To log in to an Aluu chat, you must provide a username and a password.
The username is sent to other chat participants for presentation purposes, but is not used to identify you uniquely.
Username and password are used to compute an identity key pair. Your public key identifies you uniquely and can be used by other chat participants to verify that signed messages were written by you. Your secret key is used by yourself to sign outgoing messages.
Since your keys are derived from your username and password, no secret information needs to be stored permanently in your webbrowser and you can log in to Aluu from any computer with the same identity as long as you use the same username and password. It also means that your password cannot be recovered if you forget it.