1DH_SET_METHOD(3)                    OpenSSL                   DH_SET_METHOD(3)
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NAME

6       DH_set_default_method, DH_get_default_method, DH_set_method,
7       DH_new_method, DH_OpenSSL - select DH method
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SYNOPSIS

10        #include <openssl/dh.h>
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12        void DH_set_default_method(const DH_METHOD *meth);
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14        const DH_METHOD *DH_get_default_method(void);
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16        int DH_set_method(DH *dh, const DH_METHOD *meth);
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18        DH *DH_new_method(ENGINE *engine);
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20        const DH_METHOD *DH_OpenSSL(void);
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DESCRIPTION

23       A DH_METHOD specifies the functions that OpenSSL uses for Diffie-
24       Hellman operations. By modifying the method, alternative
25       implementations such as hardware accelerators may be used. IMPORTANT:
26       See the NOTES section for important information about how these DH API
27       functions are affected by the use of ENGINE API calls.
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29       Initially, the default DH_METHOD is the OpenSSL internal
30       implementation, as returned by DH_OpenSSL().
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32       DH_set_default_method() makes meth the default method for all DH
33       structures created later.  NB: This is true only whilst no ENGINE has
34       been set as a default for DH, so this function is no longer
35       recommended.  This function is not thread-safe and should not be called
36       at the same time as other OpenSSL functions.
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38       DH_get_default_method() returns a pointer to the current default
39       DH_METHOD.  However, the meaningfulness of this result is dependent on
40       whether the ENGINE API is being used, so this function is no longer
41       recommended.
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43       DH_set_method() selects meth to perform all operations using the key
44       dh.  This will replace the DH_METHOD used by the DH key and if the
45       previous method was supplied by an ENGINE, the handle to that ENGINE
46       will be released during the change. It is possible to have DH keys that
47       only work with certain DH_METHOD implementations (e.g. from an ENGINE
48       module that supports embedded hardware-protected keys), and in such
49       cases attempting to change the DH_METHOD for the key can have
50       unexpected results.
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52       DH_new_method() allocates and initializes a DH structure so that engine
53       will be used for the DH operations. If engine is NULL, the default
54       ENGINE for DH operations is used, and if no default ENGINE is set, the
55       DH_METHOD controlled by DH_set_default_method() is used.
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57       A new DH_METHOD object may be constructed using DH_meth_new() (see
58       DH_meth_new(3)).
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RETURN VALUES

61       DH_OpenSSL() and DH_get_default_method() return pointers to the
62       respective DH_METHODs.
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64       DH_set_default_method() returns no value.
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66       DH_set_method() returns nonzero if the provided meth was successfully
67       set as the method for dh (including unloading the ENGINE handle if the
68       previous method was supplied by an ENGINE).
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70       DH_new_method() returns NULL and sets an error code that can be
71       obtained by ERR_get_error(3) if the allocation fails. Otherwise it
72       returns a pointer to the newly allocated structure.
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SEE ALSO

75       DH_new(3), DH_new(3), DH_meth_new(3)
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78       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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80       Licensed under the OpenSSL license (the "License").  You may not use
81       this file except in compliance with the License.  You can obtain a copy
82       in the file LICENSE in the source distribution or at
83       <https://www.openssl.org/source/license.html>.
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871.1.1i                            2021-07-22                  DH_SET_METHOD(3)
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