Last week, I tried to register for a service and was really surprised by a password limit of 16 characters. Why on earth yould you impose such strict limits? Never heard of correct horse battery staple?

  • smeg@feddit.uk
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    3 months ago

    I assumed as the card readers and cards are both offline devices they wouldn’t have a way to do this, are card blocks local in general?

    • SkunkWorkz@lemmy.world
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      3 months ago

      Modern cards have a chip inside them that’s basically a very tiny computer. It can check how many times the pin was incorrect.

      • smeg@feddit.uk
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        3 months ago

        That’s pretty cool. I wonder what (if any) tinkering you can do with a card if you’ve got physical access and some very precise tools.

        • SkunkWorkz@lemmy.world
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          3 months ago

          Even if you could you can’t recover the PIN from it. Since it’s not stored on the card, the chip checks the entered PIN against a secret key with cryptographic calculations if it is correct. But you can’t get the PIN from that secret key. Also if I remember correctly the chip will self destruct, as in wipes it’s data, when it detects that it’s being tampered with.