Forum › MIFARE and NFC Reader IC`s › RFID Mifare writter/reader with CR038 › Reply To: RFID Mifare writter/reader with CR038
Hi Jean-Yves,
I do not know the “CR038 reader”. But you will find a user manual if you analyze the link. Did you read page 30 of the manual? There is an example of how to authenticate. For a blank card both keys A and B are FFFFFFFFFFFF. If your key is different, then you changed the keys previously?
One recommendation: please be careful when changing a key. The access permission bits are also in the sector trailer and you should not overwrite theses bytes. It exists access permission bit combinations where you can make the block/sector inaccessible! So, read always the current values back and insert it in the new data block.
As I understand the user manual correctly, the XOR byte is the checksum of the bytes of “Node ID”, “Function Code” and “Data”. It is a simple exclusive-or operation.
The TapLinx team
I do not know the “CR038 reader”. But you will find a user manual if you analyze the link. Did you read page 30 of the manual? There is an example of how to authenticate. For a blank card both keys A and B are FFFFFFFFFFFF. If your key is different, then you changed the keys previously?
One recommendation: please be careful when changing a key. The access permission bits are also in the sector trailer and you should not overwrite theses bytes. It exists access permission bit combinations where you can make the block/sector inaccessible! So, read always the current values back and insert it in the new data block.
As I understand the user manual correctly, the XOR byte is the checksum of the bytes of “Node ID”, “Function Code” and “Data”. It is a simple exclusive-or operation.
The TapLinx team
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