Policy evolution in distributed usage control

Usage control is a generalization of access control that also addresses how data is handled after it is released. Controlling the future usage of data includes controlling the future distribution of data. The evolution of policies upon re-distribution must hence be defined. Intuitively, clients should only strengthen policies associated with a data item when they redistribute it. We provide a role-based re-distribution model for usage control that encompasses strengthening both rights and duties. By introducing orderings for events and parameter values we show how both rights and duties can be strengthened with the traditional abstraction of trace inclusion.