EC_GFp_simple_method(3) OpenSSL EC_GFp_simple_method(3)
NAME
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.
SYNOPSIS
#include <openssl/ec.h>
const EC_METHOD *EC_GFp_simple_method(void);
const EC_METHOD *EC_GFp_mont_method(void);
const EC_METHOD *EC_GFp_nist_method(void);
const EC_METHOD *EC_GFp_nistp224_method(void);
const EC_METHOD *EC_GFp_nistp256_method(void);
const EC_METHOD *EC_GFp_nistp521_method(void);
const EC_METHOD *EC_GF2m_simple_method(void);
int EC_METHOD_get_field_type(const EC_METHOD *meth);
DESCRIPTION
The Elliptic Curve library provides a number of different implementations through a single
common interface. When constructing a curve using EC_GROUP_new (see EC_GROUP_new(3)) an
implementation method must be provided. The functions described here all return a const
pointer to an EC_METHOD structure that can be passed to EC_GROUP_NEW. It is important that
the correct implementation type for the form of curve selected is used.
For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method.
For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method
implementation. All other implementations are based on this one. EC_GFp_mont_method builds
on EC_GFp_simple_method but adds the use of montgomery multiplication (see
BN_mod_mul_montgomery(3)). EC_GFp_nist_method offers an implementation optimised for use
with NIST recommended curves (NIST curves are available through EC_GROUP_new_by_curve_name
as described in EC_GROUP_new(3)).
The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method
offer 64 bit optimised implementations for the NIST P224, P256 and P521 curves
respectively. Note, however, that these implementations are not available on all
platforms.
EC_METHOD_get_field_type identifies what type of field the EC_METHOD structure supports,
which will be either F2^m or Fp. If the field type is Fp then the value
NID_X9_62_prime_field is returned. If the field type is F2^m then the value
NID_X9_62_characteristic_two_field is returned. These values are defined in the obj_mac.h
header file.
RETURN VALUES
All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an
EC_METHOD structure.
EC_METHOD_get_field_type returns an integer that identifies the type of field the
EC_METHOD structure supports.
SEE ALSO
crypto(3), ec(3), EC_GROUP_new(3), EC_GROUP_copy(3), EC_POINT_new(3), EC_POINT_add(3),
EC_KEY_new(3), d2i_ECPKParameters(3), BN_mod_mul_montgomery(3)
1.0.2k 2017-01-26 EC_GFp_simple_method(3)
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