Inference-proof view update transactions with forwarded refreshments

Abstract

Inference control aims at disabling a participant to gain a piece of information to be kept confidential. Considering a server-client architecture for information systems, we extend Controlled Query Evaluation (CQE), an inference control method to enforce confidentiality in static information systems under queries, to databases that are updatable by a client. More specifically, within the framework of the lying approach to CQE, we study how the server should translate a view update request issued by a client into a new database state in an inference-proof way. In order to avoid dangerous inferences, some such updates have to be denied even though the new database instance would be compatible with the set of integrity constraints declared in the schema and supposed to be known to the client. In contrast, seen from the client's point of view some other updates leading to an incompatible instance should not be denied. We design a control method to resolve this seemingly paradoxical situation and then prove that the general security definitions of CQE, suitably extended to capture both query evaluation and view update processing, and other properties linked to view updates hold. Moreover, we further enhance that control method by adding an inference-proof subprotocol for refreshing the views of the other clients. To ensure inferenceproofness, from the other clients' point of view, any view update might be a transaction, i.e., a sequence of elementary updates. 1

Signature-Based Inference-Usability Confinement for Relational Databases under Functional and Join Dependencies

“…Regarding advanced interactions, on the one hand we have to suitably adapt previous theoretical results [5,7] and, again, to exploit the features of the underlying database management system as far possible. On the other hand, in general an update of the database instance will require to update the (instantiated) inference signatures as well.…”

Optimality and Complexity of Inference-Proof Data Filtering and CQE

“…In both cases, open queries are reduced to propositional queries. CQE methods have been further extended to handle updates in [16]. Efficient implementations have been studied in [17].…”