McpDecryptor.py

You can run this script directly to decrypt NetEase Minecraft mod encrypted .mcp filesand directly obtain the developer_mods folder. (For map template modification only) Can also be used as a forked repository of the original repository!

vanilla_mcp_util

A utility for researching a game's script files, such as vanilla.mcp.

Features

• Unpack/Pack MCPK files.
• Decrypt .mcs files to original .pyc files.
• Anti-confusion for decrypted .mcs files (partially implemented).

Requirements

Python 3.8 or higher.

File description

• mcpk.py: Unpack MCPK file to a folder, and restore the origin path structure. Compatible for 2 variants (game script pack and resources pack, the first one is not completed implemented).
• mcs.py: Decrypt and post process mcs file that unpack from .mcp file. Returns the origin confused .pyc used for game's python marshal.loads(). Compatible for 3 variants .mcs file ()
• anti_confuser.py <mcs_file>: Anti-confusion for origin .mcs files. Returns deobfuscated .pyc file (not completely implemented yet, now is okay for redirect.mcs in 3 variants)

About MCPK

• MCPK is a custom archive format used in a game to package scripts and resources.
• About 2 variants:
  1. Script pack: python project structure but with confusion pyc file, contains a redirect.mcs in package root path as script loader(McpImporter).
  2. Resource pack: origin resources pack structure, which contains a contents.json to list all path in package.

About MCS

• MCS is a custom encrypted format for python bytecode files (.pyc).
• About 4 variants:
  1. V1 (1.0-1.25)
     • It has standard python codeobject, and non-encrypted str storage. Only opcode remapped.
  2. V2 (2.0-2.1)
     • It has changed the sort of codeobject fields, and str storage is encrypted with XOR or RC4. With opcode remapped too. It adds a magic number in code object.
     • The magic of build-in scripts is -1135027243. And the modders' scripts.
  3. V3 (2.2-2.6)
     • Similar to variant 2, but with different RC4 decrypt key, code object, and opcode remap table.
     • The magic of build-in scripts is -901139953.
  4. V4 (2.7+ with latest patch)
     • Similar to variant 3, but with more code object fields added, and a new opcode added.
     • The magic of build-in scripts is the same as V3, but use different code object, and opcode remap table. The modders' scripts' magic number is the same as V2.

Disclaimer

• This tool is intended for educational purposes only. Use of this tool may violate software licenses or terms of service.
• Don't use this tool for malicious purposes. The author is not responsible for any misuse of this tool.