Hacking Phone Pins with Sensor Data

Disturbing Situation ... You have to think about what data is being gathered by sensors, and if that new data can be used to predict other data ... and beyond.  A whole stream of inference to check.  Note the prediction does not necessarily have to be precise, just approximate. 

Hackers can guess your phone's PIN using 'harmless' sensor information
Six key sensors have no permission requirements, leaving their stored data open to any app that wants it .... "