“…Table 1 is performance comparison of login and key agreement phase, as we know that login and key agreement is the main body of an authentication scheme, and registration phase only performs one time before authentication. Let , ℎ , , and be the time for performing a modular exponentiation, a one-way hash function, a symmetric encryption/decryption, and a scalar multiplication on elliptic curve, which need 0.522 seconds, 0.0005 seconds, 0.0087 seconds, and 0.063075 seconds [17][18][19], respectively. We ignore modular addition, exclusive OR operation, and string concatenation operation which are negligible compared to others.…”