How to Encrypt Designated iOS Strings with In-App Secrets

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

What is Strings and in-app Secrets encryption?

String and in app encryption is all the ways an app can statically encrypt/hide its sensitive strings from static analysis, while maintaining the same expected behavior when running the app on a device.

Most of the raw strings you define in your swift app code will be stored after compile in the result binary in certain sections. Those strings can be anything, error messages , hardcoded passwords or names,  classes names, hints about data transferred to the server or hints about the flow of the program. generally speaking, when executing a program, your program will refer to those strings when needed in your code flow at the right time.

Raw strings of your app can be checked with simple tools, like MachoView or Otool, and view them in their sections.

Why encrypt Strings and in-app secrets?

Along with raw strings, all sensitive strings will be referred from your app code and those connections can be viewed by reversing tools like IDA/Ghidra, which gives the attacker knowledge about what conditions or circumstances will lead to the usage of a specific string and make the reversing of your app much easier and exposed.

Obfuscation is used against static reverse engineering attempts, one of the measures is encrypt the string/obfuscate them. This obfuscation should change the name of your sensitive in-app strings while maintaining the same expected behavior in the run time of your app.

Encrypting Strings and in App Secrets on iOS apps by Using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Encrypt Strings and in App Secrets 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. iOS Formats: .ipa

2. Build the feature: Encrypt Strings and in App Secrets.

   1. Building Encrypt Strings and in App Secrets by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Encrypt Strings and in App Secrets feature as shown below:
      

      Figure 1: Fusion Set that will contain the Encrypt Strings and in App Secrets feature
      Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required).

      2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Encrypt Strings and in App Secrets feature via Appdome Console, to add the Encrypt Strings and in App Secrets feature to this Fusion Set.

      3. 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):

         Figure 2: Fusion Set Detail Summary
         Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).

      4. 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, Cirlce 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 and in App Secrets feature via Appdome Console

      To build the Encrypt Strings and in App Secrets 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: Toggle (turn ON) Encrypt Strings and in App Secrets, 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 and in App Secrets.

         Figure 3: Encrypt Strings and in App Secrets 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 and in App Secrets 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 and in App Secrets

         

         Figure 4: Fusion Set that displays the newly added Encrypt Strings and in App Secrets protection

      4. Optional Configuration with Encrypt Strings and in App Secrets:

         1. Advanced In-App Secrets Protection

            Encrypt application specific sensitive data such as keys, shared secrets and tokens.

      5. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).

   Congratulations!  The Encrypt Strings and in App Secrets protection is now added to the mobile app

3. Certify the Encrypt Strings and in App Secrets feature in iOS Apps.

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