this post was submitted on 20 May 2024
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It could be simply obscure like you say, but the absence of a network doesn't guarantee it's that easy to hack.
They could use a checksum and your trick would invalidate the card until you figured out the correct algorithm, which would require a new visit to the laundromat for every new attempt, so basically impractical.
That or the card is just simply encrypted, which would make it impossible to interpret. It would be easy to implement too because the shared secret is between machines that are all physically controlled by the laundromat.
I mean how many people are gonna be walking around with card rw
Well that's the thing, you don't need a lot. You're handing out these cards and people walk out the door with them, so you can't trust they're not going to mess with them. They don't need to be walking around with a writer, you need one person to have access - either own one or have one at work or a university lab - and they can make as many cards as they want to give to their friends. Then they could use your business for years and get thousands of dollars of free service without you ever knowing.
That's the real threat here I think - a poor university student with a technical degree challenging themselves to cheat the system and help out their friends. I mean it's probably not going to happen, but a business owner who's aware of this attack vector could spend the time to get a basic encryption system going that's practically unbreakable.
Might be unbreakable, but all the attacker has to do is put money on it once and then just duplicate the card. You don't need to beat the encryption. You just need to make the machine think the card is legit
Yup, I've realised that's what people are saying. That's not an easy one to guard against I'm afraid.
I just re-read the comment chain and saw it was mentioned before. Oops lol
No worries I've been in this thread a bunch and only just got it.