xDF2 "best utilized by programmers and engineers" - how?

So my son has a few dangerousthings items and has been bugging me to get one, so I took a look. I’m a programmer and amateur engineer (love building and hacking shit, why else would I be here?) and saw the line that said “The true utility of this chip is best utilized by programmers and engineers, but there’s also nothing wrong with storing a lot of NDEF data on it either.” on the xDF2 description.

But no amount of googling will give me an idea of WHAT can be done with it - seems google really prioritizes mainstream news articles and blog posts talking about NFC web links and contact info and all the basic stuff that’s pretty common knowledge.

Can someone tell me what actually interesting sort of stuff you can do with it, that you cannot do with a simple/basic NFC or RFID tag? I can easily program some home automation stuff or a myriad of other things to happen when a basic tag is brought up to a reader. But 8kb of memory has to be useful for more than storing a contact picture. And there has to be a good reason to program something into the tag that having the programming on the reader’s end wouldn’t accomplish.

Anyone know? Any links worth reading about it?

I’m curious, and interested, however it’s gotta be worth it to have a needle that large (gag) go into my hand :smiley:

Thanks all

The xDF2 is capable of running JavaCard applets, so you could (I think) use it for WebAuthn and GPG. I actually ordered one yesterday, and a test card, to have a play with this since there are some implementations of u2f and gpg smart card on GitHub.

blurred because I was completely wrong :smiley:

I could be wrong but I don’t think so.

It can be used with the MiFare Application Directory where each “application” can store multiple files on the chip.

An application however is simply a ‘use’ there does not appear to be any on chip java environment with DESfire, so this is simply a mechanism for supporting multiple data stores on the one chip. A single chip could be both a travel pass, an access pass, and an ID card for example. While each of those uses could only read their own Data.

Urrrrgh, I think you are right, which is incredibly disappointing. What I basically want is an NFC yubikey implant. How is the Vivokey Apex going to do this? Can the Apex run javacard applets?

Sorry for the misinformation @UnbridledStupidity!

1 Like

Yes, the Apex can run full JavaCard applets (through the Fidesmo ecosystem).

Through work by @StarGate01, the Apex should be able to fully emulate an NFC-capable YubiKey.

EDIT: I’ll also note, the OTP applet is already “done” apparently, and a PGP applet is in progress.

This page talks about some of the applets:


That’s exactly what I am working on.

So far I was able to verify the following functionality at the same time, using an unprovisioned (aka. without Fidesmo, but should be the same for the release version) P71 200K chip. The Fidesmo dev card is able to carry these applets as well, but does not have enough storage for all of them at the same time.

Unfortunately custom AID enumlation is not possible using the Fidesmo ecosystem (at least not easily), so I use the unprovisoned chips and deploy using the Global Platform tools.

In conclusion, I was able to emulate all the functionality I require from my Yubikey.


That’s really awesome, nice job!