London, Oct 10 : Data security worries could soon be an anxiety of the past, courtesy the world''s first computer network protected by unbreakable quantum encryption.

The EU-sponsored project (called SECO-QC) has been successfully demonstrated at a scientific conference in Vienna.

The network connects six locations across Vienna and in the nearby town of St Poelten, using 200 km of standard commercial fibre optic cables.

The kinds of security schemes used on computer networks today are typically based on complex mathematical procedures, which are extremely hard for outsiders to crack, but not impossible given sufficient computing resources or time.

However, quantum systems use the laws of quantum theory, which have been shown to be inherently unbreakable.

Charles Bennett of IBM and Gilles Brassard of Montreal University, who was in Vienna to see the network in action, worked out the basic idea of quantum cryptography 25 years ago.

"All quantum security schemes are based on the Heisenberg Uncertainty Principle, on the fact that you cannot measure quantum information without disturbing it," BBC quoted him, as saying.

"Because of that, one can have a communications channel between two users on which it''s impossible to eavesdrop without creating a disturbance. An eavesdropper would create a mark on it. That was the key idea," he added.

The technology works by sending streams of light particles, or photons -- and that means it is entirely secure, as any eavesdropping would leave traces and immediately be detected. (ANI)