aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/ec/ec_cvt.c
blob: bfcbab35fe695d32beffbe8a704af40289f81d5c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/* 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"


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;

#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;
	
	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