I’ve recently been learning how to prevent or secure my Unity game from being extracted. I used AssetRipper to extract someone else’s game and found a script that appears to hide all the code.
The extracted script looks like this:
using UnityEngine;
public class ABC : MonoBehaviour
{
Dummy class. This could have happened for several reasons:
1. No dll files were provided to AssetRipper.
Unity asset bundles and serialized files do not contain script information to decompile.
* For Mono games, that information is contained in .NET dll files.
* For Il2Cpp games, that information is contained in compiled C++ assemblies and the global metadata.
AssetRipper usually expects games to conform to a normal file structure for Unity games of that platform.
A unexpected file structure could cause AssetRipper to not find the required files.
2. Incorrect dll files were provided to AssetRipper.
Any of the following could cause this:
* Il2CppInterop assemblies
* Deobfuscated assemblies
* Older assemblies (compared to when the bundle was built)
* Newer assemblies (compared to when the bundle was built)
Note: Although assembly publicizing is bad, it alone cannot cause empty scripts. See: https://github.com/AssetRipper/AssetRipper/issues/653
3. Assembly Reconstruction has not been implemented.
Asset bundles contain a small amount of information about the script content.
This information can be used to recover the serializable fields of a script.
See: https://github.com/AssetRipper/AssetRipper/issues/655
4. This script is unnecessary.
If this script has no asset or script references, it can be deleted.
Be sure to resolve any compile errors before deleting because they can hide references.
5. Script Content Level 0
AssetRipper was set to not load any script information.
6. Cpp2IL failed to decompile Il2Cpp data
If this happened, there will be errors in the AssetRipper.log indicating that it happened.
This is an upstream problem, and the AssetRipper developer has very little control over it.
Please post a GitHub issue at: https://github.com/SamboyCoding/Cpp2IL/issues
7. An incorrect path was provided to AssetRipper.
This is characterized by "Mixed game structure has been found at" in the AssetRipper.log file.
AssetRipper expects games to conform to a normal file structure for Unity games of that platform.
An unexpected file structure could cause AssetRipper to not find the required files for script decompilation.
Generally, AssetRipper expects users to provide the root folder of the game. For example:
* Windows: the folder containing the game's .exe file
* Mac: the .app file/folder
* Linux: the folder containing the game's executable file
* Android: the apk file
* iOS: the ipa file
* Switch: the folder containing exefs and romfs
*/
}
Could someone help me understand how to protect my game from this kind of extraction?
Thanks
Code Protection:
If there are blocks in your code that you do not want to be read or manipulated, you can use IL2CPP backend. However, remember that IL2CPP never provides complete protection. Methods can still be manipulated or called manually. Of course, this will not be as easy as Mono.
A much more useful way would be to encrypt the code. You can use any Obfuscator available on the Asset Store.
Asset Store search: https://assetstore.unity.com/search#q=obfuscator
But remember, no way can prevent your game’s codes from being manipulated and replayed. For now…
Asset Protection (3D Models, Animations Etc.):
From the Unity Website: “An AssetBundle is an archive file that contains platform-specific non-code Assets (such as Models, Textures, Prefabs, Audio clips, and even entire Scenes) that Unity can load at run time.”
AssetBundles allow Unity assets (such as 3D models, animations, textures) to be stored as a standalone package and later included in the game.
If there are assets in your game that you are afraid of being extracted, you can put them in a bundle and download them from a server after the game is installed.
But remember, if someone reaches your AssetBundle, they can extract it too.
Even if they do not reach any of them, those who are interested in this work can use rippers such as DXRipper, rippers that use DirectX or OpenGL APIs to export your entire scene.