How to Obfuscate Java Code in Android Apps

Last updated April 7, 2024 by Appdome

Learn to Obfuscate App Logic in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is Java Code in Android Apps?

Java is a programming language used in mobile app development for building Android apps. Java code consists of human-readable instructions that define the app’s functionality. These instructions use clear terms like “if,” “for,” and meaningful names for methods (functions) and variables (data holders). However, during the build process, this Java code gets compiled into bytecode, a lower-level language understood by the Java Virtual Machine (JVM), an intermediate format that the Android system interprets. Bytecode offers no protection, making it highly susceptible to reverse engineering by tools such as Smali and JADX, which take the Java source code and decompile it into a readable format that allows attackers to examine an app’s functionality and behavior. This can be risky, especially for apps that handle sensitive data or have unique algorithms.

Why Does Java Need it's Own Obfuscation?

Once an attacker has access to the .dex files (containing the bytecode), they can potentially reverse-engineer the logic behind your app and expose your intellectual property and core functionalities. Obfuscation is a security technique that deliberately obscures the internal workings of your code without affecting its functionality. Appdome’s Obfuscate App Logic feature involves renaming methods, functions, variables, and classes within the bytecode. These originally clear and descriptive names are replaced with cryptic characters, making it significantly more challenging to understand the app’s logic by simply looking at the bytecode. This process is essential in preventing attackers from using static code analysis to dissect the application’s functionality, ensuring the security and integrity of the app’s business logic, and protecting intellectual property. Through obfuscation, developers can significantly mitigate the risks associated with code tampering and piracy, preserving the application’s reliability and user trust.

In addition to Obfuscate App Logic, app developers can choose to enforce Appdome’s Dex File Encryption feature. However, it is important to note that Dex File Encryption may cause latency issues. To reduce the latency, we recommend managing the amount of code you’re encrypting.

Prerequisites for Using Obfuscate App Logic:

To use Appdome’s mobile app security build system to Obfuscate App Logic , you’ll need:

Appdome account (create a free Appdome account here)
A license for Obfuscate App Logic
Mobile App (.apk or .aab for Android)
Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)

Obfuscate App Logic on Android apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Obfuscate App Logic without an SDK or gateway:

Upload the Mobile App to Appdome.
1. Upload an app to Appdome’s Mobile App Security Build System
2. Upload Method: Appdome Console or DEV-API
3. Android Formats: .apk or .aab
4. Obfuscate App Logic Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps
Build the feature: Obfuscate App Logic.
1. Building Obfuscate App Logic by using Appdome’s DEV-API:
  1. Create and name the Fusion Set (security template) that will contain the Obfuscate App Logic feature as shown below:
  2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Obfuscate App Logic feature via Appdome Console, to add the Obfuscate App Logic feature to this Fusion Set.
  3. Open the Fusion Set Detail Summary by clicking the “...” symbol on the far-right corner of the Fusion Set. Copy the Fusion Set ID from the Fusion Set Detail Summary (as shown below):”
    
    Figure 2: Fusion Set Detail Summary
    Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).
  4. Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, App Center, Jenkins, Travis, Team City, Circle CI or other system:
    
    Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
    
    Look for sample APIs in Appdome’s GitHub Repository
2. Building the Obfuscate App Logic feature via Appdome Console
  
  To build the Obfuscate App Logic protection by using Appdome Console, follow the instructions below.
  1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALCode™ Obfuscation section.
    Like all other options in ONEShield™, Obfuscate App Logic is turned on by default, as shown below:
    Figure 3: Obfuscate App Logic option
    Note: The App Compromise Notification contains an easy to follow default remediation path for the mobile app end user. You can customize this message as required to achieve brand specific support, workflow or other messaging.
  2. How: Toggle (turn ON) Obfuscate App Logic, as shown below.
    
    Figure 3: Obfuscate App Logic option
  3. When you select the Obfuscate App Logic you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Obfuscate App Logic
    
    Figure 4: Fusion Set that displays the newly added Obfuscate App Logic protection
  4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
Congratulations! The Obfuscate App Logic protection is now added to the mobile app
Certify the Obfuscate App Logic feature in Android Apps.

After building Obfuscate App Logic, Appdome generates a Certified Secure™ certificate to guarantee that the Obfuscate App Logic protection has been added and is protecting the app. To verify that the Obfuscate App Logic protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below:

Figure 5: Certified Secure™ certificate

Each Certified Secure™ certificate provides DevOps and DevSecOps organizations the entire workflow summary, audit trail of each build, and proof of protection that Obfuscate App Logic has been added to each Android app. Certified Secure provides instant and in-line DevSecOps compliance certification that Obfuscate App Logic and other mobile app security features are in each build of the mobile app

Using Threat-Events™ for App Logic Intelligence and Control in Android Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when App Logic is detected. To consume and use Threat-Events™ for App Logic in Android Apps, use registerReceiver in the Application OnCreate, and the code samples for Threat-Events™ for App Logic shown below.

The specifications and options for Threat-Events™ for App Logic are:

Threat-Event™ Elements	Obfuscate App Logic Method Detail
Appdome Feature Name	Obfuscate App Logic
Threat-Event Mode
OFF, IN-APP DEFENSE	Appdome detects, defends and notifies user (standard OS dialog) using customizable messaging.
ON, IN-APP DETECTION	Appdome detects the attack or threat and passes the event in a standard format to the app for processing (app chooses how and when to enforce).
ON, IN-APP DEFENSE	Uses Appdome Enforce mode for any attack or threat and passes the event in a standard format to the app for processing (gather intel on attacks and threats without losing any protection).
Certified Secure™ Threat Event Check	x
Visible in ThreatScope™	x
Developer Parameters for Obfuscating App Logic Threat-Event™
Threat-Event NAME
Threat-Event DATA	reasonData
Threat-Event CODE	reasonCode
Threat-Event REF
Threat-Event SCORE
currentThreatEventScore	Current Threat-Event score
threatEventsScore	Total Threat-events score

Threat-Event Context Keys
message	Message displayed for the user on event
externalID	The external ID of the event which can be listened via Threat Events
osVersion	OS version of the current device
deviceModel	Current device model
deviceManufacturer	The manufacturer of the current device
fusedAppToken	The task ID of the Appdome fusion of the currently running app
kernelInfo	Info about the kernel: system name, node name, release, version and machine.
carrierPlmn	PLMN of the device
deviceID	Current device ID
reasonCode	Reason code of the occured event
buildDate	Appdome fusion date of the current application
devicePlatform	OS name of the current device
carrierName	Carrier name of the current device
updatedOSVersion	Is the OS version up to date
deviceBrand	Brand of the device
deviceBoard	Board of the device
buildUser	Build user
buildHost	Build host
sdkVersion	Sdk version
timeZone	Time zone
deviceFaceDown	Is the device face down
locationLong	Location longitude conditioned by location permission
locationLat	Location latitude conditioned by location permission
locationState	Location state conditioned by location permission
wifiSsid	Wifi SSID
wifiSsidPermissionStatus	Wifi SSID permission status

With Threat-Events™ enabled (turned ON), Android developers can get detailed attack intelligence and granular defense control in Android applications and create amazing user experiences for all mobile end users when App Logic is detected.

The following is a code sample for native Android apps, which uses all values in the specification above for Obfuscate App Logic:

                    IntentFilter intentFilter = new IntentFilter();
                    intentFilter.addAction("");
                    BroadcastReceiver threatEventReceiver = new BroadcastReceiver() {
                        @Override
                        public void onReceive(Context context, Intent intent) {
                            String message = intent.getStringExtra("message"); // Message shown to the user
                            String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause
                            String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code
                            String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Current threat event score
                            String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Total threat events score
                            String variable = intent.getStringExtra(""); // Any other event specific context key

                            // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                        }
                    };

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                        registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED);
                    } else {
                        registerReceiver(threatEventReceiver, intentFilter);
                    }

Java
x
 
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("");
BroadcastReceiver threatEventReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String message = intent.getStringExtra("message"); // Message shown to the user
        String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause
        String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code
        String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Current threat event score
        String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Total threat events score
        String variable = intent.getStringExtra("<Context Key>"); // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    }
};
​
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED);
} else {
    registerReceiver(threatEventReceiver, intentFilter);
}

                    val intentFilter = IntentFilter()
                    intentFilter.addAction("")
                    val threatEventReceiver = object : BroadcastReceiver() {
                        override fun onReceive(context: Context?, intent: Intent?) {
                            var message = intent?.getStringExtra("message") // Message shown to the user
                            var reasonData = intent?.getStringExtra("reasonData") // Threat detection cause
                            var reasonCode = intent?.getStringExtra("reasonCode") // Event reason code
                            var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore") // Current threat event score
                            var threatEventsScore = intent?.getStringExtra("threatEventsScore") // Total threat events score
                            var variable = intent?.getStringExtra("") // Any other event specific context key

                            // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                        }
                    }

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                        registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED)
                    } else {
                        registerReceiver(threatEventReceiver, intentFilter)
                    }

                         
                        Kotlin
                    
x
 
val intentFilter = IntentFilter()
intentFilter.addAction("")
val threatEventReceiver = object : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        var message = intent?.getStringExtra("message") // Message shown to the user
        var reasonData = intent?.getStringExtra("reasonData") // Threat detection cause
        var reasonCode = intent?.getStringExtra("reasonCode") // Event reason code
        var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore") // Current threat event score
        var threatEventsScore = intent?.getStringExtra("threatEventsScore") // Total threat events score
        var variable = intent?.getStringExtra("<Context Key>") // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    }
}
​
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED)
} else {
    registerReceiver(threatEventReceiver, intentFilter)
}

const { ADDevEvents } = NativeModules;
                const aDDevEvents = new NativeEventEmitter(ADDevEvents);

                function registerToDevEvent(action, callback) {
                    NativeModules.ADDevEvents.registerForDevEvent(action);
                    aDDevEvents.addListener(action, callback);
                }

                export function registerToAllEvents() {
                    registerToDevEvent(
                        "",
                        (userinfo) => Alert.alert(JSON.stringify(userinfo))

                        var message = userinfo["message"] // Message shown to the user
                        var reasonData = userinfo["reasonData"] // Threat detection cause
                        var reasonCode = userinfo["reasonCode"] // Event reason code
                        var currentThreatEventScore = userinfo["currentThreatEventScore"] // Current threat event score
                        var threatEventsScore = userinfo["threatEventsScore"] // Total threat events score
                        var variable = userinfo["<Context Key>"] // Any other event specific context key

                        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                    );
                }

                     
                    React Native
                
​x
 
const { ADDevEvents } = NativeModules;
const aDDevEvents = new NativeEventEmitter(ADDevEvents);
​
function registerToDevEvent(action, callback) {
    NativeModules.ADDevEvents.registerForDevEvent(action);
    aDDevEvents.addListener(action, callback);
}
​
export function registerToAllEvents() {
    registerToDevEvent(
        "",
        (userinfo) => Alert.alert(JSON.stringify(userinfo))
​
        var message = userinfo["message"] // Message shown to the user
        var reasonData = userinfo["reasonData"] // Threat detection cause
        var reasonCode = userinfo["reasonCode"] // Event reason code
        var currentThreatEventScore = userinfo["currentThreatEventScore"] // Current threat event score
        var threatEventsScore = userinfo["threatEventsScore"] // Total threat events score
        var variable = userinfo["<Context Key>"] // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    );
}
​

RegisterReceiver(new ThreatEventReceiver(), new IntentFilter(""));
                class ThreatEventReceiver : BroadcastReceiver
                {
                public override void OnReceive(Context context, Intent intent)
                {
                    String message = intent.GetStringExtra("message"); // Message shown to the user
                    String reasonData = intent.GetStringExtra("reasonData"); // Threat detection cause
                    String reasonCode = intent.GetStringExtra("reasonCode"); // Event reason code
                    String currentThreatEventScore = intent.GetStringExtra("currentThreatEventScore"); // Current threat event score
                    String threatEventsScore = intent.GetStringExtra("threatEventsScore"); // Total threat events score
                    String variable = intent.GetStringExtra("<Context Key>"); // Any other event specific context key

                    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                }
                }

                    
                    Xamarin/MAUI Android
                
​x
 
RegisterReceiver(new ThreatEventReceiver(), new IntentFilter(""));
​
class ThreatEventReceiver : BroadcastReceiver
{
  public override void OnReceive(Context context, Intent intent)
  {
    String message = intent.GetStringExtra("message"); // Message shown to the user
    String reasonData = intent.GetStringExtra("reasonData"); // Threat detection cause
    String reasonCode = intent.GetStringExtra("reasonCode"); // Event reason code
    String currentThreatEventScore = intent.GetStringExtra("currentThreatEventScore"); // Current threat event score
    String threatEventsScore = intent.GetStringExtra("threatEventsScore"); // Total threat events score
    String variable = intent.GetStringExtra("<Context Key>"); // Any other event specific context key
​
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
  }
}

                NSNotificationCenter.DefaultCenter.AddObserver(
                    (NSString)"JailbrokenDevice", // Threat-Event Identifier
                    delegate (NSNotification notification)
                    {
                        var message = notification.UserInfo.ObjectForKey("message"); // Message shown to the user
                        var reasonData = notification.UserInfo.ObjectForKey("reasonData"); // Threat detection cause
                        var reasonCode = notification.UserInfo.ObjectForKey("reasonCode"); // Event reason code
                        var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore"); // Current threat event score
                        var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore"); // Total threat events score
                        var variable = notification.UserInfo.ObjectForKey(""); // Any other event specific context key
                        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                    });

                    
                    Xamarin/MAUI iOS
                
 
NSNotificationCenter.DefaultCenter.AddObserver(
  (NSString)"", // Threat-Event Identifier
  delegate (NSNotification notification)
  {
    var message = notification.UserInfo.ObjectForKey("message"); // Message shown to the user
    var reasonData = notification.UserInfo.ObjectForKey("reasonData"); // Threat detection cause
    var reasonCode = notification.UserInfo.ObjectForKey("reasonCode"); // Event reason code
    var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore"); // Current threat event score
    var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore"); // Total threat events score
    var variable = notification.UserInfo.ObjectForKey("<Context Keys>"); // Any other event specific context key
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
  });

window.broadcaster.addEventListener("", function(userInfo) {
        var message = userInfo.message // Message shown to the user
        var reasonData = userInfo.reasonData // Threat detection cause
        var reasonCode = userInfo.reasonCode // Event reason code
        var currentThreatEventScore = userInfo.currentThreatEventScore // Current threat event score
        var threatEventsScore = userInfo.threatEventsScore // Total threat events score
        var variable = userInfo.<Context Key> // Any other event specific context key

        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
            });

                    
                    Cordova
                
​x
 
window.broadcaster.addEventListener("", function(userInfo) {
        var message = userInfo.message // Message shown to the user
        var reasonData = userInfo.reasonData // Threat detection cause
        var reasonCode = userInfo.reasonCode // Event reason code
        var currentThreatEventScore = userInfo.currentThreatEventScore // Current threat event score
        var threatEventsScore = userInfo.threatEventsScore // Total threat events score
        var variable = userInfo.<Context Key> // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
});

                import 'dart:async';
                import 'package:flutter/material.dart';
                import 'package:flutter/services.dart';

                class PlatformChannel extends StatefulWidget {
                  const PlatformChannel({super.key});

                  @override
                  State<PlatformChannel> createState() => _PlatformChannelState();
                }

                class _PlatformChannelState extends State<PlatformChannel> {
                  static const String _eventChannelName = ""; // Replace with your EventChannel name
                  static const EventChannel _eventChannel = EventChannel(_eventChannelName);

                  @override
                  void initState() {
                    super.initState();
                    _eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError);
                  }

                  void _onEvent(Object? event) {
                    setState(() {
                      // Adapt this section based on your specific event data structure
                      var eventData = event as Map;

                      // Example: Accessing 'externalID' field from the event
                      var externalID = eventData['externalID'];

                      // Customize the rest of the fields based on your event structure
                      String message = eventData['message']; // Message shown to the user
                      String reasonData = eventData['reasonData']; // Threat detection cause
                      String reasonCode = eventData['reasonCode']; // Event reason code
                      String currentThreatEventScore = eventData['currentThreatEventScore']; // Current threat event score
                      String threatEventsScore = eventData['threatEventsScore']; // Total threat events score

                      // Any other event specific context key
                      String variable = eventData['<Context Key>'];
                    });
                  }

                  // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                }

                    
                    Flutter
                
xxxxxxxxxx
 
import 'dart:async';
​
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
​
class PlatformChannel extends StatefulWidget {
  const PlatformChannel({super.key});
​
  @override
  State<PlatformChannel> createState() => _PlatformChannelState();
}
​
class _PlatformChannelState extends State<PlatformChannel> {
  static const String _eventChannelName = ''; // Replace with your EventChannel name
  static const EventChannel _eventChannel = EventChannel(_eventChannelName);
​
  @override
  void initState() {
    super.initState();
    _eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError);
  }
​
  void _onEvent(Object? event) {
    setState(() {
      // Adapt this section based on your specific event data structure
      var eventData = event as Map;
​
      // Example: Accessing 'externalID' field from the event
      var externalID = eventData['externalID'];
​
      // Customize the rest of the fields based on your event structure
      String message = eventData['message']; // Message shown to the user
      String reasonData = eventData['reasonData']; // Threat detection cause
      String reasonCode = eventData['reasonCode']; // Event reason code
      String currentThreatEventScore = eventData['currentThreatEventScore']; // Current threat event score
      String threatEventsScore = eventData['threatEventsScore']; // Total threat events score
​
      // Any other event specific context key
      String variable = eventData['<Context Key>'];
    });
  }
​
  // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}

Using Appdome, there are no development or coding prerequisites to build secured Android Apps by using Obfuscate App Logic. There is no SDK and no library to code or implement in the app and no gateway to deploy in your network. All protections are built into each app and the resulting app is self-defending and self-protecting.

Releasing and Publishing Mobile Apps with Obfuscate App Logic

After successfully securing your app by using Appdome, there are several available options to complete your project, depending on your app lifecycle or workflow. These include:

Customizing, Configuring & Branding Secure Mobile Apps
Deploying/Publishing Secure mobile apps to Public or Private app stores
Releasing Secured Android & iOS Apps built on Appdome.

How to Obfuscate Kotlin Code in Android Apps

Obfuscate Mobile Business Logic, Anti-Reversing in Android Apps

Dex Relocation, Anti-Reversing for Android Apps

If you have any questions, please send them our way at support.appdome.com or via the chat window on the Appdome platform.

Thank you!

Thanks for visiting Appdome! Our mission is to secure every app on the planet by making mobile app security easy. We hope we’re living up to the mission with your project.

How to Obfuscate Java Code in Android Apps

What is Java Code in Android Apps?

Why Does Java Need it's Own Obfuscation?

Prerequisites for Using Obfuscate App Logic:

Obfuscate App Logic on Android apps using Appdome

Upload the Mobile App to Appdome.

Upload an app to Appdome’s Mobile App Security Build System

Build the feature: Obfuscate App Logic.

Building Obfuscate App Logic by using Appdome’s DEV-API:

Building the Obfuscate App Logic feature via Appdome Console

Certify the Obfuscate App Logic feature in Android Apps.

Using Threat-Events™ for App Logic Intelligence and Control in Android Apps

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