zkOpenGov — Private Voting for Polkadot OpenGov

Website: https://zkopengov.org

Privacy-preserving tier-based voting layer for Polkadot OpenGov using ZK-SNARKs.

Overview

zkOpenGov enables anonymous voting on OpenGov referenda. Voters register on-chain (identity verified), then cast private votes via Groth16 ZK proofs that prove balance-tier membership without revealing identity or exact balance.

How It Works

1. Register: Connect your Polkadot wallet, generate a secret, and register your commitment on-chain
2. Vote: Select a proposal, choose Aye/Nay/Abstain — a ZK proof is generated in your browser proving you belong to a balance tier without revealing your address
3. Privacy: Your vote is submitted through a relayer, so your identity is never linked to your vote on-chain

Tier-Based Weighting

Instead of 1-token-1-vote (which favors whales), votes are weighted by balance tier:

Tier	Balance Range (DOT)	Vote Weight
0	1 – 100	1
1	100 – 1,000	3
2	1,000 – 10,000	6
3	10,000 – 100,000	10
4	100,000+	15

A 100k DOT holder gets 15x weight (not 1000x) over a 100 DOT holder.

Architecture

┌──────────────────┐
│  ZK Circuits     │  Circom (Groth16)
│  (Poseidon hash) │
└────────┬─────────┘
         │ verifier.sol, WASM, zkey
         ▼
┌────────┐  ┌───────────┐  ┌────────────┐
│Indexer │→ │ Contracts │←─│Client Lib  │
│(trees) │  │(Solidity) │  │(proof gen) │
└────────┘  └─────┬─────┘  └────────────┘
                  │                │
            ┌─────┴──────┐         │
            │  Relayer   │         │
            └─────┬──────┘         │
                  └────────┬───────┘
                     ┌─────┴─────┐
                     │ Frontend  │
                     │ (React)   │
                     └───────────┘

Components

Component	Directory	Description
ZK Circuits	circuits/	Circom circuit proving tier membership + vote binding
Smart Contracts	contracts/	VotingRegistry, VotingBooth, Groth16Verifier
Indexing Service	indexer/	Builds Poseidon Merkle trees, serves via REST API
Client Proof Library	client-lib/	Browser-compatible proof generation library
Relayer	relayer/	Submits votes on behalf of users (gas abstraction)
Frontend	frontend/	React UI for registration, voting, results

Quick Start

Prerequisites

• Node.js >= 18
• circom 2.x (npm install -g circom)
• snarkjs (npm install -g snarkjs)

Setup

# Install all dependencies
npm install

# Build circuits (critical path)
cd circuits && npm run build

# Compile contracts
cd contracts && npx hardhat compile

# Start indexer (demo mode)
cd indexer && npm run dev

# Start frontend
cd frontend && npm run dev

Testing

# Circuit tests
cd circuits && npm test

# Contract tests
cd contracts && npx hardhat test

# Indexer tests
cd indexer && npm test

# E2E tests (requires local node)
cd e2e && npm test

Deployed Contracts (Polkadot Hub Testnet)

Contract	Address
Groth16Verifier	0x1E8139d14c7dE8703dEfB9eAb6aDAdC7B572b8a9
VotingRegistry	0xC5a08D782CA60Bc69BddE400332bA595543bDc5E
VotingBooth	0xec99cd6cb7B9469B7CA9c918EB6481EDb08aed71

• Network: Polkadot Hub Testnet (chain ID 420420417)
• RPC: https://eth-rpc-testnet.polkadot.io/
• Compiler: resolc 1.0.0 (PolkaVM)

Privacy Model

• Registration is public (on-chain) — links your address to a commitment
• Voting is private:
  • ZK proof reveals only: tier, vote choice, nullifier (no address)
  • Nullifier = Poseidon(secret, proposalId) — deterministic but unlinkable across proposals
  • Full tree data is downloaded by all clients (no per-address queries to indexer)
  • Proof generation happens entirely in the browser
  • Vote submitted through relayer (no address link)

Hackathon

Built for DoraHacks Polkadot Solidity Hackathon (Feb 15 – Mar 24, 2026). Target: Polkadot Hub (pallet-revive EVM).

License

MIT