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<?xml version="1.0" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>X25519</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:root@localhost" /> </head> <body> <ul id="index"> <li><a href="#NAME">NAME</a></li> <li><a href="#DESCRIPTION">DESCRIPTION</a></li> <li><a href="#NOTES">NOTES</a></li> <li><a href="#EXAMPLES">EXAMPLES</a></li> <li><a href="#SEE-ALSO">SEE ALSO</a></li> <li><a href="#COPYRIGHT">COPYRIGHT</a></li> </ul> <h1 id="NAME">NAME</h1> <p>X25519, X448 - EVP_PKEY X25519 and X448 support</p> <h1 id="DESCRIPTION">DESCRIPTION</h1> <p>The <b>X25519</b> and <b>X448</b> EVP_PKEY implementation supports key generation and key derivation using <b>X25519</b> and <b>X448</b>. It has associated private and public key formats compatible with RFC 8410.</p> <p>No additional parameters can be set during key generation.</p> <p>The peer public key must be set using EVP_PKEY_derive_set_peer() when performing key derivation.</p> <h1 id="NOTES">NOTES</h1> <p>A context for the <b>X25519</b> algorithm can be obtained by calling:</p> <pre><code> EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X25519, NULL);</code></pre> <p>For the <b>X448</b> algorithm a context can be obtained by calling:</p> <pre><code> EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X448, NULL);</code></pre> <p>X25519 or X448 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> <p>X25519 or X448 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> <h1 id="EXAMPLES">EXAMPLES</h1> <p>This example generates an <b>X25519</b> private key and writes it to standard output in PEM format:</p> <pre><code> #include <openssl/evp.h> #include <openssl/pem.h> ... EVP_PKEY *pkey = NULL; EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X25519, 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);</code></pre> <p>The key derivation example in <a href="../man3/EVP_PKEY_derive.html">EVP_PKEY_derive(3)</a> can be used with <b>X25519</b> and <b>X448</b>.</p> <h1 id="SEE-ALSO">SEE ALSO</h1> <p><a href="../man3/EVP_PKEY_CTX_new.html">EVP_PKEY_CTX_new(3)</a>, <a href="../man3/EVP_PKEY_keygen.html">EVP_PKEY_keygen(3)</a>, <a href="../man3/EVP_PKEY_derive.html">EVP_PKEY_derive(3)</a>, <a href="../man3/EVP_PKEY_derive_set_peer.html">EVP_PKEY_derive_set_peer(3)</a></p> <h1 id="COPYRIGHT">COPYRIGHT</h1> <p>Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.</p> <p>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 <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p> </body> </html>
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