1 /* crypto/dh/dh_check.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
61 #include <openssl/bn.h>
62 #include <openssl/dh.h>
65 * Check that p is a safe prime and
66 * if g is 2, 3 or 5, check that it is a suitable generator
68 * for 2, p mod 24 == 11
69 * for 3, p mod 12 == 5
70 * for 5, p mod 10 == 3 or 7
74 int DH_check(const DH
*dh
, int *ret
)
89 if (BN_is_word(dh
->g
, DH_GENERATOR_2
)) {
90 l
= BN_mod_word(dh
->p
, 24);
92 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
95 else if (BN_is_word(dh
->g
, DH_GENERATOR_3
)) {
96 l
= BN_mod_word(dh
->p
, 12);
98 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
101 else if (BN_is_word(dh
->g
, DH_GENERATOR_5
)) {
102 l
= BN_mod_word(dh
->p
, 10);
103 if ((l
!= 3) && (l
!= 7))
104 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
106 *ret
|= DH_UNABLE_TO_CHECK_GENERATOR
;
108 if (!BN_is_prime_ex(dh
->p
, BN_prime_checks
, ctx
, NULL
))
109 *ret
|= DH_CHECK_P_NOT_PRIME
;
111 if (!BN_rshift1(q
, dh
->p
))
113 if (!BN_is_prime_ex(q
, BN_prime_checks
, ctx
, NULL
))
114 *ret
|= DH_CHECK_P_NOT_SAFE_PRIME
;
125 int DH_check_pub_key(const DH
*dh
, const BIGNUM
*pub_key
, int *ret
)
135 if (BN_cmp(pub_key
, q
) <= 0)
136 *ret
|= DH_CHECK_PUBKEY_TOO_SMALL
;
139 if (BN_cmp(pub_key
, q
) >= 0)
140 *ret
|= DH_CHECK_PUBKEY_TOO_LARGE
;