Hacker-proof communications get one step closer

Posted by Emma Woollacott

CAMBRIDGE, UK - It's the dream of governments, banks and large businesses - quantum cryptography, a completely watertight means of communication.


It is now a big step closer to being used practically, as researchers from Toshiba and Cambridge University's Cavendish Laboratory have developed high speed detectors capable of receiving information with much higher key rates, thereby able to receive more information faster.


Published in the New Journal of Physics' Focus Issue on 'Quantum Cryptography: Theory and Practice', the research details how quantum communication can be made possible without having to use cryogenic cooling or complicated optical setups, making it much more likely to become commercially viable soon.


The researchers claim, "With the present advances, we believe quantum key distribution is now practical for realising high band-width information-theoretically secure communication."


Quantum cryptography uses the quantum mechanical behaviour of photons to enable highly secure transmission of data beyond that achievable by classical encryption.


The photons themselves are used to distribute keys that enable access to encrypted information along fibre optic lines. Quantum indeterminacy, the quantum mechanics dictum which states that measuring an unknown quantum state will change it, means that the key information cannot be accessed by a third party without corrupting it beyond recovery and therefore making the act of hacking futile.


While the key rate described in the paper isn't that much higher than existing speeds, the new technique is much simpler to implement.


Using an attenuated (weakened) laser as a light source and a compact detector (semiconductor avalanche photodiodes), the researchers have introduced a decoy protocol for guarding against intruder attacks that would confuse with erroneous information all but the sophisticated, compact detector developed by the researchers.