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nikita

Contributor

Registered: 2022-01-23

Posts: 3

Mifare 1K - Help me decode.

I have a laundry card (Mifare 1K), which I was lucky to crack it with the android Mifare Classic Tool. Data is only in the first three sectors all other sectors are blank. I am wondering about a unique 3 Byte ID that is generated upon every recharge and it is used by the laundry machine to remember the recharge event. So if I restore the original dump with the initial higher amount after few uses it gives an error if the value on the card is higher than the previously read amount. I am not sure how this 3 byte is generated? Is it a random ID or somehow associated with recharge amount, date, time or transaction ID. This is in sector 0 block 2, which is writable.

Followings were the data on sector 0, block 2 of the same card recharged three times consequently.
(1) 010179D13143000000870A0100000056  (Unique ID: 79D131;  870A inverse of $2697;  checksum 56)
(2) 0101F6E46044000000FC0301000000C8  (Unique ID: F6E460;   FC03 inverse of $10.20; checksum C8)
(3) 0101B2BF4745000000E40701000000ED  (Unique ID: B2BF47;  E407 inverse of $20.20; checksum ED)

What could be these unique ID? Please help in decipher those bytes. I am a super newbie only been working on it for the last 3-4 days.

Thank you!

Last edited by nikita (2022-02-01 06:31:02)

Sentinel

Contributor

Registered: 2012-11-26

Posts: 191

Re: Mifare 1K - Help me decode.

Now it is clear how the checksum is calculated   01^01^79^D1^31^43^00^00^00^87^0A^01^00^00^00=56

iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

Website

Re: Mifare 1K - Help me decode.

LCR

nikita

Contributor

Registered: 2022-01-23

Posts: 3

Re: Mifare 1K - Help me decode.

LCR

Sorry I am Newbie. You mean those 3 bytes are LCR? (inductance, Capacitance and Resistance) or Longitudinal redundancy check? How can I generate those values? Little direction please.

Thank you.

Last edited by nikita (2022-02-04 04:21:21)