1/* crypto/ec/ec_cvt.c */
2/*
3 * Originally written by Bodo Moeller for the OpenSSL project.
4 */
5/* ====================================================================
6 * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in
17 *    the documentation and/or other materials provided with the
18 *    distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 *    software must display the following acknowledgment:
22 *    "This product includes software developed by the OpenSSL Project
23 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 *    endorse or promote products derived from this software without
27 *    prior written permission. For written permission, please contact
28 *    openssl-core@openssl.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 *    nor may "OpenSSL" appear in their names without prior written
32 *    permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 *    acknowledgment:
36 *    "This product includes software developed by the OpenSSL Project
37 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com).  This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
56 *
57 */
58/* ====================================================================
59 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
60 *
61 * Portions of the attached software ("Contribution") are developed by
62 * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
63 *
64 * The Contribution is licensed pursuant to the OpenSSL open source
65 * license provided above.
66 *
67 * The elliptic curve binary polynomial software is originally written by
68 * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems Laboratories.
69 *
70 */
71
72#include <openssl/err.h>
73#include "ec_lcl.h"
74
75#ifdef OPENSSL_FIPS
76# include <openssl/fips.h>
77#endif
78
79EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
80                                 const BIGNUM *b, BN_CTX *ctx)
81{
82    const EC_METHOD *meth;
83    EC_GROUP *ret;
84
85#ifdef OPENSSL_FIPS
86    if (FIPS_mode())
87        return FIPS_ec_group_new_curve_gfp(p, a, b, ctx);
88#endif
89#if defined(OPENSSL_BN_ASM_MONT)
90    /*
91     * This might appear controversial, but the fact is that generic
92     * prime method was observed to deliver better performance even
93     * for NIST primes on a range of platforms, e.g.: 60%-15%
94     * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
95     * in 32-bit build and 35%--12% in 64-bit build on Core2...
96     * Coefficients are relative to optimized bn_nist.c for most
97     * intensive ECDSA verify and ECDH operations for 192- and 521-
98     * bit keys respectively. Choice of these boundary values is
99     * arguable, because the dependency of improvement coefficient
100     * from key length is not a "monotone" curve. For example while
101     * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
102     * generally faster, sometimes "respectfully" faster, sometimes
103     * "tolerably" slower... What effectively happens is that loop
104     * with bn_mul_add_words is put against bn_mul_mont, and the
105     * latter "wins" on short vectors. Correct solution should be
106     * implementing dedicated NxN multiplication subroutines for
107     * small N. But till it materializes, let's stick to generic
108     * prime method...
109     *                                              <appro>
110     */
111    meth = EC_GFp_mont_method();
112#else
113    meth = EC_GFp_nist_method();
114#endif
115
116    ret = EC_GROUP_new(meth);
117    if (ret == NULL)
118        return NULL;
119
120    if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
121        unsigned long err;
122
123        err = ERR_peek_last_error();
124
125        if (!(ERR_GET_LIB(err) == ERR_LIB_EC &&
126              ((ERR_GET_REASON(err) == EC_R_NOT_A_NIST_PRIME) ||
127               (ERR_GET_REASON(err) == EC_R_NOT_A_SUPPORTED_NIST_PRIME)))) {
128            /* real error */
129
130            EC_GROUP_clear_free(ret);
131            return NULL;
132        }
133
134        /*
135         * not an actual error, we just cannot use EC_GFp_nist_method
136         */
137
138        ERR_clear_error();
139
140        EC_GROUP_clear_free(ret);
141        meth = EC_GFp_mont_method();
142
143        ret = EC_GROUP_new(meth);
144        if (ret == NULL)
145            return NULL;
146
147        if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
148            EC_GROUP_clear_free(ret);
149            return NULL;
150        }
151    }
152
153    return ret;
154}
155
156#ifndef OPENSSL_NO_EC2M
157EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
158                                  const BIGNUM *b, BN_CTX *ctx)
159{
160    const EC_METHOD *meth;
161    EC_GROUP *ret;
162
163# ifdef OPENSSL_FIPS
164    if (FIPS_mode())
165        return FIPS_ec_group_new_curve_gf2m(p, a, b, ctx);
166# endif
167    meth = EC_GF2m_simple_method();
168
169    ret = EC_GROUP_new(meth);
170    if (ret == NULL)
171        return NULL;
172
173    if (!EC_GROUP_set_curve_GF2m(ret, p, a, b, ctx)) {
174        EC_GROUP_clear_free(ret);
175        return NULL;
176    }
177
178    return ret;
179}
180#endif
181