Survey on Security Requirements and Models for Group Key Exchange

In this paper we provide an analytical survey on security issues that are relevant for group key exchange protocols. We start with the description of the security requirements that have been informally described in the literature and widely used to analyze security of earlier group key exchange protocols. Most of these definitions were originally stated for two-party protocols and then adapted to a group setting. These informal definitions are foundational for the later appeared formal security models for group key exchange protocols whose development, strengths, and weaknesses are also described and analyzed.