=head1 NAME
-DSA_set_default_openssl_method, DSA_get_default_openssl_method,
+DSA_set_default_method, DSA_get_default_method,
DSA_set_method, DSA_new_method, DSA_OpenSSL - select DSA method
=head1 SYNOPSIS
#include <openssl/dsa.h>
#include <openssl/engine.h>
- void DSA_set_default_openssl_method(DSA_METHOD *meth);
+ void DSA_set_default_method(const DSA_METHOD *meth);
- DSA_METHOD *DSA_get_default_openssl_method(void);
+ const DSA_METHOD *DSA_get_default_method(void);
- int DSA_set_method(DSA *dsa, ENGINE *engine);
+ int DSA_set_method(DSA *dsa, const DSA_METHOD *meth);
DSA *DSA_new_method(ENGINE *engine);
A B<DSA_METHOD> specifies the functions that OpenSSL uses for DSA
operations. By modifying the method, alternative implementations
-such as hardware accelerators may be used.
-
-Initially, the default is to use the OpenSSL internal implementation.
-DSA_OpenSSL() returns a pointer to that method.
-
-DSA_set_default_openssl_method() makes B<meth> the default method for
-all DSA structures created later. B<NB:> This is true only whilst the
-default engine for DSA operations remains as "openssl". ENGINEs
-provide an encapsulation for implementations of one or more algorithms at a
-time, and all the DSA functions mentioned here operate within the scope
-of the default "openssl" engine.
-
-DSA_get_default_openssl_method() returns a pointer to the current default
-method for the "openssl" engine.
-
-DSA_set_method() selects B<engine> for all operations using the structure B<dsa>.
-
-DSA_new_method() allocates and initializes a DSA structure so that
-B<engine> will be used for the DSA operations. If B<engine> is NULL,
-the default engine for DSA operations is used.
+such as hardware accelerators may be used. IMPORTANT: See the NOTES section for
+important information about how these DSA API functions are affected by the use
+of B<ENGINE> API calls.
+
+Initially, the default DSA_METHOD is the OpenSSL internal implementation,
+as returned by DSA_OpenSSL().
+
+DSA_set_default_method() makes B<meth> the default method for all DSA
+structures created later. B<NB>: This is true only whilst no ENGINE has
+been set as a default for DSA, so this function is no longer recommended.
+
+DSA_get_default_method() returns a pointer to the current default
+DSA_METHOD. However, the meaningfulness of this result is dependent on
+whether the ENGINE API is being used, so this function is no longer
+recommended.
+
+DSA_set_method() selects B<meth> to perform all operations using the key
+B<rsa>. This will replace the DSA_METHOD used by the DSA 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 DSA keys that only
+work with certain DSA_METHOD implementations (eg. from an ENGINE module
+that supports embedded hardware-protected keys), and in such cases
+attempting to change the DSA_METHOD for the key can have unexpected
+results.
+
+DSA_new_method() allocates and initializes a DSA structure so that B<engine>
+will be used for the DSA operations. If B<engine> is NULL, the default engine
+for DSA operations is used, and if no default ENGINE is set, the DSA_METHOD
+controlled by DSA_set_default_method() is used.
=head1 THE DSA_METHOD STRUCTURE
=head1 RETURN VALUES
-DSA_OpenSSL() and DSA_get_default_openssl_method() return pointers to the
-respective B<DSA_METHOD>s.
+DSA_OpenSSL() and DSA_get_default_method() return pointers to the respective
+B<DSA_METHOD>s.
-DSA_set_default_openssl_method() returns no value.
+DSA_set_default_method() returns no value.
-DSA_set_method() returns non-zero if the ENGINE associated with B<dsa>
-was successfully changed to B<engine>.
+DSA_set_method() returns non-zero if the provided B<meth> was successfully set as
+the method for B<dsa> (including unloading the ENGINE handle if the previous
+method was supplied by an ENGINE).
DSA_new_method() returns NULL and sets an error code that can be
obtained by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation
fails. Otherwise it returns a pointer to the newly allocated structure.
+=head1 NOTES
+
+As of version 0.9.7, DSA_METHOD implementations are grouped together with other
+algorithmic APIs (eg. RSA_METHOD, EVP_CIPHER, etc) in B<ENGINE> modules. If a
+default ENGINE is specified for DSA functionality using an ENGINE API function,
+that will override any DSA defaults set using the DSA API (ie.
+DSA_set_default_method()). For this reason, the ENGINE API is the recommended way
+to control default implementations for use in DSA and other cryptographic
+algorithms.
+
=head1 SEE ALSO
L<dsa(3)|dsa(3)>, L<DSA_new(3)|DSA_new(3)>
DSA_set_default_method(), DSA_get_default_method(), DSA_set_method(),
DSA_new_method() and DSA_OpenSSL() were added in OpenSSL 0.9.4.
-DSA_set_default_openssl_method() and DSA_get_default_openssl_method()
-replaced DSA_set_default_method() and DSA_get_default_method() respectively,
-and DSA_set_method() and DSA_new_method() were altered to use B<ENGINE>s
-rather than B<DSA_METHOD>s during development of OpenSSL 0.9.6.
+DSA_set_default_openssl_method() and DSA_get_default_openssl_method() replaced
+DSA_set_default_method() and DSA_get_default_method() respectively, and
+DSA_set_method() and DSA_new_method() were altered to use B<ENGINE>s rather than
+B<DSA_METHOD>s during development of the engine version of OpenSSL 0.9.6. For
+0.9.7, the handling of defaults in the ENGINE API was restructured so that this
+change was reversed, and behaviour of the other functions resembled more closely
+the previous behaviour. The behaviour of defaults in the ENGINE API now
+transparently overrides the behaviour of defaults in the DSA API without
+requiring changing these function prototypes.
=cut
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