ICASME: An Improved Cloud-Based Authentication Scheme for Medical Environment.

Unlike the traditional medical system, telecare medicine information system (TMIS) ensures that patients can get health-care services via the Internet at home. Authenticated key agreement protocol is very important for protecting the security in TMIS. Recently scholars have proposed a lot of authenticated key agreement protocols. In 2016, Chiou et al. demonstrated that Chen et al.'s authentication scheme fails to provide user's anonymity and message authentication and then proposed an enhanced scheme (Chiou et al., J. Med. Syst. 40(4):1-15, 2006) to overcome these drawbacks. In this paper, we demonstrate that Chiou et al.'s scheme is defenseless against key compromise impersonation (KCI) attack and also fails to provide forward security. Moreover, we propose a novel authentication scheme namely ICASME to overcome the mentioned weaknesses in this paper. Security analyses show that ICASME achieves the forward security and KCI attack resistance. In addition, it is proved that the time taken to implement the ICASME is not intolerable compared to the original protocol.