The Research On Concurrency Control Of Secure Real-Time Database

With the rapid development of computer network and the database technology, the real-time database systems (RTDBS) are widely used in various application fields. Recently, there is increasing need for supporting applications which have timing constraints while managing sensitive data in advanced database systems such as military command control systems and stock information. Therefore, the security needs to be integrated into real-time database system, namely secure real-time database system (SRTDBS). As far as SRTDBS, the concurrency control algorithm in transaction management should meet the security and timeliness. However, the traditional real-time database concurrency control protocol does not provide security supports. On the other hand, multilevel secure database system can not meet timing requirements, so the study of concurrency control protocol in SRTDBS is extremely important significance.In this paper, firstly, real-time concurrency control protocols are studied, and base on the optimistic concurrency control protocols with dynamic adjustment of serialization order, an improved protocol is presented which integrates the criticality of transaction and check the likelihood of success of transudations which should be restarted. Based on real-time control protocols, secure real-time concurrency control protocols are studied. In order to solve the conflict between security and timely, a secure real-time concurrency control protocol using multiple data versions is presented. The main works are as follows:(1) Give a comprehensive summarization about real-time concurrency control protocols, including locked-based protocols and optimistic protocols, and make analysis for them. Based on optimistic concurrency control protocols with dynamic adjustment of serialization order, an improved protocol is presented which integrates the criticality of transaction and check the likelihood of success of transudations which should be restarted.(2) Discuss secure control factor on access restricted model based BLP model, and analyze the conflict between security and timely. From this angle embarking, secure real-time concurrency control protocols are studied, by systematically analyzing of existing protocols, a secure real-time concurrency control protocol is presented. The protocol provides noninterference among transaction with different classification level using multiple data versions, and relax consistency requirement of serializability to view consistency, increase the degree of concurrency among transactions and improved performance of system. Finally, the proofs of correctness are given.(3) Simulations are implemented to examine the presented concurrency control protocols on a secure real-time database simulation model, and the results of simulation are analyzed and compared. From the results of simulations, the presented protocols have a better performance.