Methods for cryptographic delegation and enforcement of dynamic access to stored data

Abstract

Efficient methods for assigning, revoking, and realizing access to stored data involve a cryptographic key hierarchy and a set of operations performed on cryptographic keys and performed on the data objects to be protected. In addition to providing confidentiality and integrity for data objects, the methods allow access to selected data objects to be permanently revoked for all entities without requiring all instances of the data objects to be destroyed or overwritten. The methods also support access right modifications for a data object without requiring the re-encryption of the entire data object; instead, certain keys are selectively re-encrypted and re-authenticated to implement access control changes. The key hierarchy is parameterized to enable flexible performance tuning, and to provide efficient random access, keying and other security operations are performed for individual blocks within a data object rather than only for the entire data object.