SECURITY
Assistant Professor Charles Lim (back) and Dr Zhang Gong (front) with the team’s quantum power limiter device.
TWO STEPS CLOSER TO ATTACKPROOF QUANTUM COMMUNICATION Quantum key distribution (QKD) is a method for secure communication that uses quantum mechanics to encrypt information — but while the security of QKD is unbreakable in principle, vital information could still be stolen by attackers if it is incorrectly implemented.
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esearchers from the National University of Singapore (NUS), led by Assistant Professor Charles Lim, have now developed two methods to ensure that QKD communications cannot be attacked in this way.
A futureproof quantum communication protocol Typically, in QKD, two measurement settings are used — one to generate the key and the other to test the integrity of the channel. The NUS team developed an ultrasecure cryptography protocol in which users can independently test the other party’s encryption device by generating a secret key from two randomly chosen key generation settings instead of one. In a paper published in the journal Nature Communications, the researchers demonstrated that introducing an extra set of key-generating measurements for the
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users makes it harder for attackers to eavesdrop on the exchange of keys, known as a ‘side-channel attack’. “It’s a simple variation of the original protocol that started this field, but it can only be tackled now thanks to significant developments in mathematical tools,” said Professor Valerio Scarani, a co-author on the study and one of the inventors of this type of method. Compared to the original ‘device-independent’ QKD protocol, the new protocol is said to be easier to set up, as well as more tolerant to noise and loss. It is claimed to give users the highest level of security allowable by quantum communications, empowering them to independently verify their own key generation devices. With the team’s set-up, all information systems built with ‘device-independent’ QKD would be free from misconfiguration and mis-implementation.
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