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d02b48c6 | 1 | /* crypto/dh/dh_check.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
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" | |
ec577822 BM |
61 | #include <openssl/bn.h> |
62 | #include <openssl/dh.h> | |
d02b48c6 | 63 | |
6977c7e2 TH |
64 | /*- |
65 | * Check that p is a safe prime and | |
5f0477f4 | 66 | * if g is 2, 3 or 5, check that it is a suitable generator |
d02b48c6 RE |
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 | ||
f971ccb2 | 74 | int DH_check(const DH *dh, int *ret) |
d02b48c6 RE |
75 | { |
76 | int ok=0; | |
77 | BN_CTX *ctx=NULL; | |
78 | BN_ULONG l; | |
b73a69a9 | 79 | BIGNUM *t1=NULL, *t2 = NULL; |
d02b48c6 RE |
80 | |
81 | *ret=0; | |
82 | ctx=BN_CTX_new(); | |
83 | if (ctx == NULL) goto err; | |
b73a69a9 DSH |
84 | BN_CTX_start(ctx); |
85 | t1=BN_CTX_get(ctx); | |
fe69e6be | 86 | if (t1 == NULL) goto err; |
b73a69a9 DSH |
87 | t2=BN_CTX_get(ctx); |
88 | if (t2 == NULL) goto err; | |
d02b48c6 | 89 | |
b73a69a9 DSH |
90 | if (dh->q) |
91 | { | |
92 | if (BN_cmp(dh->g, BN_value_one()) <= 0) | |
93 | *ret|=DH_NOT_SUITABLE_GENERATOR; | |
94 | else if (BN_cmp(dh->g, dh->p) >= 0) | |
95 | *ret|=DH_NOT_SUITABLE_GENERATOR; | |
96 | else | |
97 | { | |
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; | |
113 | ||
114 | } | |
115 | else if (BN_is_word(dh->g,DH_GENERATOR_2)) | |
d02b48c6 RE |
116 | { |
117 | l=BN_mod_word(dh->p,24); | |
118 | if (l != 11) *ret|=DH_NOT_SUITABLE_GENERATOR; | |
119 | } | |
4486d0cd UM |
120 | #if 0 |
121 | else if (BN_is_word(dh->g,DH_GENERATOR_3)) | |
d02b48c6 RE |
122 | { |
123 | l=BN_mod_word(dh->p,12); | |
124 | if (l != 5) *ret|=DH_NOT_SUITABLE_GENERATOR; | |
4486d0cd UM |
125 | } |
126 | #endif | |
d02b48c6 RE |
127 | else if (BN_is_word(dh->g,DH_GENERATOR_5)) |
128 | { | |
129 | l=BN_mod_word(dh->p,10); | |
130 | if ((l != 3) && (l != 7)) | |
131 | *ret|=DH_NOT_SUITABLE_GENERATOR; | |
132 | } | |
133 | else | |
134 | *ret|=DH_UNABLE_TO_CHECK_GENERATOR; | |
135 | ||
e9224c71 | 136 | if (!BN_is_prime_ex(dh->p,BN_prime_checks,ctx,NULL)) |
d02b48c6 | 137 | *ret|=DH_CHECK_P_NOT_PRIME; |
b73a69a9 | 138 | else if (!dh->q) |
d02b48c6 | 139 | { |
b73a69a9 DSH |
140 | if (!BN_rshift1(t1,dh->p)) goto err; |
141 | if (!BN_is_prime_ex(t1,BN_prime_checks,ctx,NULL)) | |
4486d0cd | 142 | *ret|=DH_CHECK_P_NOT_SAFE_PRIME; |
d02b48c6 RE |
143 | } |
144 | ok=1; | |
145 | err: | |
b73a69a9 DSH |
146 | if (ctx != NULL) |
147 | { | |
148 | BN_CTX_end(ctx); | |
149 | BN_CTX_free(ctx); | |
150 | } | |
d02b48c6 RE |
151 | return(ok); |
152 | } | |
bf3d6c0c BL |
153 | |
154 | int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret) | |
155 | { | |
156 | int ok=0; | |
157 | BIGNUM *q=NULL; | |
158 | ||
159 | *ret=0; | |
160 | q=BN_new(); | |
161 | if (q == NULL) goto err; | |
162 | BN_set_word(q,1); | |
163 | if (BN_cmp(pub_key,q)<=0) | |
164 | *ret|=DH_CHECK_PUBKEY_TOO_SMALL; | |
165 | BN_copy(q,dh->p); | |
166 | BN_sub_word(q,1); | |
167 | if (BN_cmp(pub_key,q)>=0) | |
168 | *ret|=DH_CHECK_PUBKEY_TOO_LARGE; | |
169 | ||
170 | ok = 1; | |
171 | err: | |
172 | if (q != NULL) BN_free(q); | |
173 | return(ok); | |
174 | } |