Multiversion concurrency control for transactions in multilevel secure databases

Abstract

Preventing the creation of covert channels in concurrency control is the most important issue in the database security, i.e., ensuring secret information keep secret to unauthorized users while controlling concurrent transactions. Developing secure concurrency control mechanisms, however, often incurs additional problems, such as the starvation of high transactions and the possibility of non-serializable schedule due to the existence of low transactions. We, in this thesis, propose a secure multiversion concurrency control algorithm based on the concepts of a C-set and a T-lock. The main objective of our algorithm is to make the high security level transactions free from starvation while a serializable schedule is produced. Our algorithm improves the availability of multilevel secure database (MLS/DB) by resolving the starvation problem of high security level transactions when low security level transactions have the highest priority in their execution. We also show that our algorithm satisfies the security and correctness requirements.``