A novel multi-server based authentication scheme

Recently, Pippal et al. proposed a multi-server based authentication protocol to pursue the system security and computation efficiency. Nevertheless, based on our analysis, the proposed scheme is insecure against user impersonation attack and server counterfeit attack. In this study, we first demonstrate how these malicious attacks can be invoked by an adversary. Then, a security enhanced authentication protocol is developed to eliminate all identified weaknesses with the same order of computation complexity as Pippal et al.´s protocol does.