AN12113 Keys Files mismatch

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AN12113 Keys Files mismatch

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Pastek
Contributor I

Hello,
When reading through AN12113 to learn more about keys in DESFire tags, I noticed that the flowchart in page 14 shows that "Cmd.Debit" can be used on file 0x03 while only authenticated using key 0x01, which should only give it read access according to page 10.
Is there a situation where it is possible or is it a mistake? I do not yet have a full grasp of it (hence the reading of the appnotes)

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KaiLi
NXP TechSupport
NXP TechSupport

Hello @Pastek 

File NO. 03 is Value File, Debit command will decrease a value stored in a ValueFile. Cmd.Debit is a read command, so File NO.3 can be read by Debit command with KEY0 authentication. If you write or modify File NO.3, then need to use KEY3 authentication, so the document description is not inconsistent.

BR

kelly

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KaiLi
NXP TechSupport
NXP TechSupport

Hello @Pastek 

File NO. 03 is Value File, Debit command will decrease a value stored in a ValueFile. Cmd.Debit is a read command, so File NO.3 can be read by Debit command with KEY0 authentication. If you write or modify File NO.3, then need to use KEY3 authentication, so the document description is not inconsistent.

BR

kelly

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Pastek
Contributor I
So it seems I misunderstood the function of Cmd.Debit as being RW. Thank you!
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