private static function signVals($key, $vals, $prefix, $expire, $time = null)
{
$exp = ($time ? $time : time()) + $expire;
$val = $vals . '|' . $exp;
$b64 = base64_encode($val);
$cookie = $prefix . '|' . $b64;
$sig = hash_hmac("sha1", $cookie, $key);
return $cookie . '|' . $sig;
}