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.\"
.IX Title "EVP_SIGNATURE-ED25519 7"
.TH EVP_SIGNATURE-ED25519 7 "2023-05-07" "3.0.9" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
EVP_SIGNATURE\-ED25519,
EVP_SIGNATURE\-ED448,
Ed25519,
Ed448
\&\- EVP_PKEY Ed25519 and Ed448 support
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fBEd25519\fR and \fBEd448\fR \s-1EVP_PKEY\s0 implementation supports key generation,
one-shot digest sign and digest verify using PureEdDSA and \fBEd25519\fR or \fBEd448\fR
(see \s-1RFC8032\s0). It has associated private and public key formats compatible with
\&\s-1RFC 8410.\s0
.SS "\s-1ED25519\s0 and \s-1ED448\s0 Signature Parameters"
.IX Subsection "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 \fB\s-1NOT\s0\fR be specified when
signing or verifying.
See \s-1\fBEVP_PKEY\-X25519\s0\fR\|(7) for information related to \fBX25519\fR and \fBX448\fR keys.
.PP
The following signature parameters can be retrieved using
\&\fBEVP_PKEY_CTX_get_params()\fR.
.ie n .IP """algorithm-id"" (\fB\s-1OSSL_SIGNATURE_PARAM_ALGORITHM_ID\s0\fR) <octet string>" 4
.el .IP "``algorithm-id'' (\fB\s-1OSSL_SIGNATURE_PARAM_ALGORITHM_ID\s0\fR) <octet string>" 4
.IX Item "algorithm-id (OSSL_SIGNATURE_PARAM_ALGORITHM_ID) <octet string>"
The parameters are described in \fBprovider\-signature\fR\|(7).
.SH "NOTES"
.IX Header "NOTES"
The PureEdDSA algorithm does not support the streaming mechanism
of other signature algorithms using, for example, \fBEVP_DigestUpdate()\fR.
The message to sign or verify must be passed using the one-shot
\&\fBEVP_DigestSign()\fR and \fBEVP_DigestVerify()\fR functions.
.PP
When calling \fBEVP_DigestSignInit()\fR or \fBEVP_DigestVerifyInit()\fR, the
digest \fItype\fR parameter \fB\s-1MUST\s0\fR be set to \s-1NULL.\s0
.PP
Applications wishing to sign certificates (or other structures such as
CRLs or certificate requests) using Ed25519 or Ed448 can either use \fBX509_sign()\fR
or \fBX509_sign_ctx()\fR in the usual way.
.PP
Ed25519 or Ed448 private keys can be set directly using
\&\fBEVP_PKEY_new_raw_private_key\fR\|(3) or loaded from a PKCS#8 private key file
using \fBPEM_read_bio_PrivateKey\fR\|(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.
.PP
Ed25519 or Ed448 public keys can be set directly using
\&\fBEVP_PKEY_new_raw_public_key\fR\|(3) or loaded from a SubjectPublicKeyInfo
structure in a \s-1PEM\s0 file using \fBPEM_read_bio_PUBKEY\fR\|(3) (or similar function).
.PP
Ed25519 and Ed448 can be tested with the \fBopenssl\-speed\fR\|(1) application
since version 1.1.1.
Valid algorithm names are \fBed25519\fR, \fBed448\fR and \fBeddsa\fR. If \fBeddsa\fR is
specified, then both Ed25519 and Ed448 are benchmarked.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
To sign a message using a \s-1ED25519\s0 or \s-1ED448\s0 key:
.PP
.Vb 5
\&    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);
\&    }
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1\fBEVP_PKEY\-X25519\s0\fR\|(7)
\&\fBprovider\-signature\fR\|(7),
\&\fBEVP_DigestSignInit\fR\|(3),
\&\fBEVP_DigestVerifyInit\fR\|(3),
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2017\-2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.