Re: TEMPEST protection

["Cynthia H. Brown" <cynthb@sonetis.com>]

<sorry for the earlier finger glitch>

On Tue, 11 Mar 1997, Dale Thorn wrote:

> Actually, the computer you type on will be very easy to pick out
> of the noise field with modest spy equipment sitting down the street.
> 
> There's a company (I lost the brochure) who sell EM attenuator
> material, some preconfigured, and presumably some bulk.  It should
> be easy to find on the Web.  Once you get some really dramatic
> attenuation, particularly of the keyboard (and particularly during
> password confirmations, etc.), you should do your own preliminary
> monitoring with some of those band-sweep gadgets.  Steady noise
> of course is nothing compared to the spikes from some of the keyboard
> outputs...
> 
> Once you've identified all (we can hope, can't we) of the problem
> signals still leaking through the shielding (albeit at greatly
> reduced levels), you can direct different kinds of efforts there,
> including random noise from other computers which use the exact
> same output devices.

>From what I've seen, it's a lot easier for "the bad guys" to concentrate 
on monitor emissions - you can read the screen someone's looking at, and 
not just the key-clicks.  Won't get you blanked-out passwords, though.  
Much of the monitor's emissions may be out the back.

Other places to look for emissions: the power supply, and the connection 
points for peripherals.  Make sure you leave adequate ventilation, though 
(another tricky part).

Cynthia

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		   Cynthia H. Brown, P.Eng.
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