Affiliations: Department of Information Management, National Taichung
Institute of Technology, 129 Sec. 3, San-min Rd., Taichung, Taiwan 404,
R.O.C | Department of Management Information Systems, National
Chung Hsing University, 250 Kuo Kuang Road, Taichung, Taiwan 402, R.O.C.
E-mail: mshwang@nchu.edu.tw | Graduate Institute of Networking and Communication
Engineering, Chao Yang University of Technology, 168 Gifeng E. Rd., Wufeng,
Taichung County, Taiwan 413, R.O.C.
Abstract: Password authentication, which is widely used for authenticated
method, also is important protocol by requiring a username and password before
being allowed access to resources. In 2001, Lin et al. proposed the optimal
strong-password authentication protocol, called (OSPA) which is a one-time
password method by verifying with the different verifier every time for
affirming its identity. However, Chen-Ku and Tsuji-Shimizu pointed respectively
out that OSPA is vulnerable to the stolen-verifier attack and impersonation
attack. In this paper, we shall propose the improved protocol secure against
the known attacks to enhance the security
