Toward a Multilevel Secure Re- lational Data Model

Although there are several e orts underway to build multilevel secure relational database management systems, there is no clear consensus regarding what a multilevel secure relational data model exactly is. In part this lack of consensus on fundamental issues reects the subtleties involved in extending the classical (single-level) relational model to a multilevel environment. Our aim in this paper is to discuss the most fundamental aspects of the multilevel secure relational model. Speci cally, we consider two requirements: entity integrity and update semantics. Our overall goal is to preserve as much as possible the simplicity and exibility of the relational model without sacri cing security in the process.