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Declassified NSA Document Reveals the Secret History of TEMPEST

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posted on Apr, 30 2008 @ 02:02 PM

It was 1943, and an engineer with Bell Telephone was working on one of the U.S. government's most sensitive and important pieces of wartime machinery, a Bell Telephone model 131-B2. It was a top secret encrypted teletype terminal used by the Army and Navy to transmit wartime communications that could defy German and Japanese cryptanalysis.

Then he noticed something odd.

Far across the lab, a freestanding oscilloscope had developed a habit of spiking every time the teletype encrypted a letter. Upon closer inspection, the spikes could actually be translated into the plain message the machine was processing. Though he likely didn't know it at the time, the engineer had just discovered that all information processing machines send their secrets into the electromagnetic ether.

This story of how the United States first learned about the fundamental security vulnerability called "compromising emanations" is revealed for the first time in a newly-declassified 1972 paper TEMPEST: A Signal Problem (.pdf), from the National Security Agency's secret in-house journal Cryptologic Spectrum.

NSA document

I found this story and the PDF just fascination. It reminded me of a term paper on Wim van Ek, I had to do in high school. In the late 80s, Ek published thee first unclassified technical analysis of the security risks of emanations monitors. He was able to eavesdrop hundreds of metres using just $15 worth of equipment and a TV.
This is a REALLY good read. Enjoy!

posted on May, 1 2008 @ 01:08 PM
thanks for posting this excellent article and paper.
star and flag to you sir. very informative.



[edit on 1-5-2008 by snoopyuk]


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