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Apparently I don't understand how hotel card keys work. I always assumed that keys were manufactured with a random UUID inside them, and then when you checked i
by LeoPanthera 3y ago
Apparently I don't understand how hotel card keys work. I always assumed that keys were manufactured with a random UUID inside them, and then when you checked in, a random card was attached to your room and given to you.
When you try to open a door, it compares your card's ID to the room database to see if the door should open.
Is that... not how it works? Because that seems simpler than anything that involves encryption, or actually writing shit to the card.
- Kinrany 3y agoI wonder if it's possible to answer pubkey challenges without electricity
- crotchfire 3y agoHigh-end JavaCards can do this. A few have RFID/NFC interfaces, but they are expensive. https://www.cardlogix.com/product-tag/ecdsa/ https://www.cardlogix.com/product-tag/ecdsa/
- jcrawfordor 3y agoThe locks don't have network connectivity, so they have no way to check. Access has to be managed by key expiry and replacement. There are network-connected systems but they can be considerably more expensive to install.
- palata 3y agoIt would mean that the door's reader is connected to the network. Is it?
- WrongAssumption 3y agoHaving doors not work because the network is unavailable or the database is corrupted sounds neither simpler nor better.
- LeoPanthera 3y agoWell, valid key IDs could be pushed to the locks, and remembered for a short time.
- ahazred8ta 3y agoThe card machine at the front desk writes a message onto the card, which says: Hey, lock #301, this card is authorised to open you as of timestamp X, and all cards before timestamp X are now invalid. Most older e-locks are powered by a 9V battery and are not wired to a central server.
- denysvitali 3y agoUUID can be cloned (with modified cards). This could make a clone attack even easier since you don't need Key A/B to read the contents.
- LeoPanthera 3y agoI just imagined that cloning would not be a big deal considering the short life of a typical hotel stay.
- denysvitali 3y agoYou still need to tell the door somehow that the UUID you have now is valid for X days. Encrypting this information on the card itself is essier