Biblio

User authentication in wireless sensor networks is more complex than normal networks due to sensor network characteristics such as unmanned operation, limited resources, and unreliable communication. For this reason, various authentication protocols have been presented to provide secure and efficient communication. In 2017, Wu et al. presented a provable and privacy-preserving user authentication protocol for wireless sensor networks. Unfortunately, we found that Wu et al.'s protocol was still vulnerable against user impersonation attack, and had a problem in the password change phase. We show how an attacker can impersonate an other user and why the password change phase is ineffective.

Remote user authentication using smart cards is a method of verifying the legitimacy of remote users accessing the server through insecure channel, by using smart cards to increase the efficiency of the system. During last couple of years many protocols to authenticate remote users using smart cards have been proposed. But unfortunately, most of them are proved to be unsecure against various attacks. Recently this year, Yung-Cheng Lee improved Shin et al.'s protocol and claimed that their protocol is more secure. In this article, we have shown that Yung-Cheng-Lee's protocol too has defects. It does not provide user anonymity; it is vulnerable to Denial-of-Service attack, Session key reveal, user impersonation attack, Server impersonation attack and insider attacks. Further it is not efficient in password change phase since it requires communication with server and uses verification table.