This is one reason I've always wanted to have two separate authentication credentials for one user. Unfortunately, I've yet to find an acceptable or easy way to implement that on any device that would need it (your phone, your laptop, any device which you want to keep stuff private). For example: have one authentication method that unlocks the device to the typical desktop environment, command line, or whatever -- just a typical GUI that people would expect to see upon logging in. And then have another (hidden) authentication method to unlock the device into the REAL meat & potatoes. Useful for situations like this when law enforcement demands it, or when TSA/Customs in a foreign country demand you open and boot your laptop at a foreign airport. Is there any way to implement this on Android, iOS, GNU/Linux, or Windows?