EC_GFP_SIMPLE_METHOD(3ossl)

💖 EC_GFP_SIMPLE_METHOD 💖

okay bestie, welcome to the OpenSSL section 3ossl manual page for all the EC_GF* method-getter girlies 🎀 this one is short but it's got lore, it's got deprecation drama, it's got NIST curves looking cute. let's get into it ✨

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✨ 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 — the functions for obtaining EC_METHOD objects 🦋

basically they're the little matchmakers that hand you the right implementation object. periodt.

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✨ SYNOPSIS ✨

first thing, the include. iconic behavior:

#include <openssl/ec.h>

🚨 okay so listen. 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). so if you can't find them, that's why bestie, they're in hiding 🙈

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_GFp_nistp224_method(void);
const EC_GFp_nistp256_method(void);
const EC_GFp_nistp521_method(void);

const EC_METHOD *EC_GF2m_simple_method(void);

int EC_METHOD_get_field_type(const EC_METHOD *meth);

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✨ DESCRIPTION ✨

so the tea ☕: all of the const EC_METHOD *EC_GF* functions were deprecated in OpenSSL 3.0, because EC_METHOD is no longer a public concept. it's giving retired celebrity. it still exists, but nobody's supposed to be meeting it in public anymore 💅

the Elliptic Curve library ships a bunch of different implementations behind one single common interface — like, one menu, many kitchens 🍓. when you're constructing a curve using EC_GROUP_new (peep EC_GROUP_new(3)) you must hand it an implementation method. the functions described here all return a const pointer to an EC_METHOD structure that you can pass to EC_GROUP_NEW. and it's important that the correct implementation type for the form of curve you selected is the one you actually use. matching vibes only, no mismatches ✨

for F2^m curves there's literally only one implementation choice, i.e. EC_GF2_simple_method. one option, no decision fatigue, slay.

for Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. every other implementation is built on top of it, like a base layer of a really good outfit:

• 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)).

and then we have the glow-up squad 🌈:

• 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. so don't come for me if your platform said no, it's not personal, it's portability.

EC_METHOD_get_field_type() was deprecated in OpenSSL 3.0 too. applications should use EC_GROUP_get_field_type() as a replacement (see EC_GROUP_copy(3)). upgrade your fave, it's what she deserves 🫶

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✨ RETURN VALUES ✨

• all EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an EC_METHOD structure. always. no cap.
• EC_METHOD_get_field_type returns an integer that identifies the type of field the EC_METHOD structure supports. it's giving "what's your type" but for fields 💜

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✨ SEE ALSO ✨

the whole friend group 💞:

• crypto(7)
• 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)

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✨ HISTORY ✨

EC_GFp_simple_method(), EC_GFp_mont_method(void), EC_GFp_nist_method(), EC_GFp_nistp224_method(), EC_GFp_nistp256_method(), EC_GFp_nistp521_method(), EC_GF2m_simple_method(), and EC_METHOD_get_field_type() were deprecated in OpenSSL 3.0. the whole crew, all at once. it was a mass retirement party 🎉

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✨ COPYRIGHT ✨

Copyright 2013-2020 The OpenSSL Project Authors. All Rights Reserved. 👑

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>. read the license bestie, it's the rules 🎀

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and that's the whole page, mwah 💋 this was version 3.5.9, dated 2026-09-29, filed under EC_GFP_SIMPLE_METHOD(3ossl) in the OpenSSL collection. go forth and pick the right EC_METHOD, i believe in you 🦋💖✨