Table 3.

Functionality comparison

	Ours	Arshad et al. [27]	Tan et al. [26]	Awasthi et al. [24]	Wen et al. [13]
User anonymity	Yes	Yes	Yes	No	Yes
Mutual authentication	Yes	Yes	Yes	Yes	Yes
The session key perfect forward secrecy	Yes	Yes	-	-	Yes
Insider attack	Yes	Yes	Yes	Yes	Yes
Impersonation attack	Yes	No	Yes	-	-
Off-line password guessing attack	Yes	No	Yes	Yes	Yes
Replay attack	Yes	Yes	No	Yes	Yes
Modification attack	Yes	Yes	Yes	-	-