Secure group communication protocol for distributed systems

Group communication among multiple entities is required in distributed applications like groupware systems. In addition to conventional wide-area networks, local area networks (LANs) and radio networks are available to realize the applications. The LANs and radio networks provide broadcast communication at the media access control (MAC) layer, that is, every communication entity, i.e. station can receive every protocol data unit (PDU) transmitted in the network. The group communication can be easily realized by these networks. One problem in the broadcast network is how to provide the secure communication for the group. In this paper, we discuss how to provide secure broadcast communication among multiple entities in the presence of attacks by malicious entities. The protocol is based on the distributed control scheme by using reliable but unsecure broadcast networks. In the protocol, each entity in a group of entities named as a cluster decides the same secret key by exchanging the nonce, e.g. random number encryphered by the public key.