First I want to point out that I am a beginner with NFC tags. I use the NFC tools app and try to figure out what I can (and can't) do with the chip.

In the application there is an option for locking an NFC tag with password. Of course there is an option to remove the password making the chip available for writing. Let's say I want to have an NFC tag that is publicly available for everyone to read but locked with a password for write. With this application (NFC tools) what I can do to rewrite the data inside the tag is use one interaction to remove the password, another one for writing the data I want and a third interaction to lock the NFC again. My question is whether it is possible to do this with only one interaction? Maybe I have a mobile app that can make use of NFCs and the code behind can execute a procedure or a function that combines several instructions one after another. Does the NFC chip or protocol itself support this?

Single NFC interaction:

*hover the phone over NFC tag
remove password -> write data -> set password
  • 2
    What type of tag? They are not all the same. Can you write code? What OS and hardware are you using? Note that NTAG21x tags for instance don’t need you to remove password to write, you just need to authenticate before you do (in the same session). You just need a tool which allows you to do that.
    – jcaron
    May 31, 2022 at 21:08
  • @jcaron the idea I have involves a smartphone that has to be able to change the data on the chip with one hover. Is that possible without a separate device?
    – dimitar.d
    Jun 1, 2022 at 7:14
  • 1
    You haven’t replied to most of my requests for clarification. On NTAG21x tags, the “remove password” operation is actually an “authenticate” operation followed by a “write”. So as long as you have the right software for that, you could just authenticate and write whatever data you want, rather than the password protection settings. Which brings back the question of the device, operating system and if you can write you own software or are stuck using already available software.
    – jcaron
    Jun 2, 2022 at 12:33


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