Encryption, signature and sending the request

				
					    public static String url = "https://checkout-stg.addonpayments.com/EPGCheckout/rest/online/tokenize";
    
    public static RequestModel getRequestModel() {
        RequestModel requestModel = new RequestModel();

        requestModel.setCurrency("EUR");
        requestModel.setAmount(30);
        requestModel.setCountry("ES");
        requestModel.setCustomerId(1);
        requestModel.setMerchantId(116659);
        requestModel.setMerchantTransactionId("23558434");
        requestModel.setPaymentSolution("creditcards");
        requestModel.setFirstName("FirstName");
        requestModel.setLastName("LastName");
        requestModel.setCustomerEmail("email@micomercio.com");
        requestModel.setPhoneCode("34");
        requestModel.setTelephone("600000000");
        requestModel.setAddressLine1("Line 1 customer address");
        requestModel.setAddressLine2("Line 2 customer address");
        requestModel.setBuildingName("Building");
        requestModel.setBuildingNumber("42");
        requestModel.setPostCode("08001");
        requestModel.setState("Barcelona");
        requestModel.setCity("Barcelona");
        requestModel.setCustomerCountry("ES");
        requestModel.setCustomerNationalId("9999999d9R");
        requestModel.setDob("01-12-1999");
        requestModel.setChName("First name Last name");
        requestModel.setChFirstName("First name");
        requestModel.setChLastName("Last name");
        requestModel.setChEmail("correo@micomercio.com");
        requestModel.setChAddress1("Line 1 owner address");
        requestModel.setChAddress2("Line 2 owner address");
        requestModel.setChCity("Barcelona");
        requestModel.setChPostCode("08001");
        requestModel.setChState("Barcelona");
        requestModel.setChCountry("ES");
        requestModel.setTopLogo("https://docs.globalpayments.es/wp-content/uploads/2022/12/globalpayments-logo-340x80-BLANCO.png");
        requestModel.setCheckoutTitle("AddonPayments");
        requestModel.setSuccessURL("https://redirection-test.mycompany.com/");

        return requestModel;
    }
    
    

    public byte[] generateIV() {
        Random random = new Random();
        byte[] iv = new byte[16];
        random.nextBytes(iv);
        return iv;
    }

    public String base64Encode(byte[] byteArray) {
        byte[] encodedBytes = Base64.getEncoder().encode(byteArray);
        return new String(encodedBytes);
    }

    public byte[] cbcEncryption(byte[] data, byte[] key, byte[] iv, Boolean encrypt) {
        try {
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
            if (encrypt) {
                cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
            } else {
                cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);
            }

            return cipher.doFinal(data);
        } catch (NoSuchPaddingException | NoSuchAlgorithmException | IllegalBlockSizeException | BadPaddingException |
                 InvalidAlgorithmParameterException | InvalidKeyException exception) {
            exception.printStackTrace();
            return null;
        }
    }

    public byte[] hash256(byte[] data) {
        try {
            MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
            return messageDigest.digest(data);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            return null;
        }
    }
    
    public void sendRequest() {
        try {
						
            String httpQuery = Utils.getInstance().buildQuery(RequestModel.class, Constants.getRequestModel());
            String finalQueryParameter = URLEncoder.encode(httpQuery, StandardCharsets.UTF_8).replace("%3D", "=").replace("%26", "&");
            byte[] formattedRequest = finalQueryParameter.getBytes(StandardCharsets.UTF_8);

            System.out.println("Formatted Query Parameters: " + finalQueryParameter);

            System.out.println(formattedRequest.length);

            byte[] clearIV = SecurityUtils.getInstance().generateIV();

            System.out.println("Hex Iv: " + HexUtils.getInstance().bytesToHex(clearIV));
            System.out.println("Base64 Iv: " + SecurityUtils.getInstance().base64Encode(clearIV));

            String key = HexUtils.getInstance().bytesToHex(Constants.encryptionKey.getBytes());
            System.out.println("key = " + key);

            byte[] encryptedRequest = SecurityUtils.getInstance().cbcEncryption(
                    formattedRequest, // formatted request
                    Constants.encryptionKey.getBytes(),
                    clearIV,
                    true
            );

            System.out.println("Base64 Encrypted Request: " + SecurityUtils.getInstance().base64Encode(encryptedRequest));

            byte[] signature = SecurityUtils.getInstance().hash256(formattedRequest);

            HttpUrl.Builder urlBuilder = HttpUrl.parse(Constants.url).newBuilder();
            urlBuilder.addQueryParameter("merchantId", String.valueOf(Constants.getRequestModel().getMerchantId()));
            urlBuilder.addQueryParameter("encrypted", SecurityUtils.getInstance().base64Encode(encryptedRequest));
            urlBuilder.addQueryParameter("integrityCheck", HexUtils.getInstance().bytesToHex(signature).toLowerCase());

            System.out.println("Signature = " + HexUtils.getInstance().bytesToHex(signature));

            Request request = new Request.Builder()
                    .url(urlBuilder.build().toString())
                    .addHeader("apiVersion", "3")
                    .addHeader("encryptionMode", "CBC")
                    .addHeader("iv", SecurityUtils.getInstance().base64Encode(clearIV))
                    .post(new FormBody.Builder().build())
                    .build();

            Call call = client.newCall(request);
            try (Response response = call.execute()) {
                System.out.println(response.body().string());
                System.out.println(response.code());
                System.out.println(response.message());
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }