Message Security 'Unconditionally Guaranteed' After Quantum Cryptography Breakthrough

Demonstrating a feat that was until recently thought to be impossible, researchers in Geneva, Singapore, Cambridge and Waterloo, Ontario have “unconditionally guaranteed” the security and sanctity of a message transmitted between two points on earth. Their work (pdf) could lead to impenetrable communications networks for financial trading, online voting, or an endless variety of other tasks currently carried out on the internet.

In this experiment the researchers solved a problem in secure networks known as “bit commitment.” Imagine that you’re playing a game of rock-paper-scissors by exchanging emails or instant messages. If your technology were fast enough, you could in theory cheat by waiting for your opponent’s answer to arrive (say, “rock”) and sending the response that would defeat it (i.e. “paper”) so quickly that it would look as if you had both made your choices at the same time. Bit commitment guarantees that a message sent at a stated time was in fact sent at that time and could not have been intercepted and changed along the way.