Mobile PINs are a lot like passwords in that there are a number of very common ones, and [Mobile PINs]
 
 
 
has a clever proof of concept that uses a tiny microcontroller development board to emulate a keyboard to test the 20 most common unlock PINs on an Android device.
 
 
The project is based on research analyzing the security of 4- and 6-digit smartphone PINs which found some striking similarities between user-chosen unlock codes. While the research is a few years old, user behavior in terms of PIN choice has probably not changed much.
 
 
The hardware is not much more than a Digispark board, a small -based board with built-in USB connector, and an adapter.