Scheme

Phase

Registration

Login and verification

Total cost

Proposed scheme

4T_h

8T_h

12T_h

Khan et al. (2011)

2T_h

10T_h

12T_h

Wang et al. (2009)

2T_h

6T_h

8T_h

Das et al. (2004)

2T_h

7T_h

9T_h