Multicast Key Management Scheme Based on TOFT

Key management is very crucial in a secure multicast system. The key storage of the group controller and group members, the communication cost and computation cost caused by joining/leaving members, are the determining factors for the performance of the key management system. A scheme is high-performed, if it has the optimal rekeying cost and the lower storage requirements. In order to get the high efficiency and security, a novel scheme (TOFT) based on threshold-based one-way function tree is proposed in this paper. The quad-tree and the threshold-key-mechanism are used in the scheme, which improves the performance of the key management system. We present the design principle, the realization protocols including keys generation and distribution, dynamic membership management. The TOFT scheme is compared with other protocols from the following four aspects: computation cost, communication cost, storage requirements, and security. Finally, we conclude that our scheme is more efficient than others.

1. Introduction

With the applications of Internet in E-Commerce, IP multicast [1], [2] technology have being used more and more widely, such as VOD, network multimedia broadcasting, the multimedia distance education, etc. While Internet is opened, anyone joining in the group can access to these services. Therefore, the applications above need very high security and service assurance. But as there are many security issues in multicast technology, the secure multicast key management becomes the hot issue of the current study [3], [4]. The major task of multicast key management system is generating, distributing and updating of the group key (GK) for the group members. Group key is known to all the group members, and is used to encrypt, decrypt, authenticate the messages, etc, which ensures the confidentiality, authentication, and integrity. When the member leaves or joins in the group, the group key will be changed accordingly in order to get the forward/backward security [5], [6], [7]. Therefore, key management is very important for a secure multicast.