Impersonation Attack on Two Identity-Based Authenticated Key Exchange Protocols

In 2009, Holbl et al. proposed two new identity-based authenticated key exchange protocols and claimed that their protocols can withstand various attacks. In this paper, we will show that Holbl et al.´s protocols cannot resist basic impersonation attack. It also means that their protocols are vulnerable to key compromise impersonation (KCI) attacks. Furthermore, we propose improvements of their protocols with impersonation attack resilience and KCI resilience.