How to Encrypt Java Strings in Android Apps

Last updated March 11, 2024 by Appdome

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

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 Encrypt Strings:

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

Encrypt Strings on 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. 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 Strings Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps
  2. Build the feature: Encrypt Strings.

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

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

        Figure 1: Fusion Set that will contain the Encrypt Strings 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 Encrypt Strings feature via Appdome Console, to add the Encrypt Strings 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. Copy 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, Circle 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 Strings feature via Appdome Console

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

      1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALData™ Encryption section.
      2. How: Check whether is toggled On (enabled), otherwise enable it . The feature Encrypt Strings is enabled by default, as shown below. Toggle (turn ON) Encrypt Strings, as shown below.
        If needed, Customize the Threat Notification to be displayed to the mobile end-user in a standard OS dialog notification when Appdome Encrypts Strings.
        Encrypt Strings option

        Figure 3: Encrypt Strings 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.

      3. When you select the Encrypt Strings 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 Strings

        Fusion Set applied Encrypt Strings

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

      4. Extra Configuration with Encrypt Strings:
        1. Encrypt Resources

          Encrypt all Android application assets.

      5. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    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 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 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 Threat-Events™ for Strings Intelligence and Control in Android Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when Strings are detected. To consume and use Threat-Events™ for Strings in Android Apps, use registerReceiver in the Application OnCreate, and the code samples for Threat-Events™ for Strings shown below.

The specifications and options for Threat-Events™ for Strings are:

Threat-Event™ Elements Encrypt Strings Method Detail
Appdome Feature Name Encrypt Strings
Threat-Event Mode
OFF, IN-APP DEFENSE Appdome detects, defends and notifies user (standard OS dialog) using customizable messaging.
ON, IN-APP DETECTION Appdome detects the attack or threat and passes the event in a standard format to the app for processing (app chooses how and when to enforce).
ON, IN-APP DEFENSE Uses Appdome Enforce mode for any attack or threat and passes the event in a standard format to the app for processing (gather intel on attacks and threats without losing any protection).
Certified Secure™ Threat Event Check x
Visible in ThreatScope™ x
Developer Parameters for Encrypting Strings Threat-Event™
Threat-Event NAME
Threat-Event DATA reasonData
Threat-Event CODE reasonCode
Threat-Event REF
Threat-Event SCORE
currentThreatEventScore Current Threat-Event score
threatEventsScore Total Threat-events score
Threat-Event Context Keys
message Message displayed for the user on event
failSafeEnforce Timed enforcement against the identified threat
externalID The external ID of the event which can be listened via Threat Events
osVersion OS version of the current device
deviceModel Current device model
deviceManufacturer The manufacturer of the current device
fusedAppToken The task ID of the Appdome fusion of the currently running app
kernelInfo Info about the kernel: system name, node name, release, version and machine.
carrierPlmn PLMN of the device. Only available for Android devices.
deviceID Current device ID
reasonCode Reason code of the occurred event
buildDate Appdome fusion date of the current application
devicePlatform OS name of the current device
carrierName Carrier name of the current device. Only available for Android.
updatedOSVersion Is the OS version up to date
deviceBrand Brand of the device
deviceBoard Board of the device
buildUser Build user
buildHost Build host
sdkVersion Sdk version
timeZone Time zone
deviceFaceDown Is the device face down
locationLong Location longitude conditioned by location permission
locationLat Location latitude conditioned by location permission
locationState Location state conditioned by location permission
wifiSsid Wifi SSID
wifiSsidPermissionStatus Wifi SSID permission status

With Threat-Events™ enabled (turned ON), Android developers can get detailed attack intelligence and granular defense control in Android applications and create amazing user experiences for all mobile end users when Strings are detected.


The following is a code sample for native Android apps, which uses all values in the specification above for Encrypt Strings:


Important! Replace all placeholder instances of <Context Key> with the specific name of your threat event context key across all language examples. This is crucial to ensure your code functions correctly with the intended event data. For example, The <Context Key> could be the message, externalID, OS Version, reason code, etc.



Using Appdome, there are no development or coding prerequisites to build secured Android 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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