/* 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