threshold-elgamal 0.0.13

Threshold ElGamal cryptosystem

Threshold ElGamal cryptosystem

This is a library that provides methods for threshold encryption, decryption and DKG (distributed key generation) algorithm using the ElGamal cryptosystem. Threshold ElGamal encryption and decryption algorithms were based on Cachin's work, and the algorithm used for distributed key pair generation was based on a 1999 paper by Gennaro et al. Both algorithms use a form of secret sharing first introduced in a 1979 paper by Shamir.

This goes without saying, but you should NOT use this library in a production setting. It has not been pentested nor was any kind of exhaustive security analysis done. This library is developed primarily for demonstration of theoretic threshold schemes.

Installation

Before installing the library, make sure its dependencies are installed: pycryptodome, gmpy2 and setuptools. The library is written for Python >= 3.9.

You can then install the library via pip:

pip install threshold-elgamal

Getting started

The simplest way you can test out this library is by running its main function:

from threshold_elgamal import run_tc_scheme

res = run_tc_scheme(k=3, n=5, m=10)
if res is True:
    print("Success!")

You can also create your own threshold scheme manually, and then encrypt and decrypt a message of your choosing:

from threshold_elgamal import create_tc_scheme

message = 10
public_key, players, scheme = create_tc_scheme(k=3, n=5)
c1, c2 = scheme.encrypt(public_key, message=message)
decryption_shares = {player.id: player.get_decryption_share(c1) for player in players}
decrypted_msg = scheme.decrypt(c2, decryption_shares)

if decrypted_msg == message:
    print("Success!")