- NAME
- DESCRIPTION
- NOTES
- EXAMPLE
- SEE ALSO
- COPYRIGHT

# NAME

Ed25519, Ed448 - EVP_PKEY Ed25519 and Ed448 support

# DESCRIPTION

The Ed25519 and Ed448 EVP_PKEY implementation supports key generation, one-shot digest sign and digest verify using PureEdDSA and Ed25519 or Ed448 (see RFC8032). It has associated private and public key formats compatible with draft-ietf-curdle-pkix-04.

No additional parameters can be set during key generation one-shot signing or verification. In particular, because PureEdDSA is used, when signing or verifying a digest must NOT be specified.

# 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() asn EVP_DigestVerify() functions.

When calling EVP_DigestSignInit() or EVP_DigestSignUpdate() the digest parameter MUST be set to 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 Ed25519 algorithm can be obtained by calling:

     EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_ED25519, NULL);

For the 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 EVP_PKEY_new_raw_private_key(3) or loaded from a PKCS#8 private key file using 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 EVP_PKEY_new_raw_public_key(3) or loaded from a SubjectPublicKeyInfo structure in a PEM file using PEM_read_bio_PUBKEY(3) (or similar function).

# EXAMPLE

This example generates an 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);

# SEE ALSO

EVP_PKEY_CTX_new(3), EVP_PKEY_keygen(3), EVP_DigestSignInit(3), EVP_DigestVerifyInit(3),

# COPYRIGHT

Copyright 2017-2018 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 https://www.openssl.org/source/license.html.