The Effect of Confidentiality on the Structure of Databases

Abstract

We give in this work an answer to the question of how real-life confidentiality can be introduced to an open database in a declarative manner. We present five forms of real-life confidentiality, translate them in the context of logic and show that only two forms can be brought in accord with databases that make the Closed World Assumption. These two forms, which correspond to real-life situations in which we do not want to admit that we are trying to keep something secret, can be precisely defined as distortions of the database's intended model. The main result of this work is a definition of a database with unequivocal static and dynamic semantics that supports real-life confidentiality at a declarative level. Two of its properties are that we never encounter polyinstantiation and that there is no inference.