DH_SET_METHOD(3)

NAME
DH_set_default_method, DH_get_default_method, DH_set_method, DH_new_method, DH_OpenSSL - select DH method

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):

 void DH_set_default_method(const DH_METHOD *meth);

 const DH_METHOD *DH_get_default_method(void);

 int DH_set_method(DH *dh, const DH_METHOD *meth);

 DH *DH_new_method(ENGINE *engine);

 const DH_METHOD *DH_OpenSSL(void);

DESCRIPTION
All of the functions described on this page are deprecated. Applications should instead use the provider APIs.

A DH_METHOD specifies the functions that OpenSSL uses for Diffie-Hellman operations. By modifying the method, alternative implementations such as hardware accelerators may be used.

Initially, the default DH_METHOD is the OpenSSL internal implementation, as returned by DH_OpenSSL().

DH_set_default_method() makes meth the default method for all DH structures created later. NB: This function is not thread-safe and should not be called at the same time as other OpenSSL functions.

DH_get_default_method() returns a pointer to the current default DH_METHOD.

DH_set_method() selects meth to perform all operations using the key dh. This will replace the DH_METHOD used by the DH key. It is possible to have DH keys that only work with certain DH_METHOD implementations, and in such cases attempting to change the DH_METHOD for the key can have unexpected results. See DH_meth_new(3) for information on constructing custom DH_METHOD objects.

DH_new_method() allocates and initializes a DH structure. engine must be NULL and the DH_METHOD controlled by DH_set_default_method() is used.

A new DH_METHOD object may be constructed using DH_meth_new() (see DH_meth_new(3)).

RETURN VALUES
DH_OpenSSL() and DH_get_default_method() return pointers to the respective DH_METHODs.

DH_set_default_method() returns no value.

DH_set_method() returns nonzero if the provided meth was successfully set as the method for dh.

DH_new_method() returns NULL and sets an error code that can be obtained by ERR_get_error(3) if the allocation fails. Otherwise it returns a pointer to the newly allocated structure.

SEE ALSO
DH_new(3), DH_new(3), DH_meth_new(3)

HISTORY
All of these functions were deprecated in OpenSSL 3.0.

COPYRIGHT
Copyright 2000-2025 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>.