Managing key multicasting through orthogonal systems
  In this paper we propose a new protocol to manage multicast key distribution. The protocol is based on the use of orthogonal systems in vector spaces. The main advantage in comparison to other existing multicast key management protocols is that the length and the number of the messages which have to be sent are considerably smaller. This makes the protocol especially attractive when the number of legitimate receivers is large. 
Jose' Antonio Alvarez-Bermejo, Juan Antonio Lopez-Ramos, Joachim   Rosenthal, Davide Schipani
cs.CR