Blockchain Voting System

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Smart Contracts Deployment ​

This section details the process of deploying the smart contracts to a blockchain network. We use Foundry for contract deployment.

Prerequisites ​

Before deploying the contracts, ensure you have:

  1. Foundry installed (installation guide)
  2. Node.js and pnpm installed
  3. Access to a blockchain network (local Anvil, testnet, or mainnet)
  4. Sufficient funds in your deployer wallet for gas fees

Deployment Process ​

1. Local Development Deployment ​

For local development and testing:

bash
# Start a local Anvil node
anvil

# In another terminal, deploy contracts
forge script script/Deploy.s.sol --rpc-url http://localhost:8545 --private-key 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80 --broadcast

2. Testnet/Mainnet Deployment ​

For deploying to a testnet or mainnet:

bash
# Set your private key in environment variables
export PRIVATE_KEY=your_private_key_here

# Deploy to Sepolia testnet
forge script script/Deploy.s.sol --rpc-url https://sepolia.infura.io/v3/YOUR_INFURA_KEY --private-key $PRIVATE_KEY --broadcast --verify

# Deploy to Polygon mainnet
forge script script/Deploy.s.sol --rpc-url https://polygon-rpc.com --private-key $PRIVATE_KEY --broadcast --verify

Deployment Script ​

The deployment script (script/Deploy.s.sol) handles the deployment of all core contracts:

  1. VoterRegistry: Manages voter registration and verification
  2. CandidateRegistry: Manages candidate information
  3. PartyRegistry: Manages political parties
  4. ElectionRegistry: Manages elections
  5. VotingSystem: Central hub coordinating all registries

Post-Deployment Configuration ​

After deployment, you'll need to:

  1. Set contract addresses: Update environment variables in the backend
  2. Register administrators: Add admin addresses to registries
  3. Configure relayers: Set up backend relayer for gasless transactions
  4. Initialize ZK groups: Set up Semaphore groups for voter privacy

Environment Variables ​

Set these environment variables in your backend:

env
# Blockchain Configuration
BLOCKCHAIN_VOTING_SYSTEM_ADDRESS=0x...
BLOCKCHAIN_WALLET_PRIVATE_KEY=0x...

Gasless Transaction Setup ​

To enable gasless transactions for voters:

  1. Deploy relayer wallet: Create a dedicated wallet for paying gas fees
  2. Fund relayer wallet: Ensure sufficient funds for transaction fees
  3. Configure backend: Set BLOCKCHAIN_WALLET_PRIVATE_KEY to relayer wallet key
  4. Enable ZK verification: Set up Semaphore for voter anonymity

ZK Integration Deployment ​

For ZK voter privacy using Semaphore:

  1. Deploy Semaphore contracts: Follow Semaphore deployment guide
  2. Create voter groups: Set up groups for each election
  3. Configure backend: Integrate Semaphore proof generation
  4. Test ZK proofs: Verify proof generation and verification works

Verification ​

After deployment, verify contract functionality:

bash
# Run tests against deployed contracts
forge test --fork-url http://localhost:8545

# Check contract addresses
cast call 0xVotingSystemAddress "voterRegistryAddress()" --rpc-url http://localhost:8545
cast call 0xVotingSystemAddress "candidateRegistryAddress()" --rpc-url http://localhost:8545
cast call 0xVotingSystemAddress "partyRegistryAddress()" --rpc-url http://localhost:8545
cast call 0xVotingSystemAddress "electionRegistryAddress()" --rpc-url http://localhost:8545

Troubleshooting ​

Common deployment issues:

  1. Insufficient funds: Ensure deployer wallet has enough ETH/MATIC
  2. Network connectivity: Verify RPC endpoint is accessible
  3. Contract verification: Check Etherscan/Polygonscan API keys for verification
  4. Nonce issues: Reset nonce if transactions fail repeatedly

Security Considerations ​

  1. Private key management: Never commit private keys to version control
  2. Admin access: Limit admin addresses to trusted personnel only
  3. Contract upgrades: Plan for upgradeability if needed
  4. Auditing: Consider third-party security audits for production deployments