Entity Modeling in the MLS Relational Model
Kenny Smith, Marianne Winslett · 1992
Previous proposals for a multilevel secure relational model have utilized syntactic integrity properties to control problems such as polyinstantiation, pervasive ambiguity, and proliferation of tuples due to updates. Although successive versions of these models have shown steady improvement, most thorny problems have been mitigated but not resolved. We believe that the major roadblock to progress has been that no effort to date has shown what a multilevel secure database means semantically; instead the focus has been on making syntactic adjustments to avoid problems. In this paper, we introduce a belief-based semantics for multilevel secure databases that supports the description of semantic multilevel secure entities, and argue for the generality of this semantics. We also present our syntax for multilevel secure databases, and show its relationship to the semantics. Our syntax is free of most problems of previous models, and is also simpler without sacrificing security or expressive...