Apostolos Argyris has joined theoretical mathematics with solid-state physics to demonstrate a novel, nearly unbreakable encryption method. As a graduate student at the University of Athens, the Thessaloníki native implemented the first long-distance demonstration of "chaotic synchronization": using a pair of laser diodes, amplifiers, a mirror, and more than 120 kilometers of underground fiber, he disguised a message as white noise and still retrieved it clearly on the other end.

The feat is a demonstration of the "butterfly effect," the founding tenet of chaos theory. The theory holds that in sufficiently complex systems, even a slight adjustment of initial variables will produce a dramatically different result; conversely, if you can replicate input conditions precisely, you should be able to replicate the output, even if that output appears random at first glance. Argyris applied this principle by combining a digital message with a chaotic, rapidly fluctuating laser signal; the chaotic signal’s irregular shape masks the message and allows it to evade standard eavesdropping methods. An identically generated chaotic signal on the receiving end cancels out the first, leaving only the original data.

The technique currently delivers data at one gigabit per second (good enough for voice and video encryption). Argyris hopes to raise that to 10 gigabits per second by 2009. He doesn't see chaotic encryption replacing software encryption, but it could soon offer an extra layer of protection for the most sensitive communications.

--Sam M. Williams