Quantifying the security of graphical passwords
Sebastian Uellenbeck, Markus Dürmuth, Christopher Wolf, Thorsten Holz · 2013
Graphical passwords were proposed as an alternative to overcome the inherent limitations of text-based passwords, inspired by research that shows that the graphical memory of humans is particularly well developed. A graphical password scheme that has been widely adopted is the Android Unlock Pattern, a special case of the Pass-Go scheme with grid size restricted to 3x3 points and restricted stroke count.