=pod

=head1 NAME

Ed25519,

Ed448

- EVP_PKEY Ed25519 and Ed448 support

=head1 DESCRIPTION

The B<Ed25519> and B<Ed448> EVP_PKEY implementation supports key generation,

one-shot digest sign and digest verify using PureEdDSA and B<Ed25519> or B<Ed448>

(see RFC8032). It has associated private and public key formats compatible with

RFC 8410.

No additional parameters can be set during key generation, one-shot signing or

verification. In particular, because PureEdDSA is used, a digest must B<NOT> be

specified when signing or verifying.

=head1 NOTES

The PureEdDSA algorithm does not support the streaming mechanism

of other signature algorithms using, for example, EVP_DigestUpdate().

The message to sign or verify must be passed using the one-shot

EVP_DigestSign() and EVP_DigestVerify() functions.

When calling EVP_DigestSignInit() or EVP_DigestVerifyInit(), the

digest B<type> parameter B<MUST> be set to B<NULL>.

Applications wishing to sign certificates (or other structures such as

CRLs or certificate requests) using Ed25519 or Ed448 can either use X509_sign()

or X509_sign_ctx() in the usual way.

A context for the B<Ed25519> algorithm can be obtained by calling:

 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_ED25519, NULL);

For the B<Ed448> algorithm a context can be obtained by calling:

 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_ED448, NULL);

Ed25519 or Ed448 private keys can be set directly using

L<EVP_PKEY_new_raw_private_key(3)> or loaded from a PKCS#8 private key file

using L<PEM_read_bio_PrivateKey(3)> (or similar function). Completely new keys

can also be generated (see the example below). Setting a private key also sets

the associated public key.

Ed25519 or Ed448 public keys can be set directly using

L<EVP_PKEY_new_raw_public_key(3)> or loaded from a SubjectPublicKeyInfo

structure in a PEM file using L<PEM_read_bio_PUBKEY(3)> (or similar function).

Ed25519 and Ed448 can be tested within L<speed(1)> application since version 1.1.1.

Valid algorithm names are B<ed25519>, B<ed448> and B<eddsa>. If B<eddsa> is

specified, then both Ed25519 and Ed448 are benchmarked.

=head1 EXAMPLES

This example generates an B<ED25519> private key and writes it to standard

output in PEM format:

 #include <openssl/evp.h>

 #include <openssl/pem.h>

 ...

 EVP_PKEY *pkey = NULL;

 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_ED25519, NULL);

 EVP_PKEY_keygen_init(pctx);

 EVP_PKEY_keygen(pctx, &pkey);

 EVP_PKEY_CTX_free(pctx);

 PEM_write_PrivateKey(stdout, pkey, NULL, NULL, 0, NULL, NULL);

=head1 SEE ALSO

L<EVP_PKEY_CTX_new(3)>,

L<EVP_PKEY_keygen(3)>,

L<EVP_DigestSignInit(3)>,

L<EVP_DigestVerifyInit(3)>,

=head1 COPYRIGHT

Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (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

L<https://www.openssl.org/source/license.html>.

=cut