paillier-solidity

A PoC to demonstrate homomorphic addition of two ciphertexts using the Paillier cryptosystem.

By default, Solidity is unable to perform certain cryptographic operations due to the restrictions on the size of some of its data types. With the use of the solidity-BigNumber library, we can bypass these restrictions and finally perform cryptography from within a smart contract.

Prerequisites

Node.js >= 16.0 - required for Hardhat

Installation

Clone the repo: git clone https://github.com/jahali6128/paillier-solidity.git

Change to the paillier-solidity directory: cd paillier-solidity

Install the dependencies: npm install

Compile the smart contracts in the contracts directory: npx hardhat compile

Deploy Contracts

Once compiled they can be deployed using the JS script scripts/deploy.js:

npx hardhat run scripts/deploy.js
PaillierSolidity deployed to: 0x5FbDB2315678afecb367f032d93F642f64180aa3

Running Unit Tests

There are two tests for both of the functions in the PaillierSolidity contract: addEncSum and encZero.

To run these tests, enter the command: npx hardhat test

You should see an output like this if both tests passed:

  PaillierSolidity.sol
Decrypted Sum: 3
    ✔ Adding Encrypted Sums - E(a) + E(b) = E(a + b) (6289ms)
Decrypted Zero: 0
    ✔ Encrypting Zero (779ms)
    
  2 passing (7s)