Table 3.

Comparisons of the functionality features. ECC, elliptic curve cryptosystem.

	Kim et al.’ Scheme [13]	Chang et al.’ Scheme [14]	Yoon and Yoo’s Scheme [15]	Choi et al.’ Scheme [18]	Proposed Scheme
Provides user anonymity	×	∘	×	×	∘
Provides user untraceability	×	Δ	×	×	∘
Provides forward secrecy	×	×	∘	∘	∘
Provides secure password update	∘	×	−	−	∘
Provides mutual authentication	∘	∘	∘	∘	∘
Resists off-line password guessing attack	×	×	−	−	∘
Resists user impersonation attack	×	Δ	∘	×	∘
Resists lost smart card attack	×	Δ	∘	∘	∘
Resists stolen verifier attack	×	Δ	−	−	∘
Resists man-in-the-middle attack	×	Δ	∘	∘	∘
Resists replay attack	∘	∘	∘	∘	∘
Resist biometric recognition error	−	−	×	∘	∘
Usage of biometrics	×	×	∘	∘	∘
Usage of ECC	×	×	∘	∘	∘