Mark's Notebook


	I never came upon any of my discoveries through the process of rational thinking. - Albert Einstein

Acoustic Keyboard Eavesdropping

New York Times

Sunday 12 December 2004, 1:04 pm
Keywords: Computer Topics , News Articles

By Stephen Mihm

It is now possible to eavesdrop on a typist's keystrokes and, by exploiting minute variations in the sounds made by different keys, distinguish and decipher what is being typed.

Credit for this discovery goes to Dmitri Asonov, a computer-security researcher for I.B.M. at the Almaden Research Center in San Jose, Calif., who (with Rakesh Agrawal) published his results this year. The principle is a simple one. Keyboards are a bit like drums: the keys rest atop a plastic plate; different areas of the plate yield different sounds when struck. The human ear can't tell the difference, but if the sounds are recorded and processed by a highly sophisticated computer program, the computer can, with a little bit of practice, learn to translate the sounds of keystrokes into the appropriate letters and symbols.

This means that firewalls and passwords will amount to nothing if someone manages to bug a room and record the cacophony of keystrokes. Asonov managed to pull off this feat with readily available recording equipment at a short distance. Even as far away as 50 feet, and with significant background noise, he was able to replicate his success using a parabolic microphone.

http://www.nytimes.com/2004/12/12/magazine/12ACOUSTIC.html?th