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Title "DH_SET_METHOD 3"
DH_SET_METHOD 3 "2022-07-05" "1.1.1q" "OpenSSL"
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"NAME"
DH_set_default_method, DH_get_default_method, DH_set_method, DH_new_method, DH_OpenSSL - select DH method
"SYNOPSIS"
Header "SYNOPSIS" .Vb 1 #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); .Ve
"DESCRIPTION"
Header "DESCRIPTION" A \s-1DH_METHOD\s0 specifies the functions that OpenSSL uses for Diffie-Hellman operations. By modifying the method, alternative implementations such as hardware accelerators may be used. \s-1IMPORTANT:\s0 See the \s-1NOTES\s0 section for important information about how these \s-1DH API\s0 functions are affected by the use of \s-1ENGINE\s0 \s-1API\s0 calls.

Initially, the default \s-1DH_METHOD\s0 is the OpenSSL internal implementation, as returned by DH_OpenSSL().

\fBDH_set_default_method() makes meth the default method for all \s-1DH\s0 structures created later. \fB\s-1NB\s0: This is true only whilst no \s-1ENGINE\s0 has been set as a default for \s-1DH,\s0 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.

\fBDH_get_default_method() returns a pointer to the current default \s-1DH_METHOD.\s0 However, the meaningfulness of this result is dependent on whether the \s-1ENGINE API\s0 is being used, so this function is no longer recommended.

\fBDH_set_method() selects meth to perform all operations using the key dh. This will replace the \s-1DH_METHOD\s0 used by the \s-1DH\s0 key and if the previous method was supplied by an \s-1ENGINE,\s0 the handle to that \s-1ENGINE\s0 will be released during the change. It is possible to have \s-1DH\s0 keys that only work with certain \s-1DH_METHOD\s0 implementations (e.g. from an \s-1ENGINE\s0 module that supports embedded hardware-protected keys), and in such cases attempting to change the \s-1DH_METHOD\s0 for the key can have unexpected results.

\fBDH_new_method() allocates and initializes a \s-1DH\s0 structure so that engine will be used for the \s-1DH\s0 operations. If engine is \s-1NULL,\s0 the default \s-1ENGINE\s0 for \s-1DH\s0 operations is used, and if no default \s-1ENGINE\s0 is set, the \s-1DH_METHOD\s0 controlled by \fBDH_set_default_method() is used.

A new \s-1DH_METHOD\s0 object may be constructed using DH_meth_new() (see \fBDH_meth_new\|(3)).

"RETURN VALUES"
Header "RETURN VALUES" \fBDH_OpenSSL() and DH_get_default_method() return pointers to the respective \fB\s-1DH_METHOD\s0s.

\fBDH_set_default_method() returns no value.

\fBDH_set_method() returns nonzero if the provided meth was successfully set as the method for dh (including unloading the \s-1ENGINE\s0 handle if the previous method was supplied by an \s-1ENGINE\s0).

\fBDH_new_method() returns \s-1NULL\s0 and sets an error code that can be obtained by \fBERR_get_error\|(3) if the allocation fails. Otherwise it returns a pointer to the newly allocated structure.

"SEE ALSO"
Header "SEE ALSO" \fBDH_new\|(3), DH_new\|(3), DH_meth_new\|(3)
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.