OpenSSL 1.1.1-pre2

doc/man3/DH_set_method.pod

@@ -0,0 +1,88 @@
+=pod
+
+=head1 NAME
+
+DH_set_default_method, DH_get_default_method,
+DH_set_method, DH_new_method, DH_OpenSSL - select DH method
+
+=head1 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);
+
+=head1 DESCRIPTION
+
+A B<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 B<ENGINE> API calls.
+
+Initially, the default DH_METHOD is the OpenSSL internal implementation, as
+returned by DH_OpenSSL().
+
+DH_set_default_method() makes B<meth> the default method for all DH
+structures created later.
+B<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 B<meth> to perform all operations using the key B<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 (eg. 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 B<engine> will
+be used for the DH operations. If B<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
+L<DH_meth_new(3)>).
+
+=head1 RETURN VALUES
+
+DH_OpenSSL() and DH_get_default_method() return pointers to the respective
+B<DH_METHOD>s.
+
+DH_set_default_method() returns no value.
+
+DH_set_method() returns non-zero if the provided B<meth> was successfully set as
+the method for B<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
+L<ERR_get_error(3)> if the allocation fails. Otherwise it
+returns a pointer to the newly allocated structure.
+
+=head1 SEE ALSO
+
+L<DH_new(3)>, L<DH_new(3)>, L<DH_meth_new(3)>
+
+=head1 COPYRIGHT
+
+Copyright 2000-2016 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
+L<https://www.openssl.org/source/license.html>.
+
+=cut