Design and Analysis of an Adaptive Policy for Secure Real-Time Locking Protocol

A secure concurrency control algorithm must, in addition to maintaining consistency of the database, be free from covert channels arising due to data conflicts between transactions. Since the property of noninterference must be satisfied to ensure security, most existing secure concurrency control algorithms are unfair to transactions at higher access classes. In this paper, a secure two-phase locking protocol is presented, which is shown to be free from covert channels. The protocol provides reasonably fair execution of all transactions, regardless of their access class. Since many applications of advanced database systems need to support timeliness while managing sensitive information, integration of real-time transaction processing techniques with security protocols is necessary. In this paper, we discuss the difficulties for supporting both security and timeliness, and present an adaptive scheme to support necessary tradeoffs to be made between security and timeliness requirements. An algorithm-independent simulation framework is explained, and the results of a performance evaluation of Secure 2PL is provided, comparing it with secure optimistic concurrency and secure multiversion timestamp ordering. The performance of the adaptive scheme is also evaluated for a spectrum of security-factor values ranging from fully secure (1.0) right up to fully real-time (0.0).