What is SSH Key use for?

SSH keys are an alternative authentication method used to connect to SSH servers. <br> <br><a href=“https://wiki.archlinux.org/index.php/SSH_Keys”>https://wiki.archlinux.org/index.php/SSH_Keys</a> <br><pre>SSH keys serve as a means of identifying yourself to an SSH server using public-key cryptography and challenge-response authentication. One immediate advantage this method has over traditional password authentication is that you can be authenticated by the server without ever having to send your password over the network. Anyone eavesdropping on your connection will not be able to intercept and crack your password because it is never actually transmitted. Additionally, using SSH keys for authentication virtually eliminates the risk posed by brute-force password attacks by drastically reducing the chances of the attacker correctly guessing the proper credentials.</pre>

You should prob. read through the <a href=“https://help.ubuntu.com/12.04/serverguide/index.html”>Ubuntu Server Guide</a>.