PyCastX is a Python package that provides:

• Secure Elliptic Curve Cryptography (ECC) utilities
• A Genetic Algorithm-based AES S-Box optimizer for enhanced cryptographic strength
• High-entropy key generation using Shannon entropy

📦 Installation

Install directly from PyPI:

pip install pycastx

🔐 Features

🔸 Elliptic Curve Cryptography (ECC)

• Define a custom elliptic curve over a finite field.
• Generate secure private/public key pairs.
• Validate whether a point lies on the curve.
• Generate high-entropy keys based on Shannon entropy.

🔸 Genetic AES S-Box Optimizer

• Generate substitution boxes (S-boxes) using Genetic Algorithms.

• Optimize S-boxes for:

  • Non-linearity
  • Avalanche Effect

• Useful in block cipher research and analysis.

🚀 Usage Examples

✅ ECC Key Generation

from pycastx.ecc import EllipticCurve, KeyEntropyCalculator

# Define custom curve parameters
a = 56698187605326110043627228396178346077120614539475214109386828188763884139993
b = 17577232497321838841075697789794520262950426058923084567046852300633325438902
p = 76884956397045344220809746629001649093037950200943055203735601445031516197751
Gx = 63243729749562333355292243550312970334778175571054726587095381623627144114786
Gy = 38218615093753523893122277964030810387585405539772602581557831887485717997975
n = 0xA9FB57DBA1EEA9BC3E660A909D838D718AFCED59

# Initialize curve
curve = EllipticCurve(a, b, p, Gx, Gy, n)

# Key entropy calculator
entropy_calc = KeyEntropyCalculator(curve)
private_key, entropy = entropy_calc.generate_high_entropy_key(num_trials=100)
public_key = curve.public_key_from_private(private_key)

print("Private Key:", private_key)
print("Entropy:", entropy)
print("Public Key:", public_key)
print("Is Public Key Valid?", curve.is_point_on_curve(public_key))

✅ AES S-Box Generation Using Genetic Algorithm

from pycastx.sbox import DynamicAESSBoxGA

# Initialize Genetic Algorithm
ga = DynamicAESSBoxGA(population_size=50, generations=10, mutation_rate=0.05)

# Generate optimized S-box
optimized_sbox = ga.apply_ga()

print("Optimized S-Box:")
print(optimized_sbox)

🧪 Running Tests

To run all tests using unittest:

python -m unittest discover tests

📚 API Reference

class EllipticCurve(a, b, p, Gx, Gy, n)

Represents an elliptic curve over a finite field.

Methods:

• point_addition(P, Q)
• scalar_multiplication(k, P)
• generate_private_key()
• public_key_from_private(private_key)
• is_point_on_curve(P)

class KeyEntropyCalculator(curve)

Computes entropy and generates high-entropy ECC keys.

Methods:

• shannon_entropy(data)
• private_key_to_byte_array(private_key)
• generate_high_entropy_key(num_trials=100)

class DynamicAESSBoxGA(population_size, generations, mutation_rate)

Optimizes AES S-boxes using a genetic algorithm.

Methods:

• generate_sbox()
• evaluate_sbox(sbox)
• apply_ga()

📜 License

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

🤝 Contributing

Pull requests are welcome! For major changes, please open an issue first to discuss.

🧠 Acknowledgements

This package was built to support research in:

• Lightweight cryptography
• ECC-based key generation
• AES S-box design optimization

🔗 Links

• PyPI Project
• GitHub Repository