Is DESFire EV1 UID unique and always returned?

[Joulupukki]

Hi,

I understand that some smart cards may return a random UID or no UID at all. This may pose a problem because I am relying on the UID to uniquely identify cards.

Does this happen with MIFARE smart cards, more concretely with DESFire EV1? That is, when I ask a DESFire EV1 for the UID, will this value always be returned? (And is it unique or could it be a random value?)

Cheers!

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[Renke]

Hi,

the MIFARE DESFire EV1 (like other MIFARE cards) offers the feature of random UID. The random UID feature is defined in the ISO/IEC 14443, and can be enabled by an authorized user.
If random UID is enabled, the UID can only be read by an authorized user in a secured way..

For the identification of cards we recommend to use an authentication (which provides the fact that only authorized readers can read authorized cards), and then transfer the UID using an encnrypted communication (to ensure privacy).

Renke

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[Rodolfo]

Hi,
it is possible to configure DESFire EV1 card to exhibit a Random ID; such configuration can be done during card personalization.
You can find more information in this application note: page 5, page 7 and page 8.
http://www.nxp.com/documents/application_note/AN10927.pdf

Cheers
Rodolfo
PS: Ioulupukki is SantaClaus in Finish, isn't it ??

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[Joulupukki]

Since I'm working with Android, I was using tag.getId() to acquire the UID (which might return the random version if it is enabled).

I'll rely on authentication+GetCardUID instead to make sure I get the right value.

Thank you.

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[Joulupukki]

Just saw your post Rodolfo, I'll take a look at the PDF.

Yes, it is. My name was taken :).

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