The Yubico key is an inexpensive, convenient, easy-to-use system for a one-time-password mechanism. Instead of typing a password displayed on a keyfob, you plug it in a USB port and simply push a button when ready to authenticate. There is no need to install an on-premise authentication server, you can use Yubico's cloud authentication server or install one on-premise if needed. There is no setup at all, just order keys, integrate with this extension, and you are done!