How to Encrypt NSUserDefaults in iOS Apps

Last updated March 10, 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 In-App Preferences in iOS apps.

What are App Preferences (NSUserDefaults)?

In iOS app development, the NSUserDefaults class serves as an interface to the users’ defaults database, which allows an app to customize its behavior to match a user’s preferences. For example, you can allow users to specify their preferred units of measurement or media playback speed. Apps store these preferences by assigning key-value pairs to a set of parameters in a user’s defaults database, which maintain persistence across app launches.

Preferences are used for creating a sense of persistence and personalization for mobile users, in order to improve the user experience. Preferences are stored as plain-text data inside iOS apps and can be retrieved by other apps and systems.

Why Encrypt App Preferences in iOS apps?

Preferences can be any kind of text-based data that may include information about users that is highly personal, private or sensitive. For example, app preferences can be used for displaying a screen that contains a user’s preferred currency or type of credit card used to process transactions in an e-commerce app.  The use of app preferences is very broad and flexible, and there is no restriction on the type of information that can be stored in preferences and retrieved by other resources. Furthermore, App Preferences are stored as plain-text data (unencrypted) by default, which makes them an easy and target for hackers.

Prerequisites for Using Appdome's Encrypt In-App Preferences Plugins:

To use Appdome’s mobile app security build system to Encrypt In-App Preferences , you’ll need:

How to Implement Encrypt In-App Preferences in iOS Apps Using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Encrypt In-App Preferences 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. iOS Formats: .ipa
    3. Encrypt In-App Preferences is compatible with: Obj-C, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and other iOS apps.
  2. Select the defense: Encrypt In-App Preferences.

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

        Figure 1: Fusion Set that will contain the Encrypt In-App Preferences feature

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

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

        Fusion Set applied Encrypt In-App Preferences

        Figure 2: Fusion Set that displays the newly added Encrypt In-App Preferences 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 In-App Preferences feature to your security template.

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

        Figure 4: Selecting Encrypt In-App Preferences

        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 In-App Preferences:
        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 In-App Preferences

        4. Encrypt In-App Preferences Threat Code™. Appdome uses AI/ML to generate a unique code each time Encrypt In-App Preferences 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 In-App Preferences:
        1. Encrypt In-App Preferences

          Encrypt NSUserDefaults.

    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 In-App Preferences protection is now added to the mobile app
  3. Certify the Encrypt In-App Preferences feature in iOS Apps

    After building Encrypt In-App Preferences, Appdome generates a Certified Secure™ certificate to guarantee that the Encrypt In-App Preferences protection has been added and is protecting the app. To verify that the Encrypt In-App Preferences protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below: Encrypt In-App Preferences 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 In-App Preferences has been added to each iOS app. Certified Secure provides instant and in-line DevSecOps compliance certification that Encrypt In-App Preferences and other mobile app security features are in each build of the mobile app.

Using Threat-Events™ for In-App Preferences Intelligence and Control in iOS Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when In-App Preferences are detected. To consume and use Threat-Events™ for In-App Preferences in iOS Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for In-App Preferences shown below.

The specifications and options for Threat-Events™ for In-App Preferences are:

Threat-Event™ Elements Encrypt In-App Preferences Method Detail
Appdome Feature Name Encrypt In-App Preferences
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 In-App Preferences 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.
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
updatedOSVersion Is the OS version up to date
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
threatCode The last six characters of the threat code specify the OS, allowing the Threat Resolution Center to address the attack on the affected device.

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


The following is a code sample for native iOS apps, which uses all values in the specification above for Encrypt In-App Preferences:


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 iOS Apps by using Encrypt In-App Preferences. 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 In-App Preferences

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:

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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