Android offers a number of ways to lock down your device. There is the classic pattern lock, PINs, passwords, and the gimmicky face unlock. These options (mostly) get the job done, but a passcode that never changes isn't very secure. Ideally, you want something that changes frequently, and that's what TimePIN gives you. This app updates your PIN code every minute of the day and doesn't need root access to do it.
When you install TimePIN, it will need to be authorised as an administrator application, which only takes a second. The reason for this is so it can modify your PIN each time the phone or tablet is unlocked. The default behaviour of TimePIN is to make your PIN code the same as the current time. So if the time is 4:39, your PIN is 0439. It's easy for you to figure out, but no one doing a little shoulder surfing will know that's how it works.
TimePIN takes things one step further, though. It has several modifiers that morph the PIN using the time as a base. The reverse modifier is included for free and would change 0439 into 9340. For an in-app purchase, the app includes modifiers for a custom offset, doubling, and mirror mode. You might have to do a little bit of maths to unlock your device, but that's the price of security, right?
Should you set a modifier that you forget the next time you try to enter it, there's an easy way to recover. TimePIN has you set a master PIN that will always be used the first time after a reboot. So you can reboot the phone, unlock, and change the modifier. This master PIN is also used to secure your TimePIN settings.
TimePIN is a very cool app, and it's great that the dev has made it completely functional and ad-free without making you buy something. Although, you should—TimePIN is great.
If you are still pining for some extra security, here's four other Android security settings you should use.