EC_GFp_mont_method(3)

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

1.0.2t               Last change: 2019-09-10                    1

EC_GFp_simple_method(3)      OpenSSL      EC_GFp_simple_method(3)

     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)

1.0.2t               Last change: 2019-09-10                    2