Scalable Group Key Management for Secure Multicast: A Taxonomy and New Directions

Multicast is an efficient technique to distribute data to a large group of users. To prevent disclosure of distributed data to unauthorized users, multicast-based applications require confidential group communication, which is achieved by encrypting data with a group-wide shared key. The group key must be updated and redistributed to all authorized users in a secure and reliable fashion whenever a user joins or leaves the group. Thus, group key management becomes a very challenging issue for large and dynamic groups with unreliable channels. We give an overview of the approaches that have been recently proposed to address the group key management issue, show the research trends, and finally discuss several new research directions.