No additional parameters can be set during key generation.
The peer public key must be set using EVP_PKEY_derive_set_peer() when performing key derivation.
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X25519, NULL);
For the X448 algorithm a context can be obtained by calling:
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X448, NULL);
X25519 or X448 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.
#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);
The key derivation example in EVP_PKEY_derive(3) can be used with X25519 and X448.
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 https://www.openssl.org/source/license.html.