Secret keys in quantum states of light
The quantum key distribution (QKD) method uses the principles of quantum mechanics to distribute secret keys. The security of QKD is based on the fact that two parties produce a shared key known only to them. This key can be used to encrypt and decrypt messages. Specifically, the two parties send precisely controlled quantum particles of light that are detected in a controlled way. The presence of any third party trying to intercept the key would immediately be detectable. Any attempt to observe the quantum particles would modify the information they carry. With funds from the EU, the Q-CERT (Quantum key distribution certification) project aimed to promote the adoption of QKD. A partnership between academia and industry was created that helped improve the hardware used. Additionally, they developed methods to reduce the number of errors in existing systems. Systems based on quantum-generated keys are already in use by banks and the defence industry, where secure communication is crucial. The broad range of quantum encryption techniques implemented, as well as the difficulty of scaling them up are both hurdles that hamper the wider adoption of this technology. The Q-CERT team studied attacks on QKD systems and assessed the security of QKD protocols. Post-processing of the raw data collected laid the groundwork for the development of hardware and software standards that facilitate security evaluation of QKD implementations. In addition, researchers classified the attacks against QKD systems and proposed counter-measures against blinding attacks of avalanche photodiodes and saturation attacks in continuous variable QKD. Lastly, they developed a new high-speed QKD system. At specialised repeater stations, a pair of entangled photons can be received securely and the information it carries can be imparted to a different pair of entangled photons. The next steps will be to develop systems that are secure over an entire network rather than just from one point to another. Until then, the Q-CERT framework for assessing the security of QKD systems remains to be adopted. Common standards are a major step towards bringing QKD systems to a maturity level suitable for commercial use while boosting public confidence in the technology.
Keywords
Communication networks, quantum key distribution, quantum mechanics, security, Q-CERT, entangled photons
