Attack on a Constant-round Authenticated Group Key Exchange Scheme
Li Xin, Jiang Xiao-ning, YE Cheng-qing · 2006
A constant-round authenticated group key exchange for dynamic groups scheme has been proposed by Kim et al. [1]. In this paper, an impersonation attack on this scheme is proposed. It shows that any two malicious users can impersonate an honest user to agree some session keys in a new group if these two malicious users have the previous authentication transcripts of this honest user. So, this constant-round authenticated group key exchange scheme can not provide the authenticity as claimed. A proposal to repair this scheme's flaw is proposed in the end.