How to Obfuscate Mobile App Logic in Android Apps
This Knowledge Base article describes how to use Appdome’s AI/ML in your CI/CD pipeline to continuously deliver plugins that Obfuscate App Logic in Android apps.
What is code obfuscation?
One of the most used types of reverse engineering is static code analysis, where an attacker attempts to analyze the source code of an iOS or Android application in order to understand what the source code does and how it does it – all without running the app.
While there are many different methods and techniques to obfuscate mobile application code, Obfuscating App Logic is an effective way of preventing attackers from using static code analysis to understand the application’s logical flow, especially when combined with other obfuscation techniques such as binary code obfuscation and application shielding.
How does Appdome implement code obfuscation?
Appdome’s Obfuscate App Logic, when enabled, automatically obfuscates application logic classes and methods, renaming them to random strings. This solution preserves the clarity of open-source libraries by keeping them non-obfuscated. The advanced combination of this feature with string encryption and Strip Debug Information, significantly complicates unauthorized attempts to understand the code.
When enabling Appdome’s Obfuscate App Logic feature, the obfuscation of package names and dynamic classes, are included automatically. This functionality simplifies the process, making it seamless to incorporate robust code protection without necessitating manual adjustments for these components.
Detailed Features of Appdome’s Code Obfuscation:
- Excluding Specific Classes:
Excluding a class from obfuscation necessitates the exclusion of the whole package to which the class belongs. This is due to the access rules inherent to Java classes.
In the process of obfuscating a package, Appdome changes it entirely. However, any excluded classes still retain the non-obfuscated package name. Therefore, when an obfuscated class tries to access a non-obfuscated class (the excluded one), Java may raise an ‘illegal access exception’ despite both classes residing under the same package name in the original non-obfuscated app.
To prevent such cases, once a class is excluded, the class package is excluded.
In order to exclude classes, you will need to add the package of the classes you wish to exclude. For instance, excluding the class “com/appdome/test/TestClass” involves adding either “com/appdome/test” or “com.appdome.test” to the Exclude Specific Classes list.
- Multilingual Obfuscation:
When using only ASCII characters for obfuscation, it is easier to follow a flow using reverse engineering tools such as JADX or hooking methods using hacking tools such as Frida. Appdome’s new obfuscation mechanism, Multilingual Obfuscation adds another layer of protection to the app’s obfuscation, significantly complicating any attempts made by an attacker to reverse engineer the application and deconstruct the code, thereby enhancing its security. Appdome’s Multilingual Obfuscation method, differs from standard methods in that it uses Unicode characters, and a novel runtime algorithm as opposed to traditional ASCII characters, this complexity significantly complicates attempts to deconstruct the code, thereby enhancing its security.
Note: The Multilingual Obfuscation feature is supported on Android 8.0 and above. Please be aware that if the app is obfuscated using Unicode characters, you will not be able to install this app on Android 7.1.1 or earlier versions.
Prerequisites for Using Appdome's Obfuscate App Logic Plugins:
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)
How to Implement Obfuscate App Logic in 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:
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Designate the Mobile App to be protected.
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Upload an app via the Appdome Mobile Defense platform GUI or via Appdome’s DEV-API or CI/CD Plugins.
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Android Formats: .apk or .aab
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Obfuscate App Logic is compatible with: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps.
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Select the defense: Obfuscate App Logic.
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Follow the steps in Sections 2.2-2.2.2 of this article to add the Obfuscate App Logic feature to your Fusion Set via the Appdome Console.
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When you select the Obfuscate App Logic you'll notice that the Fusion Set you created in step 2.1 now bears the icon of the protection category that contains Obfuscate App Logic.
Figure 2: Fusion Set that displays the newly added Obfuscate App Logic protection
Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory). -
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 3: Fusion Set Detail Summary
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Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, Jenkins, Travis, Team City, Circle CI or other system:
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Refer to the Appdome API Reference Guide for API building instructions.
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Look for sample APIs in Appdome’s GitHub Repository.
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Create and name the Fusion Set (security template) that will contain the Obfuscate App Logic feature as shown below:Figure 1: Fusion Set that will contain the Obfuscate App Logic feature
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Add the Obfuscate App Logic feature to your security template.
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Navigate to Build > Security tab > TOTALCode™ Obfuscation section in the Appdome Console.
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Toggle On > Obfuscate App Logic.
Figure 4: Selecting Obfuscate App Logic
- Optional Configuration with Obfuscate App Logic:
- Obfuscate Package Names
Obfuscates package and class names within the application’s business logic.
- Obfuscate Dynamic Classes
Obfuscates (renames) classes to random strings.
- Obfuscate Dynamic Methods
Obfuscates (renames) methods to random strings.
- Obfuscate Linkages and Reflection
Supports obfuscation of classes and methods used in reflection and in JNI up-calls and down-calls.
- Obfuscate Crashes
Obfuscates methods and classes in crashes and stack traces.
- Exclude Specific Classes
List class or package prefixes to exclude from obfuscation.
- Obfuscation Mapping File/Script
Download mapping scripts and files in order to deobfuscate the app for further investigation.
- Multilingual Obfuscation
Employs Unicode and unique algorithms, complicating reverse engineering attempts beyond standard ASCII obfuscation methods.
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Congratulations! The Obfuscate App Logic protection is now added to the mobile app -
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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 |
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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 | |
Visible in ThreatScope™ | |
Developer Parameters for Obfuscating App Logic Threat-Event™ | |
Threat-Event NAME | NoName |
Threat-Event DATA | reasonData |
Threat-Event CODE | reasonCode |
Threat-Event REF | 6801 |
Threat-Event SCORE | |
currentThreatEventScore | Current Threat-Event score |
threatEventsScore | Total Threat-events score |
Threat-Event Context Keys | |
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message | Message displayed for the user on event |
failSafeEnforce | Timed enforcement against the identified threat |
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. Only available for Android devices. |
deviceID | Current device ID |
reasonCode | Reason code of the occurred event |
buildDate | Appdome fusion date of the current application |
devicePlatform | OS name of the current device |
carrierName | Carrier name of the current device. Only available for Android. |
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 |
threatCode | The last six characters of the threat code specify the OS, allowing the Threat Resolution Center to address the attack on the affected device. |
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:
Important! Replace all placeholder instances of <Context Key> with the specific name of your threat event context key across all language examples. This is crucial to ensure your code functions correctly with the intended event data. For example, The <Context Key> could be the message, externalID, OS Version, reason code, etc.
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IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("NoName");
BroadcastReceiver threatEventReceiver = new BroadcastReceiver() {
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
// Current threat event score
String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore");
// Total threat events score
String threatEventsScore = intent.getStringExtra("threatEventsScore");
// Replace '<Context Key>' with your specific event context key
// String variable = intent.getStringExtra("<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);
}
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val intentFilter = IntentFilter()
intentFilter.addAction("NoName")
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
// Current threat event score
var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore")
// Total threat events score
var threatEventsScore = intent?.getStringExtra("threatEventsScore")
// Replace '<Context Key>' with your specific event context key
// var variable = intent?.getStringExtra("<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)
}
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const { ADDevEvents } = NativeModules;
const aDDevEvents = new NativeEventEmitter(ADDevEvents);
function registerToDevEvent(action, callback) {
NativeModules.ADDevEvents.registerForDevEvent(action);
aDDevEvents.addListener(action, callback);
}
export function registerToAllEvents() {
registerToDevEvent(
"NoName",
(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
// Current threat event score
var currentThreatEventScore = userinfo["currentThreatEventScore"]
// Total threat events score
var threatEventsScore = userinfo["threatEventsScore"]
// Replace '<Context Key>' with your specific event context key
// var variable = userinfo["<Context Key>"]
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
);
}
x
RegisterReceiver(new ThreatEventReceiver(), new IntentFilter("NoName"));
class ThreatEventReceiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
// Message shown to the user
String message = intent.GetStringExtra("message");
// Threat detection cause
String reasonData = intent.GetStringExtra("reasonData");
// Event reason code
String reasonCode = intent.GetStringExtra("reasonCode");
// Current threat event score
String currentThreatEventScore = intent.GetStringExtra("currentThreatEventScore");
// Total threat events score
String threatEventsScore = intent.GetStringExtra("threatEventsScore");
// Replace '<Context Key>' with your specific event context key
// String variable = intent.GetStringExtra("<Context Key>");
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}
}
x
NSNotificationCenter.DefaultCenter.AddObserver(
(NSString)"NoName", // Threat-Event Identifier
delegate (NSNotification notification)
{
// Message shown to the user
var message = notification.UserInfo.ObjectForKey("message");
// Threat detection cause
var reasonData = notification.UserInfo.ObjectForKey("reasonData");
// Event reason code
var reasonCode = notification.UserInfo.ObjectForKey("reasonCode");
// Current threat event score
var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore");
// Total threat events score
var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore");
// Replace '<Context Key>' with your specific event context key
// var variable = notification.UserInfo.ObjectForKey("<Context Keys>");
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}
);
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window.broadcaster.addEventListener("NoName", 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
// Current threat event score
var currentThreatEventScore = userInfo.currentThreatEventScore
// Total threat events score
var threatEventsScore = userInfo.threatEventsScore
// Replace '<Context Key>' with your specific event context key
// var variable = userInfo.<Context Keys>
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
});
x
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class PlatformChannel extends StatefulWidget {
const PlatformChannel({super.key});
State<PlatformChannel> createState() => _PlatformChannelState();
}
class _PlatformChannelState extends State<PlatformChannel> {
// Replace with your EventChannel name
static const String _eventChannelName = "NoName";
static const EventChannel _eventChannel = EventChannel(_eventChannelName);
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
// Current threat event score
String currentThreatEventScore = eventData['currentThreatEventScore'];
// Total threat events score
String threatEventsScore = eventData['threatEventsScore'];
// Replace '<Context Key>' with your specific event context key
// String variable = eventData['<Context Keys>'];
});
}
// 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.
Related Articles:
- How to Obfuscate Non-Native Android & iOS Code and Frameworks
- How to add Native Code Obfuscation to any iOS, Android app
- How to Encrypt Java Class Files (.dex) in Android Apps
- Appdome ONEShield Mobile App Hardening
How Do I Learn More?
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.