Single-photon-detection attack on the phase-coding continuous-variable quantum cryptography

TL;DR

This paper demonstrates a single-photon-detection attack on phase-coding continuous-variable quantum cryptography, revealing potential security vulnerabilities and limitations on communication distance due to system loss and attack strategies.

Contribution

It introduces a novel attack method that compromises security in certain regimes and analyzes its impact on the scheme's maximum communication distance.

Findings

The attack can lower the BER below the system's inherent BER in some regimes.

The attack limits the maximum secure communication distance.

Security can be compromised due to system loss and attack parameters.

Abstract

The phase-coding quantum cryptographic scheme using the homodyne detection and weak coherent state [Hirano et al.,Phys. Rev. A 68, 042331 (2003)] provides the simplest continuous-variable quantum key distribution scheme from the experimental side. However, the inherent loss of the practical system will not only increase the bit error rate (BER) but also affect the security of the final key. In this paper, we propose a single-photon-detection attack, and then the security of the final key will be compromised in some parameter regimes. Our results show that the BER induced by Eve can be lower than the inherent BER induced by the loss of the system in some parameter regimes. Furthermore, our attack gives the maximal communication distance of this scheme for given experimental parameters.