How to Enforce Strong RSA Signature in Android & iOS Apps

Last updated May 20, 2024 by Appdome

Learn to Enforce Strong RSA Signature in Mobile apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

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 Enforce Strong RSA Signature :

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

Enforce Strong RSA Signature on 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. 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. Mobile App Formats: .ipa for iOS, or .apk or .aab for Android
    4. Enforce Strong RSA Signature Compatible With: Obj-C, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more
  2. Build the feature: Enforce Strong RSA Signature .

    1. Building Enforce Strong RSA Signature by using Appdome’s DEV-API:

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

        Figure 1: Fusion Set that will contain the Enforce Strong RSA Signature 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 Enforce Strong RSA Signature feature via Appdome Console, to add the Enforce Strong RSA Signature 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, as shown in Figure 1 above, and get 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 Enforce Strong RSA Signature feature via Appdome Console

      To build the Enforce Strong RSA Signature protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > Secure Communication section.
      2. When you select the Enforce Strong RSA Signature you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Enforce Strong RSA Signature

        Fusion Set applied Enforce Strong RSA Signature

        Figure 4: Fusion Set that displays the newly added Enforce Strong RSA Signature protection

      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 cleared (not selected). Appdome will detect and defend the user and app by enforcing Enforce 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™ for Enforce Strong RSA Signature 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 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 Intelligence and Control in Mobile Apps.

      4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Enforce Strong RSA Signature protection is now added to 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
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
deviceID Current device ID
reasonCode Reason code of the occured event
buildDate Appdome fusion date of the current application
devicePlatform OS name of the current device
carrierName Carrier name of the current device
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
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 :


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

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.

Want a Demo?

MiTM Attack Prevention

TomWe're here to help
We'll get back to you in 24 hours to schedule your demo.