🕵️ Lupin

A blazing-fast, lightweight steganography tool for concealing data inside normal-looking files. Lupin can be used as a CLI tool for quick operations or as a Rust library for integration into your applications.

Steganography hides the existence of data rather than just its contents. Where encryption makes a message unreadable, steganography makes it invisible: the file still looks and behaves like an ordinary PDF, PNG, or JPEG.

Lupin is named after Arsène Lupin, the fictional gentleman thief, for the same reason: hiding something in plain sight.

Supported Formats

• PDF: Appends data after the %%EOF marker (unlimited capacity, easily detectable)
• PNG: Custom ancillary chunks (unlimited capacity, zero visual artifacts, somewhat easily detectable)
• JPEG: Signed APP13 application markers, split across segments as needed (unlimited capacity, zero visual artifacts, somewhat easily detectable)

Quick Start

CLI Tool

# Install
cargo install lupin

# Or build from source: git clone && cargo build --release

# Hide data in PDF
lupin embed document.pdf secret.txt output.pdf

# Extract data
lupin extract output.pdf recovered.txt

# More options
lupin --help

More info in the CLI Guide.

Rust Library

# Cargo.toml
[dependencies]
lupin = "1.0"

use lupin::operations::{embed, extract};

// Read files
let source = std::fs::read("document.pdf")?;
let payload = std::fs::read("secret.txt")?;

// Embed with metadata
let (embedded_data, metadata) = embed(&source, &payload)?;
println!("Used {} engine", metadata.engine);

// Extract
let (extracted, info) = extract(&embedded_data)?;

More info in the Library Guide.

Documentation

• CLI Guide - Command-line usage, logging, examples
• Library Guide - Rust API, integration examples
• Architecture - How it works, adding new formats

Contributing

Contributions welcome! Please read the architecture docs to understand the codebase structure.

License

Apache License 2.0. See LICENSE for details.

Disclaimer: For educational and legitimate use only. Users are responsible for complying with applicable laws.