A graphical-based password keystroke dynamic authentication system for touch screen handheld mobile devices

Since touch screen handheld mobile devices have become widely used, people are able to access various data and information anywhere and anytime. Most user authentication methods for these mobile devices use PIN-based (Personal Identification Number) authentication, since they do not employ a standard QWERTY keyboard for conveniently entering text-based passwords. However, PINs provide a small password space size, which is vulnerable to attacks. Many studies have employed the KDA (Keystroke Dynamic-based Authentication) system, which is based on keystroke time features to enhance the security of PIN-based authentication. Unfortunately, unlike the text-based password KDA systems in QWERTY keyboards, different keypad sizes or layouts of mobile devices affect the PIN-based KDA system utility. This paper proposes a new graphical-based password KDA system for touch screen handheld mobile devices. The graphical password enlarges the password space size and promotes the KDA utility in touch screen handheld mobile devices. In addition, this paper explores a pressure feature, which is easy to use in touch screen handheld mobile devices, and applies it in the proposed system. The experiment results show: (1) EER is 12.2% in the graphical-based password KDA proposed system. Compared with related schemes in mobile devices, this effectively promotes KDA system utility; (2) EER is reduced to 6.9% when the pressure feature is used in the proposed system. The accuracy of authenticating keystroke time and pressure features is not affected by inconsistent keypads since the graphical passwords are entered via an identical size (SO min X 60 mm) human-computer interface for satisfying the lowest touch screen size and a GUI of this size is displayed on all mobile devices. (C) 2011 Elsevier Inc. All rights reserved.