Date Added: Nov 2012
There are numerous examples where it is desirable to provide differentiated access to data according to an access control policy. Hierarchical Key Assignment Schemes can be used to enforce access control policies by cryptographic means. In this paper, the authors present a new, enhanced security model for such schemes. They also give simple, efficient, and strongly-secure constructions for Hierarchical Key Assignment Schemes for arbitrary hierarchies using pseudorandom functions and forward-secure pseudorandom generators. They compare instantiations of their constructions with state-of-the-art Hierarchical Key Assignment Schemes, demonstrating that their new schemes possess an attractive trade-off between storage requirements and efficiency of key derivation.