Adding ssh keys via the user control panel

src/freedombone-controlpanel-user

 }
 
 function add_ssh_key {
+    data=$(tempfile 2>/dev/null)
+    trap "rm -f $data" 0 1 2 5 15
+    dialog --title $"Add your ssh public key" \
+           --backtitle $"Freedombone User Control Panel" \
+           --inputbox $"This will allow you to log into Freedombone if you have an ssh key on your system, and provides much stronger security than simply using a login password.\n\nWARNING: If you make any mistakes here then you may not be able to log in and will need to get the administrator to clear your ssh authorized_keys file." 15 60 2>$data
+    sel=$?
+    case $sel in
+        0)
+            SSH_PUBLIC_KEY=$(<$data)
+            if [ ${#SSH_PUBLIC_KEY} -gt 20 ]; then
+                if [[ "$SSH_PUBLIC_KEY" == "ssh-"* ]]; then
+                    if [ ! -d /home/$USER/.ssh ]; then
+                        mkdir /home/$USER/.ssh
+                    fi
+                    if [ ! -f /home/$USER/.ssh/authorized_keys ]; then
+                        touch /home/$USER/.ssh/authorized_keys
+                    fi
+                    if ! grep -q "$SSH_PUBLIC_KEY" /home/$USER/.ssh/authorized_keys; then
+                        echo "$SSH_PUBLIC_KEY" >> /home/$USER/.ssh/authorized_keys
+                        dialog --title $"New ssh key added" \
+                               --backtitle $"Freedombone User Control Panel" \
+                               --msgbox $"Your ssh key has now been added" 6 50
+                    else
+                        dialog --title $"ssh key already added" \
+                               --backtitle $"Freedombone User Control Panel" \
+                               --msgbox $"That ssh key has already been added" 6 50
+                    fi
+                else
+                    dialog --title $"Unrecognised ssh public key" \
+                           --backtitle $"Freedombone User Control Panel" \
+                           --msgbox $"This doesn't look like an ssh key" 6 50
+                fi
+            fi
+            ;;
+    esac
 }
 
 function remove_ssh_key {