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
11The following functions have been deprecated since OpenSSL 3.0, and can be
12hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
13see L<openssl_user_macros(7)>:
14
15 const EC_METHOD *EC_GFp_simple_method(void);
16 const EC_METHOD *EC_GFp_mont_method(void);
17 const EC_METHOD *EC_GFp_nist_method(void);
18 const EC_METHOD *EC_GFp_nistp224_method(void);
19 const EC_METHOD *EC_GFp_nistp256_method(void);
20 const EC_METHOD *EC_GFp_nistp521_method(void);
21
22 const EC_METHOD *EC_GF2m_simple_method(void);
23
24 int EC_METHOD_get_field_type(const EC_METHOD *meth);
25
26=head1 DESCRIPTION
27
28
29All const EC_METHOD *EC_GF* functions were deprecated in OpenSSL 3.0, since
30EC_METHOD is no longer a public concept.
31
32The Elliptic Curve library provides a number of different implementations through a single common interface.
33When constructing a curve using EC_GROUP_new (see L<EC_GROUP_new(3)>) an
34implementation method must be provided. The functions described here all return a const pointer to an
35B<EC_METHOD> structure that can be passed to EC_GROUP_NEW. It is important that the correct implementation
36type for the form of curve selected is used.
37
38For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method.
39
40For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. All
41other implementations are based on this one. EC_GFp_mont_method builds on EC_GFp_simple_method but adds the
42use of montgomery multiplication (see L<BN_mod_mul_montgomery(3)>). EC_GFp_nist_method
43offers an implementation optimised for use with NIST recommended curves (NIST curves are available through
44EC_GROUP_new_by_curve_name as described in L<EC_GROUP_new(3)>).
45
46The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method offer 64 bit
47optimised implementations for the NIST P224, P256 and P521 curves respectively. Note, however, that these
48implementations are not available on all platforms.
49
50EC_METHOD_get_field_type() was deprecated in OpenSSL 3.0.
51Applications should use EC_GROUP_get_field_type() as a replacement (see L<EC_GROUP_copy(3)>).
52
53=head1 RETURN VALUES
54
55All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an EC_METHOD structure.
56
57EC_METHOD_get_field_type returns an integer that identifies the type of field the EC_METHOD structure supports.
58
59=head1 SEE ALSO
60
61L<crypto(7)>, L<EC_GROUP_new(3)>, L<EC_GROUP_copy(3)>,
62L<EC_POINT_new(3)>, L<EC_POINT_add(3)>, L<EC_KEY_new(3)>,
63L<d2i_ECPKParameters(3)>,
64L<BN_mod_mul_montgomery(3)>
65
66=head1 HISTORY
67
68EC_GFp_simple_method(), EC_GFp_mont_method(void),
69EC_GFp_nist_method(), EC_GFp_nistp224_method(),
70EC_GFp_nistp256_method(), EC_GFp_nistp521_method(),
71EC_GF2m_simple_method(), and EC_METHOD_get_field_type()
72were deprecated in OpenSSL 3.0.
73
74=head1 COPYRIGHT
75
76Copyright 2013-2021 The OpenSSL Project Authors. All Rights Reserved.
77
78Licensed under the Apache License 2.0 (the "License").  You may not use
79this file except in compliance with the License.  You can obtain a copy
80in the file LICENSE in the source distribution or at
81L<https://www.openssl.org/source/license.html>.
82
83=cut
84