This repository contains the code for the distributed key generation protocol for the Paillier cryptosystem developed by TNO within the Shared Research Program Cyber Security.
The code is functional, but it is for now only a "local" Python prototype for illustration purposes: it consists of a single process that simply emulates behavior of the players.
The actually distributed version, with different processes per player, is still under testing, and is therefore not published here yet.
Python 3 is required.
Python dependencies are listed in the requirements.txt file;
pip install -r requirements.txt (or possibly pip3 install -r requirements.txt) will install them.
The gmpy Python library depends on a few GNU multiple precision arithmetic libraries: you can get them with sudo apt install libgmp-dev libmpfr-dev libmpc-dev.
The main source code file, contains an executable "main": cd to source and run python3 distributed_paillier.py to witness the key generation, encryption (by means of the public key) of 14, and decryption (by means of the secret key shares) of the resulting ciphertext.
Relevant functions of distributed_paillier are:
- generate_shared_paillier_key(), to generate a Paillier public key, shares of the secret key, and public masking value theta;
- the PublicKey obtained in this way is an instance of the PaillierPublicKey class of the Python "phe" library, you can use it to encrypt a value with PublicKey.encrypt(value);
- decryption of a given Ciphertext can be performed with Key.decrypt(Ciphertext, n, t, PublicKey, SecretKeyShares, theta), where n and t denote the total number of players and the privacy threshold, respectively, and PublicKey, SecretKeyShares and theta are obtain by the above key generation.