SSH KEY cOnfuiguration for only ssh access

ubuntu14.04

#!/bin/bash
for i in $(grep "^[^#;]" /etc/ssh/sshd_config); do 
        echo $i
        for s in ChallengeResponseAuthentication PasswordAuthentication PermitRootLogin X11Forwarding;do
                echo $s
                if [[ $i == "$s"* ]]; then
                        echo $i;
                        echo $s;
                        sed -i "s/$s .*/$s no/g" /etc/ssh/sshd_config;
                fi; 
        done;
done

for i in $(grep "^[#]" /etc/ssh/sshd_config); do 
        for s in ChallengeResponseAuthentication PasswordAuthentication PermitRootLogin X11Forwarding;do
                if [[ $i == "#$s"* ]]; then
                        sed -i "s/#$s .*/$s no/g" /etc/ssh/sshd_config;
                fi; 
        done;
done

sed -i "s/UsePAM .*/UsePAM yes/g" /etc/ssh/sshd_config;