A resource-constrained group key agreement protocol for imbalanced wireless networks

Secure group communication is an important research issue for network security because of the popularity of group-oriented applications such as electronic conferences and collaborative works. The secure group key agreement protocol design is crucial for achieving secure group communications. As we all know, most security technologies are currently deployed in wired networks and are not fully applicable to wireless networks involving mobile devices with limited computing capability. In 2005, Nam et al. proposed a group key agreement protocol for a wireless environment. Unfortunately, in this paper we present that their protocol has a security weakness in which participants cannot confirm that their contributions were actually involved in the group key establishment. This is an important property of group key agreement. Therefore, we propose a new group key agreement protocol for an imbalanced wireless network consisting of many mobile nodes with limited computing capability and a powerful node with less restriction. We show that the proposed protocol produces contributory group key agreement. We demonstrate that the proposed protocol is provably secure against passive attacks under the decisional Diffie–Hellman problem assumption. A simulation result on a personal digital assistant (PDA) shows that the proposed protocol is well suited for mobile devices with limited computing capability.