Arizona State University
The widespread usage of Smartphone's gives rise to new security and privacy concerns. Smartphone's are becoming a personal entrance to networks, and may store private information. Due to its small size, a Smartphone could be easily taken away and used by an attacker. Using a victim's Smartphone, the attacker can launch an impersonation attack, which threatens the security of current networks, especially online social networks. Therefore, it is necessary to design a mechanism for Smartphone's to re-authenticate the current user's identity and alert the owner when necessary.