release/src/router/openssl/crypto/dh/dh_key.c

   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 #ifdef OPENSSL_FIPS
  77         if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD)
  78                         && !(dh->flags & DH_FLAG_NON_FIPS_ALLOW))
  79                 {
  80                 DHerr(DH_F_DH_GENERATE_KEY, DH_R_NON_FIPS_METHOD);
  81                 return 0;
  82                 }
  83 #endif
  84         return dh->meth->generate_key(dh);
  85         }
  86
  87 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
  88         {
  89 #ifdef OPENSSL_FIPS
  90         if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD)
  91                         && !(dh->flags & DH_FLAG_NON_FIPS_ALLOW))
  92                 {
  93                 DHerr(DH_F_DH_COMPUTE_KEY, DH_R_NON_FIPS_METHOD);
  94                 return 0;
  95                 }
  96 #endif
  97         return dh->meth->compute_key(key, pub_key, dh);
  98         }
  99
 100 static DH_METHOD dh_ossl = {
 101 "OpenSSL DH Method",
 102 generate_key,
 103 compute_key,
 104 dh_bn_mod_exp,
 105 dh_init,
 106 dh_finish,
 107 0,
 108 NULL,
 109 NULL
 110 };
 111
 112 const DH_METHOD *DH_OpenSSL(void)
 113 {
 114         return &dh_ossl;
 115 }
 116
 117 static int generate_key(DH *dh)
 118         {
 119         int ok=0;
 120         int generate_new_key=0;
 121         unsigned l;
 122         BN_CTX *ctx;
 123         BN_MONT_CTX *mont=NULL;
 124         BIGNUM *pub_key=NULL,*priv_key=NULL;
 125
 126         ctx = BN_CTX_new();
 127         if (ctx == NULL) goto err;
 128
 129         if (dh->priv_key == NULL)
 130                 {
 131                 priv_key=BN_new();
 132                 if (priv_key == NULL) goto err;
 133                 generate_new_key=1;
 134                 }
 135         else
 136                 priv_key=dh->priv_key;
 137
 138         if (dh->pub_key == NULL)
 139                 {
 140                 pub_key=BN_new();
 141                 if (pub_key == NULL) goto err;
 142                 }
 143         else
 144                 pub_key=dh->pub_key;
 145
 146
 147         if (dh->flags & DH_FLAG_CACHE_MONT_P)
 148                 {
 149                 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
 150                                 CRYPTO_LOCK_DH, dh->p, ctx);
 151                 if (!mont)
 152                         goto err;
 153                 }
 154
 155         if (generate_new_key)
 156                 {
 157                 if (dh->q)
 158                         {
 159                         do
 160                                 {
 161                                 if (!BN_rand_range(priv_key, dh->q))
 162                                         goto err;
 163                                 }
 164                         while (BN_is_zero(priv_key) || BN_is_one(priv_key));
 165                         }
 166                 else
 167                         {
 168                         /* secret exponent length */
 169                         l = dh->length ? dh->length : BN_num_bits(dh->p)-1;
 170                         if (!BN_rand(priv_key, l, 0, 0)) goto err;
 171                         }
 172                 }
 173
 174         {
 175                 BIGNUM local_prk;
 176                 BIGNUM *prk;
 177
 178                 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
 179                         {
 180                         BN_init(&local_prk);
 181                         prk = &local_prk;
 182                         BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
 183                         }
 184                 else
 185                         prk = priv_key;
 186
 187                 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err;
 188         }
 189
 190         dh->pub_key=pub_key;
 191         dh->priv_key=priv_key;
 192         ok=1;
 193 err:
 194         if (ok != 1)
 195                 DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB);
 196
 197         if ((pub_key != NULL)  && (dh->pub_key == NULL))  BN_free(pub_key);
 198         if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);
 199         BN_CTX_free(ctx);
 200         return(ok);
 201         }
 202
 203 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
 204         {
 205         BN_CTX *ctx=NULL;
 206         BN_MONT_CTX *mont=NULL;
 207         BIGNUM *tmp;
 208         int ret= -1;
 209         int check_result;
 210
 211         if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS)
 212                 {
 213                 DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE);
 214                 goto err;
 215                 }
 216
 217         ctx = BN_CTX_new();
 218         if (ctx == NULL) goto err;
 219         BN_CTX_start(ctx);
 220         tmp = BN_CTX_get(ctx);
 221
 222         if (dh->priv_key == NULL)
 223                 {
 224                 DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
 225                 goto err;
 226                 }
 227
 228         if (dh->flags & DH_FLAG_CACHE_MONT_P)
 229                 {
 230                 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
 231                                 CRYPTO_LOCK_DH, dh->p, ctx);
 232                 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
 233                         {
 234                         /* XXX */
 235                         BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
 236                         }
 237                 if (!mont)
 238                         goto err;
 239                 }
 240
 241         if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)
 242                 {
 243                 DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY);
 244                 goto err;
 245                 }
 246
 247         if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont))
 248                 {
 249                 DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB);
 250                 goto err;
 251                 }
 252
 253         ret=BN_bn2bin(tmp,key);
 254 err:
 255         if (ctx != NULL)
 256                 {
 257                 BN_CTX_end(ctx);
 258                 BN_CTX_free(ctx);
 259                 }
 260         return(ret);
 261         }
 262
 263 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
 264                         const BIGNUM *a, const BIGNUM *p,
 265                         const BIGNUM *m, BN_CTX *ctx,
 266                         BN_MONT_CTX *m_ctx)
 267         {
 268         /* If a is only one word long and constant time is false, use the faster
 269          * exponenentiation function.
 270          */
 271         if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0))
 272                 {
 273                 BN_ULONG A = a->d[0];
 274                 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);
 275                 }
 276         else
 277                 return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);
 278         }
 279
 280
 281 static int dh_init(DH *dh)
 282         {
 283         dh->flags |= DH_FLAG_CACHE_MONT_P;
 284         return(1);
 285         }
 286
 287 static int dh_finish(DH *dh)
 288         {
 289         if(dh->method_mont_p)
 290                 BN_MONT_CTX_free(dh->method_mont_p);
 291         return(1);
 292         }