How to Optimize File Size when Obfuscating Android Apps

Learn to Prevent obfuscation of publicly available components in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

Why Prevent Obfuscation of Publicly Available Components?

Obfuscation reduces the efficiency of compression algorithms; therefore, obfuscating all the code in the app may significantly increase its file size. On the other hand, excluding publicly available elements from obfuscation decreases the size of the built app.

Which Libraries are Excluded from Obfuscation?

If you enable Favor App Size, the following libraries will remain deobfuscated:

Open Source Libraries:

Xamarin Libraries

libmonodroid.so, libmono-btls-shared.so, libmonosgen-2.0.so, libe_sqlite3.so

React Native

libfb.so, libfolly_json.so, libglog.so, libglog_init.so, libgnustl_shared.so, libicu_common.so, libimagepipeline.so, libjsc.so, libprivatedata.so, libreactnativejni.so, libyoga.so. libc++_shared.so

Unity

libunity.so, libil2cpp.so, libcri_ware_unity.so, libgpg.so

Cordova

libxwalkcore.so, libxwalkdummy.so, libsqlcipher.so

IMPORTANT: Some applications which come with anti-tampering might clash with Appdome’s binary code obfuscation. Read this article to learn more about Appdome’s Anti-Tampering functionality.

Prerequisites for Using Favor App's Size:

To use Appdome’s mobile app security build system to Prevent obfuscation of publicly available components , you’ll need:

• Appdome account (create a free Appdome account here)
• A license for Favor App's Size
• Mobile App (.apk or .aab for Android)
• Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)

Prevent obfuscation of publicly available components on Android apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Prevent obfuscation of publicly available components 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. Favor App's Size Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps

2. Build the feature: Favor App's Size.

   1. Building Favor App's Size by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Favor App's Size feature as shown below:
      

      Figure 1: Fusion Set that will contain the Favor App's Size 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 Favor App's Size feature via Appdome Console, to add the Favor App's Size 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 Favor App's Size feature via Appdome Console

      To build the Favor App's Size 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™, Favor App's Size is turned on by default, as shown below:

         Figure 3: Favor App's Size 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) Favor App's Size, as shown below.

         Figure 3: Prevent obfuscation of publicly available components option

      3. When you select the Favor App's Size you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Favor App's Size

         

         Figure 4: Fusion Set that displays the newly added Favor App's Size protection

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

   Congratulations!  The Favor App's Size protection is now added to the mobile app

3. Certify the Favor App's Size feature in Android Apps.

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