From: Dani Eder (danielravennest@yahoo.com)
Date: Wed Jun 27 2001 - 12:37:41 MDT
>
> >Eletromagnetic radiation escape. This one is
> pretty simple. The AI
> >sends out signals from the processor that, even
> though very weak by
> >the time they reach other electronics, provide an
> avenue to replicate
> >outside the jail. The way around this is to just
> TEMPEST shield.
TEMPEST is a set of requirements for electronic
equipment
that will process classified information. The
requirements are intended to reduce inadvertant
electromagnetic emissions that could be used to
eavesdrop on the classified data.
In general, any wire coming out of a computer can
in theory act as an antenna to carry signals out
of the box, and modulation of the video out to the
monitor is usually the biggest culprit,
The way you keep signals in is through a 'faraday
cage'. This is a conductive box electrically isolated
from the electronic equipment inside any equipment
outside. For a demonstration, wrap your cell phone
with plastic wrap, then aluminum foil, and try to
call it. This should work even if you are close to
the cell tower.
If you are really paranoid about not letting any
electromagnetic signals out, like the gov't was when
they were testing stealth aircraft signatures, you
can use two nested faraday cages. Needless to say,
any wires of any kind are forbidden from crossing
through the cage walls. This means your power supply
is batteries or a generator inside the box. Your
ventilation openings need conductive screens with
openings <0.1 wavelength of the highest frequency
you want to screen out, which works out ot 0.3 mm
if you are using components with transistors that
switch at 100 GHz.
Dani
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