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EVP_SIGNATURE-ED25519(7)            OpenSSL           EVP_SIGNATURE-ED25519(7)



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>.



3.0.12                            2023-05-07          EVP_SIGNATURE-ED25519(7)