1 /* crypto/dh/dh_key.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/rand.h> 63 #include <openssl/dh.h> 64 65 int DH_generate_key(DH *dh) 66 { 67 int ok=0; 68 unsigned int i; 69 BN_CTX ctx; 70 BN_MONT_CTX *mont; 71 BIGNUM *pub_key=NULL,*priv_key=NULL; 72 73 BN_CTX_init(&ctx); 74 75 if (dh->priv_key == NULL) 76 { 77 i=dh->length; 78 if (i == 0) 79 { 80 /* Make the number p-1 bits long */ 81 i=BN_num_bits(dh->p)-1; 82 } 83 priv_key=BN_new(); 84 if (priv_key == NULL) goto err; 85 if (!BN_rand(priv_key,i,0,0)) goto err; 86 } 87 else 88 priv_key=dh->priv_key; 89 90 if (dh->pub_key == NULL) 91 { 92 pub_key=BN_new(); 93 if (pub_key == NULL) goto err; 94 } 95 else 96 pub_key=dh->pub_key; 97 98 if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P)) 99 { 100 if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) 101 if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p, 102 dh->p,&ctx)) goto err; 103 } 104 mont=(BN_MONT_CTX *)dh->method_mont_p; 105 106 if (!BN_mod_exp_mont(pub_key,dh->g,priv_key,dh->p,&ctx,mont)) goto err; 107 108 dh->pub_key=pub_key; 109 dh->priv_key=priv_key; 110 ok=1; 111 err: 112 if (ok != 1) 113 DHerr(DH_F_DH_GENERATE_KEY,ERR_R_BN_LIB); 114 115 if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); 116 if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); 117 BN_CTX_free(&ctx); 118 return(ok); 119 } 120 121 int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh) 122 { 123 BN_CTX ctx; 124 BN_MONT_CTX *mont; 125 BIGNUM *tmp; 126 int ret= -1; 127 128 BN_CTX_init(&ctx); 129 tmp= &(ctx.bn[ctx.tos++]); 130 131 if (dh->priv_key == NULL) 132 { 133 DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); 134 goto err; 135 } 136 if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P)) 137 { 138 if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) 139 if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p, 140 dh->p,&ctx)) goto err; 141 } 142 143 mont=(BN_MONT_CTX *)dh->method_mont_p; 144 if (!BN_mod_exp_mont(tmp,pub_key,dh->priv_key,dh->p,&ctx,mont)) 145 { 146 DHerr(DH_F_DH_COMPUTE_KEY,ERR_R_BN_LIB); 147 goto err; 148 } 149 150 ret=BN_bn2bin(tmp,key); 151 err: 152 BN_CTX_free(&ctx); 153 return(ret); 154 } 155