Doors – Can someone unlock a locked door and lock it back again without the key

Here is a device that allows you to unlock the door via Bluetooth.

Here is a home-brew device built by an electronics enthusiast.

A while ago I heard about this and i really wanted to do it with my house as well.

In terms of security, it is secure as long as you have your phone with you and nobody can hack the signal. You pair with the Bluetooth lock once using a strong password, then on each sync it checks the phones MAC address and Password. This makes it difficult to spoof the key (but a strong password is still important).

Some more references

http://www.labnol.org/gadgets/unlock-car-door-with-mobile-phone/4892/

http://www.ohgizmo.com/2009/05/21/use-bluetooth-signals-to-open-your-garage-door/

The key sounds like a lost cause. The lock will probably need to be changed.

The mail carrier has access to the box, usually through a large panel at the top (above the doors you open). It is likely that access to the lock is possible when that large panel is open.

You probably need to coordinate with her or him and the superintendent of your building to remove and replace the lock.