Research On Controllable Chaotic Encryption Technology In Optical Access Network

The security requirements of communication networks are increasing to cope with the threats of information security.Optical access networks have attracted much attention as an important part of communication networks.There is a risk of eavesdropping in the downstream channel broadcast communication of the optical access network.Therefore,it is significant to study the security of the optical access network.In the existing optical access network security solutions schemes,upper-layer encryption schemes,optical encoding-decoding schemes,and chaotic laser communication schemes have defects such as encrypt part data only,small key space,and poor synchronization stability.The optical physical layer chaotic encryption technology has shown greater advantages in the abovementioned aspects.OFDM-PON occupies an important position in the field of optical access by virtue of its high dispersion tolerance,high spectrum efficiency,anti-multipath interference and other advantages.Taking OFDM-PON as the research object and combine with the key agreement mechanism and key distribution scheme design,this thesis focuses on the uncontrollable factors such as the complexity of the chaotic encryption scheme and the transmission performance of the encrypted signal,and proposes two controllable chaotic encryption schemes.The main work and contributions of this thesis are as follows:(1)A dynamic chaotic encryption scheme with controllable complexity is proposed.Which is composed of the encryption sub-algorithm group related to security and complexity and the dynamic key agreement mechanism.Different ONUs request the secure level and update the dynamic key with the OLT during the communication process,thereby controlling the selection of sub-algorithms with different complexity.The chaotic sequence generated by the static key is then used to encrypt the OFDM-PON signal and protect the key agreement process.The solution increases the flexibility of the chaotic encryption algorithm.Under the premise of meeting the security requirements,it controls the balance between algorithm security and encryption efficiency effectively.Under the uniform distribution of security requirements,this scheme improves the average encryption efficiency of the system by about 35% compared to only using the highest complexity algorithm.(2)Based on the chaotic key distribution scheme and the constellation probabilistic shaping scheme,a constellation shaping chaotic encryption scheme with controllable statistical distribution is proposed.First,group the QAM symbol sequence and calculate the statistical information.Second,the statistical information is encrypted by the chaotic sequence and encoded into the chaotic phase.Third,perform constellation area exchange for each group to achieve slight probabilistic shaping.Finally,the chaotic phase is added to the QAM symbol sequence after constellation shaping.By controlling the statistical distribution of the signal after probabilistic shaping,different degrees of signal transmission performance gains are realized while encrypting the signal.