The recent growth of the World Wide Web has sparked new research into using the Internet for novel types of group communication, like multiparty videoconferencing and real-time streaming. Multicast has the potential to be very useful, but it suffers from many problems like security. To achieve secure multicast communications, key management is one of the most critical problems. So far, a lot of multicast key management schemes have been proposed and most of them are centralized, which have the problem of “one point failure” and that the group controller is the bottleneck of the group. In order to solve these two problems, we propose a Decentralized Key Management Scheme (DKMS), using RSA key system as auxiliary keys. We analyze this scheme and find it has appropriate performance in security and scalability.