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?


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

Maybe some modern locks have some transmitter, but the majority of electronic locks used for years do not. The lock basically gets programmed with a handheld terminal, this terminal also gets programmed by the system that encodes the cards. Each lock needs a correct code and correct date to open that particular lock, the card is programmed with that code and operating time code, meaning the card will work when you have the room booked but after checkout the next day the card will no longer work.

For that reason if you decide to stay an extra night your card will need to be updated, it wont happen automatically.

Many modern electronic card locks use a rolling code system: the lock is preprogrammed with a set of guest key IDs it expects to see

If the lock sees any of the next code in sequence, it assumes that the previous guest have checked out or replaced their card, and will refuse to accept that previous card

where i work (not a hotel but has an access control system), credentials are assigned to readers, not the other way around. this makes it so any given badge can be given or denied access to any given door

Each lock has a room number, and a list of random numbers stored in the little computer in the lock. It keeps track of which number from the list is “active”.

The computer at reception has a list of numbers for each room’s lock, and also which one is “active”. They use the computer to store a room number and key number on the card.

When they create a new key at the front desk, they make it with the next number on the lock’s list. When you try to open the door with it, the lock gets the room and key number and thinks, “wait a second, let me check the list… that’s not the current key number… but it is the next one on the list, so I guess this is the next guest.” The lock makes the next number on the list “active” and that key will continue to work until a new key comes along with the next number on the list. If you try a key with the wrong number, or a key number that isn’t the “active” one or the next on on the list, the lock simply doesn’t open.

Some systems also include a date, so that a card will automatically stop working after a certain amount of time.

There’s variations on the theme, but they work similarly, so no radios or extra wiring is necessary. They also have special numbers for hotel staff “master keys” which are handled differently. Places with stricter security can get locks that have wired (usually) connections to computer systems that use more complicated ways determining who the card holder is and what they have permission to access.

They’re not reprogramming the room key.

Each room key has a unique identifier.

Each lock has a unique identifier.

Locks are powered and networked to a central computer.

When you’re assigned to a room, the desk clerk selects a random key, swipes it in a reader to get its identifier, and the computer records that that key’s identifier is allowed to open that door.

When lose your room key, the desk clerk selects a random key, swipes it in a reader to get its identifier, and the computer records that that key’s identifier is allowed to open that door, and that the old key’s identifier isn’t.