in hotels, if you lose your room key card, how are they able to reprogram the new one so it works and the old one doesn’t?

Question

Is there some system that transmits information to your door card reader on what the new key is, or is it something different entirely?

In: 1028

Answer 1

Imagine there’s a central computer somewhere in the hotel, connected to all the door locks in the building. Every time a card is swiped on a door, the door sends a request to this computer, basically saying something like, “hello computer, this is door #742. Someone just swiped a key card in me that has a code of b947a9fe9c923c874011958390a9859f. Should I unlock the door?” The computer checks to see if that’s a valid combination, and then tells the door what to do.

When you lose the key card to your room and ask for a new one, the person at the front desk tells the central computer that they’d like to associate a new key card (with a new code) to door #742. The central computer updates its database with the new code for door #742. Now, if someone finds the key card you lost and tries to swipe it on door #742, it won’t work because the central computer will only allow your new key card to open the door.