Security constraint processing during the update operation in a multilevel secure database management system

In a multilevel secure database management system (MLSDBMS). users cleared at different security levels access and share a database consisting of data at different sensitivity levels. A powerful and dynamic approach to assigning sensitivity levels (also called security levels) to data is one which utilizes security constraints or classification rules. Security constraints provide an effective and versatile classification policy. They can be used to assign security levels to the data depending on the content, context, and time. In this paper, we argue that security constraints are a special form of integrity constraints enforced in a MLSDBMS. As such, they can be handled during query processing, during database updates, or during database design. We then describe in detail the design and implementation of a secure update processor which handles security constraints in a multilevel secure database management system.