Subject: Re: Thoughts about the b43 RNG
From: Harvey Harrison <harvey.harrison@gmail.com>
To: Michael Buesch <mb@bu3sch.de>
Cc: bcm43xx-dev@lists.berlios.de, linux-wireless@vger.kernel.org
In-Reply-To: <1231464519.5715.32.camel@brick>
References: <200901090211.03937.mb@bu3sch.de>
	 <1231464519.5715.32.camel@brick>
Content-Type: text/plain
Date: Thu, 08 Jan 2009 17:30:56 -0800
Message-Id: <1231464656.5715.33.camel@brick> (sfid-20090109_023103_448312_ECD92558)
Mime-Version: 1.0
Sender: linux-wireless-owner@vger.kernel.org

On Thu, 2009-01-08 at 17:28 -0800, Harvey Harrison wrote:
> On Fri, 2009-01-09 at 02:11 +0100, Michael Buesch wrote:
> > I was doing some random tests on the b43 hardware RNG.
> > These are the results.
> > 
> > I patched the firmware to not access the RNG register anymore.
> > The unpatched firmware does two things. It reads the RNG register to get random values
> > and it writes 0 to the register every now and then for whatever reason.
> > Both reads and writes were patched out during my test. So the driver was
> > the only one accessing the RNG.
> > 
> > This is the result of reading a few bytes from the RNG with the patched fw:
> 
> > I'm not sure about this. There aren't any obvious patterns.
> > But maybe I'm just blind. Does somebody else see some pattern or
> > has some RNG test program to recognize such patterns?
> > 
> > So let's do another test. Let's modify the previous test to
> > write 0xFFFF instead of 0:
> > 
> 
> NIST has a pretty good test suite I think.

Packaged for debian as dieharder if you want the command-line version.

Harvey