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

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

diff --git a/doc/crypto/rand.pod b/doc/crypto/rand.pod
index 295b6810505afafdf6a9d1f84186f0f6eeee454c..1c068c85b34c144ed4981c4ded00e961bc210a2b 100644 (file)
--- a/doc/crypto/rand.pod
+++ b/doc/crypto/rand.pod
@@ -8,28 +8,46 @@ rand - pseudo-random number generator
 
  #include <openssl/rand.h>
 
- int  RAND_bytes(unsigned char *buf,int num);
- int  RAND_pseudo_bytes(unsigned char *buf,int num);
+ int  RAND_set_rand_engine(ENGINE *engine);
 
- void RAND_seed(const void *buf,int num);
- void RAND_add(const void *buf,int num,int entropy);
+ int  RAND_bytes(unsigned char *buf, int num);
+ int  RAND_pseudo_bytes(unsigned char *buf, int num);
+
+ void RAND_seed(const void *buf, int num);
+ void RAND_add(const void *buf, int num, int entropy);
  int  RAND_status(void);
- void RAND_screen(void);
 
- int  RAND_load_file(const char *file,long max_bytes);
+ int  RAND_load_file(const char *file, long max_bytes);
  int  RAND_write_file(const char *file);
- const char *RAND_file_name(char *file,int num);
+ const char *RAND_file_name(char *file, size_t num);
 
  int  RAND_egd(const char *path);
 
- void RAND_set_rand_method(RAND_METHOD *meth);
- RAND_METHOD *RAND_get_rand_method(void);
+ void RAND_set_rand_method(const RAND_METHOD *meth);
+ const RAND_METHOD *RAND_get_rand_method(void);
  RAND_METHOD *RAND_SSLeay(void);
 
  void RAND_cleanup(void);
 
+ /* For Win32 only */
+ void RAND_screen(void);
+ int RAND_event(UINT, WPARAM, LPARAM);
+
 =head1 DESCRIPTION
 
+Since the introduction of the ENGINE API, the recommended way of controlling
+default implementations is by using the ENGINE API functions. The default
+B<RAND_METHOD>, as set by RAND_set_rand_method() and returned by
+RAND_get_rand_method(), is only used if no ENGINE has been set as the default
+"rand" implementation. Hence, these two functions are no longer the recommened
+way to control defaults.
+
+If an alternative B<RAND_METHOD> implementation is being used (either set
+directly or as provided by an ENGINE module), then it is entirely responsible
+for the generation and management of a cryptographically secure PRNG stream. The
+mechanisms described below relate solely to the software PRNG implementation
+built in to OpenSSL and used by default.
+
 These functions implement a cryptographically secure pseudo-random
 number generator (PRNG). It is used by other library functions for
 example to generate random keys, and applications can use it when they
@@ -127,13 +145,12 @@ function and xor).
 When bytes are extracted from the RNG, the following process is used.
 For each group of 10 bytes (or less), we do the following:
 
-Input into the hash function the top 10 bytes from the local 'md'
-(which is initialized from the global 'md' before any bytes are
-generated), the bytes that are to be overwritten by the random bytes,
-and bytes from the 'state' (incrementing looping index). From this
-digest output (which is kept in 'md'), the top (up to) 10 bytes are
-returned to the caller and the bottom (up to) 10 bytes are xored into
-the 'state'.
+Input into the hash function the local 'md' (which is initialized from
+the global 'md' before any bytes are generated), the bytes that are to
+be overwritten by the random bytes, and bytes from the 'state'
+(incrementing looping index). From this digest output (which is kept
+in 'md'), the top (up to) 10 bytes are returned to the caller and the
+bottom 10 bytes are xored into the 'state'.
 
 Finally, after we have finished 'num' random bytes for the caller,
 'count' (which is incremented) and the local and global 'md' are fed