This page describes the steps to disable password authentication for SSH.
Please follow the steps as given below.
* cd /etc/ssh
* ls -l sshd_config (note the ownership & permission of the file)
* ci -l sshd_config (Check IN for the file sshd_config)
* vi sshd_config (open & edit the file as below)
ChallengeResponseAuthentication no
PasswordAuthentication no
saved and close the file
* /etc/init.d/sshd reload (reload the sshd service)