Updated: 2021/Apr/14


DH_set_method(3)                    OpenSSL                   DH_set_method(3)



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

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/dh.h>

        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
       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)

COPYRIGHT
       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

       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>.



1.1.1i                            2020-12-10                  DH_set_method(3)