A generalized efficiency mismatch attack to bypass detection-scrambling countermeasure

TL;DR

This paper demonstrates that a generalized efficiency mismatch attack can bypass detector randomization countermeasures in quantum communication, highlighting the need for more robust security protocols.

Contribution

It introduces a generalized attack model that can circumvent existing detector randomization defenses in quantum communication systems.

Findings

Randomization prevents initial efficiency mismatch attacks

Generalized attack strategy can bypass the countermeasure

Methodology can help certify security against detector-efficiency-mismatch attacks

Abstract

The ability of an eavesdropper to compromise the security of a quantum communication system by changing the angle of the incoming light is well-known. Randomizing the role of the detectors has been proposed to be an efficient countermeasure to this type of attack. Here we show that the proposed countermeasure can be bypassed if the attack is generalized by including more attack variables. Using the experimental data from existing literature, we show how randomization effectively prevents the initial attack but fails to do so when Eve generalizes her attack strategy. Our result and methodology could be used to security-certify a free-space quantum communication receiver against all types of detector-efficiency-mismatch type attacks.