Trustworthiness of measurement devices in round-robin differential-phase-shift quantum key distribution

TL;DR

This paper investigates the security vulnerabilities of round-robin differential-phase-shift quantum key distribution (RRDPS QKD) caused by imperfect measurement devices, demonstrating potential attacks and emphasizing the need for revised security proofs or assumptions.

Contribution

It identifies specific attacks on RRDPS QKD with uncharacterized measurement devices and discusses implications for security assumptions and device trustworthiness.

Findings

Two novel attacks on RRDPS with uncharacterized devices

Attacks remain effective even with perfect efficiency or single-photon states

Highlights the necessity for revised security proofs or device assumptions

Abstract

Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) has been proposed to raise the noise tolerability of the channel. However, in practice, the measurement device in RRDPS QKD may be imperfect. Here, we show that, with these imperfections, the security of RRDPS may be damaged, by proposing two attacks for RRDPS systems with uncharacterized measurement devices. One is valid even for a system with unit total efficiency, while the other is valid even when a single photon state is sent. To prevent these attacks, either security arguments need to be fundamentally revised or further practical assumptions on the measurement device should be put.