SteganoHide

Hide secret text messages inside perfectly normal-looking PNG images — and pull them back out again.

→ Try it: Install from PyPI

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Quick Start

pip install steganohide
steganohide

That's it. The tool launches an interactive menu — no extra setup needed.

Windows users: If steganohide doesn't work after installing, run it with the full path:

C:\Users\YOUR_USERNAME\AppData\Local\Python\pythoncore-3.14-64\Scripts\steganohide.exe

Or add the Scripts folder to your PATH.

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Features

• Encode any text message into a standard PNG image with zero visible change
• Decode hidden messages back out of encoded images instantly
• Works on any PNG image — photos, screenshots, artwork, etc.
• Uses a stop signal so the decoder knows exactly where your message ends
• Simple interactive CLI menu — no flags or arguments to memorize
• Pure Python with a single dependency (Pillow)

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How to Run Locally

Requires Python 3.8+.

# Clone the repo
git clone https://github.com/ivadebandit/steganography-tool.git
cd steganography-tool

# Install dependencies
pip install pillow

# Run the tool
python steg_tool.py

You'll see:

================================
   Image Steganography Project
================================
1 - Hide a secret message (Encode)
2 - Reveal a secret message (Decode)

Enter 1 or 2:

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Example Usage

Hiding a message:

Enter 1 or 2: 1

--- ENCODER ---
Path to your original image (e.g. photo.png): examples/picture.png
Secret message to hide: meet me at midnight
Save encoded image as (e.g. secret.png): examples/secret.png

Success! Encoded image saved as: 'examples/secret.png'
To a human viewer it looks completely normal.

Revealing it:

Enter 1 or 2: 2

--- DECODER ---
Path to the encoded image (e.g. secret.png): examples/secret.png

Scanning image: 'examples/secret.png'
Reading hidden data from pixels...

Hidden message revealed: 'meet me at midnight'

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How It Works

Every PNG pixel has three color channels: Red, Green, and Blue (values 0–255). The ASCII character set also maps every printable character to a number 0–127 — which fits perfectly inside that 0–255 range.

SteganoHide overwrites the Red channel of successive pixels with the ASCII value of each character in your message. The human eye can't detect a difference between a Red value of 82 (background color) and 72 (the letter 'H'). But Python can read it back precisely.

A stop signal (Red = 0) is written after the final character so the decoder knows when to stop. The Green and Blue channels are never touched, preserving the image's appearance.

'H' → ord('H') → 72  → stored in pixel (0,0) Red channel
'I' → ord('I') → 73  → stored in pixel (1,0) Red channel
 0  (stop)            → stored in pixel (2,0) Red channel

Why PNG and not JPEG? JPEG compression is lossy — it rounds pixel values during save, destroying the hidden data. PNG is lossless, so pixel values are preserved exactly after save.

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Project Structure

steganography-tool/
├── steg_tool.py       ← main CLI tool (encode + decode logic)
├── pyproject.toml     ← packaging config for PyPI
├── requirements.txt   ← Pillow dependency
├── LICENSE            ← MIT License
├── demo.gif           ← animated demo
└── examples/
    ├── picture.png    ← original input image
    └── secret.png     ← encoded output image

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Limitations

• Messages must be shorter than the total pixel count of the image
• Only works with PNG files (JPEG will corrupt the hidden data on save)
• Only ASCII characters are supported (values 0–127)
• A Red channel value of 0 in the original image will be mistaken for the stop signal — avoid pure black images

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Credits

Built with Pillow, the Python Imaging Library fork.

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Made for Hack Club Stardance — a summer of building real things.