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Hi there! It's my first time posting on the board, so please correct me if I mess up.

I attend a small college in the U.S., and live on campus, and I was intrigued by the college's lock system. I wanna start off by noting that I must not mess, and am not interested in messing with, the locks or keys. The lock on "my" door is not really mine, and I could get in serious trouble with the state criminal system and the college's judicial process.

Okay, so there are a few dorm buildings on campus, and each building has around 6-10 suites, and each suite has 4 bedrooms. Each student can open the door for their building with their key, but they can't get into other dorms. Each student who lives in the dorm can open the door for their suite, but not for other suites. Each student in the suite can open their room, but not the other rooms in the suite. This is all done with each student having only one key.
I suspect the way this is done is that the first few pins are the same for everyone in the dorm, and the next few pins are the same for everyone in the suite, and the remaining pins are unique to the room. The dorm lock would only have pin stacks in a few chambers, the suite lock would have them in a few more, and the rooms would have complete pin stacks. It sound like this would be pretty common, at least for college dorms, but when I try to search for more information, I can't seem to find a name for the system. Is there a name? Is this common practice? How secure is this practice?


In case it matters, it appears the locks are all SFIC locks from MBS, with a couple from Best or Arrow. They are also mastered; a few people have keys that can open up every lock in a given dorm, and I suspect that there might also be a "higher" master that opens every lock in every building on campus.

It's a masterkey system. Sounds like a complex one.

They are very common, especially in office buildings, campuses, etc.

Masterkeying reduces the security of a pin tumbler lock.
The larger and more complex the masterkey system, the less secure it is.

I imagine others will chime in with more technical info about them.

I notice you live in MA.
There is a large, active, hobbyist lockpicking culture up in that area if you want to meet up with people who have similar interests.

I thought master keying was only the reverse? Where one key opens many locks, vs. many keys opening one lock

Masterkeying can do both.

Although if you want to get technical, when one lock is keyed to open with MANY keys, such as a laundry room for a building and have all 100 apartment keys able to open that one door, that one door is often referred to as being "Maison" keyed. You can do Maison keying on one lock without masterkeying the entire facility, although to do so on a non-masterkeyed building it usually means adding a lot more master wafer pins into the lock, significantly increasing the odds that any random key that can fit in that lock, will also open that lock.

With masterkeying the odds are increased as well, but not as much as with Maison keying when you are pinning a lock to work with many, unrelated random keys who have nothing in common other than they will fit into the same keyway.

Ah, thanks! That's exactly what I was looking for.