Edit File: X25519.7
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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" X25519, X448 \&\- EVP_PKEY X25519 and X448 support .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \fBX25519\fR and \fBX448\fR \s-1EVP_PKEY\s0 implementation supports key generation and key derivation using \fBX25519\fR and \fBX448\fR. It has associated private and public key formats compatible with \s-1RFC 8410.\s0 .PP No additional parameters can be set during key generation. .PP The peer public key must be set using \fBEVP_PKEY_derive_set_peer()\fR when performing key derivation. .SH "NOTES" .IX Header "NOTES" A context for the \fBX25519\fR algorithm can be obtained by calling: .PP .Vb 1 \& EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X25519, NULL); .Ve .PP For the \fBX448\fR algorithm a context can be obtained by calling: .PP .Vb 1 \& EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X448, NULL); .Ve .PP X25519 or X448 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 X25519 or X448 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). .SH "EXAMPLES" .IX Header "EXAMPLES" This example generates an \fBX25519\fR private key and writes it to standard output in \s-1PEM\s0 format: .PP .Vb 9 \& #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); .Ve .PP The key derivation example in \fBEVP_PKEY_derive\fR\|(3) can be used with \&\fBX25519\fR and \fBX448\fR. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBEVP_PKEY_CTX_new\fR\|(3), \&\fBEVP_PKEY_keygen\fR\|(3), \&\fBEVP_PKEY_derive\fR\|(3), \&\fBEVP_PKEY_derive_set_peer\fR\|(3) .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2017\-2020 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (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>.