/* crypto/dsa/dsa_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.]

 */

#include <stdio.h>

#include <time.h>

#include "cryptlib.h"

#ifndef OPENSSL_NO_SHA

#include <openssl/bn.h>

#include <openssl/dsa.h>

#include <openssl/rand.h>

static int dsa_builtin_keygen(DSA *dsa);

EXPORT_C int DSA_generate_key(DSA *dsa)

	{

	if(dsa->meth->dsa_keygen)

		return dsa->meth->dsa_keygen(dsa);

	return dsa_builtin_keygen(dsa);

	}

static int dsa_builtin_keygen(DSA *dsa)

	{

	int ok=0;

	BN_CTX *ctx=NULL;

	BIGNUM *pub_key=NULL,*priv_key=NULL;

	if ((ctx=BN_CTX_new()) == NULL) goto err;

	if (dsa->priv_key == NULL)

		{

		if ((priv_key=BN_new()) == NULL) goto err;

		}

	else

		priv_key=dsa->priv_key;

	do

		if (!BN_rand_range(priv_key,dsa->q)) goto err;

	while (BN_is_zero(priv_key));

	if (dsa->pub_key == NULL)

		{

		if ((pub_key=BN_new()) == NULL) goto err;

		}

	else

		pub_key=dsa->pub_key;

	{

		BIGNUM local_prk;

		BIGNUM *prk;

		if ((dsa->flags & DSA_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 (!BN_mod_exp(pub_key,dsa->g,prk,dsa->p,ctx)) goto err;

	}

	dsa->priv_key=priv_key;

	dsa->pub_key=pub_key;

	ok=1;

err:

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

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

	if (ctx != NULL) BN_CTX_free(ctx);

	return(ok);

	}

#endif