Understanding Obfuscar and WPF Applications

Oct 13, 2025 by wbrum.org 22 views

Introduction

Obfuscating .NET applications is a common practice to protect intellectual property and prevent reverse engineering. However, when using obfuscators like Obfuscar, issues can arise, especially when working with WPF applications. In this article, we will explore the problem of using Obfuscar with a WPF .NET 9.0 application, specifically when setting the KeepPublicApi variable to false in the configuration file.

Understanding Obfuscar and WPF Applications

Obfuscar is a .NET obfuscator that helps protect .NET assemblies from reverse engineering and decompilation. It works by renaming types, methods, and fields, making it difficult for attackers to understand the application's logic. WPF applications, on the other hand, are built on top of the .NET framework and use XAML (Extensible Application Markup Language) to define user interfaces.

The Problem with KeepPublicApi

When using Obfuscar, the KeepPublicApi variable determines whether to keep public APIs (Application Programming Interfaces) intact or not. By default, KeepPublicApi is set to true, which means that public APIs are not obfuscated. However, when setting KeepPublicApi to false, the application may not start after obfuscation.

Configuration File Analysis

Let's take a closer look at the configuration file provided:

<?xml version='1.0'?>
<Obfuscator>
    <Var name="InPath" value=".\" />
    <Var name="OutPath" value=".\Output"/>
    <Module file="$(InPath)\ProvaSemplice.dll" />
    <AssemblySearchPath path="C:\Program Files\dotnet\packs\Microsoft.WindowsDesktop.App.Ref\9.0.2\ref\net9.0"/>
    <Var name="UseUnicodeNames" value="true" />
    <Var name="KeepPublicApi" value="false"/>
</Obfuscator>

The configuration file specifies the input and output paths, the module file to be obfuscated, and the assembly search path. It also sets UseUnicodeNames to true and KeepPublicApi to false.

Possible Causes of the Issue

There are several possible causes for the issue when setting KeepPublicApi to false:

Missing dependencies: The application may be missing dependencies that are required for obfuscation. Make sure that all necessary dependencies are included in the configuration file.
Incorrect assembly search path: The assembly search path may be incorrect, leading to missing dependencies. Verify that the assembly search path is set correctly.
Obfuscation settings: The obfuscation settings may be too aggressive, causing the application to fail. Try reducing the obfuscation settings to see if the issue persists.
WPF-specific issues: WPF applications may have specific requirements for obfuscation. Check the Obfuscar documentation for WPF-specific issues and workarounds.

Workarounds and Solutions

To resolve the issue, try the following workarounds and solutions:

Set KeepPublicApi to true: Temporarily set KeepPublicApi to true to see if the application starts correctly. If it does, you can try to identify the specific APIs that need to be obfuscated.
Use a different obfuscation tool: Consider using a different obfuscation tool that supports WPF applications and has better compatibility with .NET 9.0.
Customize the obfuscation settings: Try customizing the obfuscation settings to reduce the impact on the application. This may involve adjusting the renaming strategy, exception handling, or other settings.
Contact Obfuscar support: Reach out to Obfuscar support for further assistance and guidance on resolving the issue.

Conclusion

Obfuscating WPF .NET 9.0 applications with Obfuscar can be challenging, especially when setting KeepPublicApi to false. By understanding the possible causes of the issue and trying the workarounds and solutions outlined in this article, you can resolve the problem and protect your application from reverse engineering.

Additional Resources

For further assistance and guidance on obfuscating WPF applications with Obfuscar, refer to the following resources:

Obfuscar documentation: https://www.obfuscar.net/
WPF-specific issues and workarounds: https://www.obfuscar.net/docs/wpf/
.NET 9.0 compatibility: https://www.obfuscar.net/docs/net-9-0/

Q: What is the problem with using Obfuscar with a WPF .NET 9.0 application?

A: The problem arises when setting the KeepPublicApi variable to false in the configuration file. The application may not start after obfuscation.

Q: What is the purpose of the `KeepPublicApi` variable?

A: The KeepPublicApi variable determines whether to keep public APIs (Application Programming Interfaces) intact or not. By default, KeepPublicApi is set to true, which means that public APIs are not obfuscated.

Q: What are the possible causes of the issue when setting `KeepPublicApi` to `false`?

A: There are several possible causes for the issue:

Missing dependencies: The application may be missing dependencies that are required for obfuscation.
Incorrect assembly search path: The assembly search path may be incorrect, leading to missing dependencies.
Obfuscation settings: The obfuscation settings may be too aggressive, causing the application to fail.
WPF-specific issues: WPF applications may have specific requirements for obfuscation.

Q: How can I resolve the issue?

A: Try the following workarounds and solutions:

Set KeepPublicApi to true: Temporarily set KeepPublicApi to true to see if the application starts correctly.
Use a different obfuscation tool: Consider using a different obfuscation tool that supports WPF applications and has better compatibility with .NET 9.0.
Customize the obfuscation settings: Try customizing the obfuscation settings to reduce the impact on the application.
Contact Obfuscar support: Reach out to Obfuscar support for further assistance and guidance on resolving the issue.

Q: What are some additional resources for further assistance and guidance?

A: Refer to the following resources:

Obfuscar documentation: https://www.obfuscar.net/
WPF-specific issues and workarounds: https://www.obfuscar.net/docs/wpf/
.NET 9.0 compatibility: https://www.obfuscar.net/docs/net-9-0/

Q: Can I use Obfuscar with WPF applications?

A: Yes, Obfuscar can be used with WPF applications. However, it's essential to follow the guidelines and best practices outlined in the Obfuscar documentation to ensure successful obfuscation.

Q: What are some common mistakes to avoid when using Obfuscar with WPF applications?

A: Some common mistakes to avoid include:

Incorrect assembly search path: Make sure the assembly search path is set correctly.
Missing dependencies: Ensure that all necessary dependencies are included in the configuration file.
Obfuscation settings: Be cautious when adjusting the obfuscation settings, as they can impact the application's behavior.

Q: How can I ensure that my WPF application is properly obfuscated?

A: To ensure that your WPF application is properly obfuscated, follow these best practices:

Use the correct configuration file: Make sure to use the correct configuration file for your WPF application.
Set the correct obfuscation settings: Adjust the obfuscation settings according to your application's requirements.
Test the application thoroughly: Thoroughly test the application after obfuscation to ensure that it functions correctly.

By following these guidelines and best practices, you can successfully obfuscate your WPF .NET 9.0 application and protect it from reverse engineering.