🕵️‍♂️ whisp - Steganography CLI Tool

whisp is a modern C++ command-line application for hiding and extracting files inside image files using steganography techniques. It supports both RGB LSB encoding and alpha-channel encoding, and uses a clean modular design with support for unit testing, logging, and rich CLI parsing.

✨ Features

• 🔐 Hide any file inside PNG or BMP images
• 🎨 Two encoding methods:
  • LSB in RGB channels (1/2/4 bits configurable)
  • Alpha channel embedding
• 🧠 Automatic decoding using embedded metadata
• 🧪 Written in modern C++ with clean code and unit tests
• 📦 Uses libraries: gtest, CLI11, CImg, spdlog
• 📦 Dependency management via vcpkg

📦 Dependencies

This project uses vcpkg to manage dependencies. The toolchain file is already integrated via CMake presets.

You can find the preset toolchain settings in:

cmake/presets/toolchains/vcpkg.json

🛠️ Build Instructions

This project uses CMake Presets and Ninja Multi-Config. You can configure and build the project as follows:

List available presets

cmake --list-presets

Configure the project

cmake --preset <PRESET_NAME>

Build a specific target

cmake --build --preset <PRESET_NAME> --target <TARGET>

🚀 Usage

🔏 Encode a file using RGB LSB encoding

whisp encode --image-file input.png --secret-file secret.txt rgb --bits 2

• --bits can be 1, 2, or 4

🫥 Encode a file using alpha channel

whisp encode --image-file input.png --secret-file secret.txt alpha

The output will be saved as:

encoded_input.png

🕵️ Decode a hidden file from an image

whisp decode --image-file encoded_input.png

The tool will detect the encoding method and extract the hidden file.

🧪 Testing

To run unit tests:

cmake --build --preset <PRESET_NAME> --target whisp_tests
ctest --preset <PRESET_NAME>

⚙️ CMake Configuration Options

You can enable advanced tooling and analysis with the following options when configuring with CMake:

• -DCLANG_TIDY_ENABLE=ON – Enables clang-tidy analysis on all targets
• -DSANITIZERS_ENABLE=ON – Enables runtime sanitizers (ASan, UBSan, etc.)
• -DCOVERAGE_ENABLE=ON – Enables code coverage for unit tests and adds a coverage target

🧪 Note: Coverage collection currently works only with GCC.

🧾 Presets Overview

You can use the following CMake presets depending on your compiler:

• x64-linux-clang-* – For building with Clang
• x64-linux-gcc-* – For building with GCC

Use these presets with the --preset flag during configuration and build steps.

🧠 How It Works

• For RGB LSB, the tool stores bits of the file into the least significant bits of the image's channels.
• For Alpha, it stores data directly into the alpha channel of the image.
• A small header is embedded into the image to identify the method and bit-depth used, which allows correct decoding.

📜 License

MIT License

✍️ Author

github.com/marcmal