1=pod
2
3=head1 NAME
4
5EC_GFp_simple_method, EC_GFp_mont_method, EC_GFp_nist_method, EC_GFp_nistp224_method, EC_GFp_nistp256_method, EC_GFp_nistp521_method, EC_GF2m_simple_method, EC_METHOD_get_field_type - Functions for obtaining EC_METHOD objects
6
7=head1 SYNOPSIS
8
9 #include <openssl/ec.h>
10
11Deprecated since OpenSSL 3.0:
12
13 const EC_METHOD *EC_GFp_simple_method(void);
14 const EC_METHOD *EC_GFp_mont_method(void);
15 const EC_METHOD *EC_GFp_nist_method(void);
16 const EC_METHOD *EC_GFp_nistp224_method(void);
17 const EC_METHOD *EC_GFp_nistp256_method(void);
18 const EC_METHOD *EC_GFp_nistp521_method(void);
19
20 const EC_METHOD *EC_GF2m_simple_method(void);
21
22 int EC_METHOD_get_field_type(const EC_METHOD *meth);
23
24=head1 DESCRIPTION
25
26
27All const EC_METHOD *EC_GF* functions were deprecated in OpenSSL 3.0, since
28EC_METHOD is no longer a public concept.
29
30The Elliptic Curve library provides a number of different implementations through a single common interface.
31When constructing a curve using EC_GROUP_new (see L<EC_GROUP_new(3)>) an
32implementation method must be provided. The functions described here all return a const pointer to an
33B<EC_METHOD> structure that can be passed to EC_GROUP_NEW. It is important that the correct implementation
34type for the form of curve selected is used.
35
36For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method.
37
38For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. All
39other implementations are based on this one. EC_GFp_mont_method builds on EC_GFp_simple_method but adds the
40use of montgomery multiplication (see L<BN_mod_mul_montgomery(3)>). EC_GFp_nist_method
41offers an implementation optimised for use with NIST recommended curves (NIST curves are available through
42EC_GROUP_new_by_curve_name as described in L<EC_GROUP_new(3)>).
43
44The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method offer 64 bit
45optimised implementations for the NIST P224, P256 and P521 curves respectively. Note, however, that these
46implementations are not available on all platforms.
47
48EC_METHOD_get_field_type() was deprecated in OpenSSL 3.0.
49Applications should use EC_GROUP_get_field_type() as a replacement (see L<EC_GROUP_copy(3)>).
50
51=head1 RETURN VALUES
52
53All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an EC_METHOD structure.
54
55EC_METHOD_get_field_type returns an integer that identifies the type of field the EC_METHOD structure supports.
56
57=head1 SEE ALSO
58
59L<crypto(7)>, L<EC_GROUP_new(3)>, L<EC_GROUP_copy(3)>,
60L<EC_POINT_new(3)>, L<EC_POINT_add(3)>, L<EC_KEY_new(3)>,
61L<d2i_ECPKParameters(3)>,
62L<BN_mod_mul_montgomery(3)>
63
64=head1 HISTORY
65
66EC_GFp_simple_method(), EC_GFp_mont_method(void),
67EC_GFp_nist_method(), EC_GFp_nistp224_method(),
68EC_GFp_nistp256_method(), EC_GFp_nistp521_method(),
69EC_GF2m_simple_method(), and EC_METHOD_get_field_type()
70were deprecated in OpenSSL 3.0.
71
72=head1 COPYRIGHT
73
74Copyright 2013-2020 The OpenSSL Project Authors. All Rights Reserved.
75
76Licensed under the Apache License 2.0 (the "License").  You may not use
77this file except in compliance with the License.  You can obtain a copy
78in the file LICENSE in the source distribution or at
79L<https://www.openssl.org/source/license.html>.
80
81=cut
82