Van Eck phreaking

This week I reread with pleasure all 918 pages of Cryptonomicon by Neal Stephenson and found out that last time I had been extremely choosy in subplots. There are 4 major plots : one contemporary (a couple of geeks trying to set up a data-haven) and three WW2 stories : the Waterhouse-plot about cracking Enigma and other crypto-systems featuring a.o. Alan Turing, the Shaftoe-plot about the crazy division 2702 trying to cover-up that Enigma has been broken and the Goto Dengo-plot about hiding the Japanese Gold reserve in the jungle. Five years ago I was mostly interested in the first two subplots and later on in the book I jumped chapters quite a bit, it seems.

During the first read I assumed that the Van Eck phreaking-bit was just another paranoid misconception of the two present day main players Randy&Avi, but this week I wasn\’t so sure anymore so the first thing I did when we came home was Googling on Van Eck phreaking which really does exist!

Van Eck phreaking is a form of eavesdropping in which special equipment is used to pick up telecommunication signals or data within a computer device by monitoring and picking up the electromagnetic fields.
The U.S. government has been involved with EM interpretation for many years under a top-secret program code-named “TEMPEST”.

It seems that in 1985 the Dutch scientist Wim Van Eck wrote a paper \’Electromagnetic Radiation from Video Display Units: An Eavesdropping Risk?\’ He concluded: “If no preventive measures are taken, eavesdropping on a video-display unit is possible at several hundred meters distance, using only a normal black-and-white TV receiver, a directional antenna, and an antenna amplifier.” He proved it by taking a BBC crew around London in a van, showing them what was on the computer screens at various companies.
To me it seems that putting your computer inside a Faraday cage is a simpler counter-measure than the cumbersome method of Randy in the novel (but I have to admit, he was in prison at the time…). There is a more detailed manual on phreaking available, but the best text I found (sofar) on Van Eck phreaking is Soft Tempest: Hidden Data Transmission Using Electromagnetic Emanations by Markus G. Kuhn and Ross J. Anderson.