Researchers at Cambridge University demonstrated how a program called PIN Skimmer could be used to determine your phone’s password. The software watches your face with your phone’s camera and listens to clicks as you type through the phone’s microphone. How accurate were they? Researchers got a 4-digit PIN correct 50% of the time after 5 attempts and 60% of the time with an 8-digit PIN after 10 attempts. They suggest that longer PINs and randomizing keys might help.