Educhain Gamified

This project implements a decentralized lottery system on the Ethereum blockchain using Solidity. Participants enter the lottery by sending 0.00001 ETH, and once at least 3 players have joined, the contract owner (manager) can randomly pick a winner who receives the entire balance of the contract.

🚀 Features

• Entry Fee: Participants must send exactly 0.00001 ETH to join.

• Random Winner Selection: Uses keccak256 hashing with blockchain randomness.

• Secure Fund Handling: Only the contract manager can access the balance and pick a winner.

• Automated Reset: The lottery resets after a winner is selected.

🛠 Technology Stack

• Smart Contract Language: Solidity (^0.5.0 < 0.9.0)

• Blockchain: Ethereum-compatible networks

• Tools: Remix IDE, Hardhat, MetaMask, Ethers.js

📜 Smart Contract: lottery.sol

1️⃣ Contract Variables

• manager → The deployer who controls the lottery.

• players → A dynamic array storing participants.

2️⃣ Entry Mechanism (receive)

• Players send 0.00001 ETH to enter.

• The contract automatically adds them to the players list.

• If incorrect ETH is sent, the transaction fails.

3️⃣ Winner Selection (pickWinner)

• Can only be called by the manager.

• Requires at least 3 players.

• Uses a pseudo-random number to select a winner.

• Transfers the entire contract balance to the winner.

• Resets the players array for a new round.

📌 How to Deploy & Use

1️⃣ Deploying the Contract

• Open Remix IDE and create lottery.sol.

• Compile the contract using Solidity 0.8.x compiler.

• Deploy on Ethereum Testnet (e.g., Sepolia, Goerli) or Local Hardhat Network.

2️⃣ Participating in the Lottery

• Send 0.00001 ETH to the contract from MetaMask or a script.

Example using ethers.js:

const signer = provider.getSigner();
const tx = await signer.sendTransaction({
    to: "0xYourContractAddress",
    value: ethers.utils.parseEther("0.00001") // Entry fee
});
await tx.wait();
console.log("Successfully joined the lottery!");

3️⃣ Picking a Winner

• Call pickWinner() (only the manager can do this).

• Winner receives all ETH in the contract.

• The lottery resets for a new round.

🔐 Security Considerations

• The contract does not use Chainlink VRF, so randomness is not truly secure.

• A miner could manipulate block.prevrandao (previously block.difficulty).

• This should not be used for high-value lotteries on mainnet.

🏆 Future Improvements

✅ Implement Chainlink VRF for fair randomness.
✅ Add automated winner selection after a fixed time.
✅ Support multiple rounds without requiring manual resets.