After-gate attack on a quantum cryptosystem
Wiechers, Carlos; Lydersen, Lars Vincent Van de Wiel; Wittmann, Christoffer; Elser, Dominique; Skaar, Johannes; Marquardt, Christoph; Makarov, Vadim; Leuchs, Gerd
Journal article, Peer reviewed
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Date
2011Metadata
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- Institutt for fysikk [2712]
- Publikasjoner fra CRIStin - NTNU [38679]
Abstract
We present a method to control the detection events in quantum key
distribution systems that use gated single-photon detectors. We employ bright
pulses as faked states, timed to arrive at the avalanche photodiodes outside the
activation time. The attack can remain unnoticed, since the faked states do not
increase the error rate per se. This allows for an intercept–resend attack, where
an eavesdropper transfers her detection events to the legitimate receiver without
causing any errors. As a side effect, afterpulses, originating from accumulated
charge carriers in the detectors, increase the error rate. We have experimentally
tested detectors of the system id3110 (Clavis2) from ID Quantique. We identify
the parameter regime in which the attack is feasible despite the side effect.
Furthermore, we outline how simple modifications in the implementation can
make the device immune to this attack.