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58964a49 | 1 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
2 | * All rights reserved. |
3 | * | |
4 | * This package is an SSL implementation written | |
5 | * by Eric Young (eay@cryptsoft.com). | |
6 | * The implementation was written so as to conform with Netscapes SSL. | |
0f113f3e | 7 | * |
d02b48c6 RE |
8 | * This library is free for commercial and non-commercial use as long as |
9 | * the following conditions are aheared to. The following conditions | |
10 | * apply to all code found in this distribution, be it the RC4, RSA, | |
11 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation | |
12 | * included with this distribution is covered by the same copyright terms | |
13 | * except that the holder is Tim Hudson (tjh@cryptsoft.com). | |
0f113f3e | 14 | * |
d02b48c6 RE |
15 | * Copyright remains Eric Young's, and as such any Copyright notices in |
16 | * the code are not to be removed. | |
17 | * If this package is used in a product, Eric Young should be given attribution | |
18 | * as the author of the parts of the library used. | |
19 | * This can be in the form of a textual message at program startup or | |
20 | * in documentation (online or textual) provided with the package. | |
0f113f3e | 21 | * |
d02b48c6 RE |
22 | * Redistribution and use in source and binary forms, with or without |
23 | * modification, are permitted provided that the following conditions | |
24 | * are met: | |
25 | * 1. Redistributions of source code must retain the copyright | |
26 | * notice, this list of conditions and the following disclaimer. | |
27 | * 2. Redistributions in binary form must reproduce the above copyright | |
28 | * notice, this list of conditions and the following disclaimer in the | |
29 | * documentation and/or other materials provided with the distribution. | |
30 | * 3. All advertising materials mentioning features or use of this software | |
31 | * must display the following acknowledgement: | |
32 | * "This product includes cryptographic software written by | |
33 | * Eric Young (eay@cryptsoft.com)" | |
34 | * The word 'cryptographic' can be left out if the rouines from the library | |
35 | * being used are not cryptographic related :-). | |
0f113f3e | 36 | * 4. If you include any Windows specific code (or a derivative thereof) from |
d02b48c6 RE |
37 | * the apps directory (application code) you must include an acknowledgement: |
38 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
0f113f3e | 39 | * |
d02b48c6 RE |
40 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
41 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
42 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
43 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
44 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
45 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
46 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
47 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
48 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
49 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
50 | * SUCH DAMAGE. | |
0f113f3e | 51 | * |
d02b48c6 RE |
52 | * The licence and distribution terms for any publically available version or |
53 | * derivative of this code cannot be changed. i.e. this code cannot simply be | |
54 | * copied and put under another distribution licence | |
55 | * [including the GNU Public Licence.] | |
56 | */ | |
57 | ||
58 | #include <stdio.h> | |
b39fc560 | 59 | #include "internal/cryptlib.h" |
ec577822 BM |
60 | #include <openssl/bn.h> |
61 | #include <openssl/dh.h> | |
d02b48c6 | 62 | |
1d97c843 TH |
63 | /*- |
64 | * Check that p is a safe prime and | |
5f0477f4 | 65 | * if g is 2, 3 or 5, check that it is a suitable generator |
d02b48c6 RE |
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 | ||
f971ccb2 | 73 | int DH_check(const DH *dh, int *ret) |
0f113f3e MC |
74 | { |
75 | int ok = 0; | |
76 | BN_CTX *ctx = NULL; | |
77 | BN_ULONG l; | |
78 | BIGNUM *t1 = NULL, *t2 = NULL; | |
79 | ||
80 | *ret = 0; | |
81 | ctx = BN_CTX_new(); | |
82 | if (ctx == NULL) | |
83 | goto err; | |
84 | BN_CTX_start(ctx); | |
85 | t1 = BN_CTX_get(ctx); | |
86 | if (t1 == NULL) | |
87 | goto err; | |
88 | t2 = BN_CTX_get(ctx); | |
89 | if (t2 == NULL) | |
90 | goto err; | |
d02b48c6 | 91 | |
0f113f3e MC |
92 | if (dh->q) { |
93 | if (BN_cmp(dh->g, BN_value_one()) <= 0) | |
94 | *ret |= DH_NOT_SUITABLE_GENERATOR; | |
95 | else if (BN_cmp(dh->g, dh->p) >= 0) | |
96 | *ret |= DH_NOT_SUITABLE_GENERATOR; | |
97 | else { | |
98 | /* Check g^q == 1 mod p */ | |
99 | if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx)) | |
100 | goto err; | |
101 | if (!BN_is_one(t1)) | |
102 | *ret |= DH_NOT_SUITABLE_GENERATOR; | |
103 | } | |
104 | if (!BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL)) | |
105 | *ret |= DH_CHECK_Q_NOT_PRIME; | |
106 | /* Check p == 1 mod q i.e. q divides p - 1 */ | |
107 | if (!BN_div(t1, t2, dh->p, dh->q, ctx)) | |
108 | goto err; | |
109 | if (!BN_is_one(t2)) | |
110 | *ret |= DH_CHECK_INVALID_Q_VALUE; | |
111 | if (dh->j && BN_cmp(dh->j, t1)) | |
112 | *ret |= DH_CHECK_INVALID_J_VALUE; | |
d02b48c6 | 113 | |
0f113f3e MC |
114 | } else if (BN_is_word(dh->g, DH_GENERATOR_2)) { |
115 | l = BN_mod_word(dh->p, 24); | |
116 | if (l != 11) | |
117 | *ret |= DH_NOT_SUITABLE_GENERATOR; | |
dfb56425 | 118 | } else if (BN_is_word(dh->g, DH_GENERATOR_5)) { |
0f113f3e MC |
119 | l = BN_mod_word(dh->p, 10); |
120 | if ((l != 3) && (l != 7)) | |
121 | *ret |= DH_NOT_SUITABLE_GENERATOR; | |
122 | } else | |
123 | *ret |= DH_UNABLE_TO_CHECK_GENERATOR; | |
d02b48c6 | 124 | |
0f113f3e MC |
125 | if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL)) |
126 | *ret |= DH_CHECK_P_NOT_PRIME; | |
127 | else if (!dh->q) { | |
128 | if (!BN_rshift1(t1, dh->p)) | |
129 | goto err; | |
130 | if (!BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL)) | |
131 | *ret |= DH_CHECK_P_NOT_SAFE_PRIME; | |
132 | } | |
133 | ok = 1; | |
134 | err: | |
135 | if (ctx != NULL) { | |
136 | BN_CTX_end(ctx); | |
137 | BN_CTX_free(ctx); | |
138 | } | |
139 | return (ok); | |
140 | } | |
bf3d6c0c BL |
141 | |
142 | int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret) | |
0f113f3e MC |
143 | { |
144 | int ok = 0; | |
145 | BIGNUM *q = NULL; | |
bf3d6c0c | 146 | |
0f113f3e MC |
147 | *ret = 0; |
148 | q = BN_new(); | |
149 | if (q == NULL) | |
150 | goto err; | |
151 | BN_set_word(q, 1); | |
152 | if (BN_cmp(pub_key, q) <= 0) | |
153 | *ret |= DH_CHECK_PUBKEY_TOO_SMALL; | |
154 | BN_copy(q, dh->p); | |
155 | BN_sub_word(q, 1); | |
156 | if (BN_cmp(pub_key, q) >= 0) | |
157 | *ret |= DH_CHECK_PUBKEY_TOO_LARGE; | |
bf3d6c0c | 158 | |
0f113f3e MC |
159 | ok = 1; |
160 | err: | |
23a1d5e9 | 161 | BN_free(q); |
0f113f3e MC |
162 | return (ok); |
163 | } |