156 lines
7.8 KiB
HTML
156 lines
7.8 KiB
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<?xml version="1.0" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>EVP_SIGNATURE-ED25519</title>
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<link rev="made" href="mailto:" />
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</head>
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<body>
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<ul id="index">
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<li><a href="#NAME">NAME</a></li>
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<li><a href="#DESCRIPTION">DESCRIPTION</a>
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<ul>
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<li><a href="#EdDSA-Instances">EdDSA Instances</a></li>
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<li><a href="#ED25519-and-ED448-Signature-Parameters">ED25519 and ED448 Signature Parameters</a></li>
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</ul>
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</li>
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<li><a href="#NOTES">NOTES</a></li>
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<li><a href="#EXAMPLES">EXAMPLES</a></li>
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<li><a href="#SEE-ALSO">SEE ALSO</a></li>
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<li><a href="#COPYRIGHT">COPYRIGHT</a></li>
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</ul>
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<h1 id="NAME">NAME</h1>
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<p>EVP_SIGNATURE-ED25519, EVP_SIGNATURE-ED448, Ed25519, Ed448 - EVP_PKEY Ed25519 and Ed448 support</p>
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<h1 id="DESCRIPTION">DESCRIPTION</h1>
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<p>The <b>Ed25519</b> and <b>Ed448</b> EVP_PKEY implementation supports key generation, one-shot digest-sign and digest-verify using the EdDSA signature scheme described in RFC 8032. It has associated private and public key formats compatible with RFC 8410.</p>
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<h2 id="EdDSA-Instances">EdDSA Instances</h2>
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<p>RFC 8032 describes five EdDSA instances: Ed25519, Ed25519ctx, Ed25519ph, Ed448, Ed448ph.</p>
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<p>The instances Ed25519, Ed25519ctx, Ed448 are referred to as <b>PureEdDSA</b> schemes. For these three instances, the sign and verify procedures require access to the complete message (not a digest of the message).</p>
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<p>The instances Ed25519ph, Ed448ph are referred to as <b>HashEdDSA</b> schemes. For these two instances, the sign and verify procedures do not require access to the complete message; they operate on a hash of the message. For Ed25519ph, the hash function is SHA512. For Ed448ph, the hash function is SHAKE256 with an output length of 512 bits.</p>
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<p>The instances Ed25519ctx, Ed25519ph, Ed448, Ed448ph accept an optional <b>context-string</b> as input to sign and verify operations (and for Ed25519ctx, the context-string must be nonempty). For the Ed25519 instance, a nonempty context-string is not permitted.</p>
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<h2 id="ED25519-and-ED448-Signature-Parameters">ED25519 and ED448 Signature Parameters</h2>
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<p>Two parameters can be set during signing or verification: the EdDSA <b>instance name</b> and the <b>context-string value</b>. They can be set by passing an OSSL_PARAM array to EVP_DigestSignInit_ex().</p>
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<ul>
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<li><p>"instance" (<b>OSSL_SIGNATURE_PARAM_INSTANCE</b>) <utf8 string></p>
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<p>One of the five strings "Ed25519", "Ed25519ctx", "Ed25519ph", "Ed448", "Ed448ph".</p>
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<p>"Ed25519", "Ed25519ctx", "Ed25519ph" are valid only for an Ed25519 EVP_PKEY.</p>
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<p>"Ed448", "Ed448ph" are valid only for an Ed448 EVP_PKEY.</p>
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</li>
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<li><p>"context-string" (<b>OSSL_SIGNATURE_PARAM_CONTEXT_STRING</b>) <octet string></p>
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<p>A string of octets with length at most 255.</p>
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</li>
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</ul>
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<p>Both of these parameters are optional.</p>
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<p>If the instance name is not specified, then the default "Ed25519" or "Ed448" is used.</p>
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<p>If a context-string is not specified, then an empty context-string is used.</p>
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<p>Note that a message digest name must <b>NOT</b> be specified when signing or verifying.</p>
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<p>See <a href="../man7/EVP_PKEY-X25519.html">EVP_PKEY-X25519(7)</a> for information related to <b>X25519</b> and <b>X448</b> keys.</p>
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<p>The following signature parameters can be retrieved using EVP_PKEY_CTX_get_params().</p>
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<ul>
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<li><p>"algorithm-id" (<b>OSSL_SIGNATURE_PARAM_ALGORITHM_ID</b>) <octet string></p>
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</li>
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<li><p>"instance" (<b>OSSL_SIGNATURE_PARAM_INSTANCE</b>) <utf8 string></p>
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</li>
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<li><p>"context-string" (<b>OSSL_SIGNATURE_PARAM_CONTEXT_STRING</b>) <octet string></p>
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</li>
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</ul>
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<p>The parameters are described in <a href="../man7/provider-signature.html">provider-signature(7)</a>.</p>
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<h1 id="NOTES">NOTES</h1>
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<p>The PureEdDSA instances do 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.</p>
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<p>The HashEdDSA instances do not yet support the streaming mechanisms (so the one-shot functions must be used with HashEdDSA as well).</p>
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<p>When calling EVP_DigestSignInit() or EVP_DigestVerifyInit(), the digest <i>type</i> parameter <b>MUST</b> be set to NULL.</p>
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<p>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.</p>
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<p>Ed25519 or Ed448 private keys can be set directly using <a href="../man3/EVP_PKEY_new_raw_private_key.html">EVP_PKEY_new_raw_private_key(3)</a> or loaded from a PKCS#8 private key file using <a href="../man3/PEM_read_bio_PrivateKey.html">PEM_read_bio_PrivateKey(3)</a> (or similar function). Completely new keys can also be generated (see the example below). Setting a private key also sets the associated public key.</p>
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<p>Ed25519 or Ed448 public keys can be set directly using <a href="../man3/EVP_PKEY_new_raw_public_key.html">EVP_PKEY_new_raw_public_key(3)</a> or loaded from a SubjectPublicKeyInfo structure in a PEM file using <a href="../man3/PEM_read_bio_PUBKEY.html">PEM_read_bio_PUBKEY(3)</a> (or similar function).</p>
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<p>Ed25519 and Ed448 can be tested with the <a href="../man1/openssl-speed.html">openssl-speed(1)</a> application since version 1.1.1. Valid algorithm names are <b>ed25519</b>, <b>ed448</b> and <b>eddsa</b>. If <b>eddsa</b> is specified, then both Ed25519 and Ed448 are benchmarked.</p>
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<h1 id="EXAMPLES">EXAMPLES</h1>
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<p>To sign a message using an ED25519 EVP_PKEY structure:</p>
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<pre><code> void do_sign(EVP_PKEY *ed_key, unsigned char *msg, size_t msg_len)
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{
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size_t sig_len;
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unsigned char *sig = NULL;
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EVP_MD_CTX *md_ctx = EVP_MD_CTX_new();
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const OSSL_PARAM params[] = {
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OSSL_PARAM_utf8_string ("instance", "Ed25519ctx", 10),
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OSSL_PARAM_octet_string("context-string", (unsigned char *)"A protocol defined context string", 33),
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OSSL_PARAM_END
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};
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/* The input "params" is not needed if default options are acceptable.
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Use NULL in place of "params" in that case. */
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EVP_DigestSignInit_ex(md_ctx, NULL, NULL, NULL, NULL, ed_key, params);
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/* Calculate the required size for the signature by passing a NULL buffer. */
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EVP_DigestSign(md_ctx, NULL, &sig_len, msg, msg_len);
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sig = OPENSSL_zalloc(sig_len);
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EVP_DigestSign(md_ctx, sig, &sig_len, msg, msg_len);
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...
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OPENSSL_free(sig);
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EVP_MD_CTX_free(md_ctx);
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}</code></pre>
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<h1 id="SEE-ALSO">SEE ALSO</h1>
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<p><a href="../man7/EVP_PKEY-X25519.html">EVP_PKEY-X25519(7)</a> <a href="../man7/provider-signature.html">provider-signature(7)</a>, <a href="../man3/EVP_DigestSignInit.html">EVP_DigestSignInit(3)</a>, <a href="../man3/EVP_DigestVerifyInit.html">EVP_DigestVerifyInit(3)</a>,</p>
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<h1 id="COPYRIGHT">COPYRIGHT</h1>
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<p>Copyright 2017-2023 The OpenSSL Project Authors. All Rights Reserved.</p>
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<p>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 <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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</body>
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</html>
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