Cryptography Playground

This project explores multiple cryptographic algorithms — RSA, ElGamal, and ECDSA — through manual implementations and secure library-based approaches, in both Java and Python.

The goal is to deeply understand cryptographic principles by implementing everything from scratch before applying industry-grade libraries like BouncyCastle and Python cryptography.

Disclaimer: This project is for educational and academic purposes only.
It is not intended for use in production systems or handling real-world sensitive data.

Index

• Available Scripts
• How It Works
• How to Use
• Parameters
• Contributing
• License
  
  

Available Scripts

Java - Manual Implementations

ELGamalMain.java

• Implements ElGamal encryption from scratch.
• Input: "This an lesson about Cryptography"
  Output: Encrypted BigIntegers + original message restored.

RSAMain.java

• Implements RSA manually, including prime generation, public/private keys, encryption and decryption.
• Input: "This an lesson about Cryptography"
  Output: Encrypted BigInteger + Decrypted message.

Java - Practical RSA & ECDSA with Libraries (BouncyCastle)

Main.java

• Full-feature cryptographic suite:
  • ✔️RSA encryption/decryption
  • ✔️RSA digital signatures (PSS + PKCS#1 v1.5)
  • ✔️ECDSA signatures with verification
• All done with security-focused libraries including BouncyCastle.
• Outputs shown in both Hex and Base64.

Python - Secure Crypto (Library-based)

RSA.py

• RSA encryption/decryption using cryptography primitives.
• Securely handles message encoding and decoding.

ELGamal.py

• ElGamal encryption using secure libraries (PyCryptodome / cryptography).
• Converts between bytes and strings, encrypts and decrypts securely.
  
  

How It Works

Java - Manual

1. A custom key pair is generated (RSA or ElGamal).
2. The string message is converted to a BigInteger.
3. Encryption is performed using modular exponentiation.
4. Decryption reverses the process and restores the original message.

Java - Library-Based Crypto

1. Uses BouncyCastle for RSA/ECDSA key generation and secure crypto operations.
2. Message is converted to bytes, encrypted/decrypted.
3. Digital signatures (RSA + ECDSA) are generated and verified.

Python

1. Cryptographic keys are securely generated with the cryptography module.
2. Messages are encoded into bytes.
3. Encryption, decryption, and signature processes are securely handled using trusted libraries.
   
   

How to Use

1. Clone the repository:
   git clone https://github.com/YOUR_USERNAME/cryptography-playground.git
2. Navigate to the project directory:
   cd cryptography-playground

Java

• Compile and run the desired script:
  javac RSAMain.java
java RSAMain
• Or for the advanced project:
  javac Main.java
java Main

Make sure to include all .java dependencies in the same directory or classpath.

Python

• Install requirements (if any) and run:
  pip install cryptography pycryptodome
python RSA.py
python ELGamal.py
  
  

Parameters

No command-line parameters are required — messages are defined directly in the code for clarity. You can change them manually in the scripts.

Contributing

Feel free to contribute! Open a pull request or create an issue to suggest improvements or new crypto features. Collaboration is welcome — especially if you're experimenting with new algorithms or padding schemes.

License

This project is licensed under the MIT License. See LICENSE for more details.