How to Prevent Java Decoding to Protect Android apps

Learn to Prevent Java Decoding in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is Java Decoding?

You can use Appdome to Prevent Java Decoding to Protect Android apps. Java Decoding is a method of reverse engineering, where hackers use open-source decompilers such as Jadx to discover and display the original Java source code of an app.

Such tools operate by taking the dex files of an already compiled .apk file, converting them to Smali code and then displaying the Smali code in a form similar to a human-readable Java code.

How does Appdome prevent Java Decoding?

Appdome uses advanced dex manipulation techniques to obfuscate and complicate logic code blocks, making it harder for open-source decompilers such as Jadx to read the dex and translate it to readable Java code. Appdome ensures that the performance of the app is not hindered by the dex manipulation and only affects static code decompilers that the code should be protected from.

Enabling (toggling On) the Anti-Reverse Engineering and enabling the Anti Java decoding sub toggle, automatically prevents the use of decompilers and other reverse engineering tools to perform Java decoding.

Prerequisites for Using Anti Java Decoding:

To use Appdome’s mobile app security build system to Prevent Java Decoding , you’ll need:

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

Prevent Java Decoding on Android apps using Appdome

On Appdome, follow these simple steps to create self-defending Android Apps that Prevent Java Decoding without an SDK or gateway:

1. 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. Anti Java Decoding Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps

2. Build the feature: Anti Java Decoding.

   1. Building Anti Java Decoding by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Anti Java Decoding feature as shown below:
      

      Figure 1: Fusion Set that will contain the Anti Java Decoding feature
      Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required).

      2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Anti Java Decoding feature via Appdome Console, to add the Anti Java Decoding 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, as shown in Figure 1 above, and get 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, Cirlce CI or other system:

         1. Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
         2. Look for sample APIs in Appdome’s GitHub Repository

   2. Building the Anti Java Decoding feature via Appdome Console

      To build the Anti Java Decoding protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > Anti-Reverse Engineering section.

         Like all other options in ONEShield™, Anti Java Decoding is turned on by default, as shown below:

         Figure 3: Anti Java Decoding 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: Check whether Obfuscate App Logic is toggled On (enabled), otherwise enable it . You can see that the feature Anti Java Decoding is enabled by default, as shown below.

         Figure 3: Prevent Java Decoding option

      3. When you enable 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 Anti Java Decoding

         

         Figure 4: Fusion Set that displays the newly added Anti Java Decoding protection

      4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).

   Congratulations!  The Anti Java Decoding protection is now added to the mobile app

3. Certify the Anti Java Decoding feature in Android Apps.

   After building Anti Java Decoding, Appdome generates a Certified Secure™ certificate to guarantee that the Anti Java Decoding protection has been added and is protecting the app. To verify that the Anti Java Decoding 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 Anti Java Decoding has been added to each Android app. Certified Secure provides instant and in-line DevSecOps compliance certification that Anti Java Decoding and other mobile app security features are in each build of the mobile app