SAS-GKE: A Secure Authenticated Scalable Group Key Exchange

Abstract

Secure group communication is one of the challenging issues of present times. With the advancements of the cloud technologies and the internet services, people are getting more dependent on multi-party services, such as online meetings and classes, video and audio group calling and messaging, online conferences and webinars, and online gaming. To secure these multi-party communications, one of the most important components is the group key exchange (GKE). The existing GKE approaches are computationally expensive and do not offer scalability. These approaches only support small static groups to share a common secret key and do not properly address the situation of adding or removing group member(s). This is not acceptable for the multi-party communications with a large number of participants, especially when any participant(s) can join or leave the communications at any time. In this paper, we propose a secure, authenticated, and scalable group key exchange (SAS-GKE) that implements a constant-round contributory approach to generate the common secret key between any number of participants. SAS-GKE arranges all the participants in a three-tiered (depth = 2) m-ary tree structure that distributes the computational load between the participants in a balanced way. The proposed GKE utilizes public key authentication that prevents man-in-the-middle (MITM) attacks at every step of the group key exchange.