The “first fully integrated quantum cryptography prototype machine” has exchanged encryption keys across a 67km fiber optic network.

The advance was achieved by a team from the University of Geneva and Swiss electronics company id Quantique. In contrast to methods based on codes, the keys formed by quantum cryptography can, in principle, be completely uncrackable because the legitimate receiver of a message can test whether it has been intercepted or altered by an eavesdropper during transmission.