物理层安全星座模糊设计方法的性能研究

物理层安全加密技术是一种有效保证信息安全传输的物理层安全方法。此技术通过相位旋转、调制星座多样性、符号模糊、幅度调节和符号顺序变化等手段设计信号星座,保护调制方式与调制符号信息。现有的物理层安全加密技术存在密钥共享不保密和星座模糊度不足等缺点。多符号模糊(Mutiple Inter-symbol Obfuscation,MIO)方案采用人工噪声符号密钥与已调符号矢量叠加的加密方法来解决星座模糊度不足的问题。受MIO的启发,文中将信道系数与已调符号矢量叠加,提出了一种基于星座模糊设计(Constellation Obfuscatio Design,COD)的物理层安全加密方案。在TDD模式和信道互易的条件下,将合法信道的信道系数作为密钥,来解决密钥预分享不保密的问题。文中详细介绍了发端加密与合法接收端解密的完整传输过程,并针对高阶累积量的调制识别和智能攻击型窃听者进行接收处理分析;推导出瑞利衰落信道下的合法接收端误码率理论公式;对合法接收端、高阶累积量的调制识别窃听端和智能攻击型窃听端的误码率进行仿真,并对比了MIO方案合法接收端、窃听端的性能。仿真结果显示:合法接收端误码率为1×10-4时,COD方案的信噪比比MIO方案的低6 dB;对COD方案加密后,当信噪比为0时,调制识别成功率为11.8%,调制识别成功率最高可达25%且在信噪比大于40 dB后保持稳定;前3个数据包中,COD方案智能攻击型窃听端的误码率始终为0.284,知晓起始密钥的MIO方案窃听端的误码率则较低;信噪比在0~54 dB范围内时,合法接收端的误码率性能始终优于调制识别窃听端和智能攻击型窃听端。因此,所提COD方案能够保障安全通信,抵御调制识别和智能攻击型窃听者的攻击,并且COD方案的有效性和可靠性均优于MIO方案。

Performance Study on Constellation Obfuscation Design Method for Physical Layer Security

Physical layer security encryption technology is an effective physical layer security method to ensure the safe transmission of information.The signal constellation is designed by means of phase rotation,modulation constellation diversity,symbol obfuscation,amplitude adjustment and symbol sequence change to protect modulation mode and modulation symbol information.The existing physical layer security encryption technology has some disadvantages,such as unclassified key sharing and insufficient constellation ambiguity.The MIO scheme adoptes the encryption method of superposition of artificial noise symbol key and mo-dulated symbol vector to solve the problem of insufficient constellation ambiguity.Inspired by MIO scheme,this paper proposed a new physical layer security encryption scheme based on constellation obfuscation design(COD)by superimposing channel coefficient and modulated symbol vector.Under the condition of TDD mode and channel reciprocity,the channel coefficient of the legitimate channel is used as the key to solve the problem of unclassified key pre-sharing.This paper introduced the complete transmission process of sending-end encryption and legal-end decryption,and analyzed the reception process of high-order cumulant modulation re-cognition and intelligent attack eavesdropper.The theoretical SER(symbol error rate)equation of legitimate receiver in Rayleigh fading channel was derived.Simulation of SER performance of legitimate receiver,high order cumulant modulation re-cognition eavesdropper and intelligent attack eavesdropper were conducted.The performance of the legitimate receiver and eavesdropper of MIO scheme and COD scheme are compared.Simulation results show that when the SER of legitimate receiver is 1×10-4,the SNR(signal-to-noise ratio)of COD scheme is 6 dB lower than that of MIO scheme.After the COD scheme is encrypted,when SNR is 0,the success rate of modulation identification is 11.8%,and the highest success rate of modulation identification is 25%,which remains stable after the SNR is greater than 40 dB.In the first three data packets,the SER of the COD scheme’s intelligent attack eavesdropping terminal is always 0.284,while that of the MIO scheme’s eavesdropper who knowns the starting key is lower.With the SNR between 0 and 54dB,the SER performance of the legitimate receiver is always better than that of the modulation recognition eavesdropping terminal and the intelligent attack eavesdropping terminal.Therefore,the proposed COD scheme can guarantee the secure communication and resist the attack of modulation recognition and intelligent attack eavesdropper,and the effectiveness and reliability of COD scheme are better than MIO scheme.