Physical Layer Security Protection Technologies Of Orthogonal Frequency Division Multiplexing Passive Optical Network

Nowadays,information has become a crucial strategic resource.The increasing demand for bandwidth brings challenges to the existing optical network,and the protection of network security becomes an important task of national security.The orthogonal frequency division multiplexing passive optical network(OFDM-PON)has become one of the outstanding candidates to meet requirements of the next generation optical access network due to its high spectral efficiency,robustness to fiber dispersion,flexibility of resource allocation,and low implementation cost.However,due to the point-to-multipoint topology of passive optical network(PON)and the broadcast communication mode of downlink signal,the physical layer of access network is vulnerable to intrusion,eavesdropping and spoofing attack.Security measures in the physical layer with high flexibility and low-cost can strengthen the all-round protection of network information.The research of OFDM-PON security technology in the physical layer is of great significance,which can promote the cooperation of cross layer security mechanism and realize the high-capacity secure optical access network system.The main research results of this thesis are as follows:(1)Aiming at the problem of mutual restriction between algorithm security and computational complexity,a digital chaos encryption algorithm based on uplink and downlink plaintext mutual interference mechanism is proposed.Under the constraint of low precision fixed-point algorithm,the dynamical degradation effect of digital chaotic system is effectively improved.A Rubik's cube algorithm for dynamic nonlinear transformation of chaotic sequences is designed to expand the key space.The physical layer data protection mechanism for OFDM-PON with a key space of 2⁵⁶×(256!)²⁵⁶??10¹²⁹⁷⁹¹ is implemented when the calculation precision of the fixed-point algorithm is 14 bits.(2)Aiming at the security of key distribution and the cost of channel resources,a technology of key hide distribution based on chaotic pilot signal is proposed.Under the premise of no additional overhead and no impact on the transmission performance,the security of secret key transmission is realized by using the redundancy of the constructed chaotic pilot information.The cooperative protection mechanism of key distribution and16-QAM OFDM data security transmission is verified by experiments,in which key distribution rate is 28.4 Mb/s and data transmission rate is 7.64 Gb/s.(3)Aiming at the complexity of traditional identity authentication protocols,a hardware fingerprint identification technology based on wavelet transform and convolutional neural network is proposed.The impact of ONU device tolerance on transmission signal is taken as hardware fingerprint,and OFDM pilot signal is taken as fingerprint carrier to realize ONU hardware identity authentication at OLT.Experimental results show that the identification accuracy of legal ONU can reach 97.41%,and that of illegal ONU can reach 100%,which indicates that security threats such as unauthorized access and spoofing attack in the physical layer can be resisted.