RSA Implementation in Python

A basic implementation of the RSA (Rivest–Shamir–Adleman) public-key cryptosystem built in Python for educational purposes. This project includes functionality for key generation, encryption, and decryption.

Developed for my Applied Cryptography class

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Features

• Key Generation: Generates 512-bit public and private RSA keys using two large random prime numbers.
• Encryption: Encrypts plaintext (converted to an integer) using the public key.
• Decryption: Decrypts ciphertext (an integer) back into plaintext using the private key.
• Persistent Keys: Automatically generates, saves and loads keys from public.rsa and private.rsa files.

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Setup and Installation

You need Python 3 installed. This project also relies on the sympy library for prime number generation.

1. Clone the repository:

   git clone https://github.com/Di0go/rsa-implementation
   cd rsa-implementation/src

2. Install dependencies: This project uses sympy. It's best practice to use a virtual environment.

   # Create and activate a virtual environment
   python3 -m venv venv
   source venv/bin/activate
   
   # Install the required library
   pip install sympy

3. Run the main application file:

   python3 rsa.py

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Known Limitations and Future Work

This implementation is for educational use only; do not use it for secure, production-grade applications.

• Security Risk (Textbook RSA): The code uses raw exponentiation without any standardized padding (like OAEP). This is known as "textbook RSA" and is fundamentally insecure against various attacks.

• Message Size: Encrypting the entire message as one integer is inefficient and limits the plaintext size to the key size (512 bits).

• Key Storage: Keys are currently stored as simple string representations of Python lists. Future work should implement Base64 or PEM encoding for robust key persistence.