Security-Focused Survey on Group Key Exchange Protocols

In this paper we overview a large number of currently known group key exchange protocols while focusing on the protocols designed for more than three participants (for an overview of twoand three-party key exchange protocols we refer to [BM03, DB05c]). For each mentioned protocol we briefly describe the current state of security based on the original analysis as well as later results appeared in the literature. We distinguish between (i) protocols with heuristic security arguments based on informally defined security requirements and (ii) protocols that have been proven secure in one of the existing security models for group key exchange. Note, this paper continues the work started in [Man06] which provides an analytical survey on security requirements and currently known models for group key exchange. We emphasize that the following survey focuses on the security aspects of the protocols and does not aim to provide any efficiency comparison. The reader interested in this kind of surveys we refer to [RH03, AKNRT04].