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 <openssl/err.h> 61#include <openssl/bn.h> 62#ifndef OPENSSL_NO_RAND 63#include <openssl/rand.h> 64#endif 65#ifndef OPENSSL_NO_DH 66#include <openssl/dh.h> 67#include <openssl/fips.h> 68 69#ifdef OPENSSL_FIPS 70 71static int generate_key(DH *dh); 72static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); 73static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 74 const BIGNUM *a, const BIGNUM *p, 75 const BIGNUM *m, BN_CTX *ctx, 76 BN_MONT_CTX *m_ctx); 77static int dh_init(DH *dh); 78static int dh_finish(DH *dh); 79 80int DH_generate_key(DH *dh) 81 { 82 return dh->meth->generate_key(dh); 83 } 84 85int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 86 { 87 return dh->meth->compute_key(key, pub_key, dh); 88 } 89 90static const DH_METHOD dh_ossl = { 91"OpenSSL DH Method", 92generate_key, 93compute_key, 94dh_bn_mod_exp, 95dh_init, 96dh_finish, 970, 98NULL 99}; 100 101const DH_METHOD *DH_OpenSSL(void) 102{ 103 return &dh_ossl; 104} 105 106static int generate_key(DH *dh) 107 { 108 int ok=0; 109 int generate_new_key=0; 110 unsigned l; 111 BN_CTX *ctx; 112 BN_MONT_CTX *mont=NULL; 113 BIGNUM *pub_key=NULL,*priv_key=NULL; 114 115 if (FIPS_mode() && (BN_num_bits(dh->p) < OPENSSL_DH_FIPS_MIN_MODULUS_BITS)) 116 { 117 DHerr(DH_F_GENERATE_KEY, DH_R_KEY_SIZE_TOO_SMALL); 118 return 0; 119 } 120 121 ctx = BN_CTX_new(); 122 if (ctx == NULL) goto err; 123 124 if (dh->priv_key == NULL) 125 { 126 priv_key=BN_new(); 127 if (priv_key == NULL) goto err; 128 generate_new_key=1; 129 } 130 else 131 priv_key=dh->priv_key; 132 133 if (dh->pub_key == NULL) 134 { 135 pub_key=BN_new(); 136 if (pub_key == NULL) goto err; 137 } 138 else 139 pub_key=dh->pub_key; 140 141 if (dh->flags & DH_FLAG_CACHE_MONT_P) 142 { 143 mont = BN_MONT_CTX_set_locked( 144 (BN_MONT_CTX **)&dh->method_mont_p, 145 CRYPTO_LOCK_DH, dh->p, ctx); 146 if (!mont) 147 goto err; 148 } 149 150 if (generate_new_key) 151 { 152 l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */ 153 if (!BN_rand(priv_key, l, 0, 0)) goto err; 154 } 155 156 { 157 BIGNUM local_prk; 158 BIGNUM *prk; 159 160 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) 161 { 162 BN_init(&local_prk); 163 prk = &local_prk; 164 BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME); 165 } 166 else 167 prk = priv_key; 168 169 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) 170 goto err; 171 } 172 173 dh->pub_key=pub_key; 174 dh->priv_key=priv_key; 175 ok=1; 176err: 177 if (ok != 1) 178 DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB); 179 180 if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); 181 if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); 182 BN_CTX_free(ctx); 183 return(ok); 184 } 185 186static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 187 { 188 BN_CTX *ctx; 189 BN_MONT_CTX *mont=NULL; 190 BIGNUM *tmp; 191 int ret= -1; 192 193 ctx = BN_CTX_new(); 194 if (ctx == NULL) goto err; 195 BN_CTX_start(ctx); 196 tmp = BN_CTX_get(ctx); 197 198 if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) 199 { 200 DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE); 201 goto err; 202 } 203 204 if (FIPS_mode() && (BN_num_bits(dh->p) < OPENSSL_DH_FIPS_MIN_MODULUS_BITS)) 205 { 206 DHerr(DH_F_COMPUTE_KEY, DH_R_KEY_SIZE_TOO_SMALL); 207 goto err; 208 } 209 210 if (dh->priv_key == NULL) 211 { 212 DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); 213 goto err; 214 } 215 216 if (dh->flags & DH_FLAG_CACHE_MONT_P) 217 { 218 mont = BN_MONT_CTX_set_locked( 219 (BN_MONT_CTX **)&dh->method_mont_p, 220 CRYPTO_LOCK_DH, dh->p, ctx); 221 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) 222 { 223 /* XXX */ 224 BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME); 225 } 226 if (!mont) 227 goto err; 228 } 229 230 if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont)) 231 { 232 DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB); 233 goto err; 234 } 235 236 ret=BN_bn2bin(tmp,key); 237err: 238 BN_CTX_end(ctx); 239 BN_CTX_free(ctx); 240 return(ret); 241 } 242 243static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 244 const BIGNUM *a, const BIGNUM *p, 245 const BIGNUM *m, BN_CTX *ctx, 246 BN_MONT_CTX *m_ctx) 247 { 248 /* If a is only one word long and constant time is false, use the faster 249 * exponenentiation function. 250 */ 251 if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0)) 252 { 253 BN_ULONG A = a->d[0]; 254 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx); 255 } 256 else 257 return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx); 258 } 259 260 261static int dh_init(DH *dh) 262 { 263 FIPS_selftest_check(); 264 dh->flags |= DH_FLAG_CACHE_MONT_P; 265 return(1); 266 } 267 268static int dh_finish(DH *dh) 269 { 270 if(dh->method_mont_p) 271 BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p); 272 return(1); 273 } 274 275#endif 276#endif 277