[PHP] Files name encoder/decoder

<?php
/*
     _____ _____ _ _____ _____         _____ _____ _____ _____
 ___|     | __  |_|  _  |_   _|___ ___|_   _|   __|  _  |     |
|_ -|   --|    -| |   __| | | |- _|___| | | |   __|     | | | |
|___|_____|__|__|_|__|    |_| |___|     |_| |_____|__|__|_|_|_|
|s C R i P T z - T E A M . i N F O|

Files name encoder/decoder

iNSTALL:
Create file - index.php
Create folder - /files/

USAGE:
Copy some files into "DiR" -> /files/
Then Run for ENCODE:
index.php?action=encode
Or for DECODE:
index.php?action=decode
*/

error_reporting(0);
set_time_limit(0);

define("DiR","./files/");

function scriptz_file_decode ($encoded_file_name) {
$x = str_replace("_a584183682ba145fd581775fa2ac404e","",base64_decode(base64_decode($encoded_file_name)));
return $x;
}

function scriptz_file_encode ($file_name, $ext) {
$x = base64_encode(base64_encode(substr($file_name, 0, -4)."_a584183682ba145fd581775fa2ac404e")).".".$ext;
return $x;
}

function file_extension($filename)
{
return substr(strrchr($filename, '.'), 1);
}

if (isset($_GET["action"]) && $_GET["action"] == "encode" )
{
if ($handle = opendir(DiR)) {
    while (false !== ($entry = readdir($handle))) {
        if ($entry != "." && $entry != ".." && $entry != "index.php") {
		$ext = file_extension($entry);
		$new = scriptz_file_encode($entry, $ext);
        rename(DiR.$entry, DiR.$new);
		echo $entry." => ".$new."<br />";
        }
    }
    closedir($handle);
}
}

if (isset($_GET["action"]) && $_GET["action"] == "decode" )
{
if ($handle = opendir(DiR)) {
    while (false !== ($entry = readdir($handle))) {
        if ($entry != "." && $entry != ".." && $entry != "index.php") {
		$ext = file_extension($entry);
		$new = scriptz_file_decode($entry).".".$ext;
        rename(DiR.$entry, DiR.$new);
		echo $entry." => ".$new."<br />";
        }
    }
    closedir($handle);
}
}
?>