Here is how to set up key based authentication for OpenSSH server on Ubuntu 14.04
First, generate your keypair for the account. You can leave the private key password blank if you do not want to enter one every time.
cperson@WEB:~/.ssh$ ssh-keygen -t rsa
Copy your private key to your computer. You may need to use PuTTYgen to convert it for use with PuTTY.
Enable your account for logon with the private key by adding your public key to the authorized_keys file.
cperson@WEB:~/.ssh$ cat id_rsa.pub >> authorized_keys