DH_GENERATE_KEY(3ossl) OpenSSL DH_GENERATE_KEY(3ossl)
NAME
DH_generate_key, DH_compute_key, DH_compute_key_padded - perform
Diffie-Hellman key exchange
SYNOPSIS
#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);
DESCRIPTION
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(3) 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(3) 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.
RETURN VALUES
DH_generate_key(3) 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).
SEE ALSO
EVP_PKEY_derive(3), DH_new(3), ERR_get_error(3), RAND_bytes(3),
DH_size(3)
HISTORY
DH_compute_key_padded() was added in OpenSSL 1.0.2.
All of these functions were deprecated in OpenSSL 3.0.
COPYRIGHT
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>.
3.3.2 2024-09-04 DH_GENERATE_KEY(3ossl)
openssl 3.3.2 - Generated Sun Sep 8 18:14:03 CDT 2024