Research And Implementation On The Multilevel Secure Database Management System

In recent years, information systems that our society increasingly depends on, play more and more important roles. With this process, the human beings bring forward higher and more rigorous security requests to the information systems. Security is all about trust. DBMS takes an extremely important task of storing and sharing large amount of information. As a result, its security plays an imperative role in the information security as a whole. The security theory and technology in database, as a database theory research, is an important direction. Many overseas scholars have done much work on multilevel secure database management system and lots of high secure DBMS have been implemented, however, for a long period of time, no commercial DBMS is above B1 level, which indicates many problems are still left unresolved. The main content in this article is as follows. First, by analysing the disadvangtages of the decomposition and recovery algorithm in the usual security model, a new algorithm of double structure tables, which is suitble for master-slaver structure tables, is presented in this paper. Second, in resolving the semantic ambiguity and operational incompleteness easily emerged in master-slaver structure tables, an improved master-slaver structure table model and relative decomposition and recovery algorithm are provided. Third, considering the merits and demerits of security model, a multilevel secure transaction model is defined on the basis of security model. In addition, a secure and correct multilevel transaction scheduling algorithm is put forward by analysing many difficulties encountered in multilevel transaction. Fourth, according to the theory mentioned above, a multilevel secure DBMS is implemented and the theory and algorithms mentioned in this paper is correct by the result of our experiment.