How to Encrypt Java Strings in Android Apps

Last updated March 11, 2024 by Appdome

This Knowledge Base article describes how to use Appdome’s AI/ML in your CI/CD pipeline to continuously deliver plugins that Encrypt Strings in Android apps.

What are Strings?

In Android apps, strings are any text-based information stored in or used by the app (eg: Java strings, or strings.xml). Strings are often used to store and share text-based information such as usernames, passwords, authentication info, API keys, token, cookies, and more. Such data can be easily understood, and even extracted, from the application without using specialized tools.

Why Encrypt Strings in Android Apps?

Encrypting strings in Android apps is an important measure to protect the data from being harvested for malicious purposes. This feature enhances the security of the app against malicious attempts to read the app’s contents or harvest valuable data about users and organizations.

Detailed Features of Appdome’s TOTALData™ Encryption:

Advanced In-App Secrets Protection
Encrypt application specific sensitive data such as keys, shared secrets and tokens.

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.

Prerequisites for Using Appdome's Encrypt Strings Plugins:

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

How to Implement Encrypt Strings in Android Apps Using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Encrypt Strings without an SDK or gateway:

  1. Designate the Mobile App to be protected.

    1. Upload an app via the Appdome Mobile Defense platform GUI or via Appdome’s DEV-API or CI/CD Plugins.

    2. Android Formats: .apk or .aab
    3. Encrypt Strings is compatible with: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps.
  2. Select the defense: Encrypt Strings.

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

        Figure 1: Fusion Set that will contain the Encrypt Strings feature

      2. Follow the steps in Sections 2.2-2.2.2 of this article to add the Encrypt Strings feature to your Fusion Set via the Appdome Console.

      3. When you select the Encrypt Strings you'll notice that the Fusion Set you created in step 2.1 now bears the icon of the protection category that contains Encrypt Strings.

        Fusion Set applied Encrypt Strings

        Figure 2: Fusion Set that displays the newly added Encrypt Strings protection
        Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).

      4. 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): fusion Set Detail Summary image

        Figure 3: Fusion Set Detail Summary

      5. 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:
        1. Refer to the Appdome API Reference Guide for API building instructions.
        2. Look for sample APIs in Appdome’s GitHub Repository.
    1. Add the Encrypt Strings feature to your security template.

      1. Navigate to Build > Security tab > TOTALData™ Encryption section in the Appdome Console.
      2. Toggle On Encrypt Strings.
        Encrypt Strings option

        Figure 4: Selecting Encrypt Strings

        Note: The Appdome Platform displays the Mobile Operation Systems supported by each defense in real-time. For more details, see our OS Support Policy KB.

      3. Configure the User Experience Options for Encrypt Strings:
        With Threat-Events™ OFF, Appdome provides several user experience options for mobile brands and developers.
        1. App Compromise Notification: Customize the pop-up or toast Appdome uses to notify the user when a threat is present while using the protected mobile app.
        2. Short message Option. This is available for mobile devices that allow a banner notification for security events.
        3. Localized Message Option. Allows Appdome users to support global languages in security notifications.

          Localized Message

          Figure 5: Default User Experience Options for Appdome’s Strings

        4. Encrypt Strings Threat Code™. Appdome uses AI/ML to generate a unique code each time Encrypt Strings is triggered by an active threat on the mobile device. Use the code in Appdome Threat Resolution Center™ to help end users identify, find and resolve active threats on the personal mobile devices.
      4. Extra Configuration with Encrypt Strings:
        1. Encrypt Resources

          Encrypt all Android application assets.

    2. Initiate the build command either by clicking Build My App at the bottom of the Build Workflow (shown in Figure 4) or via your CI/CD as described in Section 2.1.4.
    Congratulations!  The Encrypt Strings protection is now added to the mobile app
  3. Certify the Encrypt Strings feature in Android Apps

    After building Encrypt Strings, Appdome generates a Certified Secure™ certificate to guarantee that the Encrypt Strings protection has been added and is protecting the app. To verify that the Encrypt Strings protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below: Encrypt Strings shown in Certificate secure

    Figure 6: 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 Strings has been added to each Android app. Certified Secure provides instant and in-line DevSecOps compliance certification that Encrypt Strings and other mobile app security features are in each build of the mobile app.


Using Appdome, there are no development or coding prerequisites to build secured Apps by using Encrypt Strings. 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 Encrypt Strings

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:

Related Articles:

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.

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