Raffle Smart Contract - Blockchain Lottery System

Overview

The Raffle project is a decentralized smart contract-based lottery system built using Solidity and deployed using Foundry. This project integrates Chainlink VRF (Verifiable Random Function) and Chainlink Automation to ensure fair, tamper-proof random winner selection and automated execution of the raffle process.

By leveraging blockchain technology, this project provides a transparent, trustless, and efficient lottery system that eliminates the need for intermediaries.

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Key Features

• Automated Execution: Uses Chainlink Automation to trigger the draw function at predetermined intervals.
• Fair Winner Selection: Utilizes Chainlink VRF for provably random and tamper-proof randomness.
• Decentralized & Transparent: Built on Ethereum, ensuring open and verifiable operations.
• Optimized Development Workflow: Developed using Foundry, a powerful smart contract development framework.
• Secure & Efficient Testing: Comprehensive test suite with Forge for smart contract testing.
• Configurable Deployment: Dynamic network-based configurations for deployment flexibility.

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Technologies & Tools Used

1. Solidity (v0.8.19)

The smart contract is written in Solidity, the leading language for Ethereum-based smart contracts. The contract implements security best practices, including reentrancy protection and gas optimization.

2. Chainlink VRF (Verifiable Random Function)

Ensures a provably fair and tamper-proof randomness mechanism for selecting winners.

• Guarantees randomness cannot be manipulated by the contract owner or participants.
• Uses Chainlink oracles to fetch random numbers securely.

3. Chainlink Automation

Automates the execution of the raffle at predetermined time intervals.

• Ensures that the contract runs autonomously without manual intervention.
• Uses upkeep registration to schedule and execute draws efficiently.

4. Foundry (Forge, Cast, Anvil)

A modern, fast, and powerful development framework for Solidity.

• Forge: Smart contract compilation, testing, and fuzzing.
• Cast: CLI tool for interacting with smart contracts.
• Anvil: Local Ethereum node for simulation and testing.

5. OpenZeppelin Library

• OpenZeppelin: Utilized for secure contract development (e.g., ERC20, Ownable, ReentrancyGuard).

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Project Structure

├── src/
│   ├── Raffle.sol               # Main Raffle contract
│   ├── VRFCoordinatorMock.sol    # Mock for testing Chainlink VRF
│   ├── AutomationMock.sol        # Mock for testing Chainlink Automation
│
├── script/
│   ├── DeployRaffle.s.sol        # Deployment script
│   ├── HelperConfig.s.sol        # Network configuration
│   ├── Interactions.s.sol        # Interaction script
│
├── test/
│   ├── RaffleTest.t.sol          # Unit and integration tests
│
├── foundry.toml                  # Foundry configuration
├── README.md                     # Project documentation

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How It Works

1. Entry Mechanism

• Users enter the raffle by sending ETH to the contract.
• The contract records participants and their entries.

2. Chainlink Automation Execution

• CheckUpkeep function verifies whether conditions for drawing the winner are met.
• If the interval has passed and there are participants, the upkeep triggers the draw.

3. Winner Selection (Chainlink VRF)

• The contract requests a random number from Chainlink VRF.
• Once the VRF provides the number, the contract selects the winner.
• The winner receives the entire prize pool.

4. Resetting the Raffle

• The contract resets for the next round.
• New entries are accepted, and the cycle repeats.

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Installation & Setup

Prerequisites

• Foundry: Install via curl -L https://foundry.paradigm.xyz | bash
• Ethereum Wallet (MetaMask) with testnet ETH.

Deployment

1. Install dependencies:

   forge install

2. Compile the contract:

   forge build

3. Run tests:

   forge test

4. Deploy on a testnet:

   forge script script/DeployRaffle.s.sol --rpc-url <TESTNET_RPC> --broadcast

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Testing & Security

1. Unit & Integration Testing

• Uses Forge for unit tests in test/RaffleTest.t.sol.
• Simulated execution of Chainlink VRF & Automation with mocks.

2. Gas Optimization

• Efficient storage usage with Solidity best practices.
• Optimized loops and calldata usage.

3. Security Measures

• Reentrancy Protection: Uses nonReentrant from OpenZeppelin.
• Access Control: Ensures only valid automation calls can trigger functions.

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Future Enhancements

• Multichain Deployment: Expanding to Layer 2 solutions like Arbitrum or Optimism.
• NFT Rewards: Instead of ETH, the winner could receive an ERC721 NFT.
• Decentralized Governance: Implementing DAO voting to set ticket prices and draw intervals.

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Author & Contributions

Developed by roudra323, a blockchain developer specializing in smart contract development and Web3 solutions.

For contributions, feel free to submit a PR or open an issue on GitHub.