Password-protect feed and make it usable in major aggregators

Could you create a PHP file, which listens for a password through a GET method. Then if the password is correct, include the feed and display the feed?

Then you could only access the page if you use the url /example/feed.php?password=PASSWORD

<?php
if ($_GET['password'] == 'PASSWORD') {
    include 'path/to/feed';
}