We consider a system where each user is in one or more elementary groups. In this system, arbitrary groups of users can be specified using the operations of union, intersection, and complement over the elementary groups in the system. Each elementary group in the system is provided with a security key that is known only to the users in the elementary group and to the system server. Thus, for any user u to securely multicast a data item d to every user in an arbitrary group G, u first forwards d to the system server which encrypts it using the keys of the elementary groups that comprise G before multicasting the encrypted d to every user in G. Every elementary group is also provided with a key tree to ensure that the cost of changing the key of the elementary group, when a user leaves the group, is small. In [E. Jung, A.X. Liu, M.G. Gouda, Key bundles and parcels: secure communication in many groups, in: LNCS 2816, Group Communications and Charges, 2003], we introduced two methods for ...
Eunjin Jung, Alex X. Liu, Mohamed G. Gouda