EC_GFp_mont_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 obtain-
       ing 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 implementa-
       tions 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 impor-
       tant 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_mont-
       gomery(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_mont-
       gomery(3)

1.0.2t                            2019-09-10           EC_GFp_simple_method(3)