I'm learning how to modify 3D models in Unreal Engine 5 games using FModel. I understand that some games use AES-encrypted asset archives, and I'm wondering what legitimate approaches exist when the encryption key is not publicly available. I've experimented with modding Unity games and would like to learn more about game files, encryption, debugging, and how different engines work. I'm familiar with the general idea of reverse engineering and tools such as Ghidra, but I'm still a beginner and can't write much code yet. Is it worth studying computer science and reverse engineering for this goal, or should I focus on games that officially support modding and learn through their tools instead?
4 Answers
A public or private-key analogy doesn’t map neatly onto every game’s asset-encryption setup. In many cases the application needs access to some secret during execution, but that doesn’t mean the key is meant to be publicly recoverable. Rather than focusing only on extracting a key, learn how packaging, key checks, and runtime decryption are designed, preferably using software you own or have permission to inspect.
If your main goal is learning, you may get more useful experience by creating a small Unreal project, packaging assets yourself, and experimenting with the encryption and loading process there. You can then compare the packaged files with the original assets and debug your own program without trying to bypass someone else’s protections.
Another broad approach is to study how the game loads and decrypts its own data at runtime rather than treating the archive as something you must unlock directly. That can teach you a lot about executable analysis and memory, but investigating protected software can violate a game’s terms or anti-cheat rules, so avoid online games and use controlled, legally permitted examples.
You don’t need to learn all of computer science before starting. Ghidra can be a useful learning tool, especially for understanding compiled programs, but it’s better to begin with fundamentals such as C or C++, assembly basics, debugging, and how Unreal packages assets. Also keep in mind that encrypted or protected assets may be intentionally restricted, so practice on your own projects, games with mod support, or files you’re authorized to analyze.
That makes sense. I’m more interested in understanding how the engine and file formats work than just changing one model, so experimenting with my own Unreal projects may be a better starting point.