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1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
bb9ad09e | 5 | EC_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 |
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6 | |
7 | =head1 SYNOPSIS | |
8 | ||
9 | #include <openssl/ec.h> | |
10 | ||
11 | const EC_METHOD *EC_GFp_simple_method(void); | |
12 | const EC_METHOD *EC_GFp_mont_method(void); | |
13 | const EC_METHOD *EC_GFp_nist_method(void); | |
14 | const EC_METHOD *EC_GFp_nistp224_method(void); | |
15 | const EC_METHOD *EC_GFp_nistp256_method(void); | |
16 | const EC_METHOD *EC_GFp_nistp521_method(void); | |
17 | ||
18 | const EC_METHOD *EC_GF2m_simple_method(void); | |
19 | ||
20 | int EC_METHOD_get_field_type(const EC_METHOD *meth); | |
21 | ||
22 | =head1 DESCRIPTION | |
23 | ||
24 | The Elliptic Curve library provides a number of different implementations through a single common interface. | |
9b86974e | 25 | When constructing a curve using EC_GROUP_new (see L<EC_GROUP_new(3)>) an |
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26 | implementation method must be provided. The functions described here all return a const pointer to an |
27 | B<EC_METHOD> structure that can be passed to EC_GROUP_NEW. It is important that the correct implementation | |
28 | type for the form of curve selected is used. | |
29 | ||
30 | For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method. | |
31 | ||
32 | For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. All | |
33 | other implementations are based on this one. EC_GFp_mont_method builds on EC_GFp_simple_method but adds the | |
9b86974e | 34 | use of montgomery multiplication (see L<BN_mod_mul_montgomery(3)>). EC_GFp_nist_method |
aafbe1cc | 35 | offers an implementation optimised for use with NIST recommended curves (NIST curves are available through |
9b86974e | 36 | EC_GROUP_new_by_curve_name as described in L<EC_GROUP_new(3)>). |
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37 | |
38 | The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method offer 64 bit | |
39 | optimised implementations for the NIST P224, P256 and P521 curves respectively. Note, however, that these | |
40 | implementations are not available on all platforms. | |
41 | ||
42 | EC_METHOD_get_field_type identifies what type of field the EC_METHOD structure supports, which will be either | |
43 | F2^m or Fp. If the field type is Fp then the value B<NID_X9_62_prime_field> is returned. If the field type is | |
44 | F2^m then the value B<NID_X9_62_characteristic_two_field> is returned. These values are defined in the | |
45 | obj_mac.h header file. | |
46 | ||
47 | =head1 RETURN VALUES | |
48 | ||
49 | All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an EC_METHOD structure. | |
50 | ||
51 | EC_METHOD_get_field_type returns an integer that identifies the type of field the EC_METHOD structure supports. | |
52 | ||
53 | =head1 SEE ALSO | |
54 | ||
9e183d22 | 55 | L<crypto(7)>, L<EC_GROUP_new(3)>, L<EC_GROUP_copy(3)>, |
9b86974e RS |
56 | L<EC_POINT_new(3)>, L<EC_POINT_add(3)>, L<EC_KEY_new(3)>, |
57 | L<d2i_ECPKParameters(3)>, | |
58 | L<BN_mod_mul_montgomery(3)> | |
aafbe1cc | 59 | |
e2f92610 RS |
60 | =head1 COPYRIGHT |
61 | ||
9e183d22 | 62 | Copyright 2013-2017 The OpenSSL Project Authors. All Rights Reserved. |
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63 | |
64 | Licensed under the OpenSSL license (the "License"). You may not use | |
65 | this file except in compliance with the License. You can obtain a copy | |
66 | in the file LICENSE in the source distribution or at | |
67 | L<https://www.openssl.org/source/license.html>. | |
68 | ||
69 | =cut |