Lars Lydersen: Bright illumination attacks on QKD

Lars Lydersen, Norwegian University of Science and Technology (NTNU)

Abstract

Quantum cryptography, although unbreakable in principle, can currently
be hacked through implementation loopholes. Especially, Quantum Key Distribution (QKD) systems using avalanche photodiode-based single-photon detectors allow the eavesdropper to capture the full key without introducing errors in the quantum channel, due to the detector's deterministic response in the linear regime. In my talk I will show you the principle behind the attack, and how it applies to the BB84-family of protocols as well as distributed-phase-reference protocols. Furthermore I discuss several techniques to force the detectors into the linear regime, and discuss countermeasures.