DESFire EV2/EV3 backward compatibility

[SecDept]

Dear everybody,

I read in MF3D(H)x3 datasheet (MIFARE DESFire EV3 contactless multi-application IC (nxp.com)) that DESFire EV2 EV3 were designed in order to maintain backward compatibility.
I wish to know if this is due either to the reader or to the card itself:
- does a EV3 card work on a EV2 reader ?
- or should I have a both EV2-EV3 compatible reader to read EV3 cards ?

Many thanks for being kind enough to answer such a noob question.

Best regards

[makinako]

One thing to remember when talking about compatibility is that while there is broad compatibility in terms of the functionality and protocol. There are instances at the lower layers where you can be caught out with older equipment.

One example is the EV1 incorrectly set the first byte of the UID to 80h instead of 08h as per ISO 14443-3. Doesn't sound like a big deal but for one of my clients it meant replacing 7000 PACS door/gate readers that weren't firmware-updateable when we moved to NXP JCOP cards with EV1 that claimed to be "fully compatible". The NXP engineers had thoughtfully fixed the bug but our old reader fleets were relying on that byte for type and random-id detection. An understandable and easy to overlook mistake but it shows every bit counts.

I'm not aware of any particular EV2/EV3 discrepancy and hopefully there is none, but the lesson is until you have tested EV3's in your device fleet, don't presume full compatibility as there are many nuances to the changes made over time that are not obvious.

[Kan_Li · Accepted solution]

Hi @SecDept ,

This is due to the reader, as mentioned in the data sheet, "MIFARE DESFire EV3 can be used as a MIFARE DESFire EV2 or a MIFARE DESFire EV1 in its default delivery configuration", so a EV3 card work with a EV2 reader.

Hope that makes sense,

Have a great day,
Kan

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