh->q)
90 : : {
91 [ # # ]: 0 : if (BN_cmp(dh->g, BN_value_one()) <= 0)
92 : 0 : *ret|=DH_NOT_SUITABLE_GENERATOR;
93 [ # # ]: 0 : else if (BN_cmp(dh->g, dh->p) >= 0)
94 : 0 : *ret|=DH_NOT_SUITABLE_GENERATOR;
95 : : else
96 : : {
97 : : /* Check g^q == 1 mod p */
98 [ # # ]: 0 : if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
99 : : goto err;
100 [ # # ][ # # ]: 0 : if (!BN_is_one(t1))
[ # # ]
101 : 0 : *ret|=DH_NOT_SUITABLE_GENERATOR;
102 : : }
103 [ # # ]: 0 : if (!BN_is_prime_ex(dh->q,BN_prime_checks,ctx,NULL))
104 : 0 : *ret|=DH_CHECK_Q_NOT_PRIME;
105 : : /* Check p == 1 mod q i.e. q divides p - 1 */
106 [ # # ]: 0 : if (!BN_div(t1, t2, dh->p, dh->q, ctx))
107 : : goto err;
108 [ # # ][ # # ]: 0 : if (!BN_is_one(t2))
[ # # ]
109 : 0 : *ret|=DH_CHECK_INVALID_Q_VALUE;
110 [ # # ][ # # ]: 0 : if (dh->j && BN_cmp(dh->j, t1))
111 : 0 : *ret|=DH_CHECK_INVALID_J_VALUE;
112 : :
113 : : }
114 [ + - ][ - + ]: 1 : else if (BN_is_word(dh->g,DH_GENERATOR_2))
[ # # ]
115 : : {
116 : 0 : l=BN_mod_word(dh->p,24);
117 [ # # ]: 0 : if (l != 11) *ret|=DH_NOT_SUITABLE_GENERATOR;
118 : : }
119 : : #if 0
120 : : else if (BN_is_word(dh->g,DH_GENERATOR_3))
121 : : {
122 : : l=BN_mod_word(dh->p,12);
123 : : if (l != 5) *ret|=DH_NOT_SUITABLE_GENERATOR;
124 : : }
125 : : #endif
126 [ + - ][ + - ]: 1 : else if (BN_is_word(dh->g,DH_GENERATOR_5))
[ + - ]
127 : : {
128 : 1 : l=BN_mod_word(dh->p,10);
129 [ - + ]: 1 : if ((l != 3) && (l != 7))
130 : 0 : *ret|=DH_NOT_SUITABLE_GENERATOR;
131 : : }
132 : : else
133 : 0 : *ret|=DH_UNABLE_TO_CHECK_GENERATOR;
134 : :
135 [ - + ]: 1 : if (!BN_is_prime_ex(dh->p,BN_prime_checks,ctx,NULL))
136 : 0 : *ret|=DH_CHECK_P_NOT_PRIME;
137 [ + - ]: 1 : else if (!dh->q)
138 : : {
139 [ + - ]: 1 : if (!BN_rshift1(t1,dh->p)) goto err;
140 [ - + ]: 1 : if (!BN_is_prime_ex(t1,BN_prime_checks,ctx,NULL))
141 : 0 : *ret|=DH_CHECK_P_NOT_SAFE_PRIME;
142 : : }
143 : : ok=1;
144 : : err:
145 [ + - ]: 1 : if (ctx != NULL)
146 : : {
147 : 1 : BN_CTX_end(ctx);
148 : 1 : BN_CTX_free(ctx);
149 : : }
150 : 1 : return(ok);
151 : : }
152 : :
153 : 406 : int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
154 : : {
155 : 406 : int ok=0;
156 : 406 : BIGNUM *q=NULL;
157 : :
158 : 406 : *ret=0;
159 : 406 : q=BN_new();
160 [ + - ]: 406 : if (q == NULL) goto err;
161 : 406 : BN_set_word(q,1);
162 [ - + ]: 406 : if (BN_cmp(pub_key,q)<=0)
163 : 0 : *ret|=DH_CHECK_PUBKEY_TOO_SMALL;
164 : 406 : BN_copy(q,dh->p);
165 : 406 : BN_sub_word(q,1);
166 [ - + ]: 406 : if (BN_cmp(pub_key,q)>=0)
167 : 0 : *ret|=DH_CHECK_PUBKEY_TOO_LARGE;
168 : :
169 : : ok = 1;
170 : : err:
171 [ + - ]: 406 : if (q != NULL) BN_free(q);
172 : 406 : return(ok);
173 : : }
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