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. IMPORTANT: See the NOTES
       section for important information about how these DH API functions are affected by the use of ENGINE API
       calls.

       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 is
       true only whilst no ENGINE has been set as a default for DH, so this function is no longer recommended.
       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.  However, the meaningfulness
       of this result is dependent on whether the ENGINE API is being used, so this function is no longer
       recommended.

       DH_set_method() selects meth to perform all operations using the key dh.  This will replace the DH_METHOD
       used by the DH key and if the previous method was supplied by an ENGINE, the handle to that ENGINE will
       be released during the change. It is possible to have DH keys that only work with certain DH_METHOD
       implementations (e.g. from an ENGINE module that supports embedded hardware-protected keys), and in such
       cases attempting to change the DH_METHOD for the key can have unexpected results.

       DH_new_method() allocates and initializes a DH structure so that engine will be used for the DH
       operations. If engine is NULL, the default ENGINE for DH operations is used, and if no default ENGINE is
       set, 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 (including
       unloading the ENGINE handle if the previous method was supplied by an ENGINE).

       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 2000-2021 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>.