Privacy-preserving access control in publicly readable storage systems

Abstract

In this paper, we focus on achieving privacy-preserving access control mechanisms for decentralized storage, primarily intended for an asynchronous message passing setting. We propose two modular constructions, one using a pull strategy and the other a push strategy for sharing data. These models yield different privacy properties and requirements on the underlying system. We achieve hidden policies, hidden credentials and hidden decisions. We additionally achieve what could be called ‘hidden policy-updates’, meaning that previously-authorized subjects cannot determine if they have been excluded from future updates or not.