A free app for Android, by Kenny Wheeler.

This Touch Lock Screen – courtesy of Kenny Wheeler – brings an innovative method for setting up – and unlocking – mobile passwords. This method gives you the opportunity to establish an advanced level of security for your phone, and all the contents within. The method is rather reminiscent of the “secret rooms behind bookshelves” concept from mystery novels – where a single book – when pressed or pulled – would open up the hidden door.

Here’s how it works in mobile form:

To set up your password with this ‘touch lock’ method, you need to select a photo you are willing to turn into your passcode. Next, set up the certain “points” within this photo that will serve as the keys – for example, you might set up touching specific positions on a person’s photo – specific positions such as the eyes, the nose, the mouth, and the hand; only you will know these secret places, and only you can unlock this puzzle.