From: Michael Motyka <mmotyka@lsil.com>
Date: Tue, 3 Nov 1998 03:03:37 +0800
To: cypherpunks@cyberpass.net
Subject: Re: TEMPEST laptops
Message-ID: <363DF8EB.24CF@lsil.com>
MIME-Version: 1.0
Content-Type: text/plain



> Understand that my comments are just some "common sense with a little 
> bit of physics" estimates, not direct knowledge of how best to shield 
> laptops.

> I'd do this in preference to worrying about what some 1978 government 
> docs had to say about the subject. TEMPEST the specs are probably a 
> mixture of "RF shielding" tips and standards, and a mix of Van Eck 
> radiation tuner designs.
>
A long time ago I ran thermal measurement boards on a piece of equipment
in liquid He under vacuum. Pretty icy. I used only standard components. 

My question is this - anyone know of any estimates of how weak a signal
could be detected and actually rendered into useful information? 

The relevance of the low-T stuff is that it seems like a nice way to
make low-noise receiving equipment. With an estimate of the capabilities
of the receiver ( @exotic-lHe and commonplace-lN2 temps ) you could then
address the emissions of the laptop with reasonable, quantitative target
levels. Sort of reverse engineer the TEMPEST specs as it were. 

It would be nice to know what needed to be done to reduce emissions to
the point that you could be fairly sure that an eavesdropper had to park
on your doorstep to make his equipment work.

> VERY FEW PEOPLE CARE ABOUT SECURITY.
>
Since they don't have anything to hide, why should they worry? Argh.
ergo - if they're hiding something they are guilty of something. Bust
the doors down boys.

Mike