🔐 Caesar Cipher with ASCII (Python)

A Python implementation of the Caesar Cipher algorithm using ASCII values (ord() / chr()) for encryption and decryption.
This project demonstrates the basics of cryptography, brute force attacks, and word-to-number conversion in Python.

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🚀 Features

• ✅ Encrypt Text → Shift characters using a key
• ✅ Decrypt Text → Retrieve original message using the key
• ✅ Brute Force Attack → Try all 26 possible shifts to crack unknown keys
• ✅ Word-to-Number Support → Key can be given as number (3) or word (three)
• ✅ Preserves Non-Alphabet Characters → Numbers, spaces, punctuation remain unchanged

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📂 Project Structure

📁 Caesar-Cipher-ASCII │── caesar_cipher.py # Main script │── README.md # Documentation (this file) │── requirements.txt # Python dependencies

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🛠️ Installation

1. Clone this repository:

   git clone https://github.com/your-username/Caesar-Cipher-ASCII.git
   cd Caesar-Cipher-ASCII

2. Install dependencies:

   pip install -r requirements.txt

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📌 Usage

Run the program:

python caesar_cipher.py

Choose a mode:

• E → Encrypt
• D → Decrypt
• B → Both (Encrypt + Decrypt)
• BF → Brute Force (try all keys)

🔑 Example (Encryption)

Do you want to (E)ncrypt, (D)ecrypt, (B)oth, or (BF) brute force? e
Enter the text: Hello World
Enter the key value: 3
Encrypted: Ebiil Tloia

🔓 Example (Decryption)

Do you want to (E)ncrypt, (D)ecrypt, (B)oth, or (BF) brute force? d
Enter the text: Ebiil Tloia
Enter the key value: 3
Decrypted: Hello World

🕵️ Example (Brute Force Attack)

Do you want to (E)ncrypt, (D)ecrypt, (B)oth, or (BF) brute force? bf
Enter the cipher text to brute force: Ebiil Tloia

...... Brute force results ......
Key 0: Ebiil Tloia
Key 1: Fcjjm Umpjb
Key 2: Gdkkn Vnqkc
...
Key 23: Hello World   ✅
Key 24: Ifmmp Xpsme
Key 25: Jgnnq Yqtnf

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📦 Requirements

• Python 3.x
• Dependencies:

  word2number

Or install manually:

pip install word2number

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📖 How it Works

1. Each character is converted to its ASCII value using ord().
2. A shift (positive or negative) is applied modulo 26.
3. The result is converted back to a character with chr().
4. Non-alphabet characters (numbers, punctuation, spaces) remain unchanged.
5. Decryption simply reverses the process.

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🎯 Learning Goals

• Understand classical cryptography (Caesar cipher)
• Implement encryption & decryption algorithms in Python
• Learn about brute force attacks and why weak ciphers fail
• Practice working with ASCII values and string manipulation

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📌 Future Improvements

• Add support for custom alphabets
• Implement ROT13 mode (common variant of Caesar Cipher)
• Add GUI version (Tkinter/Flask app)
• Extend project to other ciphers (Vigenère, Substitution)

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🤝 Contributing

Pull requests are welcome! If you’d like to improve the project, fork it and submit a PR.

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📜 License

This project is licensed under the MIT License.

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👨‍💻 Author

Your Name

• 🌐 GitHub
• 💼 LinkedIn

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