/* crypto/ec/ec_cvt.c */

/*

 * Originally written by Bodo Moeller for the OpenSSL project.

 */

/* ====================================================================

 * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.

 *

 * 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 above 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 acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    openssl-core@openssl.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED 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 OpenSSL PROJECT OR

 * ITS 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.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com).

 *

 */

/* ====================================================================

 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.

 *

 * Portions of the attached software ("Contribution") are developed by

 * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.

 *

 * The Contribution is licensed pursuant to the OpenSSL open source

 * license provided above.

 *

 * The elliptic curve binary polynomial software is originally written by

 * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems Laboratories.

 *

 */

#include <openssl/err.h>

#include "ec_lcl.h"

#ifdef OPENSSL_FIPS

# include <openssl/fips.h>

#endif

EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,

                                 const BIGNUM *b, BN_CTX *ctx)

{

    const EC_METHOD *meth;

    EC_GROUP *ret;

#ifdef OPENSSL_FIPS

    if (FIPS_mode())

        return FIPS_ec_group_new_curve_gfp(p, a, b, ctx);

#endif

#if defined(OPENSSL_BN_ASM_MONT)

    /*

     * This might appear controversial, but the fact is that generic

     * prime method was observed to deliver better performance even

     * for NIST primes on a range of platforms, e.g.: 60%-15%

     * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%

     * in 32-bit build and 35%--12% in 64-bit build on Core2...

     * Coefficients are relative to optimized bn_nist.c for most

     * intensive ECDSA verify and ECDH operations for 192- and 521-

     * bit keys respectively. Choice of these boundary values is

     * arguable, because the dependency of improvement coefficient

     * from key length is not a "monotone" curve. For example while

     * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's

     * generally faster, sometimes "respectfully" faster, sometimes

     * "tolerably" slower... What effectively happens is that loop

     * with bn_mul_add_words is put against bn_mul_mont, and the

     * latter "wins" on short vectors. Correct solution should be

     * implementing dedicated NxN multiplication subroutines for

     * small N. But till it materializes, let's stick to generic

     * prime method...

     *                                              <appro>

     */

    meth = EC_GFp_mont_method();

#else

    meth = EC_GFp_nist_method();

#endif

    ret = EC_GROUP_new(meth);

    if (ret == NULL)

        return NULL;

    if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {

        unsigned long err;

        err = ERR_peek_last_error();

        if (!(ERR_GET_LIB(err) == ERR_LIB_EC &&

              ((ERR_GET_REASON(err) == EC_R_NOT_A_NIST_PRIME) ||

               (ERR_GET_REASON(err) == EC_R_NOT_A_SUPPORTED_NIST_PRIME)))) {

            /* real error */

            EC_GROUP_clear_free(ret);

            return NULL;

        }

        /*

         * not an actual error, we just cannot use EC_GFp_nist_method

         */

        ERR_clear_error();

        EC_GROUP_clear_free(ret);

        meth = EC_GFp_mont_method();

        ret = EC_GROUP_new(meth);

        if (ret == NULL)

            return NULL;

        if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {

            EC_GROUP_clear_free(ret);

            return NULL;

        }

    }

    return ret;

}

#ifndef OPENSSL_NO_EC2M

EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,

                                  const BIGNUM *b, BN_CTX *ctx)

{

    const EC_METHOD *meth;

    EC_GROUP *ret;

# ifdef OPENSSL_FIPS

    if (FIPS_mode())

        return FIPS_ec_group_new_curve_gf2m(p, a, b, ctx);

# endif

    meth = EC_GF2m_simple_method();

    ret = EC_GROUP_new(meth);

    if (ret == NULL)

        return NULL;

    if (!EC_GROUP_set_curve_GF2m(ret, p, a, b, ctx)) {

        EC_GROUP_clear_free(ret);

        return NULL;

    }

    return ret;

}

#endif