XorInterceptor

A .NET Interceptor which does a simple XOR encryption at compile time, without embedding the plaintext literal in your IL. It scans the syntax tree for calls named Xor with zero arguments. It retrieves the interceptable location from the compiler and it will emit the interceptor method, instead of the original call.

⚠️ This currently requires .NET 9

Installation

Option A — NuGet (recommended)

NuGet

.NET CLI

dotnet add package XorInterceptor

Package Reference

<PackageReference Include="XorInterceptor" Version="1.0.*" />

Option B — Local project reference

</PropertyGroup> <!-- ... --> <InterceptorsNamespaces>$(InterceptorsNamespaces);XorInterceptor</InterceptorsNamespaces> <XorBuildSeed>$([System.Guid]::NewGuid().GetHashCode())</XorBuildSeed> </PropertyGroup> <ItemGroup> <CompilerVisibleProperty Include="XorBuildSeed" /> <ProjectReference Include="..\XorInterceptor\XorInterceptor.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" /> </ItemGroup>

Usage

You can take a look at the console application included, however it is nothing more than:

using static XorInterceptor.XorEncryption; var encryptedString = Xor( /*"Hello, World"*/); Console.WriteLine(encryptedString);

Now each time you (re)build your project the encryption changes.

⚠️ This is of course very easy to undo, since both the encrypted data and the key are next to eachother. It is more a proof of concept.

References

• https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-12#interceptors
• https://andrewlock.net/creating-a-source-generator-part-11-implementing-an-interceptor-with-a-source-generator/