Typing text passwords using touchscreens can be challenging on mobile devices. We designed a new graphical password scheme called Touchscreen Multi-layered Drawing (TMD) for use with touchscreens.;TMD is a user-drawn graphical password scheme addressing these issues. With the use of warp cells, TMD allows users to continuously draw their passwords across multiple layers in order to create more complex passwords than normally possible on a small screen.;We compared the usability of TMD to Draw A Secret (DAS) on a tablet computer and a smart phone. Results showed that TMD passwords are more memorable and eliminated the fuzzy boundaries problem. Also, participants preferred using TMD than DAS to replace text passwords on mobile devices.;We conducted a preliminary study of existing graphical passwords on smart phones and tablets. Based on our findings, we designed a scheme that avoids the fuzzy boundaries problem without memorizing images.
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