public function easyVerifyIPN()
    {
        $url       = $this->getCurrentUrl();
        $signature = $_SERVER["HTTP_API_SIGN"];
        $api_key   = $_SERVER["HTTP_API_KEY"];
        $nonce     = $_SERVER["HTTP_API_NONCE"];
        $payload   =  file_get_contents("php://input"); //// raw post body
        /// or we could use
        /// $payload   =  stream_get_contents(STDIN);

        if (!$api_key || !$nonce || !$signature || $payload == "") {
            //// missing headers OR an empty payload
            return false;
        }

        $message = $nonce . $url . $payload;
        $calculated_signature = $this->signMessage($message);
        if($calculated_signature <> $signature ){
            //// invalid IPN call
            return false;
        }
        //// valid IPN call
        return true;

    }