Secure broadcasting in large networks

It is common that users or hosts in a large network are partitioned and organized as a hierarchical tree where children of the same parent form a group. Secure broadcasting intends to provide a secure communication channel from a sending principal to a group of legal receiving principals. Only legal receiving principals can decrypt the message, and illegal receiving principals cannot acquire any information from the broadcasted message. In this paper, we propose a secure broadcasting protocol in which only one packet is transmitted for every broadcast, and the size of the broadcasted packet is small.