Trojan-horse attacks threaten the security of practical quantum cryptography

Jain N, Anisimova E, Khan I, Makarov V, Marquardt C, Leuchs G (2014)

Publication Type: Journal article

Publication year: 2014

Journal

New Journal of Physics Institute of Physics: Open Access Journals / Institute of Physics (IoP) and Deutsche Physikalische Gesellschaft

Book Volume: 16

Article Number: 123030

DOI: 10.1088/1367-2630/16/12/123030

Abstract

A quantum key distribution (QKD) system may be probed by an eavesdropper Eve by sending in bright light from the quantum channel and analyzing the back-reflections. We propose and experimentally demonstrate a setup for mounting such a Trojan-horse attack. We show it in operation against the quantum cryptosystem Clavis2 from ID Quantique, as a proof-of-principle. With just a few back-reflected photons, Eve discerns Bob's (secret) basis choice, and thus the raw key bit in the Scarani-Acín-Ribordy-Gisin 2004 protocol, with higher than 90% probability. This would clearly breach the security of the cryptosystem. Unfortunately, Eve's bright pulses have a side effect of causing a high level of afterpulsing in Bob's single-photon detectors, resulting in a large quantum bit error rate that effectively protects this system from our attack. However, in a Clavis2-like system equipped with detectors with less-noisy but realistic characteristics, an attack strategy with positive leakage of the key would exist. We confirm this by a numerical simulation. Both the eavesdropping setup and strategy can be generalized to attack most of the current QKD systems, especially if they lack proper safeguards. We also propose countermeasures to prevent such attacks.

Authors with CRIS profile

Christoph Marquardt Lehrstuhl für Experimentalphysik (Optik) Gerhard Leuchs

Involved external institutions

University of Waterloo (UW) CA Canada (CA) Max-Planck-Institut für die Physik des Lichts (MPL) / Max Planck Institute for the Science of Light DE Germany (DE)

How to cite

APA:

Jain, N., Anisimova, E., Khan, I., Makarov, V., Marquardt, C., & Leuchs, G. (2014). Trojan-horse attacks threaten the security of practical quantum cryptography. New Journal of Physics, 16. https://doi.org/10.1088/1367-2630/16/12/123030

MLA:

Jain, Nitin, et al. "Trojan-horse attacks threaten the security of practical quantum cryptography." New Journal of Physics 16 (2014).

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