Key Technology Study On Chaotic Secure Communication In Lasers Networks

Due to the advantages of high bandwidth,low loss,and resistance to electromagnetic interference,optical fiber communication has an irreplaceable position in modern communication systems.It currently carries over 90%of global communication services.However,with the continuous upgrading of various eavesdropping methods,eavesdroppers can intercept the transmitted information from optical fiber links,which pose great threats to the information security of optical communication system.As one of the mainstream technologies in secure optical communication,laser chaos has the characteristics of noise-like waveform and wide spectral bandwidth.It can not only be used as a physical entropy source for high-speed key distribution between different users,but also as a carrier for message modulation in secure communication system.In the past decades,chaos-based key distribution and secure communication have been hot research topics for scholars.This dissertation based on traditional point-to-point chaotic secure communication,focuses on the key technologies of chaotic secure communication in laser networks,and research has been conducted in four areas:multi-channel chaos generation,multi-channel chaos synchronization,secure key distribution(SKD)and chaotic secure communication in laser networks.The research contents and innovations are as follows:1.Multi-channel chaos generation based on mutually-coupled lasers networksTraditional optical-feedback semiconductor laser(SL)can only generate singlechannel chaotic signal with time delay signature(TDS)and limited bandwidth.To solve this problem,the following two multi-channel laser chaos optimization schemes are proposed in this dissertation.(1)A multi-channel low-correlation chaos generation scheme based on asymmetrical-coupling SLs networks is proposed.Due to the asymmetric coupling,the generated multi-channel chaotic signals are with low cross correlation.On the other hand,the coupling delays of each edge are different,which would cause power competition among different frequency components in the laser cavity,suppress the time delay signature of chaos,and generate multi-channel chaotic signals with delta-like autocorrelation function(ACF).(2)A TDS suppression scheme based on a heterogeneouscoupled SLs network is proposed.The beating effect introduced by heterogeneous coupling of network can effectively suppress the TDS and enhance the complexity,bandwidth of the chaotic signal.It is demonstrated that multichannel broadband chaotic signals with delta-like ACF are generated.2.Chaos synchronization of mutually-couple lasers networksChaos synchronization is the basis of SKD and chaotic encrypted communication.In order to address the issue that most present chaos synchronization systems only focus on point-to-point scenarios,this dissertation studies the chaos synchronization technology in SLs networks.(1)The cluster chaos synchronization in heterogeneous delay-coupled SLs networks are systematically investigated.The cluster classification,synchronization conditions,optimal parameters’ range,and synchronization robustness are discussed in the exemplary SLs network.Both simulation and experiment results confirm that SLs from same clusters are synchronized with cross-correlation coefficient(CC)over 0.9,while SLs in different clusters are not synchronized.(2)The chaos synchronization of asymmetrically-coupled SLs in different clusters of the SLs networks is systematically studied.By introducing cluster fusion method,the asymmetrically-coupled nodes are symmetrized and a new hybrid cluster is formed.The results show that in the hybrid clusters,SLs with originally asymmetric couplings can be synchronous.Cluster fusion provides a new method to achieve chaos synchronization of asymmetrically-coupled node.3.Study on SKD based on chaos synchronization in SLs networksConventional key distribution schemes based on "three-laser injection" induced chaos synchronization generally suffer from high correlation between the driving signal in public links and local entropy sources,and only focus on the key distribution between two users.To address these issues,two key distribution schemes based on low-correlation external injection and a three-user key distribution scheme are proposed.(1)A SKD scheme based on chaos synchronization subject to dual-path external injections is proposed.By controlling the injection delays,the local ends of users can achieve zero-lag or lead-lag chaos synchronization,and then the privacy of chaotic entropy source is improved by random synchronization slot extraction.In this scheme,dual-path external injections can reduce the CC between the driving laser and local laser outputs,improving the security of the proposed key distribution system.(2)A SKD scheme based on layer chaos synchronization in tree-type SLs network is proposed.By using the three-layer tree-type SLs network,the CC between injection signal and local entropy source is reduced,and the privacy of entropy sources is improved.The experiment results demonstrate that 0.6Gb/s secret keys are achieved.(3)A multi-user SKD scheme based on dynamic control of laser network is proposed.The key is negotiated by controlling the couplings of laser network and extracting keys of synchronization time slots.The proposed scheme can achieve SKD among multiple users.4.Network-type chaotic encryption communicationAiming at the problem that traditional chaos-based communication mainly focused on point-to-point scenarios,three network-type chaotic encryption communication schemes are proposed.(1)An intra-cluster chaotic encryption communication scheme is presented,based on false-message scrambling.By modulating false messages onto inter-cluster couplings,the privacy of the chaotic carriers is enhanced,as such the secure transmission of messages within the clusters is ensured.By discussing the linear filtered eavesdropping on the public link,the security of intra-cluster communication based on false-message scrambling is validated.(2)A flexible multipoint-to-multipoint secure communication scheme based on one-way isolation SLs networks is proposed.With one-way isolation,the symmetry of nodes is breaking,forming communication clusters and idle clusters with low correlations.Since the chaos carriers of the communication cluster would not be injected into the idle cluster,preventing eavesdropping obtaining the chaos carriers.(3)A chaotic encryption communication scheme based on heterogeneous delayed couplings and common external injections of global SLs network is proposed.With the joint effects of heterogeneous coupling and common external injections,TDS suppression and synchronization of chaotic carriers can be simultaneously achieved.Besides,networktype encryption communication is verified,and the security of communication system is improved.