Hierarchical Access Control for Secure Group Communication

Secure group communication with hierarchical access control refers to a scenario where a group of members is divided into a number of subgroups located at different privilege levels and a high_level subgroup can receive and decrypt massages within any of its descendant lower_level subgroups;but the converse is not allowed.To propose a improved scheme, which is based on the Chinese Remainder Theorem. The scheme not only enables secure hierarchical control but also provides the following properties: hiding of hierarchy and receivers, authentication of both senders and messages ,and a mechanism for the receiver to directly derive the key of a message.