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Date: Fri, 01 Feb 2002 17:50:05 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Peter Monta <pmonta@pmonta.com>
CC: garzik@havoc.gtf.org, linux-kernel@vger.kernel.org
Subject: Re: Continuing /dev/random problems with 2.4
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Peter Monta wrote:

>>The point with the tests that have been mentioned is to derive such a
>>conservative estimate, and to raise a red flag if the output suddenly
>>becomes predictable.
>>
> 
> Ah, I see; I was misled by the "truly random" remark, sorry.  So a reasonable
> sanity test for a block of audio samples might be a standard deviation
> greater than a few LSB; this will catch constant or close-to-constant
> output.
> 


However, those aren't the main failure modes you need to be concerned 
with.  Antenna effects may actually be your biggest problem -- picking 
up deterministic signals from other parts of the system.

However, I believe this is a solved problem.  It would definitely be 
interesting taking rngd and figuring out a way to drive it from /dev/dsp 
-- probably not too difficult a modification.

	-hpa



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