Physical Security of Chip-Based Quantum Key Distribution Devices

TL;DR

This paper investigates physical security vulnerabilities in chip-based quantum key distribution devices, proposing methods to detect and prevent Trojan horse attacks using integrated photonic components.

Contribution

It introduces practical strategies for enhancing security against Trojan horse attacks in integrated QKD devices, focusing on device monitoring and component placement.

Findings

Monitor photodiodes with optical isolation can detect high power sniffing attacks.

Placement of amplitude modulators affects vulnerability to Trojan horse attacks.

Proper switching times can thwart certain attack vectors.

Abstract

The security proofs of the Quantum Key Distribution (QKD) protocols make certain assumptions about the operations of physical systems. Thus, appropriate modelling of devices to ensure that their operations are consistent with the models assumed in the security proof is imperative. In this paper, we explore the Trojan horse attack (THA) using Measurement Device Independent (MDI) QKD integrated photonic chips and how to avoid some of the security vulnerabilities using only on-chip components. We show that a monitor photodiode paired appropriately with enough optical isolation, given the sensitivity of the photodiode, can detect high power sniffing attacks. We also show that the placement of amplitude modulators with respect to back reflecting components and their switching time can be used to thwart a THA.