📄 Update README.md

Author: ericperret

README.md

@@ -1 +1,50 @@
-# code
+🔐 Code
+
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](#)
+[![Pure HTML/JS](https://img.shields.io/badge/Pure-HTML%2FJS-blue.svg)](#)
+[![Cryptography](https://img.shields.io/badge/Domain-Cryptography-red.svg)](#)
+
+**Classical cipher cryptanalysis toolkit** — Break historical ciphers with statistical attacks.
+
+![Screenshot](screenshot.png)
+
+## 🚀 Features
+
+- **Vigenère Cipher** — Kasiski examination, index of coincidence
+- **Beaufort Cipher** — Reciprocal cipher analysis
+- **Caesar Cipher** — Frequency analysis, brute force
+- **XOR Cipher** — Known plaintext, crib dragging
+- **Base64** — Encoding/decoding utilities
+- **Dictionary Validation** — Verify plaintext against word lists
+- **Web Workers** — Background processing for large texts
+
+## 🛠️ Tech Stack
+
+- Pure HTML/CSS/JavaScript
+- Web Workers for parallel computation
+- Frequency analysis algorithms
+- No external dependencies
+
+## 📖 Usage
+
+1. Open \`index.html\` in your browser
+2. Paste your ciphertext
+3. Select the suspected cipher type
+4. Click **Analyze** to run attacks
+5. Review candidate plaintexts
+
+## 🎓 Techniques Implemented
+
+- **Frequency Analysis** — Letter distribution comparison
+- **Index of Coincidence** — Key length estimation
+- **Kasiski Examination** — Repeated sequence analysis
+- **Dictionary Attack** — Plaintext validation
+- **Chi-squared Test** — Statistical fitness
+
+## 📄 License
+
+MIT
+
+## 👤 Author
+
+**Eric PERRET** — [GitHub](https://github.com/ericperret)