摘要：Cloud computing is a recently developed technology for complex systems with services sharing among various registered users. Therefore, proper mutual authentication is needed between users and cloud server prior to avail the services provided by cloud servers. Recently, Hao et al. [26] proposed time-bound ticket- based mutual authentication scheme for cloud computing. However, this paper shows that their scheme is vulnerable to Denial-of-Service attack and insecure password change phase. Besides, enhanced scheme is proposed to overcome these security pitfalls. Moreover, performance comparison of both
