ec_cvt.c revision 296465 
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
75EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
76                                 const BIGNUM *b, BN_CTX *ctx)
77{
78    const EC_METHOD *meth;
79    EC_GROUP *ret;
80
81    meth = EC_GFp_nist_method();
82
83    ret = EC_GROUP_new(meth);
84    if (ret == NULL)
85        return NULL;
86
87    if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
88        unsigned long err;
89
90        err = ERR_peek_last_error();
91
92        if (!(ERR_GET_LIB(err) == ERR_LIB_EC &&
93              ((ERR_GET_REASON(err) == EC_R_NOT_A_NIST_PRIME) ||
94               (ERR_GET_REASON(err) == EC_R_NOT_A_SUPPORTED_NIST_PRIME)))) {
95            /* real error */
96
97            EC_GROUP_clear_free(ret);
98            return NULL;
99        }
100
101        /*
102         * not an actual error, we just cannot use EC_GFp_nist_method
103         */
104
105        ERR_clear_error();
106
107        EC_GROUP_clear_free(ret);
108        meth = EC_GFp_mont_method();
109
110        ret = EC_GROUP_new(meth);
111        if (ret == NULL)
112            return NULL;
113
114        if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
115            EC_GROUP_clear_free(ret);
116            return NULL;
117        }
118    }
119
120    return ret;
121}
122
123EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
124                                  const BIGNUM *b, BN_CTX *ctx)
125{
126    const EC_METHOD *meth;
127    EC_GROUP *ret;
128
129    meth = EC_GF2m_simple_method();
130
131    ret = EC_GROUP_new(meth);
132    if (ret == NULL)
133        return NULL;
134
135    if (!EC_GROUP_set_curve_GF2m(ret, p, a, b, ctx)) {
136        EC_GROUP_clear_free(ret);
137        return NULL;
138    }
139
140    return ret;
141}
142