BLC-VFS

Remember: Delete this within 24 hours.

A high-performance tool for mounting and extracting game resource packages from Arknights: Endfield (BLC format). Mounting 260,000 files of 50GB only takes 1 second

⚠️ DISCLAIMER

THIS SOFTWARE IS PROVIDED FOR EDUCATIONAL AND RESEARCH PURPOSES ONLY.

This project is a tool designed for studying file formats and encryption methods. The author does not condone or encourage:

• Piracy or copyright infringement
• Unauthorized distribution of game assets
• Commercial use of extracted content
• Any illegal activities

USE THIS SOFTWARE AT YOUR OWN RISK. THE AUTHOR IS NOT RESPONSIBLE FOR ANY MISUSE OR DAMAGES RESULTING FROM THE USE OF THIS TOOL.

🗑️ DELETE NOTICE

Please delete this repository within 24 hours of downloading/cloning.

This repository contains tools and information that may be used to extract copyrighted material. By accessing this repository, you agree to:

1. Use this software solely for educational purposes
2. Not distribute any extracted copyrighted content
3. Delete all copies of this repository within 24 hours
4. Comply with all applicable laws and regulations in your jurisdiction

📋 License

This project is licensed under the Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License.

Copyright (c) 2026 blc-vfs contributors

Licensed under the Attribution-NonCommercial-ShareAlike 4.0 International License.
You may not use this file except in compliance with the License.
You may obtain a copy of the License at:
    https://creativecommons.org/licenses/by-nc-sa/4.0/

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

🙏 Acknowledgments & Code References

This project incorporates code and concepts from the following sources:

CC BY-NC-SA 4.0 Licensed Sources:

• BydTools by SherkeyXD

  • BLC/VFS parsing and decryption implementation reference
  • Licensed under: Attribution-NonCommercial-ShareAlike 4.0

• Endfield CBT3 Reverse Engineering by Harryh

  • VFS storage and decryption analysis documentation
  • Licensed under: Attribution-NonCommercial-ShareAlike 4.0

• AnimeWwise by Escartem

  • Wwise audio processing utilities
  • Licensed under: Attribution-NonCommercial-ShareAlike 4.0

MIT Licensed Sources:

• AnimeStudio by Escartem

  • Studio tools and utilities reference
  • Licensed under: MIT License

• VGMToolbox by Manicsteiner

  • Criware USM video stream demuxing implementation
  • Licensed under: MIT License

Unlicensed Sources:

• FkArkEnd by shiikwi
  • Binary parsing reference
  • Note: This repository has no explicit license; code used with attribution

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🚀 Features

Core Functionality

• BLC File Parsing: Complete support for BLC virtual file system format
• Decryption: ChaCha20-based automatic decryption for encrypted files
• Multiple File Types: Support for BLC, PCK, and xLua formats
• High Performance: Memory-mapped I/O for efficient large file handling
• Zero-Copy Operations: Optimized data handling to minimize memory usage

User Interfaces

• CLI (Command Line Interface): Full-featured command-line tool
• GUI (Graphical User Interface): Modern interface built with egui/eframe

Supported Formats

Core Formats

Format	Extension	Description	Status
BLC	.blc	Main virtual file system container	✅ Working
CHK	.chk	Chunk integrity verification files	✅ Working

Audio Formats

Format	Extension	Description	Status
PCK	.pck	Wwise audio package files	✅ Working
WEM	.wem	Wwise encoded media (embedded in PCK)	✅ Working

Script Formats

Format	Extension	Description	Status
xLua	.lua	Encrypted Lua scripts (XXTEA)	✅ Working
Lua	.lua	Decrypted Lua source code	✅ Working

Video Formats

Format	Extension	Description	Status
USM	.usm	Cri Stream Media (video extraction)	✅ Working
M2V	.m2v	MPEG-2 video stream (extracted from USM)	✅ Working

Data/Config Formats

Format	Extension	Description	Status
SparkBytes	.bytes	TableCfg package files	✅ Working
JSON	.json	Exported configuration data	✅ Working
PathBytes	.bytes	Path-based compressed data	✅ Partial support
HGMMap	.hgmmap	Map data files	✅ Working

Binary Formats

Format	Extension	Description	Status
CompressData	.bin	Compressed data archives	✅ Working

🏗️ Architecture

Module Structure

src/
├── Binaries/
│   ├── cli.rs              # Command-line interface
│   ├── gui_main.rs         # GUI application entry point
│   └── gui/
│       ├── mod.rs          # GUI module root
│       ├── packages_window.rs  # Package browser window
│       ├── file_browser.rs     # File navigation panel
│       ├── extraction.rs       # Extraction logic UI
│       ├── pck_view.rs         # PCK viewer component
│       ├── search_panel.rs     # Search functionality
│       ├── progress_bar.rs     # Progress indicator
│       ├── status_bar.rs       # Status display
│       ├── header.rs           # Window header
│       └── types.rs            # GUI-specific types
├── VFS/
│   ├── mod.rs              # Virtual File System root
│   ├── Package/
│   │   ├── mod.rs          # Package management
│   │   └── multi_vfs.rs    # Multi-VFS support
│   ├── FileType/
│   │   ├── mod.rs          # File type dispatcher
│   │   ├── PCK/
│   │   │   ├── mod.rs      # PCK module root
│   │   │   ├── pck_parser.rs    # PCK file parser
│   │   │   ├── pck_decipher.rs  # PCK decryption
│   │   │   └── pck_extractor.rs # PCK extraction
│   │   └── xLua/
│   │       ├── mod.rs      # xLua module root
│   │       ├── lua_decipher.rs  # Lua decryption
│   │       └── xxtea.rs        # XXTEA implementation
│   ├── sparkbytes/
│   │   ├── mod.rs          # SparkBytes module root
│   │   ├── bytes_parser.rs # .bytes file parser (TableCfg)
│   │   └── types.rs        # SparkBytes type definitions
│   ├── pathbytes/
│   │   ├── mod.rs          # PathBytes module root
│   │   ├── parser.rs       # PathBytes parser
│   │   ├── compress_parser.rs  # Compressed data parser
│   │   ├── types.rs        # PathBytes type definitions
│   │   └── json.rs         # JSON export utilities
│   ├── hgmmap/
│   │   ├── mod.rs          # HGMMap module root
│   │   ├── hgmmap_parser.rs # HGMMap file parser
│   │   ├── types.rs        # HGMMap type definitions
│   │   └── json.rs         # JSON export utilities
│   └── usm/
│       ├── mod.rs          # USM module root
│       └── parser.rs       # USM video stream extractor
│   └── BLC/
│       ├── mod.rs          # BLC module root
│       ├── types.rs        # Data structures
│       ├── parser.rs       # Binary format parser
│       ├── crypto.rs       # Encryption/decryption
│       └── error.rs        # Error definitions
└── lib.rs                  # Library entry point

Key Components

1. BLC Types & Parser (types.rs, parser.rs)

• BlcMainInfo: Main information block structure
• ChunkInfo: Chunk metadata
• FileInfo: Individual file information
• UInt128: 128-bit MD5 hash representation

2. Cryptographic Module (crypto.rs)

• ChaCha20 stream cipher implementation
• Automatic BLC file decryption
• Per-file decryption support

3. Virtual File System (VFS/mod.rs)

• BLC file mounting and management
• CHK file mapping for integrity verification
• Unified file reading interface
• Transparent decryption layer

4. Error Handling (error.rs)

• Comprehensive error type definitions
• Detailed error messages for debugging

🛠️ Installation & Usage

Prerequisites

• Rust Toolchain: Install from rustup.rs
  • Minimum Rust Edition: 2021
  • Recommended: Latest stable release

Building

# Clone the repository
git clone <repository-url>
cd blc-vfs

# Build release version
cargo build --release

The build process will produce two binaries:

• blc-vfs-cli.exe - Command-line interface
• blc-vfs-gui.exe - Graphical user interface

CLI Usage

# Start interactive CLI
./target/release/blc-vfs-cli.exe

# Available commands:
mount <blc_file> [chk_folder]    # Mount a BLC file (optionally specify CHK folder)
list                               # List all mounted files
extract <file_path>                # Extract a single file
extract-all [output_dir]           # Extract all files to directory
info                               # Display VFS information
help                               # Show available commands
quit / exit                        # Exit the program

GUI Usage

# Launch graphical interface
./target/release/blc-vfs-gui.exe

The GUI provides:

• 📁 Package browser with drag-and-drop support
• 🔍 Real-time file search functionality
• 📊 Progress tracking during extraction
• 🎨 Modern, responsive interface

✅ Verified Capabilities

• ✅ Successfully mount BLC files
• ✅ Parse complete file listings
• ✅ Extract individual and batch files
• ✅ Automatic decryption of encrypted content
• ✅ Support for multiple platforms (Windows, Android bundles)
• ✅ Memory-efficient large file handling
• ✅ Partial .bytes file support: TableCfg package (42A8FCA6) .bytes files → JSON
• ✅ ExtendData .bin files
• ❌ Streaming .bytes files (not yet supported)

🔬 Technical Highlights

Performance Optimizations

1. Memory Mapping (mmap): Zero-copy reads for large files using memmap2
2. Parallel Processing: Multi-threaded extraction via rayon
3. Efficient Cryptography: Stream cipher operations minimize memory overhead
4. Type Safety: Rust's ownership system ensures memory safety without garbage collection

Comparison with Python Implementation

Feature	Python Version	This Implementation
Performance	Slower	~10-50x faster
Memory Usage	Higher	Significantly lower
Type Safety	Dynamic typing	Static typing
Error Handling	Exceptions	Result<T, E> pattern
Concurrency	GIL limited	Native multi-threading
Binary Size	Requires interpreter	Single executable

📊 Dependencies

Runtime Dependencies

• chacha20 v0.9 - ChaCha20 stream cipher
• base64 v0.22 - Base64 encoding/decoding
• serde v1.0 - Serialization framework
• thiserror v2.0 - Error derivation macros
• memmap2 v0.9 - Memory-mapped file I/O
• walkdir v2.5 - Directory traversal
• md-5 v0.10 - MD5 hashing
• byteorder v1.5 - Byte order utilities
• serde_json v1.0 - JSON serialization for .bytes parsing

GUI Dependencies

• eframe v0.29 - egui framework integration
• egui v0.29 - Immediate mode GUI library
• rfd v0.15 - Native file dialogs
• rayon v1.10 - Parallel processing

🤝 Contributing

Contributions are welcome! Please follow these guidelines:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Note: All contributions must comply with the CC BY-NC-SA 4.0 license terms.

📄 Code of Conduct

• Respect copyright and intellectual property
• Use only for educational/research purposes
• Do not redistribute extracted copyrighted materials
• Credit original authors when referencing their work
• Comply with all applicable laws

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