How to Encrypt Assets in Android Apps

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

What are Mobile Application Assets?

Mobile application assets provide a way to enhance the functionality and visual appearance of your mobile application. These assets are essential components of mobile app development and can include a variety of elements:

Images and Graphics: These are visual files like icons, logos, and background images that help define the look of the app. They can be static or dynamic, depending on the functionality and design requirements.

Audio and Video Files: Media files that provide auditory and visual content. These might include background music, sound effects, instructional videos, or promotional media.

Fonts and Text Files: Custom fonts can be included to maintain brand consistency and enhance aesthetics. Text files, often in the form of XML or JSON, can also be used for localization, allowing the app to support multiple languages.

Animations: Assets for animations might include sprite sheets or data files that describe animation sequences. These are used to create engaging and dynamic user interfaces.

Data Files: These might include configuration files, databases, or JSON/XML files that the app uses to store information locally or to configure its behavior.

UI Elements: This can include buttons, sliders, and other interactive components that make up the user interface.

These files, which are necessary for the app’s functionality and performance, are stored on the device under the assets folder of the application and are used during runtime.

Why Should Developers Encrypt Application Assets in Android Apps?

Encrypting application assets in Android apps is crucial primarily for ensuring security and protecting intellectual property. Encryption helps safeguard sensitive data contained within assets, such as configuration files with API keys or proprietary algorithms, from unauthorized access and exploitation. Moreover, it prevents tampering, ensuring that assets cannot be easily modified. This is particularly vital for maintaining the functionality and security of an app, as tampered assets can lead to malfunctions or introduce security vulnerabilities. Overall, encryption serves as a critical measure in securing an app’s operational integrity and safeguarding user data.

Prerequisites for Using Encrypt Assets:

To use Appdome’s mobile app security build system to Encrypt Assets , you’ll need:

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

Encrypt Assets on Android apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Encrypt Assets 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. Encrypt Assets Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps

2. Build the feature: Encrypt Assets.

   1. Building Encrypt Assets by using Appdome’s DEV-API:

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

      Figure 1: Fusion Set that will contain the Encrypt Assets 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 Encrypt Assets feature via Appdome Console, to add the Encrypt Assets 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 Encrypt Assets feature via Appdome Console

      To build the Encrypt Assets protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALData™ Encryption section.

         Like all other options in ONEShield™, Encrypt Assets is turned on by default, as shown below:

         Figure 3: Encrypt Assets 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) Encrypt Assets, as shown below.

         Figure 3: Encrypt Assets option

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

         

         Figure 4: Fusion Set that displays the newly added Encrypt Assets protection

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

   Congratulations!  The Encrypt Assets protection is now added to the mobile app

3. Certify the Encrypt Assets feature in Android Apps.

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