Dex Relocation, Anti-Reversing for Android Apps

Last updated November 29, 2023 by Appdome

Learn to Use Dex Relocation in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is Dex Relocation?

In Android, compiled Java/Kotlin code resides in classes.dex files. Appdome’s Dex Relocation refers to a security technique that modifies a mobile app’s compiled code by obfuscating the logical control flow, thereby protecting Android apps against static code analysis and other forms of reverse engineering. The purpose of Dex relocation is to make reverse engineering tools ineffective and even unusable, making the code difficult to trace and understand.

Why Use Appdome's Dex Relocation?

Implementing Appdome’s Dex Relocation offers a crucial layer of protection for Android apps. By obfuscating the logical flow of the compiled code, it deters potential attackers by making the code significantly more difficult to decipher and exploit. In essence, Dex Relocation ensures the application’s integrity, safeguards user data, and protects the developer’s intellectual assets. To do this, Appdome uses several techniques such as applying call obfuscation to the compiled Java code and modifying the function call targets to obscure functions.

Appdome’s Dex Relocation doesn’t operate in isolation. When combined with Appdome’s TotalCode Obfuscation techniques, a reinforced protective layer emerges. These techniques complement and fortify each other, resulting in a comprehensive defense strategy that offers heightened resistance against potential threats.

Prerequisites for Using Dex Relocation:

To use Appdome’s mobile app security build system to Use Dex Relocation , you’ll need:

Use Dex Relocation on Android apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Use Dex Relocation 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. Dex Relocation Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps
  2. Build the feature: Dex Relocation.

    1. Building Dex Relocation by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Dex Relocation feature as shown below:
      2. fusion set that contains Dex Relocation

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

      3. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Dex Relocation feature via Appdome Console, to add the Dex Relocation feature to this Fusion Set.

      4. 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): fusion Set Detail Summary image

        Figure 2: Fusion Set Detail Summary
        Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).

      5. 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 Dex Relocation feature via Appdome Console

      To build the Dex Relocation protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALCode™ Obfuscation section.
      2. When you select the Dex Relocation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Dex Relocation

        Fusion Set applied Dex Relocation

        Figure 4: Fusion Set that displays the newly added Dex Relocation protection

      3. Extra Configuration with Dex Relocation:
        1. Favor Loading Time

          Automatically detect and optimize obfuscation of publicly available components in order to preserve application loading time.

        2. Exclude Specific Classes

          List class or package prefixes to exclude and not obfuscate.

        3. No Mapping File/Script

          Changes the flow logic, but does not rename functions. No mapping file or script needed.

      4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Dex Relocation protection is now added to the mobile app

Using Appdome, there are no development or coding prerequisites to build secured Android Apps by using Dex Relocation. 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 Dex Relocation

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:

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If you have any questions, please send them our way at 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.

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