The Research And Implementation About MLS/DTMS

With the continuous development of information technology and information industry, more and more information need to process and exchange, and the most effective tool of processing information is database applications. On the one hand, we must improve the system efficiency, to share information resources as far as possible, on the other hand we must prevent getting resources by using the shared platforms unlawfully. The research and implementation of the Multi-level security Distributed Transaction Management has been subjected to the attention of the people, but also as an important research topic of information security.The concurrency control mechanism based on signal-lock of E.Bertino et al solves the problem of covert channel and hunger, but in high-load circumstances, a large number of low level transactions always raise some signals which need high level transactions to serve, which led high level transactions to suffer from hunger. S.Pal has proposed a locking protocol using two committed versions to solve the above problem. However, it imposes a deadline within when all high level transactions' read data must be completed. If not completed, then such transactions have to be aborted, possibly resulting in indenite delay. Moreover, higher level transactions are always read older versions of the data, which usually may not be acceptable.To solve the problem above, we propose a secure concurrency control algorithm that is based on a locking strategy and that requires only two versions, one committed and one noncommitted version of data, all read operations, high or low, are performed on the previous committed version while the write operation proceeds on the uncommitted version. So it has the two advantages of signal lock mechanism and two versions.In addition, the traditional multi-level security distributed commit protocol is not suitable for using in multilevel secure distributed databases systems to meet the requirements of the safety and serializability. In this work, based on the security concurrency control mechanism, we propose a multi-level security distributed commit protocol(S2VBSEP) which based on signal lock and allow a distributed transaction to proceed even when a participant has released its low-level read locks prematurely to meet the safety requirements and the serial requirement.Finally, we design and implementation multi-level security distributed transaction management prototype system based on the theory of this paper. Through experimental prototype, we proved that the multi-level security concurrency control protocol and multi-level security distributed commit algorithms are achievable and feasible.