YubiText and 3-factor password authentication

As I said in the last post, I obtained YubiKey USB tokens and started to play with it. One of the programs I made is YubiText, it allows to input text when a YubiKey is plugged. For instance, one can use it as a way to type a password. This post will describe how it works and how I use it to have something I call 3-factor password authentication.