random.4 revision 1.27
$OpenBSD: random.4,v 1.27 2011/01/09 00:06:50 deraadt Exp $
Copyright (c) 1996, 1997 Michael Shalayeff
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THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.Dd $Mdocdate: January 7 2011 $ .Dt RANDOM 4 .Os .Sh NAME .Nm random , .Nm arandom .Nd random data source devices .Sh SYNOPSIS .Fd #include <sys/types.h> .Fd #include <dev/rndvar.h> .Sh DESCRIPTION The various .Nm devices produce random output data with different random qualities. Entropy data is collected from system activity (like disk, network, and clock device interrupts and such), and then run through various hash or message digest functions to generate the output. All the random devices are expected to provide high quality pseudo-random output data.
Copyright (c) 1996, 1997 Michael Shalayeff
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
.Dd $Mdocdate: January 7 2011 $ .Dt RANDOM 4 .Os .Sh NAME .Nm random , .Nm arandom .Nd random data source devices .Sh SYNOPSIS .Fd #include <sys/types.h> .Fd #include <dev/rndvar.h> .Sh DESCRIPTION The various .Nm devices produce random output data with different random qualities. Entropy data is collected from system activity (like disk, network, and clock device interrupts and such), and then run through various hash or message digest functions to generate the output. All the random devices are expected to provide high quality pseudo-random output data.
p The .Xr arc4random 3 function in userland libraries seeds itself from this device (or with the .Xr sysctl 3 interface), providing a second level of ARC4 hashed data without the need to access these devices every time. .Sh FILES l -tag -width /dev/arandom -compact t Pa /dev/random t Pa /dev/arandom .El .Sh SEE ALSO .Xr arc4random 3 , .Xr md5 3 , .Xr random 3 , .Xr amdpm 4 , .Xr glxsb 4 , .Xr pchb 4 , .Xr md5 9 , .Xr arc4random 9 .Sh HISTORY A .Nm device first appeared in the Linux operating system. This is a cloned interface.
p ARC4 routines added by David Mazieres. .Sh BUGS No randomness testing suite provided.