Policy-Based Cryptography and Applications

In this paper, we introduce the concept of policy-based cryptography which makes it possible to perform policy enforcement in large-scale open environments like the Internet, while respecting the data minimization principle according to which only strictly necessary information should be collected for a given purpose. We propose concrete policy-based encryption and signature schemes, based on bilinear pairings, which allow performing relatively efficient encryption and signature operations with respect to credential-based policies formalized as boolean expressions written in generic conjunctive-disjunctive normal form. We illustrate the privacy properties of our policy-based cryptographic schemes through the description of three application scenarios.