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EC_GFP_SIMPLE_METHOD(3) | Library Functions Manual | 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
—
obtain 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. Each implementation is optimised for different scenarios. An implementation is represented by an EC_METHOD structure. When constructing a curve using 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(3). 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,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
() 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(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
<openssl/obj_mac.h>
header file.
RETURN VALUES
AllEC_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
BN_mod_mul_montgomery(3), d2i_ECPKParameters(3), EC_GROUP_copy(3), EC_GROUP_new(3), EC_KEY_new(3), EC_POINT_add(3), EC_POINT_new(3)HISTORY
EC_GFp_simple_method
() and
EC_GFp_mont_method
() first appeared in
OpenSSL 0.9.7 and have been available since OpenBSD
3.2.
EC_GFp_nist_method
(),
EC_GF2m_simple_method
(), and
EC_METHOD_get_field_type
() first appeared
in OpenSSL 0.9.8 and have been available since OpenBSD
4.5.
EC_GFp_nistp224_method
(),
EC_GFp_nistp256_method
(), and
EC_GFp_nistp521_method
() first appeared in
OpenSSL 1.0.1 and have been available since OpenBSD
5.3.March 23, 2018 | Debian |