1.\" $OpenBSD: X25519.3,v 1.1 2017/04/10 17:45:06 schwarze Exp $ 2.\" OpenSSL X25519.pod 69687aa8 Mar 28 23:57:28 2017 +0200 3.\" 4.\" This file was written by Dr. Stephen Henson <steve@openssl.org>. 5.\" Copyright (c) 2017 The OpenSSL Project. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in 16.\" the documentation and/or other materials provided with the 17.\" distribution. 18.\" 19.\" 3. All advertising materials mentioning features or use of this 20.\" software must display the following acknowledgment: 21.\" "This product includes software developed by the OpenSSL Project 22.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 23.\" 24.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 25.\" endorse or promote products derived from this software without 26.\" prior written permission. For written permission, please contact 27.\" openssl-core@openssl.org. 28.\" 29.\" 5. Products derived from this software may not be called "OpenSSL" 30.\" nor may "OpenSSL" appear in their names without prior written 31.\" permission of the OpenSSL Project. 32.\" 33.\" 6. Redistributions of any form whatsoever must retain the following 34.\" acknowledgment: 35.\" "This product includes software developed by the OpenSSL Project 36.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 37.\" 38.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 39.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 41.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 42.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 43.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 44.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 45.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 47.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 48.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 49.\" OF THE POSSIBILITY OF SUCH DAMAGE. 50.\" 51.Dd $Mdocdate: April 10 2017 $ 52.Dt X25519 3 53.Os 54.Sh NAME 55.Nm X25519 56.Nd EVP_PKEY X25519 support 57.Sh DESCRIPTION 58The 59.Nm 60.Vt EVP_PKEY 61implementation supports key generation and key derivation using X25519. 62It has associated private and public key formats compatible with 63draft-ietf-curdle-pkix-03. 64.Pp 65No additional parameters can be set during key generation. 66.Pp 67The peer public key must be set using 68.Xr EVP_PKEY_derive_set_peer 3 69when performing key derivation. 70.Pp 71A context for the 72.Nm 73algorithm can be obtained by calling: 74.Pp 75.Dl EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(NID_X25519, NULL); 76.Sh EXAMPLES 77Generate an 78.Nm 79private key and write it to standard output in PEM format: 80.Bd -literal 81#include <openssl/evp.h> 82#include <openssl/pem.h> 83 84EVP_PKEY *pkey = NULL; 85EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(NID_X25519, NULL); 86EVP_PKEY_keygen_init(pctx); 87EVP_PKEY_keygen(pctx, &pkey); 88EVP_PKEY_CTX_free(pctx); 89PEM_write_PrivateKey(stdout, pkey, NULL, NULL, 0, NULL, NULL); 90.Ed 91.Pp 92The key derivation example in 93.Xr EVP_PKEY_derive 3 94can be used with 95.Nm . 96.Sh SEE ALSO 97.Xr EVP_PKEY_CTX_new 3 , 98.Xr EVP_PKEY_derive 3 , 99.Xr EVP_PKEY_keygen 3 100