1/*
2 * Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
4 *
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 */
10
11#include <openssl/err.h>
12#include "crypto/bn.h"
13#include "ec_local.h"
14
15EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
16 const BIGNUM *b, BN_CTX *ctx)
17{
18 const EC_METHOD *meth;
19 EC_GROUP *ret;
20
21#if defined(OPENSSL_BN_ASM_MONT)
22 /*
23 * This might appear controversial, but the fact is that generic
24 * prime method was observed to deliver better performance even
25 * for NIST primes on a range of platforms, e.g.: 60%-15%
26 * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
27 * in 32-bit build and 35%--12% in 64-bit build on Core2...
28 * Coefficients are relative to optimized bn_nist.c for most
29 * intensive ECDSA verify and ECDH operations for 192- and 521-
30 * bit keys respectively. Choice of these boundary values is
31 * arguable, because the dependency of improvement coefficient
32 * from key length is not a "monotone" curve. For example while
33 * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
34 * generally faster, sometimes "respectfully" faster, sometimes
35 * "tolerably" slower... What effectively happens is that loop
36 * with bn_mul_add_words is put against bn_mul_mont, and the
37 * latter "wins" on short vectors. Correct solution should be
38 * implementing dedicated NxN multiplication subroutines for
39 * small N. But till it materializes, let's stick to generic
40 * prime method...
41 * <appro>
42 */
43 meth = EC_GFp_mont_method();
44#else
45 if (BN_nist_mod_func(p))
46 meth = EC_GFp_nist_method();
47 else
48 meth = EC_GFp_mont_method();
49#endif
50
51 ret = EC_GROUP_new_ex(bn_get_lib_ctx(ctx), meth);
52 if (ret == NULL)
53 return NULL;
54
55 if (!EC_GROUP_set_curve(ret, p, a, b, ctx)) {
56 EC_GROUP_free(ret);
57 return NULL;
58 }
59
60 return ret;
61}
62
63#ifndef OPENSSL_NO_EC2M
64EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
65 const BIGNUM *b, BN_CTX *ctx)
66{
67 const EC_METHOD *meth;
68 EC_GROUP *ret;
69
70 meth = EC_GF2m_simple_method();
71
72 ret = EC_GROUP_new_ex(bn_get_lib_ctx(ctx), meth);
73 if (ret == NULL)
74 return NULL;
75
76 if (!EC_GROUP_set_curve(ret, p, a, b, ctx)) {
77 EC_GROUP_free(ret);
78 return NULL;
79 }
80
81 return ret;
82}
83#endif
84