Matthew Lakier
PhD Student @ UWaterloo

3D Pattern Lock

The 3D Pattern authentication technique enables people to unlock their smartphones by hovering their finger above the screen. It is more resistant to “smudge attacks” (fingerprint residues left on the screen), and shows promise for being more resistant to “shoulder-surfing attacks” (someone else looks at your screen and sees your PIN or pattern). Our authentication technique is enabled by “pre-touch”, a feature that may become available in commercial smartphones. Pre-touch enables your phone to sense your finger's position before it even touches the screen. We prototyped our authentication technique by simulating pre-touch using a motion capture system. This involved putting retro-reflective markers on the phone and on the user's thumb.

Our 3D Pattern technique started as a final project for a graduate course on privacy-enhancing technologies. As a team of three, we generated ideas for pre-touch-based authentication techniques together, ultimately focusing on a simple extension of Android’s pattern lock. I implemented the 3D pattern technique and the instrumentation required to use the motion capture system. The other members of my team assisted with implementing conventional PIN and pattern locks. We conducted a user study to evaluate the performance and shoulder-surfing-resistance of our technique compared to the conventional authentication techniques.

Technical Report