UnityAsset.NET

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A .NET library undergoing active refactoring, currently focused on high-performance parsing and reading of Unity Engine asset files.

Only support Unity 2017.x or later.

Features

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BundleFile

• Parsing and Reading
• Serialization
• Patching (Will be re-introduced in a future version)
• Calculate/Patch crc32

SerializedFile

• Parsing and Reading
• Serialization
• Patching (Temporarily removed)

Asset

• Parsing based on TypeTree
• Serialization (Temporarily removed)
• Patching (Temporarily removed)

Testing

The tests were written with an LLM rather than by hand. They are a regression net rather than a specification: they pin what the code does today, so treat a change in their expectations as something to review rather than to trust.

dotnet test tests/UnityAsset.NET.Tests/UnityAsset.NET.Tests.csproj

Examples

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Unity CN Decryption

To load BundleFile with Unity CN Encryption, there are two ways.

// Hex string format (32 characters)
Setting.DefaultUnityCNKey = "587865636f6472506547616b61326536";  // Represents "XxecodrPeGaka2e6" in hex
BundleFile bf = new BundleFile( @"path to your bundlefile");

or

// Plain string format (16 characters)
BundleFile bf = new BundleFile( @"path to your bundlefile", "XxecodrPeGaka2e6");

or, per session, so two games with different keys can be loaded at once:

using var session = new AssetManager(options: new UnitySessionOptions { UnityCnKey = "XxecodrPeGaka2e6" });

To remove Unity CN Encryption form File, you can simply save BundleFile without key

// Temporarily removed
bf.Serialize(@"path to save file", CompressionType.Lz4HC, CompressionType.Lz4HC);

Stripped Version

Some BundleFile's version may be stripped, to load those file you can set a specific version

Setting.DefaultUnityVerion = "2020.3.48f1"

or per session, which also applies to the serialized files inside a bundle:

using var session = new AssetManager(options: new UnitySessionOptions { DefaultUnityVersion = "2020.3.48f1" });

Roadmap

• v0.4: Re-architect and re-implement a robust and flexible serialization API.
• v0.5: Re-introduce patching capabilities based on the new object model.

Credits

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This project stands on the shoulders of these amazing open-source projects:

• Studio by Razmoth
• AssetStudio by aelurum
• AssetsTools.NET by nesrak1
• UnityPy by K0lb3
• RustyAssetBundleEXtractor by UniversalGameExtraction