Here is a link to a super simple explanation of how to set this up: http://www.petefreitag.com/item/532.cfm
In case it goes away here is the content copied and pasted - this is not my work it is from Pete Freitag :
Setting up public key authentication over SSH
Every time I want to setup public key authentication over SSH, I have to look it up, and I've never found a simple guide, so here's mine.
Generate key on local machine
ssh-keygen -t rsa
It will ask you for a password but you can leave it blank.
Note you could also pick -t dsa if you prefer.
Ensure that the remote server has a .ssh directory
Make sure the server your connecting to has a .ssh directory in your home directory. If it doesn't exist you can run the ssh-keygen command above, and it will create one with the correct permissions.
Copy your local public key to the remote server
If your remote server doesn't have a file called ~/.ssh/authorized_keys2 then we can create it. If that file already exists, you need to append to it instead of overwriting it, which the command below would do:
scp ~/.ssh/id_rsa.pub remote.server.com:.ssh/authorized_keys2
Now ssh to the remote server
Now you can ssh to the remote server without entering your password.
Now keep in mind that all someone needs to login to the remote server, is the file on your local machine~/.ssh/id_rsa, so make sure it is secure.