DH_generate_key, DH_compute_key, DH_compute_key_padded - perform Diffie-Hellman
key exchange
#include <openssl/dh.h>
The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining
OPENSSL_API_COMPAT with a suitable version
value, see
openssl_user_macros(7):
int DH_generate_key(DH *dh);
int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh);
All of the functions described on this page are deprecated. Applications should
instead use
EVP_PKEY_derive_init(3) and
EVP_PKEY_derive(3).
DH_generate_key() performs the first step of a Diffie-Hellman key
exchange by generating private and public DH values. By calling
DH_compute_key() or
DH_compute_key_padded(), these are combined
with the other party's public value to compute the shared key.
DH_generate_key() expects
dh to contain the shared parameters
dh->p and
dh->g. It generates a random private DH value
unless
dh->priv_key is already set, and computes the corresponding
public value
dh->pub_key, which can then be published.
DH_compute_key() computes the shared secret from the private DH value in
dh and the other party's public value in
pub_key and stores it
in
key.
key must point to
DH_size(dh) bytes of memory.
The padding style is RFC 5246 (8.1.2) that strips leading zero bytes. It is
not constant time due to the leading zero bytes being stripped. The return
value should be considered public.
DH_compute_key_padded() is similar but stores a fixed number of bytes.
The padding style is NIST SP 800-56A (C.1) that retains leading zero bytes. It
is constant time due to the leading zero bytes being retained. The return
value should be considered public.
DH_generate_key() returns 1 on success, 0 otherwise.
DH_compute_key() returns the size of the shared secret on success, -1 on
error.
DH_compute_key_padded() returns
DH_size(dh) on success, -1 on
error.
The error codes can be obtained by
ERR_get_error(3).
EVP_PKEY_derive(3),
DH_new(3),
ERR_get_error(3),
RAND_bytes(3),
DH_size(3)
DH_compute_key_padded() was added in OpenSSL 1.0.2.
All of these functions were deprecated in OpenSSL 3.0.
Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
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
<
https://www.openssl.org/source/license.html>.