2083393_en-US

[#1]

NTAG 424 DNA can still be erased even if locked?

Hi, I want to use NTAG 424 DNA tags to include in products, with a URL to access additional details. I'd like to lock these tags so they can't be changed or erased by anyone after shipping.

I tried the lock features in the NXP TagWriter Android app, both "Soft protection" and "Lock tag". Both of these were effective in preventing writing different data to the tags. However, I can still use the "Erase to factory default" feature to wipe the content. After this, the tags appear as having "empty" content, and since they're locked I can't write on them again, so they effectively became useless.

Is there a different way to lock them so they can't be erased? Maybe with different software?

BTW, I also tried to use "Password protection" to protect writing these tags, but I kept getting an error that the feature is not supported by these tags.

I'm attaching the output of TagInfo when scanning a tag that was first soft protected and then erased and is now un-writable.

Thanks, any insights would be appreciated.

Re: NTAG 424 DNA can still be erased even if locked?

Great, that worked for recovering those tags, thanks for the reply.

Sounds like the fact that the locking command in the writer app might either have a bug or is incorrectly worded.

Anyway, I'll try out the app you linked to.

Thanks,

Daniel

Re: NTAG 424 DNA can still be erased even if locked?

Hello @dgobera, Good Day!

Thank you very much for your interest in our products.

For being able to write again to the "erased to factory default" tags, you may try using the ''Remove protection'' feature of the NXP TagWriter app, this has worked for me when replicating the procedure you described, after that you should be able to write an NDEF to the tag again.

For preventing the tag from being overwritten or erased, the write access right of the NDEF file within the tag must be changed, this procedure is described in section 8.2.3.3 and 11.7 of the NTAG 424 DNA Data Sheet. In order to perform this procedure, I would suggest having a look at our recommended RFIDDiscover Software application, which is a tool that is meant to be used with the PEGODA Contactless Smart Card Reader And offers an easy way of exploring the NTAG 424 DNA and other smart cards' features.

Please consider that in order to have access to the tool you would need to sign an NDA since this software is part of NXP's secure resources.

My best regards,
Daniel.