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 static int generate_key(DH *dh); 66 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); 67 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 68 const BIGNUM *a, const BIGNUM *p, 69 const BIGNUM *m, BN_CTX *ctx, 70 BN_MONT_CTX *m_ctx); 71 static int dh_init(DH *dh); 72 static int dh_finish(DH *dh); 73 74 int DH_generate_key(DH *dh) 75 { 76 return dh->meth->generate_key(dh); 77 } 78 79 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 80 { 81 return dh->meth->compute_key(key, pub_key, dh); 82 } 83 84 static DH_METHOD dh_ossl = { 85 "OpenSSL DH Method", 86 generate_key, 87 compute_key, 88 dh_bn_mod_exp, 89 dh_init, 90 dh_finish, 91 0, 92 NULL 93 }; 94 95 const DH_METHOD *DH_OpenSSL(void) 96 { 97 return &dh_ossl; 98 } 99 100 static int generate_key(DH *dh) 101 { 102 int ok=0; 103 int generate_new_key=0; 104 unsigned l; 105 BN_CTX *ctx; 106 BN_MONT_CTX *mont; 107 BIGNUM *pub_key=NULL,*priv_key=NULL; 108 109 ctx = BN_CTX_new(); 110 if (ctx == NULL) goto err; 111 112 if (dh->priv_key == NULL) 113 { 114 priv_key=BN_new(); 115 if (priv_key == NULL) goto err; 116 generate_new_key=1; 117 } 118 else 119 priv_key=dh->priv_key; 120 121 if (dh->pub_key == NULL) 122 { 123 pub_key=BN_new(); 124 if (pub_key == NULL) goto err; 125 } 126 else 127 pub_key=dh->pub_key; 128 129 if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P)) 130 { 131 if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) 132 if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p, 133 dh->p,ctx)) goto err; 134 } 135 mont=(BN_MONT_CTX *)dh->method_mont_p; 136 137 if (generate_new_key) 138 { 139 l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */ 140 if (!BN_rand(priv_key, l, 0, 0)) goto err; 141 } 142 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, priv_key,dh->p,ctx,mont)) 143 goto err; 144 145 dh->pub_key=pub_key; 146 dh->priv_key=priv_key; 147 ok=1; 148 err: 149 if (ok != 1) 150 DHerr(DH_F_DH_GENERATE_KEY,ERR_R_BN_LIB); 151 152 if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); 153 if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); 154 BN_CTX_free(ctx); 155 return(ok); 156 } 157 158 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 159 { 160 BN_CTX *ctx; 161 BN_MONT_CTX *mont; 162 BIGNUM *tmp; 163 int ret= -1; 164 165 ctx = BN_CTX_new(); 166 if (ctx == NULL) goto err; 167 BN_CTX_start(ctx); 168 tmp = BN_CTX_get(ctx); 169 170 if (dh->priv_key == NULL) 171 { 172 DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); 173 goto err; 174 } 175 if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P)) 176 { 177 if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) 178 if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p, 179 dh->p,ctx)) goto err; 180 } 181 182 mont=(BN_MONT_CTX *)dh->method_mont_p; 183 if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont)) 184 { 185 DHerr(DH_F_DH_COMPUTE_KEY,ERR_R_BN_LIB); 186 goto err; 187 } 188 189 ret=BN_bn2bin(tmp,key); 190 err: 191 BN_CTX_end(ctx); 192 BN_CTX_free(ctx); 193 return(ret); 194 } 195 196 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 197 const BIGNUM *a, const BIGNUM *p, 198 const BIGNUM *m, BN_CTX *ctx, 199 BN_MONT_CTX *m_ctx) 200 { 201 if (a->top == 1) 202 { 203 BN_ULONG A = a->d[0]; 204 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx); 205 } 206 else 207 return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx); 208 } 209 210 211 static int dh_init(DH *dh) 212 { 213 dh->flags |= DH_FLAG_CACHE_MONT_P; 214 return(1); 215 } 216 217 static int dh_finish(DH *dh) 218 { 219 if(dh->method_mont_p) 220 BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p); 221 return(1); 222 } 223