Runs on an Arduino Leonardo compatible device (needs to be able to act as a keyboard)
My setup runs on a jtron beetle, with a slightly hacked (for size) Grove NFC unit I have soldered the jtron to a USB port on my motherboard, and it works quite well.
It checks scanned NFC tags for the correct UID, and if a match is found, it types the password and presses the return key. Video
The NFC library used is this one from Seeed Studio which has been added as a submodule in the lib. Be sure to pull the nested submodule as well by using: git submodule update --init --recursive
after having cloned from here.
That's it. Happy hacking. ~Robotto