Integrity in Multilevel Secure Database Management Systems

Integrity is usually considered to be at odds with security in multilevel databases. Integrity constraints enforce conditions on relations between data, while security constraints enforce separation between data. If an integrity constraint is defined over data at different security levels, a direct conflict results. However, the solution is not to sacrifice the integrity constraint altogether. Compromise solutions can often be found that guarantee some, although not all, of the desired results of the constraint. In this essay we will show that by dividing the desired goals of integrity into three areas — consistency, correctness, and availability — one can often find solutions to integrity problems that achieve some, if not all, of the goals without sacrificing security. The rest of this essay is structured as follows. After a brief overview of security issues in multilevel databases, we discuss integrity and describe the three integrity properties: consistency, correctness, and availability. Then we discuss integrity in relational databases and integrity of transactions. We also discuss integrity of object-oriented databases.