Toshiba unveils quantum security

has announced that it has developed two new technologies to realise ‘unconditionally secure’ quantum key distribution (QKD) by overcoming a potential security loophole.

In principle, quantum key distribution provides an absolutely secure means for transmitting secret keys between two parties on fibre optical networks. However, the QKD systems developed so far have a vulnerability which leaves them open to hacking. The weak laser diode used to generate single photon pulses which carry the quantum keys, will sometimes generate pulses with multiple photons.

As a result, an eavesdropper could split off one of these extra photons and measure it, while leaving the other photons in the pulse undisturbed, thus determining part of the key while remaining undetected. Furthermore, an eavesdropper could even determine the entire key, by blocking the single-photon pulses and allowing only the multi-photon pulses to travel through the fibre.

Now two solutions to this problem have been found, the first of which has already been implemented by Toshiba in their QKD system.