EC_GFp_simple_method (3)
Leading comments
Automatically generated by Pod::Man 4.07 (Pod::Simple 3.32) Standard preamble: ========================================================================
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 anEC_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 anEC_METHOD
structure.
EC_METHOD_get_field_type returns an integer that identifies the type of field the
EC_METHOD
structure supports.