Subcarrier wave quantum key distribution with leaky and flawed devices

Abstract

In this paper, we consider the influence of device imperfections on the performance of the subcarrier wave quantum key distribution system. For instance, we consider the utilization of a non-phase-randomized coherent light source, the possibility of detector blinding, and its consequences. The common opinion is that the presence of a coherent light source in the system provides the possibility for a photon number splitting attack to an eavesdropper. We show that the attack is inapplicable or inefficient in the case of the considered states (without assumption of phase randomization). We also provide the conditions for estimation of a detector blinding attack. Moreover, we demonstrate that not only hardware countermeasures are applicable to revealing the attack, but also utilization of special protocol construction can be implied. Thus, we conclude that the imperfections of the considered devices can easily be leveled due to the features of implemented states and protocol construction.