Journal of Communications
Multi-Factor Authentication (MFA) has been widely used in various scenarios. By combining multiple forms of authentication, MFA effectively provides security assurance. Due to the rapid developments of mobile devices, especially Smartphones, more and more sensitive information is now stored or accessible on Smartphones. How to protect Smartphones' security is now more important than ever. Unfortunately, because of the special features of Smartphones such as computational limitations and input constraints, existing MFA schemes could not be directly used on Smartphones.