"Acoustic Cryptanalysis: On Nosy People and Noisy  Machines"

 

Summary at :

http://www.securiteam.com/securityreviews/5TP0C0ACUG.html

Technical Paper at :

http://www.wisdom.weizmann.ac.il/~tromer/acoustic/

Layman's Paper at :

http://www.newscientist.com/news/news.jsp?id=ns99994979

Quoting from the Summary :

A powerful method for extracting information from supposedly secure

systems is side-channel attacks: cryptanalytic techniques that rely on

information unintentionally leaked by computing devices. Most side-channel

attack research has focused on electromagnetic emanations (TEMPEST), power

consumption and, recently, diffuse visible light from CRT displays. The

oldest eavesdropping channel, namely acoustic emanations, has received

little attention. Our preliminary analysis of acoustic emanations from

personal computers shows them to be a surprisingly rich source of

information on CPU activity.