bugtraq - Re: /dev/random is probably not

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Message-ID: <200507060751.45185.tom@electric-sheep.org>
Date: Wed, 6 Jul 2005 07:51:44 +0200
From: Thomas <tom@...ctric-sheep.org>
To: bugtraq@...urityfocus.com
Cc: "Robert Foxworth" <rfoxwor1@...pabay.rr.com>
Subject: Re: /dev/random is probably not


> At the last place at which I worked, a few years ago, a "random
> number" was generated, and used in a FIPS 140-1 compliant
> encryption device, by capturing 128 ethernet frames in sequence
> from the local in-house network, gathering the LSB from the
> arrival time of each frame, and using those values to generate
> an encryption key. This was part of the "activation sequence"
> which had to be done, once, on each such device.
>
> Any studies out there on the randomness of such a number?
> At first glance a non-deterministic network would seem to be
> able to generate a useful number for the key.

It doesn't look like a good source of entropy. At least it wouldn't
withstand an active attack during this activation phase.


> - Bob Foxworth, GSEC, CISSP

Thomas Biege

-- 
Tom <tom@...ctric-sheep.org>
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