An efficient dynamic group key agreement protocol for imbalanced wireless networks

Owing to the popularity of wireless networks, the group key agreement (GKA) design is critical for providing secure group communications over an insecure wireless channel. In 2005, Nam et al. proposed a GKA protocol for imbalanced wireless networks in which an imbalanced wireless network consists of many mobile nodes with limited computing capability and a powerful node with less restriction. In 2007, Tseng showed that Nam et al.'s protocol is not a contributory GKA, while he also proposed a new GKA protocol. However, neither GKA protocol is concerned with dynamic member joining/leaving. This is an important functionality of GKA, especially for a wireless network environment. In this paper, we propose a dynamic group key agreement protocol for imbalanced wireless networks, and show that it requires less computation cost for dynamic member joining/leaving as compared to the previously proposed protocols. We also show that the proposed protocol is provably secure against passive attacks under the decision Diffie-Hellman problem and the hash function assumptions. Furthermore, by the pre-shared two-party key between a mobile node and the powerful node in the existing imbalanced wireless networks, we propose a generalized GKA protocol that requires only several hash functions. Copyright (C) 2010 John Wiley & Sons, Ltd.