/* 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"
#include <openssl/sha.h>
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rand.h>

int DSA_generate_key(DSA *dsa)
	{
	int ok=0;
	unsigned int i;
	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;

	i=BN_num_bits(dsa->q);
	for (;;)
		{
		BN_rand(priv_key,i,1,0);
		if (BN_cmp(priv_key,dsa->q) >= 0)
			BN_sub(priv_key,priv_key,dsa->q);
		if (!BN_is_zero(priv_key)) break;
		}

	if (dsa->pub_key == NULL)
		{
		if ((pub_key=BN_new()) == NULL) goto err;
		}
	else
		pub_key=dsa->pub_key;

	if (!BN_mod_exp(pub_key,dsa->g,priv_key,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);
	}