Safeguarding Quantum Key Distribution Through Detection Randomization

T. Ferreira da Silva, G. C. do Amaral, G. B. Xavier, G. P. Temporao and J. P. von der Weid
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 21, 3 (2014)

ABSTRACT

We propose and experimentally demonstrate a scheme to render the detection apparatus of a quantum key distribution system immune to the main classes of hacking attacks in which the eavesdropper explores the back-door opened by the single-photon detectors. The countermeasure is based on the creation of modes that are not deterministically accessible to the eavesdropper. We experimentally show that the use of beamsplitters and extra single-photon detectors at the receiver station passively creates randomized spatial modes that erase any knowledge the eavesdropper might have gained when using bright-light faked states. Additionally, we experimentally show a detector-scrambling approach where the random selection of the detector used for each measurement-equivalent to an active spatial mode randomization-hashes out the side-channel open by the detection efficiency mismatch-based attacks. The proposed combined countermeasure represents a practical and readily implementable solution against the main classes of quantum hacking attacks aimed on the single-photon detector so far, without intervening on the inner working of the devices.

DOI: http://dx.doi.org/10.1109/JSTQE.2014.2361793



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