Data usage control enforcement in distributed systems

Distributed usage control is concerned with how data may or may not be used in distributed system environments after initial access has been granted. If data flows through a distributed system, there exist multiple copies of the data on different client machines. Usage constraints then have to be enforced for all these clients. We extend a generic model for intra-system data flow tracking-that has been designed and used to track the existence of copies of data on single clients-to the cross-system case. When transferring, i.e., copying, data from one machine to another, our model makes it possible to (1) transfer usage control policies along with the data to the end of local enforcement at the receiving end, and (2) to be aware of the existence of copies of the data in the distributed system. As one example, we concretize "transfer of data" to the Transmission Control Protocol (TCP). Based on this concretized model, we develop a distributed usage control enforcement infrastructure that generically and application-independently extends the scope of usage control enforcement to any system receiving usagecontrolled data. We instantiate and implement our work for OpenBSD and evaluate its security and performance.