Abstract
Continuous-variable quantum key distribution (CV-QKD) with a real local oscillator (LO) experiences a phase attack security challenge due to the reference pulses transmitted along with quantum signals over an unsecure quantum channel. In this paper, a phase attack on reference pulses of CV-QKD with a real LO is investigated. The performance of the discrete-modulated (DM) CV-QKD under this attack is analyzed analytically and by simulation, and compared with the Gaussian-modulated (GM) CV-QKD. It is found that such an attack by an eavesdropper's, significantly reduce the transmission distance for the GM based CV-QKD, whereas, the DM based CV-QKD shows a high tolerance to high phase noise. Based on phase attack monitoring, a new adaptive modulation scheme is proposed for CV-QKD to adaptively switch between GM and DM so as to maintain the optimum secret key rate.
Highlights
Quantum key distribution (QKD) is one of most promising practical applications of quantum cryptography
Inspired by the above works, we propose an adaptive modulation scheme for CV-QKD that switches between GM and DM based on the deviation of phase compensation error
We found that the discrete-modulated based CV-QKD has good robustness against the phase noise compared to Gaussianmodulated (GM) CV-QKD
Summary
Quantum key distribution (QKD) is one of most promising practical applications of quantum cryptography. The authors in [20] proposed a method to monitor the deviation of phase compensation error on quantum signals and on reference pulses to discover eavesdropping, so that Alice and Bob can switch the quantum channel to more secure one. The new adaptive modulation CV-QKD could find application in the context of agile and versatile quantum cryptography, where the same hardware could be used for dynamically switching modulation schemes according to the prevailing phase attack in order to achieve the optimum secret key rate. The rest of this paper is organized as follows: Section II presents CVQKD system model with a real LO that can be used for DM or GM input data It is followed by describing the phase errors compensation and phase attack method by Eve. Section III demonstrates the security analysis of CV-QKD protocol under phase attack.
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