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 OpenSSL license (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 "ec_local.h"
13
14EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
15                                 const BIGNUM *b, BN_CTX *ctx)
16{
17    const EC_METHOD *meth;
18    EC_GROUP *ret;
19
20#if defined(OPENSSL_BN_ASM_MONT)
21    /*
22     * This might appear controversial, but the fact is that generic
23     * prime method was observed to deliver better performance even
24     * for NIST primes on a range of platforms, e.g.: 60%-15%
25     * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
26     * in 32-bit build and 35%--12% in 64-bit build on Core2...
27     * Coefficients are relative to optimized bn_nist.c for most
28     * intensive ECDSA verify and ECDH operations for 192- and 521-
29     * bit keys respectively. Choice of these boundary values is
30     * arguable, because the dependency of improvement coefficient
31     * from key length is not a "monotone" curve. For example while
32     * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
33     * generally faster, sometimes "respectfully" faster, sometimes
34     * "tolerably" slower... What effectively happens is that loop
35     * with bn_mul_add_words is put against bn_mul_mont, and the
36     * latter "wins" on short vectors. Correct solution should be
37     * implementing dedicated NxN multiplication subroutines for
38     * small N. But till it materializes, let's stick to generic
39     * prime method...
40     *                                              <appro>
41     */
42    meth = EC_GFp_mont_method();
43#else
44    if (BN_nist_mod_func(p))
45        meth = EC_GFp_nist_method();
46    else
47        meth = EC_GFp_mont_method();
48#endif
49
50    ret = EC_GROUP_new(meth);
51    if (ret == NULL)
52        return NULL;
53
54    if (!EC_GROUP_set_curve(ret, p, a, b, ctx)) {
55        EC_GROUP_clear_free(ret);
56        return NULL;
57    }
58
59    return ret;
60}
61
62#ifndef OPENSSL_NO_EC2M
63EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
64                                  const BIGNUM *b, BN_CTX *ctx)
65{
66    const EC_METHOD *meth;
67    EC_GROUP *ret;
68
69    meth = EC_GF2m_simple_method();
70
71    ret = EC_GROUP_new(meth);
72    if (ret == NULL)
73        return NULL;
74
75    if (!EC_GROUP_set_curve(ret, p, a, b, ctx)) {
76        EC_GROUP_clear_free(ret);
77        return NULL;
78    }
79
80    return ret;
81}
82#endif
83