NFCのトピックRe: AN12113 Keys Files mismatch

AN12113 Keys Files mismatch

Pastek — Tue, 02 Jan 2024 16:42:39 GMT

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)

Re: AN12113 Keys Files mismatch

KaiLi — Thu, 04 Jan 2024 05:44:24 GMT

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.

kelly

Re: AN12113 Keys Files mismatch

Pastek — Thu, 04 Jan 2024 16:48:29 GMT

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