Security analysis and improvement of bio-hashing based three-factor authentication scheme for telecare medical information systems

The deployment of telecare medical information system (TMIS) over public networks gives rise to the threat of exposing sensitive medical information to illegal entities. Although a number of three-factor authentication (3FA) schemes have been developed to address this challenge, most of them are found to be flawed. Understanding security and privacy failures of authentication protocols is a prerequisite to both fixing existing protocols and designing future ones. In this paper, we investigate the 3FA protocol of Lu et al. for TMIS (J Med Syst 39:32, 2015) and reveal that it cannot achieve the claimed security and privacy goals. (1) It fails to provide anonymity and untraceability, and is susceptible to the following attacks targeting user privacy: identity revelation attack, identity guessing attack and tracking attack. (2) It is susceptible to offline password guessing attack, user impersonation attack, and server impersonation attack. Then we present an improved 3FA scheme and show that the new scheme fulfills session key secrecy and mutual authentication using the formal verification tool ProVerif. Moreover, detailed heuristic security analysis is also presented to demonstrate that our new scheme is capable of withstanding various attacks, and provides desired security features. Additionally, performance analysis shows that our proposed protocol is a practical solution for TMIS.