A hybrid key tree scheme for multicast to balance security and efficiency requirements

Security and efficiency of rekeying are crucial requirements for multicast key management. However, the two requirements pull in different directions and balancing them to meet the application needs is still an open issue. In this paper we introduce a hybrid key tree scheme to balance security, namely the resistance to collusion, and the efficiency. The resistance to collusion is measured by an integer parameter. The communication and the storage requirements for the controller depend on this parameter too, and they decrease as the resistance to collusion is relaxed. We analytically evaluate the efficiency of our scheme and compare with the previous work. The results show that our scheme allows a fine-tuning of security requirements versus efficiency requirements at run-time, which is not possible with the previous key management schemes.