Twice as Nice? A Preliminary Evaluation of Double Android Unlock Patterns

Android unlock patterns are a widely used form of graphical passwords, and like all password schemes, numerous studies have shown that users select a relatively guessable and non-diverse set of passwords. While proposals have been put forth for hardening patterns, such as increasing the number of or changing the location of contact points, none of these proposals has been implemented in the decade-plus since the interface's launch. We propose a new approach; instead of increasing the individual complexity, users select two sequential Android patterns, so called Double Patterns, that are visually super imposed on one another. This allows more complexity without dramatically changing the interface. We report on our preliminary findings of a large user study (n=634) of Double Patterns, finding strong evidence that the scheme is highly usable and increases the complexity of user choice.