Table 6. Functionality analysis of authentication schemes.

	Password Changing	Mutual Authentication	Without time synchronization	User Anonymity
Khan et al. [7]	Yes	Yes	No	No
Lin and Lai [8]	Yes	No	No	No
Li and Hwang [11]	Yes	Yes	Yes	No
Ko [44]	Yes	Yes	No	No
Vaidya et al. [45]	Yes	Yes	No	Yes
Xue et al. [46]	Yes	Yes	No	Yes
Tseng et al. [47]	Yes	Yes	No	Yes
Wang et al. [48]	No	Yes	No	No
Shin et al. [49]	Yes	Yes	Yes	Yes
Our scheme	Yes	Yes	Yes	Yes