Scalable secure one-to-many group communication using dual encryption

Multicasting is a scalable solution for group communication. Whereas secure unicast is a well-understood problem, scalable secure multicast poses several unique security problems, namely groupmembership control, scalable key distribution to a dynamic group. We address scalability in the pro-posed protocol by using hierarchical subgrouping. Third party hosts or members of the multicast group,designated as subgroup members, are responsible for secret key distribution and group membershipmanagement at the subgroup level. Unlike existing secure multicast protocols, our protocol, throughdual encryption, can use “untrusted” subgroup managers to distribute data encryption keys securely. Weanalytically prove the correctness of the protocol in ensuring secure communication, describe possiblecollusion scenarios and our protocol’s ability to overcome them. We compare our protocol with exist-ing scalable key distribution schemes through simulation using real-life multicast traces and show thatour protocol alleviates the encryption overhead at the sender by distributing some of the work amongthe subgroup managers. The proposed protocol performs better than existing scalable protocols as thenumber of active members in a multicast group increases.