Table 1.

A summary of security results for existing SUA-WSN (smart-card-based user authentication scheme for wireless sensor networks) schemes.

Scheme	Security Justification	Major Weaknesses
Das [12]	Heuristic arguments	No key-exchange functionality
He et al. (2010) [13]	Heuristic arguments	No key-exchange functionality
Khan and Alghathbar [14]	Heuristic arguments	No key-exchange functionality
Chen and Shih [15]	Computational complexity approach (only for entity authentication)	No key-exchange functionality
Yeh et al. [16]	Heuristic arguments	Failures of mutual authentication and forward secrecy [30]
Kumar et al. (2011) [2]	Computer security approach	Vulnerability to a node capture attack [24]
Kumar et al. (2012) [17]	Computer security approach	Failures of authenticated key exchange, user anonymity and two-factor security [3,23]
Yoo et al. [18]	Computer security approach	Vulnerability to a man-in-the-middle attack [22]
Vaidya et al. [19]	Computer security approach	Failure of user authentication [25]
Xue et al. [20]	Heuristic arguments	Vulnerability to a privileged insider attack [26]
Shi and Gong [21]	Heuristic arguments	Failures of authenticated key exchange and two-factor security [27]
Kumar et al. (2013) [22]	Heuristic arguments
He et al. (2013) [23]	Computer security approach
Chi et al. [24]	Heuristic arguments
Kim et al. [25]	Heuristic arguments
Khan and Kumari [3]	Heuristic arguments
Jiang et al. [26]	Heuristic arguments
Choi et al. [27]	Computer security approach	No provision of user anonymity