Research On Physical Layer Encryption Scheme Based On Signal Multi-Domain Feature Scrambling In O-OFDM System

The rapid development of the Internet has promoted happiness and convenience in travel,payment,entertainment,work and other aspects.While enjoying the convenience brought by Internet,the problems of data security cannot be ignored.The global expenditure on information security is increasing year by year,and our country attaches great importance to data security.Therefore,it is necessary to study the encryption of information.Optical fiber communication technology plays an important role in the interconnection and data transmission between networks on the main road in the current Internet.Optical OFDM technology combines the advantages of optical fiber communication and OFDM technology,with large transmission capacity,high tolerance of dispersion and polarization dispersion,and high frequency spectrum utilization.It has attracted much attention in optical communication research and has a wide range of application scenarios,such as optical access network system,optical wireless system and so on.Therefore,it is very important to study encryption schemes in optical OFDM system.Physical layer encryption schemes have the advantages of flexible encryption mode,operation of various data and low implementation complexity compared with other layers.Therefore,this thesis studies the physical layer encryption schemes of optical OFDM system.By investigating various encryption algorithms,this thesis designs encryption schemes for different domains of OFDM signals in view of the characteristics of optical OFDM signals with different signal domains.The system can be encrypted by scrambling a certain domain or cascade scrambling between different domains.This thesis proposes two encryption schemes,The core of the first encryption scheme is to increase the complexity of the encryption algorithm by encrypting different domains of cascaded OFDM signals,namely complex domain,subcarrier domain and symbol domain,so as to improve the security of the algorithm.At the same time,cat mapping,which is an endomorphism chaotic system,is used to ensure the consistency of the region after mapping,and it will not bring error code diffusion.The core of the second encryption scheme lies in the use of a new key generation method,which introduces the genetic evolution of the organism,and evolves into a new population through the crossover and mutation operation of the initial population,and the generated heart population is used as the key in the encryption.By controlling the threshold of crossover and variation,the new population can be greatly different from the original population.The two schemes have analyzed the bit error rate,PAPR and security performance of the COOFDM system through feasibility verification.The results show that both schemes can achieve the purpose of secure transmission under the condition of ensuring the system performance.