A new dynamic cryptographic key generation scheme for a hierarchy

Access control is very important in information protection systems. We propose a new dynamic cryptographic key generation scheme for access control in a hierarchy. The method can achieve the following three goals. First, the storage space needed to store public information is smaller than that required in the previous work. Second, when a security class is added to the hierarchy, we assign a secret key and a public derivation key to the security class without affecting the keys of the other security classes in the hierarchy. Third, when a security class is deleted from the hierarchy, we simply erase the keys of that security class in the hierarchy and change the derivation hey of its immediate ancestor