function H($text, $key, $encode){
	$lntext = strlen($text);
        $result = "";
        $fordlt = -$lntext ;
	$KeyLength = strlen($key);
	if($encode){ $Sign = -1; }else{ $Sign = 1;}
	for($i=0; $i < $lntext; $i++){
		$ik = (int)($i / $KeyLength) + 1;
		$result.= chr(ord(substr($text, $fordlt++, 1)) + $Sign * ord($key[$ik]));
	}
	return $result;
}