US technology manufacturer Apple has revealed that it's working on functionality that'd allow you to unlock doors using your mobile phone or a similar gadget. The hardware and software giant filed a patent (PDF link) for a device that uses near-field communication to identify people and grant them access.

The patent says: "The device can communicate with an external device to open a lock. By way of example, the electronic device may be a model of an iPhone. The external device may be any suitable electronic device such as a portable media player, personal data assistant or electronic lock that may be used to access a door, car, house or other physical area".

You'd have to register your phone or other device with the door, and then rotate an onscreen dial to enter a pin code. If the pin matches, the door would be unlocked. However, the patent also proposed encrypting the communications so that hackers wouldn't be able to "listen in" by placing monitoring devices nearby.

Apple recently sued rival smartphone manufacturer HTC for a claimed violation of twenty of its patents.