Newsgroups: comp.dcom.lans
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Motorola wireless lan?
Message-ID: <1990Oct30.175448.27635@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <418@bartal.CRLABS.COM> <67070@bu.edu.bu.edu> <1990Oct26.155442.27053@zoo.toronto.edu> <67319@bu.edu.bu.edu>
Date: Tue, 30 Oct 90 17:54:48 GMT

In article <67319@bu.edu.bu.edu> kwe@buit13.bu.edu (Kent England) writes:
>An observation of a deterministic pseudo-random number sequence does not
>help much in determining the algorithm and seed used to generate the
>PSN sequence...

Sorry, not true.  Determining the algorithm by observation is indeed hard.
However, the algorithm is usually a property of the system design, i.e.
it is fixed and can in principle be determined by examining another copy
of the system.  Given the algorithm, determining the seed from the
sequence often is no big deal:  methods for cryptanalysis of the more
common types of pseudorandom-number generators have been published.

>... You might find spread spectrum
>technology to be sufficiently secure for your purposes...

Relying on a commercially-available spread-spectrum system for your security
is foolish, I'm afraid.  It will stop a casual eavesdropper but will be only
a minor nuisance to a sophisticated industrial spy.
-- 
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  henry@zoo.toronto.edu   utzoo!henry