Invalid tag on xnt

I was able to view my key on the pc now. What should i do to help fix the issue with it not being read by the android

looks like you have been struggling for a year…:confounded:

Let’s get this sorted for you.

I have a few questions for you to answer and a few things for you to try…

So you can now read it with your proxmark on a PC correct?

your KBR1 can still read the UID?

Your phone is “seeing” your implant, But you can’t read or write the NDEF contents with your android phone?

Formatting hasn’t worked with TagWriter Format function?

Formatting with DT support tool has not worked?

and you tried BOTH functions?

Can you try NFC Tools Format

Can you try writing an NDEF message with your phone to the NTAG216 card that you would have received with your Proxmark3.
And then try reading it?
What result do you get?

Have you confirmed your proxmark is set up correctly?

What commands have you tried on your proxmark so far?

hf search

Once you reply with the answers and results, if you have no luck, we can try a few more things…

if you are unaware, an easy way to reply to my questions, would be to highlight the text and select “quote.”

So the app NXP is the only app that will read it. It will scan it and show me the data. The same data id get if I ran hf mfu info. The proxmark seems to be picking it up now just fine. The rest of the apps I try to use on android all bring up an android prompt saying invalid card. Im unsure how to use proxmark as its my first time getting this dirty with the code. I don’t know what the next step would be. Thank you in advanced for the help.

On the proxmark I’ve tried to restore but I’m unsure how to input the files and key. I feel like if I could restore it with a blank file that might fix the issue but I’m unsure as to how to get a blank file and how to write it via the proxmark.

Sorry. Yes it does still work. The chip seems to have data on it still as well but its only allowing access to the uid as far as I can see.

The cards that came with the proxmark read and write on the phone just fine.


So, we know what type of tag this is, it’s an XNT.

The proxmark3 easy commands that you will need will all start hf mfu. I would suggest that you try hf mfu help.

If you can read the entire contents of the NTAG 216 you should be able to blank out any sectors that are causing issues.

So that error is no longer an issue. I fixed that. I just need to know how to obtain and write a blank card to it.

I think i write that is a way that was hard to understand. I’m still having the error on android but the error in proxmark is gone

can you just confirm for me what happens after you scan do this on DT support tool

Format, then scan your xNT

Yes. I get an invalid tag reading still. The app doesn’t even try to read it. Android takes over and says invalid tag.

hmmm, I would guess this would be

Mifare Ultralight

I would be using the
hf 14a library
But I’m no Proxmark expert, or fan to be fair

before we carry on @Royale did you ever change the password?

I think we might need to use some shell commands to wipe it…but I would rather not risk that until we have exhausted all other options…

Im okay with using shell commands to wipe it. Starting fresh is just fine. I did put a password almost a year ago through the DT app but i know it. I have it written down.

Both work for an ntag216.

Personally I would dump the contents (harder if a password is set) and write null blocks to everything after the first NDEF… But that’s just me.

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do you also have a copy of the NDEF record you wrote.
I know it was only small (but do you know what actual size it was)

Cool thanks, I haven’t tried that, but good to know :+1: