/* crypto/dh/dh_key.c */

 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

  * All rights reserved.

  *

  * This package is an SSL implementation written

  * by Eric Young (eay@cryptsoft.com).

  * The implementation was written so as to conform with Netscapes SSL.

  * 

  * This library is free for commercial and non-commercial use as long as

  * the following conditions are aheared to.  The following conditions

  * apply to all code found in this distribution, be it the RC4, RSA,

  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

  * included with this distribution is covered by the same copyright terms

  * except that the holder is Tim Hudson (tjh@cryptsoft.com).

  * 

  * Copyright remains Eric Young's, and as such any Copyright notices in

  * the code are not to be removed.

  * If this package is used in a product, Eric Young should be given attribution

  * as the author of the parts of the library used.

  * This can be in the form of a textual message at program startup or

  * in documentation (online or textual) provided with the package.

  * 

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  * 3. All advertising materials mentioning features or use of this software

  *    must display the following acknowledgement:

  *    "This product includes cryptographic software written by

  *     Eric Young (eay@cryptsoft.com)"

  *    The word 'cryptographic' can be left out if the rouines from the library

  *    being used are not cryptographic related :-).

  * 4. If you include any Windows specific code (or a derivative thereof) from 

  *    the apps directory (application code) you must include an acknowledgement:

  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

  * 

  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  * SUCH DAMAGE.

  * 

  * The licence and distribution terms for any publically available version or

  * derivative of this code cannot be changed.  i.e. this code cannot simply be

  * copied and put under another distribution licence

  * [including the GNU Public Licence.]

  */

 /*

  © Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

  */

 #include <stdio.h>

 #include "cryptlib.h"

 #include <openssl/bn.h>

 #include <openssl/rand.h>

 #include <openssl/dh.h>

 #if (defined(SYMBIAN) && (defined(__WINSCW__) || defined(__WINS__)))

 #include "libcrypto_wsd_macros.h"

 #include "libcrypto_wsd.h"

 #endif

 static int generate_key(DH *dh);

 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);

 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,

 			const BIGNUM *a, const BIGNUM *p,

 			const BIGNUM *m, BN_CTX *ctx,

 			BN_MONT_CTX *m_ctx);

 static int dh_init(DH *dh);

 static int dh_finish(DH *dh);

 EXPORT_C int DH_generate_key(DH *dh)

 	{

 	return dh->meth->generate_key(dh);

 	}

 EXPORT_C int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)

 	{

 	return dh->meth->compute_key(key, pub_key, dh);

 	}

 #ifndef EMULATOR

 static DH_METHOD dh_ossl = {

 "OpenSSL DH Method",

 generate_key,

 compute_key,

 dh_bn_mod_exp,

 dh_init,

 dh_finish,

 0,

 NULL,

 NULL

 };

 #else

 GET_STATIC_VAR_FROM_TLS(dh_ossl,dh_key,DH_METHOD)

 #define dh_ossl (*GET_WSD_VAR_NAME(dh_ossl,dh_key, s)())

 const DH_METHOD temp_s_dh_ossl = {

 "OpenSSL DH Method",

 generate_key,

 compute_key,

 dh_bn_mod_exp,

 dh_init,

 dh_finish,

 0,

 NULL,

 NULL

 };

 #endif

 EXPORT_C const DH_METHOD *DH_OpenSSL(void)

 {

 	return &dh_ossl;

 }

 static int generate_key(DH *dh)

 	{

 	int ok=0;

 	int generate_new_key=0;

 	unsigned l;

 	BN_CTX *ctx;

 	BN_MONT_CTX *mont=NULL;

 	BIGNUM *pub_key=NULL,*priv_key=NULL;

 	ctx = BN_CTX_new();

 	if (ctx == NULL) goto err;

 	if (dh->priv_key == NULL)

 		{

 		priv_key=BN_new();

 		if (priv_key == NULL) goto err;

 		generate_new_key=1;

 		}

 	else

 		priv_key=dh->priv_key;

 	if (dh->pub_key == NULL)

 		{

 		pub_key=BN_new();

 		if (pub_key == NULL) goto err;

 		}

 	else

 		pub_key=dh->pub_key;

 	if (dh->flags & DH_FLAG_CACHE_MONT_P)

 		{

 		mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,

 				CRYPTO_LOCK_DH, dh->p, ctx);

 		if (!mont)

 			goto err;

 		}

 	if (generate_new_key)

 		{

 		l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */

 		if (!BN_rand(priv_key, l, 0, 0)) goto err;

 		}

 	{

 		BIGNUM local_prk;

 		BIGNUM *prk;

 		if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)

 			{

 			BN_init(&local_prk);

 			prk = &local_prk;

 			BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);

 			}

 		else

 			prk = priv_key;

 		if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err;

 	}

 	dh->pub_key=pub_key;

 	dh->priv_key=priv_key;

 	ok=1;

 err:

 	if (ok != 1)

 		DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB);

 	if ((pub_key != NULL)  && (dh->pub_key == NULL))  BN_free(pub_key);

 	if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);

 	BN_CTX_free(ctx);

 	return(ok);

 	}

 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)

 	{

 	BN_CTX *ctx=NULL;

 	BN_MONT_CTX *mont=NULL;

 	BIGNUM *tmp;

 	int ret= -1;

         int check_result;

 	if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS)

 		{

 		DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE);

 		goto err;

 		}

 	ctx = BN_CTX_new();

 	if (ctx == NULL) goto err;

 	BN_CTX_start(ctx);

 	tmp = BN_CTX_get(ctx);

 	if (dh->priv_key == NULL)

 		{

 		DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);

 		goto err;

 		}

 	if (dh->flags & DH_FLAG_CACHE_MONT_P)

 		{

 		mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,

 				CRYPTO_LOCK_DH, dh->p, ctx);

 		if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)

 			{

 			/* XXX */

 			BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);

 			}

 		if (!mont)

 			goto err;

 		}

         if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)

 		{

 		DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY);

 		goto err;

 		}

 	if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont))

 		{

 		DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB);

 		goto err;

 		}

 	ret=BN_bn2bin(tmp,key);

 err:

 	if (ctx != NULL)

 		{

 		BN_CTX_end(ctx);

 		BN_CTX_free(ctx);

 		}

 	return(ret);

 	}

 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,

 			const BIGNUM *a, const BIGNUM *p,

 			const BIGNUM *m, BN_CTX *ctx,

 			BN_MONT_CTX *m_ctx)

 	{

 	/* If a is only one word long and constant time is false, use the faster

 	 * exponenentiation function.

 	 */

 	if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0))

 		{

 		BN_ULONG A = a->d[0];

 		return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);

 		}

 	else

 		return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);

 	}

 static int dh_init(DH *dh)

 	{

 	dh->flags |= DH_FLAG_CACHE_MONT_P;

 	return(1);

 	}

 static int dh_finish(DH *dh)

 	{

 	if(dh->method_mont_p)

 		BN_MONT_CTX_free(dh->method_mont_p);

 	return(1);

 	}