EVP_SIGNATURE-ED25519(7SSL) OpenSSL EVP_SIGNATURE-ED25519(7SSL)
NAME
EVP_SIGNATURE-ED25519, EVP_SIGNATURE-ED448, 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 RFC 8410.
ED25519 and ED448 Signature Parameters
No additional parameters can be set during one-shot signing or
verification. In particular, because PureEdDSA is used, a digest must
NOT be specified when signing or verifying. See EVP_PKEY-X25519(7) for
information related to X25519 and X448 keys.
The following signature parameters can be retrieved using
EVP_PKEY_CTX_get_params().
"algorithm-id" (OSSL_SIGNATURE_PARAM_ALGORITHM_ID) <octet string>
The parameters are described in provider-signature(7).
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
type 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.
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).
Ed25519 and Ed448 can be tested with the openssl-speed(1) application
since version 1.1.1. Valid algorithm names are ed25519, ed448 and
eddsa. If eddsa is specified, then both Ed25519 and Ed448 are
benchmarked.
EXAMPLES
To sign a message using a ED25519 or ED448 key:
void do_sign(EVP_PKEY *ed_key, unsigned char *msg, size_t msg_len)
{
size_t sig_len;
unsigned char *sig = NULL;
EVP_MD_CTX *md_ctx = EVP_MD_CTX_new();
EVP_DigestSignInit(md_ctx, NULL, NULL, NULL, ed_key);
/* Calculate the requires size for the signature by passing a NULL buffer */
EVP_DigestSign(md_ctx, NULL, &sig_len, msg, msg_len);
sig = OPENSSL_zalloc(sig_len);
EVP_DigestSign(md_ctx, sig, &sig_len, msg, msg_len);
...
OPENSSL_free(sig);
EVP_MD_CTX_free(md_ctx);
}
SEE ALSO
EVP_PKEY-X25519(7) provider-signature(7), EVP_DigestSignInit(3),
EVP_DigestVerifyInit(3),
COPYRIGHT
Copyright 2017-2021 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>.
3.0.13 2025-09-18 EVP_SIGNATURE-ED25519(7SSL)
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