THE FIRST ZERO-KNOWLEDGE & TRULY DECENTRALIZED VOTING SYSTEM USING ETHEREUM, TRUFFLE, ZOKRATES.JS & REACT-JS

This proposal is showcasing the ability to deploy a voting system on blockchain with minimal computational overhead such that is becomes browser-friendly. This is mainly done by scrapping traditional additive homomorphic voting schemes in favour of a zero-knowledge SNARK proof of membership. The lightweight library of Zokrates-JS allows us to use an ES6 module within our react script to perform zero-knowledge operations. This is coupled with a Web3 library to communicate the zero-knowledge proofs with the Election Contract. Unlike other proposals, this project doesn't require a Trusted Authority for Tally decryption as it exploits the disassociation between a voter and their SNARK-proof (Vote Ballot) to pass the vote value whilst utilizing Unique Identifiers to provide self-verifiability of vote process completion.

"True Decentralized voting using blockchain and zero-knowledge proofs"- Rayyan Jafri, Faculty of Science & Engineering, The University of Groningen, The Netherlands

HOW TO INSTALL: Blockchain Components: Install your local blockchain (Ganache, Ganache-CLI, TestRPC..) then from the project root: npm install - Install deps npm install -g truffle - Install truffle

DAPP cd dapp - Navigate to DAPP root yarn install - Install deps

HOW TO RUN:

Blockchain: ganache-cli - Run your local blockchain, we used ganache.

The port specifications are configured within the truffle-config.js file in the project root directory.

truffle deploy - Deploy the ZK Voter and it's libraries to the aforementioned blockchain.

(Note the log that follows after deployment. Copy the contract address provided under the Election Contract, we will use it in the DApp setup) DApp: Prerequisite: We have not added a config file that may be read yet, so you must manually obtain the Election deployment address (see previous section) and paste it into the ELECTION_ADDRESS variable within /dapp/src/assets/contracts/ElectionAbi.js. (Note: If you alter the Election contract, you must re-compile via truffle compile and paste the new JSON ABI found within build/contracts/Election.json)

cd dapp - Navigate to the DApp directory yarn start - Start up the DApp

HOW TO TEST: ==> Blockchain Component

truffle develop - Enter a development environment Run truffle test from the project root directory. This will spool a local development blockchain for you and conduct the tests which can be evaluated at /test/electionTest.js/

==> Zero-Knowledge Circuits

cargo test - Run a cargo test

./snarks/test/ - Test Directory

====> DEVELOPER NOTES <======

Assets: Due to a bug in Zokrates-JS I found (see: Zokrates/ZoKrates#909), we must unfortunately locate and compile the zero-knowlege circuits ourselves instead of directly loading pre-compiled binaries. All the required assets are located within the DApp/snarks/client-side.

Vote-Key Generation: The Vote-Key is a hash combination of your Secret Key and your chosen Unique Identifier. To compute a hash, you must open the ZK circuit at: /snarks/client-side/hashFunction.zok

Submitting Vote/Proof Generation: In order to prove your membership and generate a proof, you need to open the ZK circuit at: /snarks/client-side/membershipTest.zok.

Once Zokrates-JS includes the PR from issue 909 into their next release, compilation can be disregarded in favour of pre-compile binaries. Though self-compilation is exhausting, it does show the true transparency of zero-knowledge proofs, and can provide valuable learning insight to users on the functionality within the source-code.

Future additions (If I find the the time, feel free to create a PR): BONUS: >>> Improve the ZK circuit from 3 layers to dynamic layers using Zokrates Generic Functions <<<< BONUS: >>> Upgrade to Truffle Beta and utilize Revert Messages for better User clarification on incorrect method calls <<< BONUS: >>> Make UI Responsive <<< BONUS: >>> Add Error UI Pop-Ups <<<

Rough work log:

• Studied Zokrates Docs

• Studied EVM Docs (Skimmed through, more like)

• Studied Soldiity Docs

• Research complete on Membership Test

• Alpha Code for Membership Test

• Simple Election Contract with voting and tallying.

• A seperate Merkle contract that is just a mind doodle at this point

• Research on Hash Functions suitable for SNARK and On-Chain use

• On-Chain MiMC Hashing implemented

• Zero-Knowledge MiMC Hashing implemented

• Both MiMC Hash functions synchronized to produce same output (FINALLY!)

• Merkle Generation implemented

• Proof of Membership using ZKP MiMC implemented

• A little insight gained in arithmetic circuits

• Proof of Membership tested and optimized for circuits (removed some if conditions, removed generic properties such as dynamic tree size due to circuit constraints)

• Verifier Contract produced

• DApp UI

• DApp Conduct Election

• DApp Generate Vote Key (found bug in Zokrates-JS for pre-compiled CLI binaries)

• Dapp Submit Vote (found bug in Zokrates-JS for runtime proof generation)

• Merkle Array functioning as it should

• Solve Dapp Submit Vote bug found in Zokrates-JS

• Add Nullifier

• Ditched Homomorphic Encryption in favour of simpler disasociation method

• Vote value included within ZK-SNARK

• Tests added

• Readme made more clear