The 2048 bit RSA key will be created at the initial start of the program, you have to select a password and a username and recieve a key id at the end of this process. Your friends need this key id to add you to their contact list. I suggest you either do this setup by phone with your friends or send them the key id using another IM or email. Adding new users is easy, you enter their key id, click fetch public key and enter a username for that user.

Right-clicking a user in your contact list gives you the option to start a chat, transfer a file or use the remote desktop feature. If you select one of those options the other user will receive a popup window asking him if he wants to accept the connection. Users should recieve those messages even if they sit behind a firewall.

CSpace currently supports Microsoft Windows and Gnu / Linux.