Protect image contents from unauthorised people - php

Question

We all know, this is a very important issue for many web developers. They want to protect direct access or direct readability to their confidential images. The folder that contains all the images is open and anyone can visit that folder, but I want to do something that can protect my image contents, means, if an unauthorised guy looks for an image he may get the image by visiting the appropriate folder but the contents will be invisible or difficult to understand. I think if I get a solution here, many guys will be helped from this question. Writing .htaccess isn't always a stable choice. So, after brainstorming I found some ways how I can protect image contents from direct access. I want to use Imagick with PHP to perform any kind of image editing.
Adding and removing a layer: After uploading, add a layer to make contents of the image invisible. So, if anyone reaches the folder you've stored the images will be meaningless as he will see the layer not the image content. Then remove the layer and show to them who have proper rights.
Converting the image to another format: Convert the image to any format like .txt, .exe, .bin, .avi or any other format so that without editing, the image won't be visible. Convert back to show it to the authorised user.
Image grid: Divide the image into some grids, say, if the image is medium 100 grids and change the position of the grids to make the contents unclear. To do this, we can name each grid like 1, 2, 3 and so on, then change the position to $position - 20. So the grid of position 25 will go to 5, 100 will go to 80, 1 will go to 81 and so on. Reverse the same way to display to the authorised users.
It is never possible to protect completely but we can make it harder. I don't know which of the three is possible with Imagick and which is not. Please tell me if you know. Thanks in advance.

Answer 1

You can put these images in a different folder outside of the public_html (so nobody can access them). Then via script, if a user is logged in, you get the image file content and then change the header. If a user is not logged, you can display a random image or showing a default image.
for example, the public html folder is: /var/www your image folder can be: /registered_user/images/
Then in your PHP script you can write:
<?php
if(!userLogged() || !isset($_GET['image'])) {
header('Location: /');
die();
}
$path = '/registered_user/images/';
$file = clean($_GET['image']); // you can create a clean function that only get valid character for files
$filename = $path . $file;
if(!file_exists($filename)) {
$filename = '/var/www/images/bogus.jpg';
}
$imageInfo = getimagesize($filename);
header ('Content-length: ' . filesize($filename));
header ('Content-type: ' . $imageInfo['mime']);
readfile ($filename);