Research On Dynamic Secure Encryption Technology For OFDM-PON

The optical access network sends downlink signals in the form of broadcast,and some optical devices in the uplink channel are vulnerable to illegal attacks,which leads to the hidden danger of eavesdropping and interference in the optical access network.The optical access network is also the part that is closest to the user end in the communication network,so enhancing the security of the optical access network is vital to improve the security of the entire communication network.At present,the reported security enhancement technologies for the optical access network mainly include the upper layer encryption,laser secure communication,optical codec,optical quantum key distribution and physical layer encryption.Among them,the physical layer encryption technology has the advantages of processing a variety of data,performing multiple operations,protecting all data,flexible implementation,et al.In addition,the characteristics such as randomness,initial value sensitivity and non-repeatability of chaotic dynamics are similar to the confusion and diffusion characteristics of cryptography,and the chaotic sequence is convenient to generate,which can provide a good means for covert communication.Therefore,the physical layer encryption technology based on chaos is considered as one of the best solutions to ensure the secure communication of the optical access network.This article takes the OFDM-PON system as the research object,and proposes a chaotic physical layer multilevel separated encryption scheme and a chaotic physical layer constellation point key generation and management method.The main innovations are as follows:1)A chaotic multilevel separated encryption scheme is proposed to enhance the randomness and unpredictability of encrypted symbols.The signal is encrypted at four levels based on one-dimensional chaotic logic mapping.The encryption process is implemented by two modules: matrix mapping and separated encryption.The simulation and the experimental verification in the OFDM-PON platform of the scheme have been completed.The research results show that only legitimate users who accurately obtain the four basic conditions of matrix mapping rule,specific used encryption algorithms,algorithm application order and security key can successfully recover the valid data;the scheme has less impact on system transmission performance and has good compatibility with the existing encryption algorithms;the scheme improves the security of the communication system significantly at the cost of a lower increase in computational complexity.2)Based on the idea of static key distribution technology,a chaotic constellation point key generation and management method is proposed to guarantee the security of the pre-shared process of the key.Key generation rule based on the constellation points is agreed in advance between the sending and receiving ends,and the generated key is related to the characteristics of the newly uploaded user data.Using the relevant parameters instead of the security key to transmit in the uplink channel reduces the probability that illegal attackers directly intercept the security key.Users can dynamically change the relevant parameters according to their own needs to achieve the change of security key.This method and chaotic multilevel separated encryption scheme are jointly applied to a communication system,and the simulation verification has been completed.The research results show that the method enhances the ability of the communication system to resist illegal attacks,and has less impact on the computational complexity and transmission performance of the system;the system can obtain a larger key space with the help of the method;the need for memory space at the sending and receiving ends can be alleviated by modifying the key generation rule of the method.