Password protect changing wallpaper

Question

In order to prevent someone (other than me) from changing my background, how can I make wallpaper changing an action requiring a password?

Answer 1

Password protect changing wallpaper

The script below provides a mild password protection for changing the wallpaper in "home" situations. Mild because the password is stored inside the script in plain text. Nevertheless it should prevent average users from changing the wallpaper.

What it does is that when a user changes the wallpaper, it changes back immediately, and the user is prompted for a password. If the password is correct, the wallpaper changes into the newly set one, otherwise nothing happens.

To minimize the risk, store the script in an unexpected place under an unexpected name, and /or as a hidden file.

To use it:

Copy the script below into an empty file, set a password of your choice in the head section (I wouldn't choose your sudo password for security reasons, since it is in plain text!) and save it as name.py, run it by the command:

python3 /path/to/name.py

The script:

#!/usr/bin/env python3

import time
import subprocess

set_password = "monkey"

key = "org.gnome.desktop.background picture-uri "
read = "gsettings get "+key; change = "gsettings set "+key
set_wallpaper = subprocess.check_output(["/bin/bash", "-c", read]).decode("utf-8").strip()
pass_window ='zenity --entry --entry-text="Enter password" --text="Enter password" --title="password" --hide-text'

def check_wall():
    global set_wallpaper
    curr_wallpaper = subprocess.check_output(["/bin/bash", "-c", read]).decode("utf-8").strip()
    if curr_wallpaper != set_wallpaper:
        subprocess.Popen(["/bin/bash", "-c", change+set_wallpaper])
        try:
            entered_password = subprocess.check_output(
                ["/bin/bash", "-c", pass_window]).decode("utf-8").strip()
        except Exception:
            entered_password = None
        if entered_password == set_password:
            subprocess.Popen(["/bin/bash", "-c", change+curr_wallpaper])
            set_wallpaper = curr_wallpaper
    else:
        pass

while True:
    check_wall()
    time.sleep(3)

---

posted on gist.gisthub

Answer 2

This turned out to be a nice challenge. Try,

$ sudo mv /usr/bin/gsettings /usr/bin/gsettings2
$ sudo gedit /usr/bin/gsettings
$ sudo chmod +x /usr/bin/gsettings

When gedit comes up on the second instruction, add:

#!/bin/bash
if [ "$1" == "set" ] && [ "$2" == "org.gnome.desktop.background" ] && [ "$3" == "picture-uri" ]; then
    a=$(zenity --entry="Password")
    h1=$(/bin/echo $a | /usr/bin/md5sum | /bin/cut -f1 -d" ")
    h2='a799d7cf3d9ca647f1320fc6bfaf7408' #Password hash
    if [ "$h1" == "$h2" ]; then
    gsettings2 set org.gnome.desktop.background picture-uri $4
    else
        zenity --notification --text="Wrong password. Come again another day"
    fi
else
    $(gsettings2 $@)
fi

To undo,

$ sudo rm /usr/bin/gsettings
$ sudo mv /usr/bin/gsettings2 /usr/bin/gsettings

You can go to this md5 generator, put your string and replace a799d7cf3d9ca647f1320fc6bfaf7408 with whatever you like. Try finding out for yourself what this corresponds. You'll realize how secure this is.

Even if somebody views this file, without your password they cannot change it (This is similar to how linux stores your passwords :P).