steps to disable mac ssh password auth
cd ~/.ssh/
ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod go-w ~/
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
sudo launchctl stop com.openssh.sshd
sudo launchctl start com.openssh.sshd