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#ifndef OPENSSL_FIPS 74 75int 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 *ret=0; 83 ctx=BN_CTX_new(); 84 if (ctx == NULL) goto err; 85 q=BN_new(); 86 if (q == NULL) goto err; 87 88 if (BN_is_word(dh->g,DH_GENERATOR_2)) 89 { 90 l=BN_mod_word(dh->p,24); 91 if (l != 11) *ret|=DH_NOT_SUITABLE_GENERATOR; 92 } 93#if 0 94 else if (BN_is_word(dh->g,DH_GENERATOR_3)) 95 { 96 l=BN_mod_word(dh->p,12); 97 if (l != 5) *ret|=DH_NOT_SUITABLE_GENERATOR; 98 } 99#endif 100 else if (BN_is_word(dh->g,DH_GENERATOR_5)) 101 { 102 l=BN_mod_word(dh->p,10); 103 if ((l != 3) && (l != 7)) 104 *ret|=DH_NOT_SUITABLE_GENERATOR; 105 } 106 else 107 *ret|=DH_UNABLE_TO_CHECK_GENERATOR; 108 109 if (!BN_is_prime_ex(dh->p,BN_prime_checks,ctx,NULL)) 110 *ret|=DH_CHECK_P_NOT_PRIME; 111 else 112 { 113 if (!BN_rshift1(q,dh->p)) goto err; 114 if (!BN_is_prime_ex(q,BN_prime_checks,ctx,NULL)) 115 *ret|=DH_CHECK_P_NOT_SAFE_PRIME; 116 } 117 ok=1; 118err: 119 if (ctx != NULL) BN_CTX_free(ctx); 120 if (q != NULL) BN_free(q); 121 return(ok); 122 } 123 124int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret) 125 { 126 int ok=0; 127 BIGNUM *q=NULL; 128 129 *ret=0; 130 q=BN_new(); 131 if (q == NULL) goto err; 132 BN_set_word(q,1); 133 if (BN_cmp(pub_key,q) <= 0) 134 *ret|=DH_CHECK_PUBKEY_TOO_SMALL; 135 BN_copy(q,dh->p); 136 BN_sub_word(q,1); 137 if (BN_cmp(pub_key,q) >= 0) 138 *ret|=DH_CHECK_PUBKEY_TOO_LARGE; 139 140 ok = 1; 141err: 142 if (q != NULL) BN_free(q); 143 return(ok); 144 } 145 146#endif 147