<?php
require_once 'Crypt/HMAC.php';

$hash = new Crypt_HMAC('SECRETKEY''sha1');

if (isset(
$_COOKIE['stamp'])) {
    if (
$_COOKIE['stamp'] == $hash->hash($_COOKIE['data'])) {
        echo 
"Validated!\n";
    } else {
        echo 
"<blink>Not validated</blink>";
    }
} else {
    
$_COOKIE['data'] = '00110100011';
    
$_COOKIE['stamp'] = $hash->hash($_COOKIE['data']);
}
?>