Research And Implementation On Protection Technology Of High Secure DBMS

The proliferation of the internet and development of computer technology have strong impact on society and pepople's life.Because of an increasing amount of sensitive information being stroed in computer systems, it not only makes information managed by DBMS huge and complicated, but also makes the computer systems becoming the target of hackers.How to protect the security of database is becoming an important direction in the information security.Database security theory and technology is an important research field of database theory.In this paper, we focus on secure data modle, inference control and transaction processing in multilevel secure environment. First, an improved polyinstantiation model, enableing to control the covert channel caused by foreign key, is put forward for eliminating ambiquity of null value and resolving the problem of data spanning. Meanwhile, this model can promote query efficiency. Second, discussing the detecting and eliminating of inference channel, different channel detecting methord are provided according to static, dynamic and compositional channel, and a new algorithm of eliminating the inference channel by promoting security was presented. Third, discussing many problems encountered by transaction, which is from single-level to multilevel, and a transaction schedule algorithm is given based on data replicated architecture. According to the theory mentioned above, a mls/dbms is developed, and the experiment result has showed the correctness of the theory.