Multi-factor user authentication and key agreement scheme for wireless sensor networks using Chinese remainder theorem

To formulate a secure and efficient user authentication scheme for wireless sensor networks(WSNs) is a complicated task, because sensors are placed in unattended locations and have limited computation, storage and communication capabilities. Till date, several user authentication and key agreement schemes for WSNs have been introduced by various researchers. Not long ago, Vorugunti et al. suggested a multi-factor user authentication scheme for WSNs and asserted that their scheme withstands against all known attacks. Although, we find out that their scheme notwithstanding against session specific information leakage attack and session key exposer by gateway node. Moreover, it lacks of user anonymity, forward secrecy and multi-factor security. To eliminate these shortcomings, we suggest an improved user authentication scheme and its security is verified by formal analysis using Burrows-Abadi-Needham(BAN) logic and informal analysis. In comparison with six recently proposed schemes, the proposed scheme attains a fine balance among efficiency and security, and it is more appropriate for practical environments.