Practical Attacks on Decoy State Quantum Key Distribution Systems with Detector Efficiency Mismatch

TL;DR

This paper demonstrates that detector efficiency mismatch in decoy state quantum key distribution systems can be exploited by practical attack strategies, posing serious security threats without detection.

Contribution

It introduces a modified faked states attack using quantum nondemolition measurements and photon number resolving detectors, highlighting new vulnerabilities in QKD systems.

Findings

Attacks can compromise secret keys without alarms

Lower bound of detector mismatch for successful attack identified

Practical attack strategies pose serious security threats

Abstract

To the active basis choice decoy state quantum key distribution systems with detector efficiency mismatch, we present a modified attack strategy, which is based on faked states attack, with quantum nondemolition measurement ability to restress the threat of detector efficiency mismatch. Considering that perfect quantum nondemolition measurement ability dose not exist in real life, we also propose a practical attack strategy using photon number resolving detectors. Theoretical analysis and numerical simulation results show that, without changing the channel, our attack strategies are serious threats to decoy state quantum key distribution systems. The eavesdropper may get some information ab out the secret key without causing any alarms. Besides, the lower bound of detector efficiency mismatch to run our modified faked states attack successfully with perfect quantum nondemolition measurement ability is also given out, which provides the producers of quantum key distribution systems with a reference and can be treated as the approximate secure bound of detector efficiency mismatch in decoy state quantum key distribution systems.