NTAG424DNA authorisation issues

[sachakeystone]

I'm working with NTAG424 DNA tags in an Android project using the TapLinx SDK (via the DESFireFactory.getNTAG424DNA() interface). I’ve confirmed that the tag is correctly detected as an NTAG424 DNA (ISO 14443-4, NFC Forum Type 4), and I can successfully read the version string and UID.

However, all attempts to authenticate fail with the following:

• Default factory keys (all zeros, all 0xFF, known NXP test keys) → Error 9140

• UID-based key diversification attempts → Error 9140

• Key numbers 1–4 → Error 919D

• Files (0x01, 0x02, etc.) → access denied

The chip appears to be personalized, but the supplier claims it is "unformatted" from manufacturing. I’ve tested multiple chips from different batches — all show the same behavior.

Questions:

1. Is it possible that these chips have been pre-personalized or diversified at the factory?

2. Can you confirm what the expected authentication behavior should be for truly blank, factory-default NTAG424 DNA chips?

3. Is there any method to reset or reinitialize these tags (e.g., factory wipe)?

4. Are there any public tools or example apps (TapLinx or otherwise) that can verify factory-state chips?

Happy to provide the full diagnostic logs if needed.

Thanks in advance!

[EduardoZamora]

Hello @sachakeystone

Hope you are doing well.

According to NTAG 424 DNA Data Sheet, Section 10.3, 0x9140 corresponds to NO_SUCH_KEY -> Invalid key number specified.

You should be able to authenticate (AuthenticateEV2First) the tag by using Key number 00h, which should be an AES-128, all 0's by default. Also, a personalization procedure is described in NTAG 424 DNA and NTAG 424 DNA TagTamper features and hints, Chapter 5, which describes and breaks-down the PICC activation, File selection, Authentication, among others. Please, use it as a reference for your application.

I will strongly recommend you using RFIDDiscover, which is a tool for testing and configuring the tags and cards based on our devices, that allows you to log the relevant data exchange. It is also recommended using PEGODA Contactless Smart Card Reader | NXP Semiconductors together with this tool. Something important to remark is that RFID Discover is secured under NDA; you can try requesting an NDA directly from the NDA online form. After this, you must request the tool through the Secure Files (Secure Access Rights FAQs | NXP Semiconductors).

For quick testing, you could use TagWriter; this app allows you to read, write, write-protect and erase (if available) your Tags.

Additionally, NFC TagInfo by NXP reads the Meta information and data from contactless RFID and NFC transponders. This allows you to see what technology is enabling your contactless cards. This app should help you identify applications contained on your cards and tags, identify IC types and IC manufacturer and read out and display the complete tag memory layout.

Regards,
Eduardo.