[79460] in Cypherpunks
Building a Tempest Interceptor (fwd)
daemon@ATHENA.MIT.EDU (Ray Arachelian)
Fri May 2 16:34:53 1997
Date: Fri, 2 May 1997 14:53:54 -0400 (EDT)
From: Ray Arachelian <sunder@brainlink.com>
To: cypherpunks@toad.com
Reply-To: Ray Arachelian <sunder@brainlink.com>
This was on the Surveillance List...
by Frank Jones
aka SpyKing@thecodex.com
http://www.thecodex.com
Copyright 1997
The is very little public knowledge about TEMPEST. Most infomation, includi=
ng how to safeguard against monitoring, has been classified by the governme=
nt. You can view an article I wrote on TEMPEST at: http://www.thecodex.com=
/c_tempest.html and another at: http://www.thecodex.com/rise.html
In order to protect computers and CRT=92s from electromagnetic emission mon=
itoring (interception, recontruction and viewing) it is necessary to use sh=
ielding. This shielding is available in several forms but that is another a=
rticle...=20
Once the shielding is installed, how do you test it for leakage? It is nece=
ssary to see if you can monitor the device yourself. Since TEMPEST monitor=
ing equipment is normally very expensive and hard to come by, here=20
is a simple way to construct a =93simple=94 monitoring device that will hel=
p=20
you detemine if your computer can be =93snooped=94 on by outside sources...=
=20
this device was designed for =93defensive=94 purposes and should NOT be use=
d offensively... it does not have the distance capability of my DataScan=20
device but it WILL work as a laboratory benchtop demo device...
Like Van Eck and Moller, I have deliberately flawed the article for the tec=
hnically challenged... After all, we don=92t want everyone to have one=20
of these, do we?
TEMPEST Interceptor - Follow my instructions...
You need to learn something about electronics to make this happen.=20
The first lesson will be to construct a sync generator to drive the=20
computer monitor without any signal or video.=20
To start this you must take your spectrum analyzer, turn off every applianc=
e=20
in the area. Put the analyzer near the computer monitor, turn on the monito=
r but NOT the computer. Start searching around 15Khz. You should get a stro=
ng signal somewhere between 14Khz & 17Khz. Log that frequency. Next try loo=
king around 30Hz to 60Hz. Which is stronger 30 or 60? Log that.=20
Next we=92re gonna build a =93computer sync generator=94 (video gear will =
not work). Most technician=92s who have tried to build a TEMPEST intercepto=
r have been trying to use =93off-the-shelf=94 products. Don't believe what =
you read or hear, they won't work. You=92ve got to build a computer sync ge=
nerator.=20
It isn't really so hard to do. Get yourself a copy of the "CMOS Cookbook".=
=20
It's around. In there it shows how to build a 555 timer. It is a small and=
simple circut. Maybe 5 components. The 555 has in it all the clock and ele=
ctronics to make a timer from 1Hz to 10Mhz. Follow the instructions and=20
make a variable timer (it is really simple). Make the first one run at the=
exact frequency of the monitor, say 16 Khz. Next make a seperate one at th=
e second frequency say 30 Hz. Then tie them together with a .o1 Mfd cap. Th=
e output should drive your monitor (generator is done).
Two minor things I forgot to mention. The output of the 555 is about 5 to=
=20
12 volts. You will need to attenuate it to about .3 volts. Several resistor=
s will do.
The other thing is that you need a negative pulse out of the 555. The norma=
l output of a 555 is a square wave. On and off . You must vary the duty cyc=
le=20
to create a square wave which is most of the time on and the sync duration =
off. =20
You now need a seperate dedicated computer monitor. Open the input plug and=
find the shielded cable inside. Attach the output of your circut to the=20
center-conductor and the battery minus from your circut to the shield. You=
=20
have a solid black screen on the monitor. Turn up the brightness. There sho=
uld be no rolling and weaving. If so... adjust the pot in YOUR CIRCUIT not =
the monitor, to stop it. =20
Next step. Collect the signal you hear and see on your anaylzer/receiver.=
=20
Take the output of your reciever tuned to those frequencies. Connect the=20
output through a .01 mfd cap to the output of the sync generator and =93vio=
la=94 you should start to see the monitors radiated signal on your monitor.=
=20
Shielding your viewing monitor from the recieving monitor and small=20
adjustments in your generator frequency should do it. In fact no=20
adjustments should still do it.=20
The antenna that you use is critical.=20
Make sure you use the right one... ;-)
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