crypto/ecdsa/ecs_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 "cryptlib.h"
#include <openssl/ecdsa.h>

int ECDSA_generate_key(ECDSA *ecdsa)
{	
	int ok=0;
	BN_CTX *ctx=NULL;
	BIGNUM *priv_key=NULL,*order=NULL;
	EC_POINT *pub_key=NULL;

	if (!ecdsa || !ecdsa->group)
	{
		ECDSAerr(ECDSA_F_ECDSA_GENERATE_KEY,ECDSA_R_MISSING_PARAMETERS);
		return 0;
	}

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

	if (ecdsa->priv_key == NULL)
	{
		if ((priv_key = BN_new()) == NULL) goto err;
	}
	else
		priv_key = ecdsa->priv_key;

	if (!EC_GROUP_get_order(ecdsa->group, order, ctx)) goto err;
	do
		if (!BN_rand_range(priv_key, order)) goto err;
	while (BN_is_zero(priv_key));

	if (ecdsa->pub_key == NULL)
	{
		if ((pub_key = EC_POINT_new(ecdsa->group)) == NULL) goto err;
	}
	else
		pub_key = ecdsa->pub_key;

	if (!EC_POINT_copy(pub_key, EC_GROUP_get0_generator(ecdsa->group))) goto err;
	if (!EC_POINT_mul(ecdsa->group, pub_key, priv_key, NULL, NULL, ctx)) goto err;

	ecdsa->priv_key = priv_key;
	ecdsa->pub_key  = pub_key;
	ok=1;
err:	if (order)	BN_free(order);
	if ((pub_key  != NULL) && (ecdsa->pub_key  == NULL)) EC_POINT_free(pub_key);
	if ((priv_key != NULL) && (ecdsa->priv_key == NULL)) BN_free(priv_key);
	if (ctx != NULL) BN_CTX_free(ctx);
	return(ok);
}

int ECDSA_check_key(ECDSA *ecdsa)
{
	int ok=0;
	BN_CTX *ctx=NULL;
	BIGNUM *order=NULL;
	EC_POINT *point=NULL;

	if (!ecdsa || !ecdsa->group || !ecdsa->pub_key)
		return 0;
	
	if ((ctx = BN_CTX_new()) == NULL) goto err;
	if ((order = BN_new()) == NULL) goto err;
	if ((point = EC_POINT_new(ecdsa->group)) == NULL) goto err;

	/* testing whether pub_key is a valid point on the elliptic curve */
	if (!EC_POINT_is_on_curve(ecdsa->group,ecdsa->pub_key,ctx)) goto err;
	/* testing whether pub_key * order is the point at infinity */
	if (!EC_GROUP_get_order(ecdsa->group,order,ctx)) goto err;
	if (!EC_POINT_copy(point,ecdsa->pub_key)) goto err;
	if (!EC_POINT_mul(ecdsa->group,point,order,NULL,NULL,ctx)) goto err;
	if (!EC_POINT_is_at_infinity(ecdsa->group,point)) goto err;
	/* in case the priv_key is present : check if generator * priv_key == pub_key */
	if (ecdsa->priv_key)
	{
		if (BN_cmp(ecdsa->priv_key,order) >= 0) goto err;
		if (!EC_POINT_copy(point,EC_GROUP_get0_generator(ecdsa->group))) goto err;
		if (!EC_POINT_mul(ecdsa->group,point,ecdsa->priv_key,NULL,NULL,ctx)) goto err;
		if (EC_POINT_cmp(ecdsa->group,point,ecdsa->pub_key,ctx) != 0) goto err;
	}
	ok = 1;
err:
	if (ctx   != NULL) BN_CTX_free(ctx);
	if (order != NULL) BN_free(order);
	if (point != NULL) EC_POINT_free(point);
	return(ok);
}