Decentralized Distributed Data Usage Control

Data usage control provides mechanisms for data owners to remain in control over how their data is used after it has been shared. Many data usage policies can only be enforced on a global scale, as they refer to data usage events happening within multiple distributed systems: ‘not more than three employees may ever read this document’, or ‘no copy of this document may be modified after it has been archived’. While such global policies can be enforced by a centralized enforcement infrastructure that observes all data usage events in all relevant systems, such a strategy involves heavy communication. We show how the overall coordination overhead can be reduced by deploying a decentralized enforcement infrastructure. Our contributions are: (i) a formal distributed data usage control system model; (ii) formal methods for identifying all systems relevant for evaluating a given policy; (iii) identification of situations in which no coordination between systems is necessary without compromising policy enforcement; (iv) proofs of correctness of (ii, iii).