GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcrypto/dh/dh_check.c Lines: 31 38 81.6 %
Date: 2017-11-07 Branches: 19 36 52.8 %

Line Branch Exec Source
1
/* $OpenBSD: dh_check.c,v 1.16 2016/07/05 02:54:35 bcook Exp $ */
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
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
int
75
DH_check(const DH *dh, int *ret)
76
{
77
	int ok = 0;
78
	BN_CTX *ctx = NULL;
79
	BN_ULONG l;
80
	BIGNUM *q = NULL;
81
82
20
	*ret = 0;
83
10
	ctx = BN_CTX_new();
84
10
	if (ctx == NULL)
85
		goto err;
86
10
	q = BN_new();
87
10
	if (q == NULL)
88
		goto err;
89
90

24
	if (BN_is_word(dh->g, DH_GENERATOR_2)) {
91
4
		l = BN_mod_word(dh->p, 24);
92
4
		if (l == (BN_ULONG)-1)
93
			goto err;
94
4
		if (l != 11)
95
			*ret |= DH_NOT_SUITABLE_GENERATOR;
96

18
	} else if (BN_is_word(dh->g, DH_GENERATOR_5)) {
97
6
		l = BN_mod_word(dh->p, 10);
98
6
		if (l == (BN_ULONG)-1)
99
			goto err;
100
6
		if (l != 3 && l != 7)
101
			*ret |= DH_NOT_SUITABLE_GENERATOR;
102
	} else
103
		*ret |= DH_UNABLE_TO_CHECK_GENERATOR;
104
105
10
	if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL))
106
		*ret |= DH_CHECK_P_NOT_PRIME;
107
	else {
108
10
		if (!BN_rshift1(q, dh->p))
109
			goto err;
110
10
		if (!BN_is_prime_ex(q, BN_prime_checks, ctx, NULL))
111
			*ret |= DH_CHECK_P_NOT_SAFE_PRIME;
112
	}
113
10
	ok = 1;
114
err:
115
10
	BN_CTX_free(ctx);
116
10
	BN_free(q);
117
10
	return ok;
118
}
119
120
int
121
DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
122
{
123
	BIGNUM *q = NULL;
124
125
712
	*ret = 0;
126
356
	q = BN_new();
127
356
	if (q == NULL)
128
		return 0;
129
356
	BN_set_word(q, 1);
130
356
	if (BN_cmp(pub_key, q) <= 0)
131
		*ret |= DH_CHECK_PUBKEY_TOO_SMALL;
132
356
	BN_copy(q, dh->p);
133
356
	BN_sub_word(q, 1);
134
356
	if (BN_cmp(pub_key, q) >= 0)
135
		*ret |= DH_CHECK_PUBKEY_TOO_LARGE;
136
137
356
	BN_free(q);
138
356
	return 1;
139
356
}