Optimised quantum hacking of superconducting nanowire single-photon detectors

TL;DR

This paper demonstrates a practical method to hack superconducting nanowire single-photon detectors using bright-light control, revealing vulnerabilities in quantum key distribution systems and discussing potential countermeasures.

Contribution

It provides the first experimental demonstration of bright-light hacking on SNSPDs in a shunted configuration, highlighting security risks in quantum communication.

Findings

Bright-light control can blind and manipulate SNSPDs within microseconds.

The attack produces fake clicks without increasing timing jitter.

Five different SNSPD designs were tested, confirming vulnerability.

Abstract

We explore bright-light control of superconducting nanowire single-photon detectors (SNSPDs) in the shunted configuration (a practical measure to avoid latching). In an experiment, we simulate an illumination pattern the SNSPD would receive in a typical quantum key distribution system under hacking attack. We show that it effectively blinds and controls the SNSPD. The transient blinding illumination lasts for a fraction of a microsecond and produces several deterministic fake clicks during this time. This attack does not lead to elevated timing jitter in the spoofed output pulse, and hence does not introduce significant errors. Five different SNSPD chip designs were tested. We consider possible countermeasures to this attack.