LuckySix

Lucky Six, a Solidity-based game built with Foundry, features 35 numbers drawn in order randomly in each round from 1 to 48. The lottery is automated, and when the first ticket is played in a round, a countdown of roundDuration seconds begins, enabling participation during this period. After the countdown, a request for a random salt is sent, and upon receiving it, the system generates random numbers and two joker positions for the round. System then initiates a new round, perpetuating this cycle indefinitely.

Users participate by playing one or multiple tickets in the current round, selecting a set of 6 unique numbers and specifying their desired spending amount. The details of user-played tickets in each round are securely stored on the blockchain. If a player's chosen combination matches all 6 numbers drawn from the pool of 35, they become eligible to redeem a prize. The prize amount is calculated by multiplying the ticket value with the coefficient corresponding to the last correctly guessed number. Additionally, each occurrence of a joker in the combination results in a doubled prize. In the event that a user's combination doesn't match any of the 35 drawn numbers, they receive a prize equal to the ticket value multiplied by 100!

Features

The lottery contract balance is divided into two distinct pools: one for users to claim prizes, and the other for the lottery owner, containing the platformFee paid by users for participating in the lottery.
The lottery process operates smoothly with the forwarder address of the keepers from the Chainlink Automation v2.1, ensuring seamless and continuous automation.
The salt utilized to draw random numbers (and jokers) for each round is generated using Chainlink VRF (Verifiable Random Function).
The drawn numbers and jockers for each round are efficiently packed into a single 256-word using 6 bits for each number. This packing strategy optimizes the cost of a single SSTORE operation when storing this data on the blockchain.
The lottery is designed to be UUPS Upgradeable, providing flexibility for the inclusion of additional features in future updates. Unclaimed winning tickets are securely stored in subsequent versions.
The ReentrancyGuard module is implemented to safeguard against reentrant calls to a payout function.
The Ownable module provides a fundamental access control mechanism, allowing the owner to configure the forwarderAddress, platformFee and roundDuration.
The Pausable module incorporates an emergency stop mechanism, enabling the owner to temporarily halt keepers from automating the lottery.

Automation

The checkUpkeep function checks the current lottery state and encodes the corresponding function which changes lottery state as a bytes array. Keepers utilize this data to invoke the performUpkeep function, where the encoded performData is decoded and then executed.

bytes4 selector = abi.decode(performData, (bytes4));
(bool success,) = address(this).delegatecall(abi.encodeWithSelector(selector));

Randomness

The seed for randomness lastVerifiedRandomNumber is acquired through Chainlink VRF. Subsequently, all other numbers are generated in sequence from that seed, shown below:

randomNumbers[i] = uint256(keccak256(abi.encode(block.timestamp, lastVerifiedRandomNumber, i)));

All the listed features have been individually tested, and you can view the behavior in the test/ directory.

Deploy script

Based on the provided block.chainid, the deployment script initiates the deployment of the LuckySix contract to the designated network. Subsequently, it deploys the ERC1967Proxy proxy contract, associating it with the implemented code, and finally initializes the game.

LuckySix implementation = new LuckySix();
ERC1967Proxy proxy = new ERC1967Proxy(address(implementation), "");
LuckySix game = LuckySix(payable(address(proxy)));
game.initialize(COORDINATOR_ADDRESS, KEYHASH, SUBSCRIPTION_ID);

Following the deployment of the lottery, the script proceeds to add a new consumer, namely the LuckySix contract, to the VRF subscription. In this context, COORDINATOR represents the VRFCoordinatorV2Interface specific to the given network.

COORDINATOR.addConsumer(SUBSCRIPTION_ID, lotteryAddress);

Subsequently, within the Chainlink Automation network, LINK tokens are granted approval to the Registrar of the specified network, and a new Upkeep is registered, resulting in the generation of an upkeepId.

RegistrationParams memory params = RegistrationParams({
    ...
});
LINK_TOKEN.approve(address(REGISTRAR), params.amount);
uint256 upkeepId = REGISTRAR.registerUpkeep(params);

Finally, the Chainlink registry address for the specified network is utilized to instantiate IKeeperRegistryMaster. This step involves obtaining the unique forwarder address of the Keeper with the given upkeepId, which is then employed to set permissioned access for the performUpkeep function.

IKeeperRegistryMaster registry = IKeeperRegistryMaster(REGISTRY_ADDRESS);
address forwarderAddress = registry.getForwarder(upkeepId);
game.setKeeperAddress(forwarderAddress);

Lottery addresses

Sepolia: 0x4153a9Ea482a8cCb1737662FF840def7E087A6c8
Mumbai: 0x86E074017b01541fcb8CB548Cbd61d9fF9D23a9a

License

This project is licensed under the Apache License, Version 2.0.