Step 1: Steps to generate headerSecrets and encrypted data

Generate headerSecrets:

{    
"clientID": "42Zuw71Ok7e2TGAgHPKttM7PFGMspJLLy3ewq15dhgjtGM9l", "clientSecret":"MDB9krmA8OqYdgjTKflkXXU7BTNAJgVDEWBmhWjQ8YBvAPNKNPLbxnJGSKcKiEV9",  "epoch": "1724136430"
}
Key :- (This key is unique for each client) (Will Provided by iServeU)

Sample Code:

 
val dataToEncrypt = JSONObject().apply { put(StringConstants.DEVICE_SL_NO, deviceSlNo)
put(StringConstants.USER_NAME, Constants.transactionDataModel?.loginId) }
 

 

Step 2: Get epoch using code

Convert this JSON to String then pass the string and key into encrypt method.

 
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
 {
  val epochTime = Instant.now().epochSecond
 }

 

Step 3: How to call the encrypted headerSecrets

Sample Code:

 
val encryptedData = generateEncryptedData(dataToEncrypt.toString().toByteArray(),
ENCRYPTION_KEY)
 

Note:

ENCRYPTION_KEY will be provided by iServeU.

Encrypt method (Kotlin):

 

fun encryptRequest(incomingJsonReq: Any, key: String): String {
    // Decode the Base64 encoded key based on SDK version
    val decodedKey = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        java.util.Base64.getDecoder().decode(key)
    } else {
        android.util.Base64.decode(key, android.util.Base64.NO_WRAP)
    }

// Generate a random IV
val iv = ByteArray(16)
SecureRandom().nextBytes(iv)

// Convert payload to byte array
val payloadBytes = incomingJsonReq.toString().toByteArray()

// Initialize AES cipher
val secretKeySpec = SecretKeySpec(decodedKey, "AES")
val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
val ivSpec = IvParameterSpec(iv)
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivSpec)

// Encrypt the data
val encryptedBytes = cipher.doFinal(payloadBytes)

// Combine IV and encrypted data
val result = ByteArray(iv.size + encryptedBytes.size)
System.arraycopy(iv, 0, result, 0, iv.size)
System.arraycopy(encryptedBytes, 0, result, iv.size, encryptedBytes.size)

// Return Base64 encoded result based on SDK version
return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    java.util.Base64.getEncoder().encodeToString(result)
} else {
    android.util.Base64.encodeToString(result, android.util.Base64.NO_WRAP)
}
}

 

Encrypt method (JAVA):

 
// —------- Encryption Method —-----------
    public static String EncryptRequest(Object incomingJsonReq, String key) throws Exception {
        byte[] decodedKey = null;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            decodedKey = Base64.getDecoder().decode(key);
        } else {
            Log.e("@@", "Using device with OS < O");
            decodedKey = android.util.Base64.decode(key, android.util.Base64.NO_WRAP);
        }
        // Generate a random IV
        byte[] iv = new byte[16];
        SecureRandom random = new SecureRandom();
        random.nextBytes(iv);
        // Convert payload to byte array
        byte[] payloadBytes = incomingJsonReq.toString().getBytes();
        // Initialize AES cipher
        SecretKeySpec secretKeySpec = new SecretKeySpec(decodedKey, "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        IvParameterSpec ivSpec = new IvParameterSpec(iv);
        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivSpec);
        // Encrypt the data
        byte[] encryptedBytes = cipher.doFinal(payloadBytes);
        // Combine IV and encrypted data
        byte[] result = new byte[iv.length + encryptedBytes.length];
        System.arraycopy(iv, 0, result, 0, iv.length);
        System.arraycopy(encryptedBytes, 0, result, iv.length, encryptedBytes.length);
        // Return Base64 encoded result
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            return Base64.getEncoder().encodeToString(result);
        } else {
            return android.util.Base64.encodeToString(result, android.util.Base64.NO_WRAP);
        }
    }

 

Note: 

  • The encrypted method will return one headerSecrets which will be sent in place of clientID and clientSecret.
  • In place of clientID and clientSecret send headerSecrets.

 

Step 4: Data Model Base64 Encryption of Transaction data

 

 
val dataModel = DataModel(/*add all required params*/)
val gson = Gson()
val getData = gson.toJson(dataModel)
val bytes = getData.toString().toByteArray()
val responseToBase64 = String(android.util.Base64.encode(bytes, android.util.Base64.NO_WRAP))

 

Step 5: Intent Data to Send

 
val intent = Intent(this@MainDemoActivity, MatmActivity::class.java)
intent.putExtra("data", responseToBase64)
intent.putExtra("supportEncryption", true)
startActivity(intent)

 

Step 6: Callback data handle

 
override fun onMatmSDKFinish(message: String?)
 {
   val decodedData = android.util.Base64.decode(message , android.util.Base64.NO_WRAP)
   val actualData = String(encryptedData, Charsets.UTF_8)
   activityMainBinding?.callbackText?.text = "message: $decodedData"
 }