264 lines
7.0 KiB
C
264 lines
7.0 KiB
C
/* crypto/dh/dh_key.c */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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#include <stdio.h>
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#include "cryptlib.h"
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#include <openssl/bn.h>
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#include <openssl/rand.h>
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#include <openssl/dh.h>
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static int generate_key(DH *dh);
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static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
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static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
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const BIGNUM *a, const BIGNUM *p,
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const BIGNUM *m, BN_CTX *ctx,
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BN_MONT_CTX *m_ctx);
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static int dh_init(DH *dh);
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static int dh_finish(DH *dh);
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int DH_generate_key(DH *dh)
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{
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return dh->meth->generate_key(dh);
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}
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int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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{
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return dh->meth->compute_key(key, pub_key, dh);
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}
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static DH_METHOD dh_ossl = {
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"OpenSSL DH Method",
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generate_key,
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compute_key,
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dh_bn_mod_exp,
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dh_init,
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dh_finish,
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0,
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NULL,
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NULL
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};
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const DH_METHOD *DH_OpenSSL(void)
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{
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return &dh_ossl;
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}
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static int generate_key(DH *dh)
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{
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int ok=0;
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int generate_new_key=0;
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unsigned l;
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BN_CTX *ctx;
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BN_MONT_CTX *mont=NULL;
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BIGNUM *pub_key=NULL,*priv_key=NULL;
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ctx = BN_CTX_new();
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if (ctx == NULL) goto err;
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if (dh->priv_key == NULL)
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{
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priv_key=BN_new();
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if (priv_key == NULL) goto err;
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generate_new_key=1;
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}
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else
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priv_key=dh->priv_key;
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if (dh->pub_key == NULL)
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{
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pub_key=BN_new();
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if (pub_key == NULL) goto err;
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}
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else
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pub_key=dh->pub_key;
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if (dh->flags & DH_FLAG_CACHE_MONT_P)
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{
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mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
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CRYPTO_LOCK_DH, dh->p, ctx);
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if (!mont)
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goto err;
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}
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if (generate_new_key)
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{
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l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */
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if (!BN_rand(priv_key, l, 0, 0)) goto err;
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}
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{
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BIGNUM local_prk;
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BIGNUM *prk;
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if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
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{
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BN_init(&local_prk);
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prk = &local_prk;
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BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
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}
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else
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prk = priv_key;
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if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err;
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}
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dh->pub_key=pub_key;
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dh->priv_key=priv_key;
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ok=1;
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err:
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if (ok != 1)
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DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB);
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if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key);
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if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);
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BN_CTX_free(ctx);
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return(ok);
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}
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static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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{
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BN_CTX *ctx=NULL;
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BN_MONT_CTX *mont=NULL;
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BIGNUM *tmp;
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int ret= -1;
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int check_result;
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if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS)
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{
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DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE);
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goto err;
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}
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ctx = BN_CTX_new();
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if (ctx == NULL) goto err;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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if (dh->priv_key == NULL)
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{
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DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
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goto err;
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}
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if (dh->flags & DH_FLAG_CACHE_MONT_P)
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{
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mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
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CRYPTO_LOCK_DH, dh->p, ctx);
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if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
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{
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/* XXX */
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BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
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}
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if (!mont)
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goto err;
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}
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if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)
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{
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DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY);
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goto err;
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}
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if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont))
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{
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DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB);
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goto err;
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}
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ret=BN_bn2bin(tmp,key);
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err:
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if (ctx != NULL)
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{
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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return(ret);
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}
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static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
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const BIGNUM *a, const BIGNUM *p,
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const BIGNUM *m, BN_CTX *ctx,
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BN_MONT_CTX *m_ctx)
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{
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/* If a is only one word long and constant time is false, use the faster
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* exponenentiation function.
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*/
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if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0))
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{
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BN_ULONG A = a->d[0];
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return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);
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}
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else
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return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);
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}
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static int dh_init(DH *dh)
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{
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dh->flags |= DH_FLAG_CACHE_MONT_P;
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return(1);
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}
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static int dh_finish(DH *dh)
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{
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if(dh->method_mont_p)
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BN_MONT_CTX_free(dh->method_mont_p);
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return(1);
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}
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