Quantum key distribution with untrusted detectors

TL;DR

This paper introduces a new quantum key distribution protocol that is secure against detector side-channel attacks, requiring no trusted detectors but assuming no information leaks from the labs, promising improved practicality and security.

Contribution

It proposes a third approach to secure QKD against detector attacks, surpassing device-independent and measurement-device-independent methods in certain scenarios.

Findings

Security guaranteed in low-loss regime

Robust against some eavesdropping in high-loss regime

Requires no trusted detectors but no information leaks from labs

Abstract

Side-channel attacks currently constitute the main challenge for quantum key distribution (QKD) to bridge theory with practice. So far two main approaches have been introduced to address this problem, (full) device-independent QKD and measurement-device-independent QKD. Here we present a third solution that might exceed the performance and practicality of the previous two in circumventing detector side-channel attacks, which arguably is the most hazardous part of QKD implementations. Our proposal has, however, one main requirement: the legitimate users of the system need to ensure that their labs do not leak any unwanted information to the outside. The security in the low-loss regime is guaranteed, while in the high-loss regime we already prove its robustness against some eavesdropping strategies.