针对基于本地本振光的连续变量量子密钥分发在不安全的量子信道中传输参考脉冲存在相位攻击的安全问题,提出一种窃听和篡改参考脉冲相位的攻击方法,该攻击方法可增大接收端的相位补偿误差,从而降低实际系统的安全密钥率。基于相位补偿噪声模型,实际系统在参考脉冲相位攻击下的安全密钥率被分析。同时,提出一种基于监听相位补偿噪声方差的相位攻击探测方法。仿真结果表明,通过训练信号估计得到的安全密钥率与理论分析结果一致,并且通过监听训练信号和参考脉冲的相位补偿噪声方差可以有效判断相位攻击是否存在。

Continuous-variable quantum-key distribution based on the local-oscillator approach has been encountered with new security issues due to reference pulses transmitted over insecure quantum channels. Herein, a attack method for eavesdropping and tampering with phases of reference pulses is proposed, allowing the phase-compensation error in the receiver to be increased and secure-key rate of practical systems to be decreased. The secure-key rate of a practical system under phase attack of reference pulses is analyzed using the phase-compensation noise model. Moreover, a method for detecting phase attack is proposed, wherein the phase-compensation-noise variances are monitored. Simulation results show that the secure-key rate estimated by training signals is consistent with its theoretical value, and phase attack can be detected by monitoring phase-compensation-noise variances of the training signals and reference pulses.