Das Werkstatt

PROBLEM
===============

I was basically forced to buy a yubico key (2 actually: 1 backup) although I didn't want to:
The model is a 30 EUR Yubico "Security Key C NFC".

Now Github 2 factor authentication was pissing me off for quite a while now, because I very often DO NOT have my phone with me (on purpose) when I want to *work* on the computer.

So I thought: I have spent money on Yubikeys, now just laying around anyways, so: let's try it.

Trying to follow the github instructions to add the Security Key as "passkey":
* Security key "touch me" LED lit up.
* I touched it.
* I got this error message:

passkey registration failed github
cannot use this passkey

SOLUTION
===============

The Security Key needs a PIN set - *once*.

I've used the Appimage for "YubiKey Manager" (GUI) provided by Yubico
(because all tools I found in the default repositories of Xubuntu 20.04 (or Android) would not list my "Security Key C NFC")

Now, the key shows up and you can set a PIN.
Once that PIN is set, continue the same instructions on Github as before - and now Firefox *will* ask you for a pin before you may touch your key.

Works.