QuietFileCombine

A lightweight C# library for file steganography — silently embed one or more files inside a carrier file while keeping the carrier fully functional.

Built on .NET Framework 4.5.2 | Uses Base64 encoding | Singleton pattern API

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How It Works

QuietFileCombine appends a hidden payload to the end of a carrier file using special boundary markers ([COMBINE_START] / [COMBINE_END]) and Base64 encoding. The carrier file (e.g. a .flv video) remains fully playable and functional. The embedded file(s) can be extracted at any time.

Supports multi-layer nesting: a carrier can hold a file that itself holds another file.

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Features

• Combine any two files into one without breaking the carrier
• Extend an already-combined file with additional hidden files
• Extract (split) hidden files back from a combined carrier
• Multi-layer embedding support
• Zero external dependencies — pure .NET BCL

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Quick Start

1. Add the library to your project

Reference QuietFileCombine.dll or include the source files directly.

2. Get the API instance

using QuietFileCombine.API;

var api = QuietFileCombineAPI.GetInstance();

3. Embed a file

// Embed Action.exe inside Video.flv — Video.flv stays playable
api.CombineDistinctFile(@"C:\Video.flv", @"C:\Action.exe");

4. Add another file to an existing combined carrier

// Extend the combined Video.flv with a second hidden file
api.ExtendFile(@"C:\Video.flv", @"C:\Action2.exe");

5. Extract hidden files

string outputInfo;
if (api.IsCanSplit(@"C:\Video.flv", out outputInfo))
{
    // outputInfo contains details about embedded files
    Console.WriteLine(outputInfo);
}

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API Reference

Method	Description
GetInstance()	Returns the singleton instance of the API
CombineDistinctFile(mainFile, additionFile)	Embeds additionFile into mainFile
ExtendFile(mainFile, extendedFile)	Adds another file to an already-combined carrier
IsAllowExtended(mainFile)	Returns true if the file can be extended further
IsCanSplit(mainFile, out info)	Checks whether the carrier contains hidden files

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Examples

Basic — embed an image into a video

Combine:

video.flv + picture.png  →  video.flv  (video still plays; image is hidden inside)

Split:

video.flv  →  video.flv + picture.png  (original image is restored)

Advanced — multi-layer nesting

Combine:

picture.png + crack.exe  →  picture.png
video.flv   + picture.png  →  video.flv

Split:

video.flv    →  video.flv + picture.png
picture.png  →  picture.png + crack.exe

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Project Structure

QuietFileCombine/
├── QuietFileCombine.sln
└── QuietFileCombine/
    ├── API/
    │   └── QuietFileCombineAPI.cs   # Core steganography logic
    ├── Program.cs                   # Usage example
    ├── QuietFileCombine.csproj
    └── App.config

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Requirements

• .NET Framework 4.5.2 or later
• Windows (uses System.IO and System.Convert)

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License

This project is provided for educational purposes. Use responsibly.

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