In 1985, Wim van Eck published a paper which described how the state of a CRT monitor could be reproduced remotely based on the device’s electromagnetic radiation. Van Eck or TEMPEST devices, whatever you prefer to call them, aren’t just the secret sauce in your favorite science fiction, though for some reason there hasn’t been a lot of amateur or open source activity here. I’m not sure why, but I suspect as software radios become more affordable, people will start experimenting more in this space.
There are two open source Van Eck projects that I know of. The first, pictured above, is Erik Thiele’s Tempest for Eliza project. By drawing specific black and white patterns on your monitor, Tempest is able to generate audible signals in the AM range. You can use Tempest to play an mp3 file that you can tune in on your radio.
Tempest for Eliza is a fun demo, but what about being able to read someone’s monitor remotely?
There’s a second open source project, called EckBox, that claims to do just this. By piping the audio from a radio through an 8-bit analog to digital converter, EckBox claims to be able to read this data from a PC parallel port and reproduce the image of an 800×600 monitor. Looking at the code, it seems almost too simple to be true. Likewise, the project hasn’t been updated since June 2004 and there aren’t many references or screenshots or words of success floating around the net. Anyone with a parallel port and an ADC want to give this a shot and let us know how it works?