📦 PNGstagram

Steganography for the Web — hide and reveal messages in PNG images

https://elizavetara.github.io/PNGstagram/

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🖼 What is PNGstagram?

PNGstagram is a minimalist web app that lets you hide secret messages inside PNG images using the least significant bits (LSBs) of pixel colors — right in your browser.
No installation, no server, no trace.

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✨ Features

• 🧠 Client-side steganography (no data leaves your browser)
• 📝 Encode text messages into images
• 🔍 Decode hidden messages from PNGs
• 🎨 Clean, tab-based UI
• 🔐 (Optional) Easily extendable to AES encryption or file embedding

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🚀 How to Use

1. Open index.html in your browser.
2. Encode tab:
   • Upload a PNG image
   • Enter your secret message
   • Click “Encode & Download”
3. Decode tab:
   • Upload a PNG with a hidden message
   • Click “Read Hidden Message”
   • The secret is revealed!

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🧪 How it Works

• Each pixel has Red, Green, Blue, Alpha channels (4 bytes)
• We modify the least significant bit (LSB) of R, G, and B to store message bits
• Message length is stored in the first 4 bytes (32 bits)
• Total: 3 bits per pixel, invisible to the human eye

🧮 Data Capacity Examples

Image Size	Total Pixels	Usable Bits	Usable Bytes	Approx. Text Capacity
100 × 100	10,000	30,000	~3.75 KB	~3,750 characters
500 × 500	250,000	750,000	~93.75 KB	~90,000 characters
1000 × 1000	1,000,000	3,000,000	~375 KB	~375,000 characters
1920 × 1080	2,073,600	6,220,800	~777 KB	~750,000 characters

(Text estimates assume ~1 byte per character in UTF-8 for typical English text)

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💡 Example Use Cases

• Easter eggs in flyers or posters
• Hidden invitations, challenge clues
• Teaching digital privacy and steganography

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🔓 License

MIT — free to use, share, and modify.