How to Enforce Strong RSA Signature in Android & iOS Apps
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:
- Hashing: The message is hashed using a secure hashing algorithm (e.g., SHA-256).
- Encryption: The hash is encrypted using the sender’s private key, creating the RSA signature.
- 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:
- Appdome account (create a free Appdome account here)
- A license for Enforce Strong RSA Signature
- Mobile App (.ipa for iOS, or .apk or .aab for Android)
- Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)
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:
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Upload the Mobile App to Appdome.
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Upload an app to Appdome’s Mobile App Security Build System
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Upload Method: Appdome Console or DEV-API
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Mobile App Formats: .ipa for iOS, or .apk or .aab for Android
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Enforce Strong RSA Signature Compatible With: Obj-C, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more
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Build the feature: Enforce Strong RSA Signature .
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Building Enforce Strong RSA Signature by using Appdome’s DEV-API:
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Create and name the Fusion Set (security template) that will contain the Enforce Strong RSA Signature feature as shown below:
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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.
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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):
Figure 2: Fusion Set Detail Summary
Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory). -
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:
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Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
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Look for sample APIs in Appdome’s GitHub Repository
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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). -
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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.
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Where: Inside the Appdome Console, go to Build > Security Tab > Secure Communication section.
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How: Check whether is toggled On (enabled), otherwise enable it . The feature Enforce Strong RSA Signature is enabled by default, as shown below. Toggle (turn ON) Enforce Strong RSA Signature , 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 Enforces Strong RSA Signature .
Figure 3: Enforce Strong RSA Signature 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. -
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
Figure 4: Fusion Set that displays the newly added Enforce Strong RSA Signature protection
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Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Enforce Strong RSA Signature :
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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 .
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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.
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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.
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Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
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Congratulations! The Enforce Strong RSA Signature protection is now added to the mobile app -
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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:
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 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 |
| 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.
xxxxxxxxxxIntentFilter intentFilter = new IntentFilter();intentFilter.addAction("SslInvalidMinRSASignature");BroadcastReceiver threatEventReceiver = new BroadcastReceiver() { public void onReceive(Context context, Intent intent) { String message = intent.getStringExtra("message"); // Message shown to the user String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code // Current threat event score String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Total threat events score String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Replace '<Context Key>' with your specific event context key // String variable = intent.getStringExtra("<Context Key>"); // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) }};if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) { registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED);} else { registerReceiver(threatEventReceiver, intentFilter);}xxxxxxxxxxval intentFilter = IntentFilter()intentFilter.addAction("SslInvalidMinRSASignature")val threatEventReceiver = object : BroadcastReceiver() { override fun onReceive(context: Context?, intent: Intent?) { var message = intent?.getStringExtra("message") // Message shown to the user var reasonData = intent?.getStringExtra("reasonData") // Threat detection cause var reasonCode = intent?.getStringExtra("reasonCode") // Event reason code // Current threat event score var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore") // Total threat events score var threatEventsScore = intent?.getStringExtra("threatEventsScore") // Replace '<Context Key>' with your specific event context key // var variable = intent?.getStringExtra("<Context Key>") // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) }}if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) { registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED)} else { registerReceiver(threatEventReceiver, intentFilter)}x
let center = NotificationCenter.defaultcenter.addObserver(forName: Notification.Name("SslInvalidMinRSASignature"), object: nil, queue: nil) { (note) in guard let usrInf = note.userInfo else { return } let message = usrInf["message"]; // Message shown to the user let reasonData = usrInf["reasonData"]; // Threat detection cause let reasonCode = usrInf["reasonCode"]; // Event reason code // Current threat event score let currentThreatEventScore = usrInf["currentThreatEventScore"]; // Total threat events score let threatEventsScore = usrInf["threatEventsScore"]; // Replace '<Context Key>' with your specific event context key // let variable = usrInf["<Context Key>"]; // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)}xxxxxxxxxx[[NSNotificationCenter defaultCenter] addObserverForName: @"SslInvalidMinRSASignature" object:nil queue:nil usingBlock:^(NSNotification *org_note) { __block NSNotification *note = org_note; dispatch_async(dispatch_get_main_queue(), ^(void) { // Message shown to the user NSString *message = [[note userInfo] objectForKey:@"message"]; // Threat detection cause NSString *reasonData = [[note userInfo] objectForKey:@"reasonData"]; // Event reason code NSString *reasonCode = [[note userInfo] objectForKey:@"reasonCode"]; // Current threat event score NSString *currentThreatEventScore = [[note userInfo] objectForKey:@"currentThreatEventScore"]; // Total threat events score NSString *threatEventsScore = [[note userInfo] objectForKey:@"threatEventsScore"]; // Replace '<Context Key>' with your specific event context key // NSString *variable = [[note userInfo] objectForKey:@"<Context Key>"]; // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) });}];xxxxxxxxxxconst { ADDevEvents } = NativeModules;const aDDevEvents = new NativeEventEmitter(ADDevEvents);function registerToDevEvent(action, callback) { NativeModules.ADDevEvents.registerForDevEvent(action); aDDevEvents.addListener(action, callback);}export function registerToAllEvents() { registerToDevEvent( "SslInvalidMinRSASignature", (userinfo) => Alert.alert(JSON.stringify(userinfo)) var message = userinfo["message"] // Message shown to the user var reasonData = userinfo["reasonData"] // Threat detection cause var reasonCode = userinfo["reasonCode"] // Event reason code // Current threat event score var currentThreatEventScore = userinfo["currentThreatEventScore"] // Total threat events score var threatEventsScore = userinfo["threatEventsScore"] // Replace '<Context Key>' with your specific event context key // var variable = userinfo["<Context Key>"] // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) );}x
RegisterReceiver(new ThreatEventReceiver(), new IntentFilter("SslInvalidMinRSASignature")); class ThreatEventReceiver : BroadcastReceiver{ public override void OnReceive(Context context, Intent intent) { // Message shown to the user String message = intent.GetStringExtra("message"); // Threat detection cause String reasonData = intent.GetStringExtra("reasonData"); // Event reason code String reasonCode = intent.GetStringExtra("reasonCode"); // Current threat event score String currentThreatEventScore = intent.GetStringExtra("currentThreatEventScore"); // Total threat events score String threatEventsScore = intent.GetStringExtra("threatEventsScore"); // Replace '<Context Key>' with your specific event context key // String variable = intent.GetStringExtra("<Context Key>"); // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) }}x
NSNotificationCenter.DefaultCenter.AddObserver( (NSString)"SslInvalidMinRSASignature", // Threat-Event Identifier delegate (NSNotification notification) { // Message shown to the user var message = notification.UserInfo.ObjectForKey("message"); // Threat detection cause var reasonData = notification.UserInfo.ObjectForKey("reasonData"); // Event reason code var reasonCode = notification.UserInfo.ObjectForKey("reasonCode"); // Current threat event score var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore"); // Total threat events score var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore"); // Replace '<Context Key>' with your specific event context key // var variable = notification.UserInfo.ObjectForKey("<Context Keys>"); // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...) });xxxxxxxxxxwindow.broadcaster.addEventListener("SslInvalidMinRSASignature", function(userInfo) { var message = userInfo.message // Message shown to the user var reasonData = userInfo.reasonData // Threat detection cause var reasonCode = userInfo.reasonCode // Event reason code // Current threat event score var currentThreatEventScore = userInfo.currentThreatEventScore // Total threat events score var threatEventsScore = userInfo.threatEventsScore // Replace '<Context Key>' with your specific event context key // var variable = userInfo.<Context Keys> // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)});x
import 'dart:async';import 'package:flutter/material.dart';import 'package:flutter/services.dart';class PlatformChannel extends StatefulWidget { const PlatformChannel({super.key}); State<PlatformChannel> createState() => _PlatformChannelState();}class _PlatformChannelState extends State<PlatformChannel> { // Replace with your EventChannel name static const String _eventChannelName = "SslInvalidMinRSASignature"; static const EventChannel _eventChannel = EventChannel(_eventChannelName); void initState() { super.initState(); _eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError); } void _onEvent(Object? event) { setState(() { // Adapt this section based on your specific event data structure var eventData = event as Map; // Example: Accessing 'externalID' field from the event var externalID = eventData['externalID']; // Customize the rest of the fields based on your event structure String message = eventData['message']; // Message shown to the user String reasonData = eventData['reasonData']; // Threat detection cause String reasonCode = eventData['reasonCode']; // Event reason code // Current threat event score String currentThreatEventScore = eventData['currentThreatEventScore']; // Total threat events score String threatEventsScore = eventData['threatEventsScore']; // Replace '<Context Key>' with your specific event context key // String variable = eventData['<Context Keys>']; }); } // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)}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:
- Customizing, Configuring & Branding Secure Mobile Apps
- Deploying/Publishing Secure mobile apps to Public or Private app stores
- Releasing Secured Android & iOS Apps built on Appdome.
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.
