Controlling an actively-quenched single photon detector with bright light

TL;DR

This paper demonstrates that actively-quenched single-photon detectors used in quantum key distribution can be controlled with bright light, revealing vulnerabilities that threaten the security of quantum communication systems.

Contribution

It shows the generality of bright-light control attacks on various avalanche photodiode detectors, including actively-quenched models, and uncovers new blinding mechanisms in commercial detectors.

Findings

Active-quenched detectors are vulnerable to bright-light control attacks.

Identified two new blinding mechanisms in a commercial detector model.

Highlights the need to incorporate detector imperfections into QKD security proofs.

Abstract

We control using bright light an actively-quenched avalanche single-photon detector. Actively-quenched detectors are commonly used for quantum key distribution (QKD) in the visible and near-infrared range. This study shows that these detectors are controllable by the same attack used to hack passively-quenched and gated detectors. This demonstrates the generality of our attack and its possible applicability to eavsdropping the full secret key of all QKD systems using avalanche photodiodes (APDs). Moreover, the commercial detector model we tested (PerkinElmer SPCM-AQR) exhibits two new blinding mechanisms in addition to the previously observed thermal blinding of the APD, namely: malfunctioning of the bias voltage control circuit, and overload of the DC/DC converter biasing the APD. These two new technical loopholes found just in one detector model suggest that this problem must be solved in general, by incorporating generally imperfect detectors into the security proof for QKD.