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Hi! So i got a library card, and turned out they used default keys on the sector to protect the card. There is only sector 3 with data other than sector 0. I was trying to find out how it works and since i got it this happens on block 0:
No use:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 F5
One use:
00 08 00 00 00 00 00 00 00 00 00 00 00 00 02 55
Two:
90 10 00 00 00 00 00 00 00 00 00 00 00 00 00 AB
three:
10 09 00 00 00 00 00 00 00 00 00 00 00 00 00 DB
four:
90 21 00 00 00 00 00 00 00 00 00 00 00 00 00 1B
five:
90 28 00 00 00 00 00 00 00 00 00 00 00 00 00 5A
Also there is this on block 1 but it doesn't change:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 10 F1
So i can see there is a counter that goes up every time, like on my second book if i change 90 10 to binary I get: 1001 0000 0001 0000
And that shows i got two books out. And you can do that for every line. So here is my question: how do you get the last byte? I think is just a checksum but I have no clue how to get it.
Oh if you try to go back with the counter, lets say i dump old data like i had one book and then use it now, the counter will go to six anyways so i think all the info is realated to my uid.
Thanks!
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