How do magnetic strips on hotel doors work so that, if you fail to return one, you can’t break into the same hotel room, occupied by somebody else, the following night?
All the electronic door locks are centrally controlled, and the needed magnetic card to get into them changes when a person leaves. This is why they have such high rates of adoption by hotels that can afford it - no need to worry if someone copies the key.
The mag stripe keycards likely just have a code on them that the door lock reader reads. If it matches what’s in the central system for that room, it opens. If not, it shows the red blinking light.
So if you keep your card, they almost certainly just clear the code for the room, and assign a randomly generated new one when a new guest shows up. I imagine that the maintenance and cleaning cards are programmed to open every room, and they probably also keep closer tabs on those, and likely reset the codes on those periodically (daily I’d guess) as well.
Those card strips contain like 200 bytes, which is way more than enough to encode a ridiculously huge number. For example, a 64 bit number can record from 0 to 18,446,744,073,709,551,616. Which is WAY more than enough to give every visitor a unique numeric code probably for millions of years.
Expanding on this a bit - I’ve been working in hotel reception for quite some time, for my bona fides.
First off, when a key is made (whether magstripe or the newer RFID type), they’re made for a certain number of nights, depending on how long the guest is staying. They will automatically stop working at some time of the day (shortly after regular checkout time) on the day the guest is due to check out.
For example, if patron X is staying for one night on (say) Monday night, their key will be good until noon on Tuesday. At 12:01 pm, that key will stop working, along with any others made for that guest.
Secondly, at check out, the clerk will ‘check out’ the card the guest has, no matter what time it is. Someone checks out at (say) 9:00 am, I will lay the key on the machine, click ‘check out room’, and that key, along with any others made for that guest, stop working.*
So, if you extend your stay a day after checkin, or get a late checkout, make sure the reception clerk has updated your keycard to reflect that!
*To be clearer, that not only wipes the keycard, it also lets the central key system know that that key is not allowed to open the door anymore.
Our keys are programmed for a certain number of nights. After that they don’t work. We have an older system than @galen_ubal and we don’t have a way to tell the key system “they’re checked out” by putting the key on something.
If we have to evict someone/lock them out for non-payment we check out the old key in the computer program then make new keys and have security insert the new keys. Boom! Locked out. This is also how we make new keys when someone loses their old ones and requests new keys and not duplicates.
Master keys - security, maintenance and housekeeping - are usually good for 30 days. There is also somewhere a master master key kept locked up until it’s needed. We’ve never had to, but it’s there just in case.
Others have covered it, but just to boil it down: the key is nothing more than a note with a secret number on it.
It’s the central computer that keeps track of what doors, at what time, will open for that number.
I attended a sales presentation at an upscale hotel in Orlando. (I was a band director and they wanted me to have my band stay at their property.) The salesman told us that the locks on the rooms were completely programmable by security. We could issue the kids keys for their rooms and have the keys only work at certain times of the day. For example, you could designate 1:00-4:00pm as pool time and have the keys lock the kids out of rooms during that time (for prevention of returning home with “more” band kids than you left with). The locks could even be programmed not to open the doors from the inside, if that were desired. I was horrified at that thought. My band students are not my prisoners. (We were assured that the doors would open in the event of a fire alarm.) I didn’t much care for the guy who thought that locking the doors from the inside was a great idea.
I would take the comment about being able to lock the doors against egress with a grain of salt, as it would violate the State building code. Simply unlocking the door “when the fire alarm goes off” is not permitted. Furthermore, most building and code enforcement officials I know would throw a fit if they learned that it was even POSSIBLE for the system to lock the doors against the direction of egress. The door hardware would have to be changed to exit hardware that ALWAYS permits free egress.
Having also worked in hotel reception, I’m horrified at the idea that the Fire Control system had anything to do with warning the staff and guests about a fire. (As well as telling the magnetically held-open fire doors to swing shut across the hallway. Explaining to a guest why half of the hallway was occluded by a part of the wall on hinges, was great fun.)
LOF*$%ingL at letting that thing potentially lock guests in their rooms.
And I meant, “if the Fire Control system had anything to do besides warning guests about a fire.”
Spurrious fire alarms in a 300 room upscale hotel at 3AM: not good times.
I still knock wood in superstitious gratitude that I never had to deal with a serious medical or criminal situation during my tenure.
Just to add that at Disney hotels you are encouraged to keep your card as a souvenir when you checkout.
Honestly, I didn’t really believe the guy. I think it would be horribly unsafe. What if the fire affected communication with the locking system?
I suspect that the salesman was really meaning that the system could log every time the door was opened, from the inside or the outside. As someone who has traveled with large numbers of students, I would find that feature useful. Preventing the doors from even opening is not acceptable in any form. Even if I could be 100% assured that the doors would fail open in an emergency, I would not like the message that gives my students. If I can’t trust you, you don’t travel with me. I don’t need locks.
I too was horrified by the idea that the system might prevent people from leaving their rooms. And then I saw this:
Could it be that someone confused the words log and lock ???
I don’t think so. Another band director in the group was very interested in this and confirmed this feature. I would not allow my kid to be in his class. Thinking this was a legitimate feature to use with kids is disgusting.
No. You can interrogate the locks to see when/who opened the door. So if Joe Schmoe puts up a Do Not Disturb then goes out for the day and then comes back and claims his computer/whatever was stolen security can pull a record of when the door was opened and it will show which key and when. If it is a hotel worker’s key it will say “maintenance 6” or whatever. We’ve had to do it. It has saved housekeeping’s bacon a few times.
I worked in a hotel with the electronic locks back before the turn of the century. There was no central control for the locks. A new kew had the date of check out and stopped working on that date. When a newly programed key was used it elinimated the use of any customer key that was not programed at the same time. So if a customer requested an additional key he had to be give a complete set of keys.
The maintenance key that I had worked for a year. If a member of the crew left and did not turn in his key then a new maintenance key was issued and every lock had to be opened by the new key once to wipe out the old key.
Then there was the hotel managers key. It would open a lock even if the dead bolt was thrown on the inside. Need it one night because the lock was not working and it was not on property. I could not open the lock to let the cusstomer into his room. I tried everything I could and finally came up with tapping the lock as I pulled the key. The door opened. When I took the lock apart I found the wire from the dead bolt to the key pad had a break in it. My tapping made just enough contact to tell the key pad the dead bolt was not thrown. T forget what the customer was comped because he had to wait until I could get the door open and then repair the lock.
Yep.
We once had a 7 day stay at a nearby hotel (while our kitchen was being remodeled) and decided to extend it a few. The afternoon of the 7th day, the key didn’t work - they had forgotten to update it.
Re deadbolts. Someone here mentioned that supposedly the master key (electronic) would also unlock the deadbolt - which surprises me as those seem (to me) like they are purely mechanical. I guess there’s some circuitry inside the door that connects to that deadbolt?
But then there’s the other thing, which IS purely mechanical: the “chain” on the door - could be a swinging arm from the frame, that catches a ball attached to the door (allows the door to be opened a couple inches)
like this
or the L-shaped version
What do hotels do if a guest has one of these enabled, and hotel staff truly need to get in the room? e.g. guest is causing disruption, has long overstayed a reservation, or there’s a funny smell coming from the room?
Taking the door off the hinges or entering from the connecting room door? In the case of a funny smell and a mystery re: the wellbeing of the guest-ramming down the door.
Generally not possible to unhinge the door unless you are on the hinge side of the door (i.e. in the room), and many hotel rooms don’t connect with adjacent rooms at all.
If the door can be opened enough to physically access the security chain/link, bolt cutters should be able to get through that.
There are almost as many different doorlock arrangements as there are hotels. In some the deadbolt is an integral part of the overall electronic lock. In other’s it’s a fully separate conventional mechanical deadbolt.
In other’s it’s not really a deadbolt at all, merely a lever/handle on the inside that looks like and turns like a deadbolt handle would, but is really just an electrical switch which acts as in input to the door lock computer, locking out at least some of the master key level(s).
This last would keep out a housekeeper or building maintainer, but probably not Security and certainly not whatever level of manager has the really fancy computer key.
And if not, or for getting past those U-shaped entangling latch gizmos, a Sawzall is not quite the universal key, but it’s close. Once the door’s opened more than a crack just poke the blade through, squeeze the trigger & pretty quickly you’re in and with minimal damage to the room.