A Secure Identity-based Authenticated Group Key Agreement Scheme

摘要

Authenticated group key agreement problem is important in many modern collaborative and distributed applications such as conference systems like IP telephony and video conferencing. Over pass ten years, many ID-based authenticated groups key agreement (AGKA) protocols have been proposed due to the simple key management complexity. In 2004, Choi et al proposed an efficient ID-based authenticated group key agreement (also called CHL protocol). Unfortunately, their protocols were found to be vulnerable to the replay attacks (ZC Attack) and insider colluding attacks. In this paper, we first review the CHL protocol and show the attacks against the protocols. Later, we proposed an improved version of CHL protocol. The extended protocol employs a count related to special session to resist to the replay attack. In our present protocols, each user's verified value is related to all other users so that the proposed protocols can resist to insider colluding attacks. In a word, our protocols are more secure than previous protocol without loss of computation.