||Recently, the smartphone has become a widely used handheld device for entertainments and commercial activities in daily life. However, currently, the smartphone has no transparent and continuous authentication mechanisms to improve the security level especially on commercial applications. In this paper, a non-intrusive and continuous approach for authenticating the smartphone user is proposed. The proposed approach uses the orientation sensor, which is a built-in device of a smartphone, to perceive the way of a user for holding the smartphone for biometrics. To test the proposed approach, we have developed an application that emulates two general functions of a smartphone, namely, the address book and the gallery, to collect orientation-sensor-based biometrics. The experiment results show that the proposed approach has a successful verification rate about 30% and a false acceptance rate over 25%. Therefore, the orientation-sensor-based feature may be used as a part for user verification.|
|| N. L. Clarke and S. M. Furnell, “Authenticating mobile phone users using keystroke analysis”, Int. J. Inf. Secur., Vol. 6, pp. 1-14, 2007.|
 N. Clarke, S. Karatzouni, and S. Furnell, “Flexible and transparent user authentication for mobile devices”, D. Gritzalis and J. Lopez (Eds.): SEC 2009, IFIP AICT 297, pp. 1-12, 2009.
 M.N. DOJA and N. Kumar, “User authentication schemes for mobile and handheld devices”, INFOCOMP Journal of Computer Science, vol. 7, pp. 38-47, 2008.
 S. Furnell, “Beyond the PIN: Enhancing user authentication for mobile devices”, Computer Fraud & Security, pp. 12-17, Aug. 2008.
 Gartner Inc., “Gartner says mobile phone sales will exceed one billion in 2009”, Egham, U.K., 20 July 2005, available from: http://www.gartner.com/press_releases/asset_132473_11.html
 Gartner Inc., “Gartner Says Number of mobile payment users worldwide to Increase 70 percent in 2009”, STAMFORD, Conn., 28 May 2009, available from: http://www.gartner.com/it/page.jsp?id=995812
 Gartner Inc., “Gartner identifies the top 10 consumer mobile applications for 2012”, STAMFORD, Conn., 18 November 2009, available from: http://www.gartner.com/it/page.jsp?id=1230413
 Google, Android™ Platform, available from: http://www.android.com/; http://developer.android.com/index.html
 HTC, Wildfire, available from: http://www.htc.com/www/product/wildfire/overview.html
 International Data Corporation (IDC) Worldwide Quarterly Mobile Phone Tracker, “Smartphone Market Grows 79.7% Year Over Year in First Quarter of 2011, According to IDC”, Kathy Nagamine, 05 May 2011, available from: http://www.idc.com/getdoc.jsp?containerId=prUS22815911
 S. Lin, K. Ying, S. chen, Z. Lee, “Particle swarm optimization for parameter determination and feature selection of support vector machines”, Expert system with applications. vol.35, no.4, pp.1817-1824, 2008.
 R. Meier, Professional Android™ 2 Application Development. Wiley Publishing Inc., pp.467-468, ISBN:978-0-470-56552-0, March 2010.
 Taido Nakajima, Gloria Lin, Pareet Rahul, “Systems and methods for identifying unauthorized users of an electronic device”, US Patent & Trademark Office, Serial No. 389106, 2009. available from: http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220100207721%22.PGNR.&OS=DN/20100207721&RS=DN/20100207721
 K. Revett, H. Jahankhani, S. T. de Magalhaes, H. M.D. Santos, “A survey of user authentication based on mouse dynamics”, Communications in Computer and Information Science (Global E-Security), Vol. 12, pp. 210-219, 2008.