WebAssembly Protection for Blazor

Shield provides specialized protection for Blazor WebAssembly applications, securing your client-side .NET code that runs directly in the browser.

Understanding Blazor WebAssembly Security Challenges

Blazor WebAssembly applications compile your C# code to WebAssembly (WASM), allowing it to run directly in the browser. This presents unique security challenges:

The compiled WASM code is delivered to the client's browser
Application logic and intellectual property may be exposed
Standard .NET obfuscation techniques need adaptation for WASM

Shield addresses these challenges with specialized protection techniques designed for Blazor WebAssembly applications.

Protection Strategy for Blazor WebAssembly

Shield applies a multi-layered approach to securing Blazor WebAssembly applications:

IL Code Protection: Applies transformations to your .NET code before WASM compilation
Assembly Obfuscation: Renames and obfuscates assemblies while maintaining compatibility with the WASM runtime
Resource Protection: Encrypts embedded resources and assets
Reference Protection: Hides method calls and type references
WASM-specific Features: Applies protection techniques optimized for the browser environment

Implementation

Prerequisites

ByteHide Shield (Team, Scale, or Enterprise edition)
Blazor WebAssembly project

Configuration

Create a shield.config.json file in the root of your Blazor WebAssembly project:

{
  "preset": "custom",
  "protections": {
    "rename": {
      "rename_public": false,
    },
    "constants_encryption": {},
    "constants_protection": {},
    "resources": {
      "compress": true,
      "encrypt": true
    }
  }
}

Shield will automatically detect that your assembly is a Blazor WebAssembly application and apply the necessary optimizations for WebAssembly compatibility.

Integration with MSBuild

Add Shield to your Blazor WebAssembly project using the NuGet package:

dotnet add package ByteHide.Shield

Recommended Protections

For Blazor WebAssembly applications, these protections provide the best balance of security and performance:

Protection	Recommendation	Notes
Renamer	✓ Essential	Set `rename_public` to false for WebAssembly projects
Constants Encryption	✓ Recommended	Secures sensitive values and strings
Constants Mutation	✓ Recommended	Adds additional security to constant values
Control Flow	Use with caution	Avoid if you need to debug the application as it prevents WebAssembly debugging
Resource Protection	✓ Recommended	Secures embedded resources and assets

Control Flow protection should be avoided if you need to debug your Blazor WebAssembly application, as it will prevent WebAssembly debugging capabilities. While the application will function correctly, debugging will not be possible.

Testing Protected Applications

After applying Shield protection to your Blazor WebAssembly application:

Build your application in Release mode
Verify that the protected application loads correctly in different browsers
Test all functionality, especially any JavaScript interop features
Check performance in targeted browser environments

Blazor WebAssembly applications run in the browser's security sandbox. While Shield significantly increases the difficulty of reverse engineering, it's important to maintain a defense-in-depth approach to security. Never store sensitive data or credentials in your client-side Blazor code.

Compatibility Considerations

Shield's Blazor WebAssembly protection is compatible with:

Blazor WebAssembly 3.2+
All modern browsers (Chrome, Firefox, Safari, Edge)
JavaScript interop
Progressive Web Apps (PWAs)
Hybrid desktop applications using WebView