Database systems for real-time applications must satisfy timing constraints associated with transactions, in addition to maintaining data consistency. In addition to real-time requirements, security is usually required in many applications. Multilevel security requirements introduce a new dimension to transaction processing in real-time database systems. In this paper, we argue that due to the con icting goals of each requirement, trade-o s need to be made between security and timeliness. We rst de ne mutual information, a measure of the degree to which security is being satis ed by a system. A secure two-phase locking protocol is then described and a scheme is proposed to allow partial violations of security for improved timeliness. Analytical expressions for the mutual information of the resultant covert channel are derived and a feedback control scheme is proposed that does not allow the mutual information to exceed a speci ed upper bound. Results showing the e cacy of the scheme obtained through simulation experiments are also discussed.
In REF , the trade offs between timeliness and security are addressed and then a scheme which allows partial violations of security for improved timeliness has been proposed.
Integrating Security and Real-Time Requirements using Covert Channel Capacity
IEEE Transactions on Knowledge and Data Engineering
Computer Science