Paper 2014/762

Access Control in Publicly Verifiable Outsourced Computation

James Alderman, Christian Janson, Carlos Cid, and Jason Crampton

Abstract

Publicly Verifiable Outsourced Computation (PVC) allows devices with restricted resources to delegate expensive computations to more powerful external servers, and to verify the correctness of results. Whilst this is highly beneficial in many situations, it also increases the visibility and availability of potentially sensitive data, and thus we may wish to limit the set of entities with access to input data and results. Additionally, within an organization it is extremely unlikely that every user would have uncontrolled access to all functionality. It is also not always reasonable to publish the results of a sensitive computation. Thus there is a need to apply access control mechanisms in PVC environments. In this work, we define a new framework for Publicly Verifiable Outsourced Computation with Access Control (PVC-AC) that applies cryptographic enforcement mechanisms to address these concerns, and we provide a provably secure instantiation using Key Assignment Schemes. We also discuss example policies of interest in this setting.