How to Enforce Strong RSA Signature in Android & iOS Apps

Last updated May 20, 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 Enforce Strong RSA Signature in Mobile apps.

What is an RSA Signature?

RSA (Rivest-Shamir-Adleman) is a widely used encryption and authentication algorithm. An RSA signature is a cryptographic method for ensuring that a message or file has not been altered. It involves using a private key to create the signature and a corresponding public key to verify it.

How RSA Signature Works:

  1. Hashing: The message is hashed using a secure hashing algorithm (e.g., SHA-256).
  2. Encryption: The hash is encrypted using the sender’s private key, creating the RSA signature.
  3. Verification: The recipient decrypts the signature using the sender’s public key and compares it to a newly generated hash of the message.

If the hashes match, the message is verified as authentic and unaltered.

Why Enforce Strong RSA Signature in Mobile Apps?

Enforcing a strong RSA signature in mobile apps is vital for several reasons:

  • It ensures data integrity, confirming that the data has not been tampered with during transmission.
  • It provides authentication, verifies the sender’s identity, and protects against impersonation attacks.
  • RSA signatures offer non-repudiation, meaning the sender cannot deny having sent the message, which serves as legal proof of origin.

Compliance with regulatory requirements and industry standards, such as PCI-DSS, HIPAA, and GDPR, often necessitates the use of robust cryptographic methods to protect sensitive information. Using robust security measures like strong RSA signatures builds user confidence and trust in the app, enhancing its reputation and reliability. Therefore, implementing strong RSA signatures is crucial for maintaining data security, regulatory compliance, and user trust in mobile applications.

Note: For enhanced security, it is recommended that RSA keys be at least 2048 bits long.

Prerequisites for Using Appdome's Enforce Strong RSA Signature Plugins:

To use Appdome’s mobile app security build system to Enforce Strong RSA Signature , you’ll need:

How to Implement Enforce Strong RSA Signature in Mobile Apps Using Appdome

On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Enforce Strong RSA Signature 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. Mobile App Formats: .ipa for iOS, or .apk or .aab for Android
    3. Enforce Strong RSA Signature is compatible with: Obj-C, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more.
  2. Select the defense: Enforce Strong RSA Signature .

      1. Create and name the Fusion Set (security template) that will contain the Enforce Strong RSA Signature feature as shown below:
        fusion set that contains Enforce Strong RSA Signature

        Figure 1: Fusion Set that will contain the Enforce Strong RSA Signature feature

      2. Follow the steps in Sections 2.2-2.2.2 of this article to add the Enforce Strong RSA Signature feature to your Fusion Set via the Appdome Console.

      3. When you select the Enforce Strong RSA Signature you'll notice that the Fusion Set you created in step 2.1 now bears the icon of the protection category that contains Enforce Strong RSA Signature .

        Fusion Set applied Enforce Strong RSA Signature

        Figure 2: Fusion Set that displays the newly added Enforce Strong RSA Signature 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 Enforce Strong RSA Signature feature to your security template.

      1. Navigate to Build > Security tab > Secure Communication section in the Appdome Console.
      2. Toggle On > Enforce Strong RSA Signature .

        (a) Choose to monitor this attack vector by checking the Threat Events checkbox associated with Enforce Strong RSA Signature as shown below.

        (b) To receive mobile Threat Monitoring, check the ThreatScope™ box as shown below. For more details, see our knowledge base article on ThreatScope™ Mobile XDR.
        Enforce Strong RSA Signature  option

        Figure 4: Selecting Enforce Strong RSA Signature

        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. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Enforce Strong RSA Signature :
        1. Threat-Events™ OFF > In-App Defense

          If the Threat-Events™ setting is not selected. Appdome will detect and defend the user and app by enforcing Strong RSA Signature .

        2. Threat-Events™ ON > In-App Detection

          When this setting is used, Appdome detects the use of a weak certificate signature and passes Appdome’s Threat-Event™ attack intelligence to the app’s business logic for processing, enforcement, and user notification. For more information on consuming and using Appdome Threat-Events™ in the app, see section Using Threat-Events™ to Enforce Strong RSA Signature Enforce Intelligence and Control in Mobile Apps.

        3. Threat-Events™ ON > In-App Defense

          When this setting is used, Appdome detects and defends against Strong RSA Signature (same as Appdome Enforce) and passes Appdome’s Threat-Event™ attack intelligence to the app’s business logic for processing. For more information on consuming and using Appdome Threat-Events™ in the app, see section Using Threat-Events™ for Enforce Strong RSA Signature Enforce Intelligence and Control in Mobile Apps.

      4. Configure the User Experience Options for Enforce Strong RSA Signature :
        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 Strong RSA Signature

        4. Enforce Strong RSA Signature Threat Code™. Appdome uses AI/ML to generate a unique code each time Enforce Strong RSA Signature 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.
    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 Enforce Strong RSA Signature protection is now added to the mobile app
  3. Certify the Enforce Strong RSA Signature feature in Mobile Apps

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

Using Threat-Events™ for Strong RSA Signature Intelligence and Control in Mobile Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when Strong RSA Signature is detected. To consume and use Threat-Events™ for Strong RSA Signature in Mobile Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for Strong RSA Signature shown below.

The specifications and options for Threat-Events™ for Strong RSA Signature are:

Threat-Event™ Elements Enforce Strong RSA Signature Method Detail
Appdome Feature Name Enforce Strong RSA Signature
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
Visible in ThreatScope™
Developer Parameters for Enforcing Strong RSA Signature Threat-Event™
Threat-Event NAME SslInvalidMinRSASignature
Threat-Event DATA reasonData
Threat-Event CODE reasonCode
Threat-Event REF 6801
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
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.
host The host that failed minimum requirement RSA signature validation
DeveventDetailedErrorMessage Error message
extendedMessageText Extended message
certificateCN Certificate common name
certificateSHA1 Certificate SHA1

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


The following is a code sample for native Mobile apps, which uses all values in the specification above for Enforce Strong RSA Signature :


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 Mobile Apps by using Enforce Strong RSA Signature . 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 Enforce Strong RSA Signature

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 to Enforce Strong ECC Signature in iOS Apps

How to use Secure Certificate Pinning in Android & iOS Apps

How to Enforce SHA-256 Digest in Android & iOS Apps

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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