Quantum key distribution (QKD) is a method for secure communication that uses quantum mechanics to encrypt information. While the security of QKD is unbreakable in principle, if it is incorrectly implemented, vital information could still be stolen by attackers. These are known as side-channel attacks, where the attackers exploit weaknesses in the setup of the information system to eavesdrop on the exchange of secret keys. Researchers from the National University of Singapore (NUS) have developed two methods, one theoretical and one experimental, to ensure that QKD communications cannot be attacked in this way, reports Phys.org. The first is an ultra-secure cryptography protocol that can be deployed in any communication network that needs long-term security. The second is a first-of-its-kind device that defends QKD systems against bright light pulse attacks by creating a power threshold. “Rapid advances in quantum computing and algorithmic research mean we can no longer take today’s toughest security software for granted. Our two new approaches hold promise to ensuring that the information systems which we use for banking, health, and other critical infrastructure and data storage can hold up any potential future attacks,” said assistant professor Charles Lim, from the NUS Department of Electrical and Computer Engineering and Centre for Quantum Technologies, who led the two research projects. With the team’s setup, all information systems built with “device-independent” QKD would be free from misconfiguration and mis-implementation. “Our method allows data to be safe against attackers even if they have unlimited quantum computing power,” said Lim. “This approach could lead to a truly secure information system, eliminating all side-channel attacks and allowing end users to monitor its implementation security easily and with confidence.”