A Classical-Light Attack on Energy-Time Entangled Quantum Key Distribution, and Countermeasures [book]

Jonathan Jogenfors
2015 unpublished
Quantum key distribution (QKD) is an application of quantum mechanics that allows two parties to communicate with perfect secrecy. Traditional QKD uses polarization of individual photons, but the development of energytime entanglement could lead to QKD protocols robust against environmental effects. The security proofs of energy-time entangled QKD rely on a violation of the Bell inequality to certify the system as secure. This thesis shows that the Bell violation can be faked in energy-time
more » ... in energy-time entangled QKD protocols that involve a postselection step, such as Franson-based setups. Using pulsed and phase-modulated classical light, it is possible to circumvent the Bell test which allows for a local hidden-variable model to give the same predictions as the quantum-mechanical description. We show that this attack works experimentally and also how energy-time-entangled systems can be strengthened to avoid our attack.
doi:10.3384/lic.diva-114073 fatcat:ia642jx3rzeeniefkcah3ppbgu