155714Skris/* crypto/dh/dh_check.c */ 255714Skris/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 355714Skris * All rights reserved. 455714Skris * 555714Skris * This package is an SSL implementation written 655714Skris * by Eric Young (eay@cryptsoft.com). 755714Skris * The implementation was written so as to conform with Netscapes SSL. 8296341Sdelphij * 955714Skris * This library is free for commercial and non-commercial use as long as 1055714Skris * the following conditions are aheared to. The following conditions 1155714Skris * apply to all code found in this distribution, be it the RC4, RSA, 1255714Skris * lhash, DES, etc., code; not just the SSL code. The SSL documentation 1355714Skris * included with this distribution is covered by the same copyright terms 1455714Skris * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15296341Sdelphij * 1655714Skris * Copyright remains Eric Young's, and as such any Copyright notices in 1755714Skris * the code are not to be removed. 1855714Skris * If this package is used in a product, Eric Young should be given attribution 1955714Skris * as the author of the parts of the library used. 2055714Skris * This can be in the form of a textual message at program startup or 2155714Skris * in documentation (online or textual) provided with the package. 22296341Sdelphij * 2355714Skris * Redistribution and use in source and binary forms, with or without 2455714Skris * modification, are permitted provided that the following conditions 2555714Skris * are met: 2655714Skris * 1. Redistributions of source code must retain the copyright 2755714Skris * notice, this list of conditions and the following disclaimer. 2855714Skris * 2. Redistributions in binary form must reproduce the above copyright 2955714Skris * notice, this list of conditions and the following disclaimer in the 3055714Skris * documentation and/or other materials provided with the distribution. 3155714Skris * 3. All advertising materials mentioning features or use of this software 3255714Skris * must display the following acknowledgement: 3355714Skris * "This product includes cryptographic software written by 3455714Skris * Eric Young (eay@cryptsoft.com)" 3555714Skris * The word 'cryptographic' can be left out if the rouines from the library 3655714Skris * being used are not cryptographic related :-). 37296341Sdelphij * 4. If you include any Windows specific code (or a derivative thereof) from 3855714Skris * the apps directory (application code) you must include an acknowledgement: 3955714Skris * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40296341Sdelphij * 4155714Skris * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 4255714Skris * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 4355714Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 4455714Skris * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 4555714Skris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 4655714Skris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 4755714Skris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 4855714Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 4955714Skris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 5055714Skris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 5155714Skris * SUCH DAMAGE. 52296341Sdelphij * 5355714Skris * The licence and distribution terms for any publically available version or 5455714Skris * derivative of this code cannot be changed. i.e. this code cannot simply be 5555714Skris * copied and put under another distribution licence 5655714Skris * [including the GNU Public Licence.] 5755714Skris */ 5855714Skris 5955714Skris#include <stdio.h> 6055714Skris#include "cryptlib.h" 6155714Skris#include <openssl/bn.h> 6255714Skris#include <openssl/dh.h> 6355714Skris 64296341Sdelphij/*- 65296341Sdelphij * Check that p is a safe prime and 66194206Ssimon * if g is 2, 3 or 5, check that it is a suitable generator 6755714Skris * where 6855714Skris * for 2, p mod 24 == 11 6955714Skris * for 3, p mod 12 == 5 7055714Skris * for 5, p mod 10 == 3 or 7 7155714Skris * should hold. 7255714Skris */ 7355714Skris 74109998Smarkmint DH_check(const DH *dh, int *ret) 75296341Sdelphij{ 76296341Sdelphij int ok = 0; 77296341Sdelphij BN_CTX *ctx = NULL; 78296341Sdelphij BN_ULONG l; 79296341Sdelphij BIGNUM *q = NULL; 8055714Skris 81296341Sdelphij *ret = 0; 82296341Sdelphij ctx = BN_CTX_new(); 83296341Sdelphij if (ctx == NULL) 84296341Sdelphij goto err; 85296341Sdelphij q = BN_new(); 86296341Sdelphij if (q == NULL) 87296341Sdelphij goto err; 8855714Skris 89296341Sdelphij if (BN_is_word(dh->g, DH_GENERATOR_2)) { 90296341Sdelphij l = BN_mod_word(dh->p, 24); 91296341Sdelphij if (l != 11) 92296341Sdelphij *ret |= DH_NOT_SUITABLE_GENERATOR; 93296341Sdelphij } 9459191Skris#if 0 95296341Sdelphij else if (BN_is_word(dh->g, DH_GENERATOR_3)) { 96296341Sdelphij l = BN_mod_word(dh->p, 12); 97296341Sdelphij if (l != 5) 98296341Sdelphij *ret |= DH_NOT_SUITABLE_GENERATOR; 99296341Sdelphij } 10059191Skris#endif 101296341Sdelphij else if (BN_is_word(dh->g, DH_GENERATOR_5)) { 102296341Sdelphij l = BN_mod_word(dh->p, 10); 103296341Sdelphij if ((l != 3) && (l != 7)) 104296341Sdelphij *ret |= DH_NOT_SUITABLE_GENERATOR; 105296341Sdelphij } else 106296341Sdelphij *ret |= DH_UNABLE_TO_CHECK_GENERATOR; 10755714Skris 108296341Sdelphij if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL)) 109296341Sdelphij *ret |= DH_CHECK_P_NOT_PRIME; 110296341Sdelphij else { 111296341Sdelphij if (!BN_rshift1(q, dh->p)) 112296341Sdelphij goto err; 113296341Sdelphij if (!BN_is_prime_ex(q, BN_prime_checks, ctx, NULL)) 114296341Sdelphij *ret |= DH_CHECK_P_NOT_SAFE_PRIME; 115296341Sdelphij } 116296341Sdelphij ok = 1; 117296341Sdelphij err: 118296341Sdelphij if (ctx != NULL) 119296341Sdelphij BN_CTX_free(ctx); 120296341Sdelphij if (q != NULL) 121296341Sdelphij BN_free(q); 122296341Sdelphij return (ok); 123296341Sdelphij} 124142425Snectar 125160814Ssimonint DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret) 126296341Sdelphij{ 127296341Sdelphij int ok = 0; 128296341Sdelphij BIGNUM *q = NULL; 129160814Ssimon 130296341Sdelphij *ret = 0; 131296341Sdelphij q = BN_new(); 132296341Sdelphij if (q == NULL) 133296341Sdelphij goto err; 134296341Sdelphij BN_set_word(q, 1); 135296341Sdelphij if (BN_cmp(pub_key, q) <= 0) 136296341Sdelphij *ret |= DH_CHECK_PUBKEY_TOO_SMALL; 137296341Sdelphij BN_copy(q, dh->p); 138296341Sdelphij BN_sub_word(q, 1); 139296341Sdelphij if (BN_cmp(pub_key, q) >= 0) 140296341Sdelphij *ret |= DH_CHECK_PUBKEY_TOO_LARGE; 141160814Ssimon 142296341Sdelphij ok = 1; 143296341Sdelphij err: 144296341Sdelphij if (q != NULL) 145296341Sdelphij BN_free(q); 146296341Sdelphij return (ok); 147296341Sdelphij} 148