Hierarchical Access Control For Stateless Multicast Key Distribution Protocols

Multicast communication is a kind of packet transmission mechanism which a single packet can be sent to multiple users. Most of the group key distribution protocol applies only to unicast communication, the stateful multicast key distribution protocol has been put forward to apply to group communication and implement the hierarchical access control of multicast communication. Compared to the independent key tree, the scheme of constructing hierarchical access control directed graph can reduce the storage and communication overhead. The group key distribution protocols can be divided into two categories:the stateful and the stateless. For the former one, users must keep online and update their internal state (i.e., private key) as long as they still stay in this group. If one user is not online, or group key fails to update message transmission, the user will not be able to decrypt the subsequent updated group key messages. While for the later one, users are not allowed users to maintain any internal states. The user’s private key is set at the time of initializing the group, after that it will not be changed. As long as the users receive the current updated group key update messages, they can extract the group key from the updated group key messages with their private keys.The construction of the date group needs to solve the issue of merging sub-trees, but the above schemes did not solve this issue. Pattern matching algorithm is proposed in this paper to solve the issue of merging sub-trees. Two schemes are put forward in this paper to solve hierarchical access control problem in stateless group key distribution protocols. In first scheme, numbers of receivers switch among service groups, which will bring about that large amount of keys should be updated. Therefore, communication overhead will constantly increase with receivers switching frequently. At that time, the scheme of key distribution based on independent key tree is presented in this scenario. However, the second scheme is applicable to the application scenarios that a few users switch among service groups. It is also based on the hierarchical access control directed graph proposed in the above stateful key distribution protocol.