Research On The Security Of Electro-Optical Phase Chaotic Communication System With Key Space Enhancement

As the main method of network information transmission,optical fiber communication has the characteristics of large capacity,high speed,and wide bandwidth.However,with the frequent incidents of illegal users attacking the optical network through eavesdropping and deliberate sabotage,the security of the optical network has been seriously threatened.Chaotic laser communication is a message encryption technology of the physical layer,using the hardware parameters of the system as the secret key to realize the encryption and demodulation of the message.Among them,the electro-optical chaotic feedback system has been widely studied due to its advantages of the high complexity of chaotic signal,easy parameter control,and low cost,but illegal eavesdroppers can use statistical analysis methods,such as autocorrelation function and delayed mutual information,to obtain the secret key and reconstruct the chaotic system,resulting in the message can be deciphered.Although there are existing schemes with great time-delay concealment performance,due to the complexity of the system structure,there is a problem of insufficient robustness of chaotic synchronization.At the same time,it is necessary to further increase the key space of the system.Therefore,solving the above problems is of great significance to enhance the security of optical networks.The research contents of this paper are as follows:1)In order to solve the problems of easy exposure of time-delay signatures,cross-correlation characteristics between different loops and the need to further expand the key space in the traditional electro-optical feedback mutual-coupled chaotic system,this paper proposes a three loops electro-optical phase chaotic communication system.First,the system is formed by the nonlinear coupling of three phase chaotic loops.,and the introduction of multiple nonlinear transformations and pseudo-random binary sequences in the system can effectively improve the complexity of chaotic signals.The simulation results show that when the feedback gain coefficient is greater than 2.5,all the time-delay signatures of the system can be completely concealed,and the cross-correlation characteristics between different chaotic loops are greatly weakened.Secondly,since the synchronization performance is not sensitive to the mismatch of feedback gain coefficients,the chaotic synchronization of the system has strong robustness.Finally,multiple time-delays in the system expand the key space and can effectively resist exhaustive attacks.2)To solve the problems that the time-delay signatures are difficult to conceal,the robustness of chaotic synchronization is insufficient and the key space needs to be further expanded in the traditional electro-optical feedback mutual coupling chaotic system,this paper proposes an additional chaotic phase shift electro-optical phase chaotic communication system.Based on the mutual coupling structure,the system uses the chaotic signal generated by the system itself to drive the phase modulator to generate additional chaotic phase-shift,effectively increasing the complexity of the chaotic signal and improving the security performance of the system.The simulation results show that the system can completely conceal all the time-delay signatures of the system with a low feedback gain coefficient,and the security performance is greatly improved compared with the existing schemes.Secondly,the analysis results of the influence of different parameter mismatches on the chaotic synchronization performance prove that the synchronization robustness of the proposed system is strong.At the same time,the key space of the system is extended to an ideal order due to the existence of multiple time-delays.Finally,the information demodulation with a low symbol error rate is realized under the condition that the parameters of the transmitter and the receiver are well-matched,and the communication reliability of the system is enhanced.