Cryptanalysis of User Authentication Scheme Preserving Anonymity for Ubiquitous Devices

As the mobile network such as using cell phone, tablet PC, notebook services are gradually increased, a smart card comes to one of the useful thing, because of its convenience and portable. Contemporary, smart card-based authentication also can be one of the most generally authentication method. In 2015, Djellali et al. proposed user authentication scheme with preserving user anonymity and mutual authentication. Also, it provides light and profitable mechanism which can be easily applied to limited power or resources. They claimed their scheme is resisted many networks threat. Unfortunately, we discover some vulnerable weakness. In this paper, we demonstrate that their scheme is still unstable to some network threats, such as insider attack, offline-password guessing attack, impersonation attack and replay attack.