Quantum hacking of a continuous-variable quantum-key-distribution system using a wavelength attack

摘要

The security proofs of continuous-variable quantum key distribution are based on the assumptions that theneavesdropper can neither act on the local oscillator nor control Bob’s beam splitter. These assumptions maynbe invalid in practice due to potential imperfections in the implementations of such protocols. In this paper,nwe consider the problem of transmitting the local oscillator in a public channel and propose a wavelengthnattack which allows the eavesdropper to control the intensity transmission of Bob’s beam splitter by switchingnthe wavelength of the input light. Specifically we target continuous-variable quantum key distribution systemsnthat use the heterodyne detection protocol using either direct or reverse reconciliation. Our attack is proved tonbe feasible and renders all of the final keys shared between the legitimate parties insecure, even if they havenmonitored the intensity of the local oscillator. To prevent our attack on commercial systems, a simple wavelengthnfilter should be randomly added before performing monitoring detection.