These are updates/fixes to DH/DSA/RAND docs based on the fixes to the RSA

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

diff --git a/doc/crypto/RAND_set_rand_method.pod b/doc/crypto/RAND_set_rand_method.pod
index 0e3e3d728a3df33da23a315174c24987937ac1ea..c9bb6d9f27b3f0f67bebc2ce7d61e3dadacf2c7b 100644 (file)
--- a/doc/crypto/RAND_set_rand_method.pod
+++ b/doc/crypto/RAND_set_rand_method.pod
@@ -2,28 +2,36 @@
 
 =head1 NAME
 
-RAND_set_rand_method, RAND_get_rand_method, RAND_SSLeay - Select RAND method
+RAND_set_rand_method, RAND_get_rand_method, RAND_SSLeay - select RAND method
 
 =head1 SYNOPSIS
 
  #include <openssl/rand.h>
 
- void RAND_set_rand_method(RAND_METHOD *meth);
+ void RAND_set_rand_method(const RAND_METHOD *meth);
 
- RAND_METHOD *RAND_get_rand_method(void);
+ const RAND_METHOD *RAND_get_rand_method(void);
 
  RAND_METHOD *RAND_SSLeay(void);
 
 =head1 DESCRIPTION
 
-A B<RAND_METHOD> specifies the functions that OpenSSL uses for random
-number generation. By modifying the method, alternative
-implementations such as hardware RNGs may be used.  Initially, the
-default is to use the OpenSSL internal implementation. RAND_SSLeay()
-returns a pointer to that method.
+A B<RAND_METHOD> specifies the functions that OpenSSL uses for random number
+generation. By modifying the method, alternative implementations such as
+hardware RNGs may be used. IMPORTANT: See the NOTES section for important
+information about how these RAND API functions are affected by the use of
+B<ENGINE> API calls.
 
-RAND_set_rand_method() sets the RAND method to B<meth>.
-RAND_get_rand_method() returns a pointer to the current method.
+Initially, the default RAND_METHOD is the OpenSSL internal implementation, as
+returned by RAND_SSLeay().
+
+RAND_set_default_method() makes B<meth> the method for PRNG use. B<NB>: This is
+true only whilst no ENGINE has been set as a default for RAND, so this function
+is no longer recommended.
+
+RAND_get_default_method() returns a pointer to the current RAND_METHOD.
+However, the meaningfulness of this result is dependant on whether the ENGINE
+API is being used, so this function is no longer recommended.
 
 =head1 THE RAND_METHOD STRUCTURE
 
@@ -34,10 +42,12 @@ RAND_get_rand_method() returns a pointer to the current method.
         void (*cleanup)(void);
         void (*add)(const void *buf, int num, int entropy);
         int (*pseudorand)(unsigned char *buf, int num);
+       int (*status)(void);
  } RAND_METHOD;
 
 The components point to the implementation of RAND_seed(),
-RAND_bytes(), RAND_cleanup(), RAND_add() and RAND_pseudo_rand().
+RAND_bytes(), RAND_cleanup(), RAND_add(), RAND_pseudo_rand()
+and RAND_status().
 Each component may be NULL if the function is not implemented.
 
 =head1 RETURN VALUES
@@ -45,13 +55,29 @@ Each component may be NULL if the function is not implemented.
 RAND_set_rand_method() returns no value. RAND_get_rand_method() and
 RAND_SSLeay() return pointers to the respective methods.
 
+=head1 NOTES
+
+As of version 0.9.7, RAND_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 RAND functionality using an ENGINE API function,
+that will override any RAND defaults set using the RAND API (ie.
+RAND_set_rand_method()). For this reason, the ENGINE API is the recommended way
+to control default implementations for use in RAND and other cryptographic
+algorithms.
+
 =head1 SEE ALSO
 
-L<rand(3)|rand(3)>
+L<rand(3)|rand(3)>, L<engine(3)|engine(3)>
 
 =head1 HISTORY
 
 RAND_set_rand_method(), RAND_get_rand_method() and RAND_SSLeay() are
 available in all versions of OpenSSL.
 
+In the engine version of version 0.9.6, RAND_set_rand_method() was altered to
+take an ENGINE pointer as its argument. As of version 0.9.7, that has been
+reverted as the ENGINE API transparently overrides RAND defaults if used,
+otherwise RAND API functions work as before. RAND_set_rand_engine() was also
+introduced in version 0.9.7.
+
 =cut