[ewpratten]

Wipe the card.

Make a dump after doing "hf mf ndefformat".

Then make a dump after writing a payload from an iPhone. (since iPhone seems to want ndefformat anyways)

Then wipe again and make a dump after writing from Android.

[stavros]

Here you go: https://www.pastery.net/xajezk+gbkqqz+aqwygg+ukrdad/

[ewpratten]

Thank you very much!

Something's clearly up there. You can see that even IOS and Android disagree with each other on what NDEF should look like by a few bytes. Very interesting.

[stavros]

Yep, 89 EC A9 7F 8C 2A 00 00 on iOS versus FF FF FF FF FF FF on Android. Interesting how the number of bytes is different, I should play with them a bit.

[ewpratten]

There's lots of info about the NDEF "packet" format online.

I used this page as reference when I was putting together the "magic bytes" in the final section of the blog post: https://www.oreilly.com/library/view/beginning-nfc/978144932...

[stavros]

This is fantastic, thanks!

Also, one thing that might be of interest: Even after a wipe and an ndefformat, my Android-written tag can be read by my iPhone 15.

NFC tools will only read it in compatibility mode, though.

[ewpratten]

Are you sure? The NFC app for iPhone can always read tags. Its specifically getting phones without the app to read them.

Try wiping, then writing a URL from Android.

Then just tap to the iPhone and see if Safari opens or not. It shouldn't