Wavelength attack scheme on continuous-variable quantum key distribution system using heterodyne detection protocol

TL;DR

This paper presents a wavelength attack on continuous-variable quantum key distribution systems using heterodyne detection, exploiting imperfections in the local oscillator transmission to compromise security.

Contribution

The authors propose a novel wavelength attack targeting CV QKD systems and demonstrate its feasibility, highlighting a critical security vulnerability.

Findings

The attack can compromise key security even with intensity monitoring.

Adding a wavelength filter can prevent the attack.

The attack exploits control over the beam splitter via wavelength switching.

Abstract

The security proof of continuous variable quantum key distribution(CV QKD) based on two assumptions that the eavesdropper can neither act on the local oscillator nor control Bob's beam splitter. These assumptions maybe invalid in practice due to some potential imperfections of the implementations of the protocol. In [Phys.Rev.A, 84.062308], we found that one can control the intensity transmission of the beam splitter by switching the wavelength of the input light. In this paper, we revisit the problem of transmitting the local oscillator in public channel, and propose a wavelength attack targeting the CV QKD systems using heterodyne protocol. Our attack is proved to be feasible and renders all final key shared between the legitimate parties insecure even they have monitored the intensity. To prevent our attack, a wavelength filter should be added before performing the heterodyne detection.