Research On Multilevel Security Oriented Network Secure Communication Model And Its Key Technologies

Classified security protection that is a national policy about information security assuranceis a key research content of information security，which is gained widely attention in informationsecurity realm. After information system is classified, information isolated island would beformed because of strictly barrier among information systems undoubtedly. So, on the premise ofnot violating normal working of information system and classified security characteristics, howto keep continuously interconnection among information systems is a key problem in theimplementation of classified security protection. Network security communication is animportant method of secure interconnection among information systems. However, the existingsecure communication technology that reckons without multilevel security attributes can notsatisfy the demand of secure communication among information systems in classified securityprotection so that the research on MLS oriented secure communication technology is urgency.The main works and creations of this paper are as the following:1. After analyzing the existing secure communication models and its relevant models, thispaper points out the shortcomings of the existing models, and their problems about MLS appliedto actual network. At the same time, the key problems that are urgent to solve about MLSoriented network communication are expounded.2. To solve the problems that are appeared when multilevel security is applied to actualnetwork, such as flexibility, availability, security and secure communication etc., this paper putsforward a multilevel security oriented network secure communication model based onmulti-dimension control. In the model, relational restraints among protection domains mayeffectively accomplish inter-domain and intra-domain interconnection control. The trust degreethat reflects confidence on behaviors of subject may solve the problem that a subject mightaccess an object in special situation, at the same time, the methods about treatment of subject andobject after a subject‘s illegal access are considered adequately for strengthening availability ofBLP model. Relational restraints among objects may control limited access of associated objectsand similar objects so that the risk of information leakage caused by aggregation of objects isreduced for strengthening restriction on confidentiality of BLP model. Moreover, logical virtualnetwork with secure level may be built by establishing different secure level tunnel and restraintsof secure tunnel, which can accomplish secure data transmission and segregation of information,and then reduce the probability of information leakage.3．For the problem about secure label bound to information object, this paper puts forward amethod for binding secure label to information object based on unified description of information object. Firstly, the method analyzes types of information objects, and describesmulti-types information objects uniformly. Then, it expounds secure label of object based on xml,at the same time, gives an algorithm about binding secure label to information object. Finally,operations on information object in multilevel security network are discussed. The method cannot only unify the method of binding between multi-types information object and secure label,which may improve flexibility of binding, but also accomplish fine-grained mandatory accesscontrol, which may solve the problem that access control of heterogeneous data amongmultilevel secure system is more difficult.4. To solve the problem of information leakage caused by aggregation among objects, thispaper deeply analyzes the relations among objects, and respectively puts forward level inferencemethod for aggregated information of objects based on associated attributes and clusteringanalysis. Highly associated objects are found by dependency relationships and association rules,and then similar objects are clustered by concept analysis and concept gravity. Finally, theprobability of higher level information inferred by aggregation of associated objects and similarobjects is computed by probability estimates of fuzzy sets on secure level of attribute andattribute set. The methods may contribute to establish access control policy in multilevel securenetwork, and control restricted access of associated objects and similar objects in order to reducethe risk on information system.5. For accomplishing secure transmission and segregation of information amongnonequivalence interconnection members, this paper designs secure communication protocolcluster in multilevel security network that is composed of multilevel secure tunnel establishmentprotocol and security transmission protocol. In tunnel establishment protocol, multilevel securetunnels are established among nonequivalence members by coalition, virtual subject andmapping of secure label. It may not only accomplish secure transmission and segregation ofdifferent level information, but also authorization of subject in order to overcome theheterogeneous of secure label in different information systems. In secure transmission protocol,protocol format, operation mode and work procedure are designed, and then binding betweensecure label and data stream is enforced by IPSO in order to accomplish mandatory accesscontrol based on data stream.