NAME

SYNOPSIS

 #include <openssl/ec.h>

The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

 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() was deprecated in OpenSSL 3.0. Applications should use EC_GROUP_get_field_type() as a replacement (see EC_GROUP_copy(3)).

RETURN VALUES

EC_METHOD_get_field_type returns an integer that identifies the type of field the EC_METHOD structure supports.

SEE ALSO

HISTORY

COPYRIGHT

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.