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Re: /dev/random is probably not
From: Thomas <tom () electric-sheep org>
Date: Wed, 6 Jul 2005 07:51:44 +0200

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 () electric-sheep org>
fingerprint = F055 43E5 1F3C 4F4F 9182  CD59 DBC6 111A 8516 8DBF


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