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 #ifndef OPENSSL_FIPS 66 67 static int generate_key(DH *dh); 68 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); 69 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 70 const BIGNUM *a, const BIGNUM *p, 71 const BIGNUM *m, BN_CTX *ctx, 72 BN_MONT_CTX *m_ctx); 73 static int dh_init(DH *dh); 74 static int dh_finish(DH *dh); 75 76 int DH_generate_key(DH *dh) 77 { 78 return dh->meth->generate_key(dh); 79 } 80 81 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 82 { 83 return dh->meth->compute_key(key, pub_key, dh); 84 } 85 86 static DH_METHOD dh_ossl = { 87 "OpenSSL DH Method", 88 generate_key, 89 compute_key, 90 dh_bn_mod_exp, 91 dh_init, 92 dh_finish, 93 0, 94 NULL 95 }; 96 97 const DH_METHOD *DH_OpenSSL(void) 98 { 99 return &dh_ossl; 100 } 101 102 static int generate_key(DH *dh) 103 { 104 int ok=0; 105 int generate_new_key=0; 106 unsigned l; 107 BN_CTX *ctx; 108 BN_MONT_CTX *mont; 109 BIGNUM *pub_key=NULL,*priv_key=NULL; 110 111 ctx = BN_CTX_new(); 112 if (ctx == NULL) goto err; 113 114 if (dh->priv_key == NULL) 115 { 116 priv_key=BN_new(); 117 if (priv_key == NULL) goto err; 118 generate_new_key=1; 119 } 120 else 121 priv_key=dh->priv_key; 122 123 if (dh->pub_key == NULL) 124 { 125 pub_key=BN_new(); 126 if (pub_key == NULL) goto err; 127 } 128 else 129 pub_key=dh->pub_key; 130 131 if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P)) 132 { 133 if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) 134 if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p, 135 dh->p,ctx)) goto err; 136 } 137 mont=(BN_MONT_CTX *)dh->method_mont_p; 138 139 if (generate_new_key) 140 { 141 l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */ 142 if (!BN_rand(priv_key, l, 0, 0)) goto err; 143 } 144 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, priv_key,dh->p,ctx,mont)) 145 goto err; 146 147 dh->pub_key=pub_key; 148 dh->priv_key=priv_key; 149 ok=1; 150 err: 151 if (ok != 1) 152 DHerr(DH_F_DH_GENERATE_KEY,ERR_R_BN_LIB); 153 154 if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); 155 if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); 156 BN_CTX_free(ctx); 157 return(ok); 158 } 159 160 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 161 { 162 BN_CTX *ctx; 163 BN_MONT_CTX *mont; 164 BIGNUM *tmp; 165 int ret= -1; 166 int check_result; 167 168 ctx = BN_CTX_new(); 169 if (ctx == NULL) goto err; 170 BN_CTX_start(ctx); 171 tmp = BN_CTX_get(ctx); 172 173 if (dh->priv_key == NULL) 174 { 175 DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); 176 goto err; 177 } 178 if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P)) 179 { 180 if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) 181 if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p, 182 dh->p,ctx)) goto err; 183 } 184 185 mont=(BN_MONT_CTX *)dh->method_mont_p; 186 187 if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) 188 { 189 DHerr(DH_F_DH_COMPUTE_KEY,DH_R_INVALID_PUBKEY); 190 goto err; 191 } 192 if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont)) 193 { 194 DHerr(DH_F_DH_COMPUTE_KEY,ERR_R_BN_LIB); 195 goto err; 196 } 197 198 ret=BN_bn2bin(tmp,key); 199 err: 200 BN_CTX_end(ctx); 201 BN_CTX_free(ctx); 202 return(ret); 203 } 204 205 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 206 const BIGNUM *a, const BIGNUM *p, 207 const BIGNUM *m, BN_CTX *ctx, 208 BN_MONT_CTX *m_ctx) 209 { 210 if (a->top == 1) 211 { 212 BN_ULONG A = a->d[0]; 213 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx); 214 } 215 else 216 return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx); 217 } 218 219 220 static int dh_init(DH *dh) 221 { 222 dh->flags |= DH_FLAG_CACHE_MONT_P; 223 return(1); 224 } 225 226 static int dh_finish(DH *dh) 227 { 228 if(dh->method_mont_p) 229 BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p); 230 return(1); 231 } 232 233 #endif 234