Running a Checksum Validation of Android & iOS Apps

Learn to Validate the file you received has not been tampered with. in Mobile apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is checksum?

A checksum, otherwise known as “hash”, is a sequence of numbers and letters used for checking data for errors. A checksum is produced by running a program that puts the original file through an algorithm such as MD5, SHA-1, and SHA-256/512. By executing a cryptographic hash function, the algorithm produces the checksum as an input of a fixed length.

Why Should Developers use Checksum Validation??

A checksum validation is used when you received a file and would like to verify that the original file has not been modified or tampered with. If you know the checksum of the original file, running a checksum validation that results in a checksum of the same length proves that no changes were made to your copy. Any change made to the original file, be it one character or one digit, will result in producing an entirely different checksum.

Prerequisites to Using Checksum Validation:

To use Appdome’s mobile app security build system to Validate the file you received has not been tampered with. , you’ll need:

• Appdome account (create a free Appdome account here)
• A license for Checksum Validation
• Mobile App (.ipa For iOS device or .apk or .aab For Mobile)
• Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)

Validate the file you received has not been tampered with. on Mobile apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Validate the file you received has not been tampered with. 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 device or .apk or .aab
   4. Checksum Validation Compatible With: Obj-C, C+, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more

2. Build the feature: Checksum Validation.

   1. Building Checksum Validation by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Checksum Validation feature as shown below:
      

      Figure 1: Fusion Set that will contain the Checksum Validation 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 Checksum Validation feature via Appdome Console, to add the Checksum Validation 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 Checksum Validation feature via Appdome Console

      To build the Checksum Validation protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > ONEShield™ section . Like all other options in ONEShield™, Checksum Validation is turned on by default, as shown below:

         Figure 3: Checksum Validation 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.

      2. When you select the Checksum Validation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Checksum Validation

         

         Figure 4: Fusion Set that displays the newly added Checksum Validation protection

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

   Congratulations!  The Checksum Validation protection is now added to the mobile app

3. Certify the Checksum Validation feature in Mobile Apps.

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