Implement verification code without the need for the GD library

<?php
//+-------------------------------------------------
//| * File validate_image.php
//| * Function Realization Site Login authentication Code
//| * Version 1.0.0
//| * Date 2005-4-1
//| * Author of Northwest Wolf QQ 500784 Cokeyang at hotmail.com
//| * Copyright http://www.adibaby.com[temporarily closed]
//| * Use method:
//| In advance to support the GD library to do some pictures, recommend the use of GIF format, file name and pictures
//| The number in the face is consistent, put the picture into a folder. Set the data inside CONFIG.
//| Reference
//| Verify page Contrast
//| $_cookie[' Validate '] = = MD5 ($_post[' input ')
|==================config start===================
$image _path= "numimage";//Picture file path not followed by '/'
$image _ext = "gif";//Picture file name extension
===================config end=====================
$imagelist = Array ();
if ($handle =opendir ($image _path)) {
while (False!== ($file =readdir ($handle))) {
$filename =explode (".", $file);
$imagelist [] = $filename [0];
Unset ($filename);
}
Closedir ($handle);
unset ($imagelist [0]);
Unset ($imagelist [1]);
}
Srand ((float) microtime () *103e//| reference
//| Verify page Contrast
//| $_cookie[' Validate '] = = MD5 ($_post[' input ')
|==================config start===================
$image _path= "numimage";//Picture file path not followed by '/'
$image _ext = "gif";//Picture file name extension
===================config end=====================
$imagelist = Array ();
if ($handle =opendir ($image _path)) {
while (False!== ($file =readdir ($handle))) {
$filename =explode (".", $file);
$imagelist [] = $filename [0];
Unset ($filename);
}
Closedir ($handle);
unset ($imagelist [0]);
Unset ($imagelist [1]);
}
Srand ((float) microtime () *10000000);
$filename = $imagelist [Array_rand ($imagelist)];
Setcookie ("Validate", MD5 ($filename));
Header (' content-type:application/'. $image _ext);
echo Implode ("", File ($image _path.) /". $filename.". $image _ext));
?>