Post B4h3HS7CKt4xNtZxei by mattblaze@federate.social
 (DIR) More posts by mattblaze@federate.social
 (DIR) Post #B4g3H2qY5bZzrDdZVw by ariadne@social.treehouse.systems
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       @th @mattblaze yeah i encountered that recently in germany and was just like ????????????? why
       
 (DIR) Post #B4g4nnjFPxYsTsPCHw by rhelune@todon.eu
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       @ariadne @th @mattblaze What if you wanted to have a drink at the rooftop bar before going to your room?
       
 (DIR) Post #B4g4rFodRp1gSYZWOe by ariadne@social.treehouse.systems
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       @rhelune @th @mattblaze exactly
       
 (DIR) Post #B4gLvMxoVnWT0YPgBM by halfa@mastodon.tedomum.net
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       @ariadne @rhelune @th @mattblaze floors with shared amenities are usually open to all cards (provided you have one). Some hotels also doing restric your floors, but simply required a valid card to take the elevator, trying to prevent non-customer coming into the hotel from being able to wander in the corridors. This is obviously defeated by stairs (that are usually present) or simply by riding the elevator with other people.
       
 (DIR) Post #B4h3HRHnPzxioTWuXI by mattblaze@federate.social
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       Physical security and cryptography can learn from each other, part 11367:Hotels wisely don't put the room number on guest keycards so if someone finds your card, they'd have to exhaustively search the hotel to find the room it opens.Some hotels now have elevators programmed to only let you call the floor for which your keycard is coded, preventing guests from wandering to other floors.But it also means the elevator can be used as an efficient oracle to determine the floor of a found key.
       
 (DIR) Post #B4h3HS7CKt4xNtZxei by mattblaze@federate.social
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       In other words, restricting the elevator in this way is a bad tradeoff. It makes it harder for guests to visit their friends on other floors, but it reduces the complexity for an outsider burglar from O(|rooms|) to O(|floors|) + O(|rooms_per_floor|), a much more feasible search space.
       
 (DIR) Post #B4h3HSWinzUmf3WLRI by mattblaze@federate.social
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       (The point here is not about securing any specific hotel or keycard system. The point is that thinking about security in abstract terms can reveal properties and weaknesses that aren't otherwise obvious.)