Table 4. Computation cost comparison of the proposed user authentication scheme with others.
| Attributes | Wen [3] | Zhu [34] | Wu et al. [57] | Cheng et al. [58] | Lee [59] | Proposed |
|---|---|---|---|---|---|---|
| A 1 | 2t h + t m | 2t h + t m | 2t h + t m | t h | 2t h | 2t h |
| A 2 | 9t h + t q | 5t h + t q | 6t h + t m + 2t q | 12t h + t m + t q | 8t h + t m + 2t q | 5t h + t m + t q |
| A 3 | 4t h | 4t h + t m | NA | NA | NA | 4t h |
| A 4 | NA | NA | NA | NA | NA | 3t h |
| A 5 | 2 | 3 | 2 | 2 | 2 | 2 |
A 1: Computation cost in registration phase, A 2: Computation cost in login phase and authentication phase, A 3: Computation cost in password change phase, A 4: Computation cost in smartcard revocation phase, A 5: Number of message communications, NA: Not applicable (this pase is not proposed by the author (s)).