Add aep and sureware implementations and clean up some error reasons

[openssl.git] / doc / crypto / DH_set_method.pod

diff --git a/doc/crypto/DH_set_method.pod b/doc/crypto/DH_set_method.pod
index dca41d8dbc8adcf2528f27d1b7a6a4d4e9e91553..d990bf878603692173a0f6abd1e69ea3f243a3ce 100644 (file)
--- a/doc/crypto/DH_set_method.pod
+++ b/doc/crypto/DH_set_method.pod
@@ -2,20 +2,21 @@
 
 =head1 NAME
 
-DH_set_default_method, DH_get_default_method, DH_set_method,
-DH_new_method, DH_OpenSSL - select DH method
+DH_set_default_openssl_method, DH_get_default_openssl_method,
+DH_set_method, DH_new_method, DH_OpenSSL - select DH method
 
 =head1 SYNOPSIS
 
  #include <openssl/dh.h>
+ #include <openssl/engine.h>
 
- void DH_set_default_method(DH_METHOD *meth);
+ void DH_set_default_openssl_method(DH_METHOD *meth);
 
- DH_METHOD *DH_get_default_method(void);
+ DH_METHOD *DH_get_default_openssl_method(void);
 
- DH_METHOD *DH_set_method(DH *dh, DH_METHOD *meth);
+ int DH_set_method(DH *dh, ENGINE *engine);
 
- DH *DH_new_method(DH_METHOD *meth);
+ DH *DH_new_method(ENGINE *engine);
 
  DH_METHOD *DH_OpenSSL(void);
 
@@ -28,20 +29,26 @@ such as hardware accelerators may be used.
 Initially, the default is to use the OpenSSL internal implementation.
 DH_OpenSSL() returns a pointer to that method.
 
-DH_set_default_method() makes B<meth> the default method for all B<DH>
-structures created later.
+DH_set_default_openssl_method() makes B<meth> the default method for all DH
+structures created later. B<NB:> This is true only whilst the default engine
+for Diffie-Hellman operations remains as "openssl". ENGINEs provide an
+encapsulation for implementations of one or more algorithms, and all the DH
+functions mentioned here operate within the scope of the default
+"openssl" engine.
 
-DH_get_default_method() returns a pointer to the current default
-method.
+DH_get_default_openssl_method() returns a pointer to the current default
+method for the "openssl" engine.
 
-DH_set_method() selects B<meth> for all operations using the structure B<dh>.
+DH_set_method() selects B<engine> as the engine that will be responsible for
+all operations using the structure B<dh>. If this function completes successfully,
+then the B<dh> structure will have its own functional reference of B<engine>, so
+the caller should remember to free their own reference to B<engine> when they are
+finished with it. NB: An ENGINE's DH_METHOD can be retrieved (or set) by
+ENGINE_get_DH() or ENGINE_set_DH().
 
-DH_get_method() returns a pointer to the method currently selected
-for B<dh>.
-
-DH_new_method() allocates and initializes a B<DH> structure so that
-B<method> will be used for the DH operations. If B<method> is B<NULL>,
-the default method is used.
+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 Diffie-Hellman opertaions is used.
 
 =head1 THE DH_METHOD STRUCTURE
 
@@ -56,7 +63,7 @@ the default method is used.
      /* compute shared secret */
         int (*compute_key)(unsigned char *key, BIGNUM *pub_key, DH *dh);
 
-     /* compute r = a ^ p mod m. May be NULL */
+     /* compute r = a ^ p mod m (May be NULL for some implementations) */
         int (*bn_mod_exp)(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
                                 const BIGNUM *m, BN_CTX *ctx,
                                 BN_MONT_CTX *m_ctx);
@@ -75,17 +82,17 @@ the default method is used.
 
 =head1 RETURN VALUES
 
-DH_OpenSSL(), DH_get_default_method() and DH_get_method() return
-pointers to the respective B<DH_METHOD>s.
+DH_OpenSSL() and DH_get_default_openssl_method() return pointers to the
+respective B<DH_METHOD>s.
 
-DH_set_default_method() returns no value.
+DH_set_default_openssl_method() returns no value.
 
-DH_set_method() returns a pointer to the B<DH_METHOD> previously
-associated with B<dh>.
+DH_set_method() returns non-zero if the ENGINE associated with B<dh>
+was successfully changed to B<engine>.
 
-DH_new_method() returns B<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.
+DH_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 SEE ALSO
 
@@ -96,4 +103,9 @@ L<dh(3)|dh(3)>, L<DH_new(3)|DH_new(3)>
 DH_set_default_method(), DH_get_default_method(), DH_set_method(),
 DH_new_method() and DH_OpenSSL() were added in OpenSSL 0.9.4.
 
+DH_set_default_openssl_method() and DH_get_default_openssl_method()
+replaced DH_set_default_method() and DH_get_default_method() respectively,
+and DH_set_method() and DH_new_method() were altered to use B<ENGINE>s
+rather than B<DH_METHOD>s during development of OpenSSL 0.9.6.
+
 =cut