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
EC_GROUP_new_curve_GFp(const BIGNUM * p,const BIGNUM * a,const BIGNUM * b,BN_CTX * ctx)76 EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
77 {
78 const EC_METHOD *meth;
79 EC_GROUP *ret;
80
81 #if defined(OPENSSL_BN_ASM_MONT)
82 /*
83 * This might appear controversial, but the fact is that generic
84 * prime method was observed to deliver better performance even
85 * for NIST primes on a range of platforms, e.g.: 60%-15%
86 * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
87 * in 32-bit build and 35%--12% in 64-bit build on Core2...
88 * Coefficients are relative to optimized bn_nist.c for most
89 * intensive ECDSA verify and ECDH operations for 192- and 521-
90 * bit keys respectively. Choice of these boundary values is
91 * arguable, because the dependency of improvement coefficient
92 * from key length is not a "monotone" curve. For example while
93 * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
94 * generally faster, sometimes "respectfully" faster, sometimes
95 * "tolerably" slower... What effectively happens is that loop
96 * with bn_mul_add_words is put against bn_mul_mont, and the
97 * latter "wins" on short vectors. Correct solution should be
98 * implementing dedicated NxN multiplication subroutines for
99 * small N. But till it materializes, let's stick to generic
100 * prime method...
101 * <appro>
102 */
103 meth = EC_GFp_mont_method();
104 #else
105 meth = EC_GFp_nist_method();
106 #endif
107
108 ret = EC_GROUP_new(meth);
109 if (ret == NULL)
110 return NULL;
111
112 if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx))
113 {
114 unsigned long err;
115
116 err = ERR_peek_last_error();
117
118 if (!(ERR_GET_LIB(err) == ERR_LIB_EC &&
119 ((ERR_GET_REASON(err) == EC_R_NOT_A_NIST_PRIME) ||
120 (ERR_GET_REASON(err) == EC_R_NOT_A_SUPPORTED_NIST_PRIME))))
121 {
122 /* real error */
123
124 EC_GROUP_clear_free(ret);
125 return NULL;
126 }
127
128
129 /* not an actual error, we just cannot use EC_GFp_nist_method */
130
131 ERR_clear_error();
132
133 EC_GROUP_clear_free(ret);
134 meth = EC_GFp_mont_method();
135
136 ret = EC_GROUP_new(meth);
137 if (ret == NULL)
138 return NULL;
139
140 if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx))
141 {
142 EC_GROUP_clear_free(ret);
143 return NULL;
144 }
145 }
146
147 return ret;
148 }
149
150 #ifndef OPENSSL_NO_EC2M
EC_GROUP_new_curve_GF2m(const BIGNUM * p,const BIGNUM * a,const BIGNUM * b,BN_CTX * ctx)151 EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
152 {
153 const EC_METHOD *meth;
154 EC_GROUP *ret;
155
156 meth = EC_GF2m_simple_method();
157
158 ret = EC_GROUP_new(meth);
159 if (ret == NULL)
160 return NULL;
161
162 if (!EC_GROUP_set_curve_GF2m(ret, p, a, b, ctx))
163 {
164 EC_GROUP_clear_free(ret);
165 return NULL;
166 }
167
168 return ret;
169 }
170 #endif
171