A Flask-based web application that allows users to encrypt and decrypt text using two well-known cryptographic techniques: RSA Algorithm and Caesar Cipher. This app is designed for educational purposes to demonstrate both symmetric and asymmetric encryption in a beginner-friendly interface.

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• 🧠 Implements RSA (Asymmetric Encryption)
• 🔁 Supports Caesar Cipher (Symmetric Encryption)
• 🌐 Clean web interface using Flask & HTML templates
• 🧪 Encrypt and decrypt both messages and characters
• 📦 Easy to run locally (no database required)

RSA is an asymmetric cryptographic algorithm, meaning it uses a public key for encryption and a private key for decryption.

1. Select two prime numbers P = 53 and Q = 59
2. Compute n = P * Q = 3127
3. Compute φ(n) = (P - 1)(Q - 1) = 3016
4. Choose a public exponent e = 3 such that 1 < e < φ(n) and e is coprime to φ(n)
5. Compute private key d such that d = (k * φ(n) + 1) / e, for some integer k

Example:

• Plaintext: "HI" → 8 9
• Encrypted: c = (89^3) % 3127 = 1394
• Decrypted: p = (1394^2011) % 3127 = 89 → "HI"

A substitution cipher that shifts each letter by a fixed number (shift) in the alphabet.

• Plaintext: HELLO
• Shift: 3
• Encrypted: KHOOR
• Decrypted: HELLO (by shifting back)

• Python 3.x
• Flask

git clone https://github.com/surjeetsinhthakur123/Text-Encryption-And-Decryption-Using-Rsa-Algorithm-and-Caesar-Ciphar-Tool.git
cd Text-Encryption-And-Decryption-Using-Rsa-Algorithm-and-Caesar-Ciphar-Tool
pip install flask

Run the app:

python app.py

Then visit http://localhost:5000 in your browser.

• Learn and visualize basic cryptographic methods
• Understand the difference between symmetric & asymmetric encryption
• Educational tool for Python + Flask + Cryptography

Contributions are welcome! To contribute:

1. Fork the repository
2. Create a new branch
3. Make your changes
4. Submit a pull request

Thanks to these amazing people for their contributions:

Feel free to add your name here via a pull request if you contribute!

This project is licensed under the MIT License.

Surjeet Sinh Thakur
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