flesh

src/lib/libc/crypt/arc4random.3

@@ -1,4 +1,4 @@
-.\" $OpenBSD: arc4random.3,v 1.15 2000/04/28 21:02:55 deraadt Exp $
+.\" $OpenBSD: arc4random.3,v 1.16 2000/04/28 21:16:25 deraadt Exp $
 .\"
 .\" Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
 .\" All rights reserved.
@@ -49,10 +49,30 @@
 .Sh DESCRIPTION
 The
 .Fn arc4random
-function uses the key stream generator employed by the
-arc4 cipher, which uses 8*8 8 bit S-Boxes.
+function provides a high quality 32-bit pseudo-random
+number very quickly.
+.Fn arc4random
+seeds itself on a regular basis from the kernel strong random number
+subsystem described in
+.Xr random 4 .
+On each call, an ARC4 generator is used to generate a new result.
+The
+.Fn arc4random
+function uses the ARC4 ciper key stream generator,
+which uses 8*8 8 bit S-Boxes.
 The S-Boxes can be in about (2**1700) states.
 .Pp
+.Fn arc4random
+fits into a middle ground not covered by other subsystems such as
+the strong, slow, and resource expensive random
+devices described in
+.Xr random 4
+versus the fast but poor quality interfaces described in
+.Xr rand 3 ,
+.Xr random 3 ,
+and
+.Xr drand48 3 .
+.Pp
 The
 .Fn arc4random_stir
 function reads data from