release/src-rt-6.x.4708/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, BN_MONT_CTX *m_ctx);
  70 static int dh_init(DH *dh);
  71 static int dh_finish(DH *dh);
  72
  73 int DH_generate_key(DH *dh)
  74 {
  75 #ifdef OPENSSL_FIPS
  76     if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD)
  77         && !(dh->flags & DH_FLAG_NON_FIPS_ALLOW)) {
  78         DHerr(DH_F_DH_GENERATE_KEY, DH_R_NON_FIPS_METHOD);
  79         return 0;
  80     }
  81 #endif
  82     return dh->meth->generate_key(dh);
  83 }
  84
  85 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
  86 {
  87 #ifdef OPENSSL_FIPS
  88     if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD)
  89         && !(dh->flags & DH_FLAG_NON_FIPS_ALLOW)) {
  90         DHerr(DH_F_DH_COMPUTE_KEY, DH_R_NON_FIPS_METHOD);
  91         return 0;
  92     }
  93 #endif
  94     return dh->meth->compute_key(key, pub_key, dh);
  95 }
  96
  97 int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
  98 {
  99     int rv, pad;
 100     rv = dh->meth->compute_key(key, pub_key, dh);
 101     if (rv <= 0)
 102         return rv;
 103     pad = BN_num_bytes(dh->p) - rv;
 104     if (pad > 0) {
 105         memmove(key + pad, key, rv);
 106         memset(key, 0, pad);
 107     }
 108     return rv + pad;
 109 }
 110
 111 static DH_METHOD dh_ossl = {
 112     "OpenSSL DH Method",
 113     generate_key,
 114     compute_key,
 115     dh_bn_mod_exp,
 116     dh_init,
 117     dh_finish,
 118     0,
 119     NULL,
 120     NULL
 121 };
 122
 123 const DH_METHOD *DH_OpenSSL(void)
 124 {
 125     return &dh_ossl;
 126 }
 127
 128 static int generate_key(DH *dh)
 129 {
 130     int ok = 0;
 131     int generate_new_key = 0;
 132     unsigned l;
 133     BN_CTX *ctx;
 134     BN_MONT_CTX *mont = NULL;
 135     BIGNUM *pub_key = NULL, *priv_key = NULL;
 136
 137     ctx = BN_CTX_new();
 138     if (ctx == NULL)
 139         goto err;
 140
 141     if (dh->priv_key == NULL) {
 142         priv_key = BN_new();
 143         if (priv_key == NULL)
 144             goto err;
 145         generate_new_key = 1;
 146     } else
 147         priv_key = dh->priv_key;
 148
 149     if (dh->pub_key == NULL) {
 150         pub_key = BN_new();
 151         if (pub_key == NULL)
 152             goto err;
 153     } else
 154         pub_key = dh->pub_key;
 155
 156     if (dh->flags & DH_FLAG_CACHE_MONT_P) {
 157         mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
 158                                       CRYPTO_LOCK_DH, dh->p, ctx);
 159         if (!mont)
 160             goto err;
 161     }
 162
 163     if (generate_new_key) {
 164         if (dh->q) {
 165             do {
 166                 if (!BN_rand_range(priv_key, dh->q))
 167                     goto err;
 168             }
 169             while (BN_is_zero(priv_key) || BN_is_one(priv_key));
 170         } else {
 171             /* secret exponent length */
 172             l = dh->length ? dh->length : BN_num_bits(dh->p) - 1;
 173             if (!BN_rand(priv_key, l, 0, 0))
 174                 goto err;
 175         }
 176     }
 177
 178     {
 179         BIGNUM local_prk;
 180         BIGNUM *prk;
 181
 182         if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) {
 183             BN_init(&local_prk);
 184             prk = &local_prk;
 185             BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
 186         } else
 187             prk = priv_key;
 188
 189         if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont))
 190             goto err;
 191     }
 192
 193     dh->pub_key = pub_key;
 194     dh->priv_key = priv_key;
 195     ok = 1;
 196  err:
 197     if (ok != 1)
 198         DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB);
 199
 200     if ((pub_key != NULL) && (dh->pub_key == NULL))
 201         BN_free(pub_key);
 202     if ((priv_key != NULL) && (dh->priv_key == NULL))
 203         BN_free(priv_key);
 204     BN_CTX_free(ctx);
 205     return (ok);
 206 }
 207
 208 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
 209 {
 210     BN_CTX *ctx = NULL;
 211     BN_MONT_CTX *mont = NULL;
 212     BIGNUM *tmp;
 213     int ret = -1;
 214     int check_result;
 215
 216     if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
 217         DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE);
 218         goto err;
 219     }
 220
 221     ctx = BN_CTX_new();
 222     if (ctx == NULL)
 223         goto err;
 224     BN_CTX_start(ctx);
 225     tmp = BN_CTX_get(ctx);
 226
 227     if (dh->priv_key == NULL) {
 228         DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE);
 229         goto err;
 230     }
 231
 232     if (dh->flags & DH_FLAG_CACHE_MONT_P) {
 233         mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
 234                                       CRYPTO_LOCK_DH, dh->p, ctx);
 235         if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) {
 236             /* XXX */
 237             BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
 238         }
 239         if (!mont)
 240             goto err;
 241     }
 242
 243     if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
 244         DHerr(DH_F_COMPUTE_KEY, DH_R_INVALID_PUBKEY);
 245         goto err;
 246     }
 247
 248     if (!dh->
 249         meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) {
 250         DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
 251         goto err;
 252     }
 253
 254     ret = BN_bn2bin(tmp, key);
 255  err:
 256     if (ctx != NULL) {
 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, BN_MONT_CTX *m_ctx)
 266 {
 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         BN_ULONG A = a->d[0];
 273         return BN_mod_exp_mont_word(r, A, p, m, ctx, m_ctx);
 274     } else
 275         return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
 276 }
 277
 278 static int dh_init(DH *dh)
 279 {
 280     dh->flags |= DH_FLAG_CACHE_MONT_P;
 281     return (1);
 282 }
 283
 284 static int dh_finish(DH *dh)
 285 {
 286     if (dh->method_mont_p)
 287         BN_MONT_CTX_free(dh->method_mont_p);
 288     return (1);
 289 }