RFID Login - A DIY Yubikey, but for a Raspberry Pi!

So, I built the first stage today, a way to check your key/s UID as otherwise anyone can log in as you! It is a simple python script that will run on a Raspberry Pi. I want to make another version soon that will work on arduino as that way I can keep my RasPi for the actual device and use an arduino for tests. It checks for cards using rfid.request and retrieves the UID using rfid.anticoll. It also formats everything nicely and has a 0.1s delay to reduce load on microprocessors.