Research On Multicast Group Key Management In Wireless Network

Multicast is a communication mechanism with progressive, efficient, group-oriented applications over the network, which provides one-to-many and many-to-many transmission mode. With the emergence of rich multicast services, such as mobile TV services, video on demand, interactive group communication and video conferencing, etc., multicast has a broad application prospect for its little demand of sender resources, network bandwidth and storage overhead. However, due to the nature of open-access in wireless network, multicast services are vulnerable to various security attacks in the air, such as eavesdropping attack, denial of service attack and disguise attack. In order to ensure that multicast services can be safely transferred to the group members in the wireless network, the use of access control mechanisms and the transmission mechanism is necessary. A standard way of access control mechanism is to use a symmetric group key, only the authorized users would be able to share the symmetric group key. Therefore, how to achieve efficient group rekeying and allow users to enjoy multicast services safely is an important issue that we must pay attention to.The characteristics about the users in wireless network are cluster and mobility. The users in a certain area of wireless network form a cluster. A common mechanism to manage users is to use a binary tree which belongs to centralized group key management technology, most of the existing group key management schemes are designed through the logical key tree (LKH). The purpose of updating the group key is to satisfy the forward security and backward security when members join or leave the group, and how to reduce the rekeying overhead and improve the efficiency of rekeying also need to be considered.In this thesis, we make a deep research and analysis about group rekeying of mobile users in the wireless multicast environment. Based on the existing wireless mobile group key management schemes, we propose several safe and efficient multicast group key management schemes. In these schemes, mobile users can enjoy seamless multicast services when mobile users move across different regions, not only the security is guaranteed, the rekeying overhead has also been greatly optimized. Some major works in this thesis are shown in the following aspects:First of all, we describe the concept of multicast technology and classify the group key management schemes, each category is analysed about research status at home and abroad respectively.Next, based on the generalized Chinese remainder theorem, we study the master key encryption algorithm, and a novel area based multiple group key management (AMGKM) scheme is proposed according to the improved master key encryption algorithm. The AMGKM scheme continues to provide services whilst users subscribed to multiple services migrate among different wireless network area and has an efficient communication overhead. The scheme reduces the signal load at the core network and satisfies the forward security and the backward security, the membership changes are also supported. Compared with other schemes, the AMGKM has more efficient rekeying overhead.Then, according to the group rekeying methods, a novel area-based mobile multicast group key management scheme is proposed. A general way of rekeying is that the new group key is distributed to the corresponding users through LKH. But as the increase of the number of users, rekeying overhead will be also increased. Our scheme utilizes a secure coprocessor (SC), and almost all the group members can calculate the new group key according to the same key update message, which avoids the group key’s direct transmission in the air and has strong security, also the rekeying overhead and communication overhead are reduced observably. Our scheme improves the single point of failure, mitigates the signal load when users move across the network and supports the membership changes.Finally, we summarize the problems in the wireless multicast group key management scheme and give a concluding statement for the future research directions.