Graphical passwords based on robust discretization

This paper generalizes Blonder's graphical passwords to arbitrary images and solves a robustness problem that this generalization entails. The password consists of user-chosen click points in a displayed image. In order to store passwords in cryptographically hashed form, we need to prevent small uncertainties in the click points from having any effect on the password. We achieve this by introducing a robust discretization, based on multigrid discretization.