you could add a random number to the encrypted data on the card and require it to always be the same or larger than the last time that card was seen, and then increment it every time the card is used.
The problem with that is that if the machines don’t talk to one another then there’s no way to make that system work across machines. I guess if each machine enforced it then you would eventually run out of machines that work for your hacked card.
If there’s no central control or ledger, couldn’t you just rewrite the card with the original values and the machines wouldn’t know any difference?
Oh yeah, that’s true, so you wouldn’t have destroyed the card, but it’s not a useful hack if they’ve done even the most basic security measures.
That said, I would be fascinated to know what was on that card. I’d give it pretty good odds of having absolutely no security measures whatsoever.
you could add a random number to the encrypted data on the card and require it to always be the same or larger than the last time that card was seen, and then increment it every time the card is used.
The problem with that is that if the machines don’t talk to one another then there’s no way to make that system work across machines. I guess if each machine enforced it then you would eventually run out of machines that work for your hacked card.