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0 pointsnapoleongl2y ago0 comments

These days the locks are online so that you can block a lost keycard from the front desk. Previously you had to open the lock with a never keycard than the lost one to make the lost one inoperable. That works kinda fine in a small hotel but not when you 48000 rooms with millionaires in them.

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foota2y ago

Fwiw you could probably build this in a way that it continues to operate without internet. This creates a new attack vector (disable the internet and you can't revoke access) but that's probably acceptable given the physical attacks possible.

amenghra2y ago

Each key gets a revision number. When the first set of keys are created, they get revision number 0. The lock records a high water mark of the revision numbers it has seen. Only keys matching the water mark get to unlock the door.

When you want to revoke a key, you re-issue a new set with a higher revision number. When the guest checks out, you issue the next revision number to the next guest, effectively disabling the previous set.

You do all this as a fallback when the network fails. This way, you can still disable keys in real-time when people checkout of their room.

nijave2y ago

Does this use something like asymmetric keys so door can verify a key came from the issuing system or is there still some online/network portion?

Assuming it does use asymmetric keys to prevent someone from creating counterfeit access cards, there would still be a window (if the network is unavailable) where the old key would continue to work until a new key is scanned the first time on the door lock?

themerone2y ago

I think this is similar to how most hotel locks work.

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darkclouds2y ago

Same tech they use for staff in mental health hospitals and wards, but strangely noone hacks the mental health hospitals.

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