Secure quantum key distribution with a subset of malicious devices

TL;DR

This paper proposes a secure quantum key distribution protocol resilient to malicious device manipulation by using redundancy and distributed post-processing, significantly improving security and efficiency in practical scenarios.

Contribution

It introduces an efficient distributed QKD post-processing protocol with proven security against malicious devices, enhancing key rates and simplifying setups under realistic assumptions.

Findings

Significant improvement in secret key rate under realistic corruption models

Simpler QKD setups with comparable finite-size key rates to trusted-device scenarios

Security proof applicable to various corruption models of malicious devices

Abstract

The malicious manipulation of quantum key distribution (QKD) hardware is a serious threat to its security, as, typically, neither end users nor QKD manufacturers can validate the integrity of every component of their QKD system in practice. One possible approach to re-establish the security of QKD is to use a redundant number of devices. Following this idea, we introduce an efficient distributed QKD post-processing protocol and prove its security in a variety of corruption models of the possibly malicious devices. We find that, compared to the most conservative model of active and collaborative corrupted devices, natural assumptions lead to a significant enhancement of the secret key rate and considerably simpler QKD setups. Furthermore, we show that, for most practical situations, the resulting finite-size secret key rate is similar to that of the standard scenario assuming trusted devices.