Malicious Participants in Group Key Exchange: Key Control and Contributiveness in the Shadow of Trust (Extended Abstract)
Emmanuel Bresson, Mark Manulis · 2007
Group key exchange protocols allow their participants to compute a secret key which can be used to ensure security and privacy for various multi- party applications. The resulting group key should be computed through coop- eration of all protocol participants such that none of them is trusted to have any advantage concerning the protocol's output. This trust relationship states the main difference between group key exchange and group key transport protocols. Obvi- ously, misbehaving participants in group key exchange protocols may try to influ- ence the resulting group key, thereby disrupting this trust relationship, and also causing further security threats. This paper analyzes the currently known secu- rity models for group key exchange protocols with respect to this kind of attacks by malicious participants and proposes an extended model to remove the identi- fied limitations. Additionally, it proposes an efficient and provably secure generic solution, a compiler, to guarantee these additional security goals for group keys exchanged in the presence of malicious participants.