Real-time monitoring of single-photon detectors against eavesdropping in quantum key distribution systems

T. Ferreira da Silva, G. B. Xavier, G. P. Temporao and J. P. von der Weid
OPTICS EXPRESS 20 (2012)

ABSTRACT

By employing real-time monitoring of single-photon avalanche
photodiodes we demonstrate how two types of practical eavesdropping
strategies, the after-gate and time-shift attacks, may be detected. Both
attacks are identified with the detectors operating without any special
modifications, making this proposal well suited for real-world applications.
The monitoring system is based on accumulating statistics of the times
between consecutive detection events, and extracting the afterpulse and
overall efficiency of the detectors in real-time using mathematical models
fit to the measured data. We are able to directly observe changes in the
afterpulse probabilities generated from the after-gate and faint after-gate
attacks, as well as different timing signatures in the time-shift attack. We
also discuss the applicability of our scheme to other general blinding
attacks.

DOI: http://dx.doi.org/10.1364/OE.20.018911



Categories: Publications