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131 .IX Title "EC_GFp_simple_method 3"
132 .TH EC_GFp_simple_method 3 "2017-12-07" "1.0.2n" "OpenSSL"
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138 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.
140 .IX Header "SYNOPSIS"
142 \& #include <openssl/ec.h>
144 \& const EC_METHOD *EC_GFp_simple_method(void);
145 \& const EC_METHOD *EC_GFp_mont_method(void);
146 \& const EC_METHOD *EC_GFp_nist_method(void);
147 \& const EC_METHOD *EC_GFp_nistp224_method(void);
148 \& const EC_METHOD *EC_GFp_nistp256_method(void);
149 \& const EC_METHOD *EC_GFp_nistp521_method(void);
151 \& const EC_METHOD *EC_GF2m_simple_method(void);
153 \& int EC_METHOD_get_field_type(const EC_METHOD *meth);
156 .IX Header "DESCRIPTION"
157 The Elliptic Curve library provides a number of different implementations through a single common interface.
158 When constructing a curve using EC_GROUP_new (see \fIEC_GROUP_new\fR\|(3)) an
159 implementation method must be provided. The functions described here all return a const pointer to an
160 \&\fB\s-1EC_METHOD\s0\fR structure that can be passed to \s-1EC_GROUP_NEW.\s0 It is important that the correct implementation
161 type for the form of curve selected is used.
163 For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method.
165 For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. All
166 other implementations are based on this one. EC_GFp_mont_method builds on EC_GFp_simple_method but adds the
167 use of montgomery multiplication (see \fIBN_mod_mul_montgomery\fR\|(3)). EC_GFp_nist_method
168 offers an implementation optimised for use with \s-1NIST\s0 recommended curves (\s-1NIST\s0 curves are available through
169 EC_GROUP_new_by_curve_name as described in \fIEC_GROUP_new\fR\|(3)).
171 The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method offer 64 bit
172 optimised implementations for the \s-1NIST P224, P256\s0 and P521 curves respectively. Note, however, that these
173 implementations are not available on all platforms.
175 EC_METHOD_get_field_type identifies what type of field the \s-1EC_METHOD\s0 structure supports, which will be either
176 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
177 F2^m then the value \fBNID_X9_62_characteristic_two_field\fR is returned. These values are defined in the
178 obj_mac.h header file.
180 .IX Header "RETURN VALUES"
181 All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an \s-1EC_METHOD\s0 structure.
183 EC_METHOD_get_field_type returns an integer that identifies the type of field the \s-1EC_METHOD\s0 structure supports.
185 .IX Header "SEE ALSO"
186 \&\fIcrypto\fR\|(3), \fIec\fR\|(3), \fIEC_GROUP_new\fR\|(3), \fIEC_GROUP_copy\fR\|(3),
187 \&\fIEC_POINT_new\fR\|(3), \fIEC_POINT_add\fR\|(3), \fIEC_KEY_new\fR\|(3),
188 \&\fId2i_ECPKParameters\fR\|(3),
189 \&\fIBN_mod_mul_montgomery\fR\|(3)