I am trying to verify a payment receipt on server side. I am getting a {"status":21002, "exception":"java.lang.IllegalArgumentException"} in return

Here is the code:

private final static String _sandboxUriStr = "https://sandbox.itunes.apple.com/verifyReceipt";

public static void processPayment(final String receipt) throws SystemException
{
    final BASE64Encoder encoder = new BASE64Encoder();
    final String receiptData = encoder.encode(receipt.getBytes());


    final String jsonData = "{\"receipt-data\" : \"" + receiptData + "\"}";

    System.out.println(receipt);
    System.out.println(jsonData);

    try
    {
        final URL url = new URL(_productionUriStr);
        final HttpURLConnection conn = (HttpsURLConnection) url.openConnection();
        conn.setRequestMethod("POST");
        conn.setDoOutput(true);
        final OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
        wr.write(jsonData);
        wr.flush();

        // Get the response
        final BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = rd.readLine()) != null)
        {
            System.out.println(line);
        }
        wr.close();
        rd.close();
    }
    catch (IOException e)
    {
        throw new SystemException("Error when trying to send request to '%s', %s", _sandboxUriStr, e.getMessage());
    }
}

My receipt looks like this:

{\n\t"signature" = "[exactly_1320_characters]";\n\t"purchase-info" = "[exactly_868_characters]";\n\t"environment" = "Sandbox";\n\t"pod" = "100";\n\t"signing-status" = "0";\n}

Receipt data with a BASE64 encoded receipt looks like this:

Blockquote

{"receipt-data" : "[Block_of_chars_76x40+44=3084_chars_total]"}

Does someone have an Idea, or sample code how can I get from receipt string to reply JSON, mentioned here: [http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/StoreKitGuide/VerifyingStoreReceipts/VerifyingStoreReceipts.html#//apple_ref/doc/uid/TP40008267-CH104-SW1]?

Thank you