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135 .IX Title "EC_GFP_SIMPLE_METHOD 3"
136 .TH EC_GFP_SIMPLE_METHOD 3 "2021-08-24" "1.1.1l" "OpenSSL"
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142 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
144 .IX Header "SYNOPSIS"
146 \& #include <openssl/ec.h>
148 \& const EC_METHOD *EC_GFp_simple_method(void);
149 \& const EC_METHOD *EC_GFp_mont_method(void);
150 \& const EC_METHOD *EC_GFp_nist_method(void);
151 \& const EC_METHOD *EC_GFp_nistp224_method(void);
152 \& const EC_METHOD *EC_GFp_nistp256_method(void);
153 \& const EC_METHOD *EC_GFp_nistp521_method(void);
155 \& const EC_METHOD *EC_GF2m_simple_method(void);
157 \& int EC_METHOD_get_field_type(const EC_METHOD *meth);
160 .IX Header "DESCRIPTION"
161 The Elliptic Curve library provides a number of different implementations through a single common interface.
162 When constructing a curve using EC_GROUP_new (see \fBEC_GROUP_new\fR\|(3)) an
163 implementation method must be provided. The functions described here all return a const pointer to an
164 \&\fB\s-1EC_METHOD\s0\fR structure that can be passed to \s-1EC_GROUP_NEW.\s0 It is important that the correct implementation
165 type for the form of curve selected is used.
167 For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method.
169 For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. All
170 other implementations are based on this one. EC_GFp_mont_method builds on EC_GFp_simple_method but adds the
171 use of montgomery multiplication (see \fBBN_mod_mul_montgomery\fR\|(3)). EC_GFp_nist_method
172 offers an implementation optimised for use with \s-1NIST\s0 recommended curves (\s-1NIST\s0 curves are available through
173 EC_GROUP_new_by_curve_name as described in \fBEC_GROUP_new\fR\|(3)).
175 The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method offer 64 bit
176 optimised implementations for the \s-1NIST P224, P256\s0 and P521 curves respectively. Note, however, that these
177 implementations are not available on all platforms.
179 EC_METHOD_get_field_type identifies what type of field the \s-1EC_METHOD\s0 structure supports, which will be either
180 F2^m or Fp. If the field type is Fp then the value \fBNID_X9_62_prime_field\fR is returned. If the field type is
181 F2^m then the value \fBNID_X9_62_characteristic_two_field\fR is returned. These values are defined in the
182 obj_mac.h header file.
184 .IX Header "RETURN VALUES"
185 All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an \s-1EC_METHOD\s0 structure.
187 EC_METHOD_get_field_type returns an integer that identifies the type of field the \s-1EC_METHOD\s0 structure supports.
189 .IX Header "SEE ALSO"
190 \&\fBcrypto\fR\|(7), \fBEC_GROUP_new\fR\|(3), \fBEC_GROUP_copy\fR\|(3),
191 \&\fBEC_POINT_new\fR\|(3), \fBEC_POINT_add\fR\|(3), \fBEC_KEY_new\fR\|(3),
192 \&\fBd2i_ECPKParameters\fR\|(3),
193 \&\fBBN_mod_mul_montgomery\fR\|(3)
195 .IX Header "COPYRIGHT"
196 Copyright 2013\-2017 The OpenSSL Project Authors. All Rights Reserved.
198 Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
199 this file except in compliance with the License. You can obtain a copy
200 in the file \s-1LICENSE\s0 in the source distribution or at
201 <https://www.openssl.org/source/license.html>.