Sources for Controlled TEMPEST CPU Emanations

Date: Thu, 19 Aug 1999 20:47:41 +0300 (EEST)
From: Berke Durak <>
Subject: Sources for Controlled CPU TEMPEST Emanations

Since a lot of people are requesting it, I'm making the sources
available at:


Please note that these sources are just quick hacks... I mean it. 
tempest-cpu broadcasts, on *my* P120 a nice tune on
87.5FM. tempest-crt is somewhat cleaner and "transmits" 4-level
FSK-modulated data on a specified AM frequency. I have not even
checked if it is possible to demodulate it, but it is probably
feasible. Since it is a quick hack it requires a 16-bit RGB
display with specific byte ordering. tempest-pci is something
I tried today based on suggestions I received; it tries to
send data-dependent signals by indirectly using the PCI bus:
it writes patterns of zeroes and ones synchronously to a file,
which is expected to lie on an EIDE or SCSI harddisk connected
via a PCI controller. Should these patterns be transmitted
by block-mode 32-bit DMA to the disks, signals at the "sub"
and "super" harmonics of the PCI clock should be detectable.
So far I only managed to get weakly data-dependent buzzes on my
radio. Again, I don't have radio equipment. So try this one out.
You could also check the PCI (or whatever) bus with an oscilloscope.
Although simple, I've tried to make this one minimally
clean and usable.

Thanks to all the people who sent me comments.
Berke Durak
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Berke Durak
Last modified: Sun Aug 22 23:46:55 EEST 1999