Dice Game

🟡 Intermediate | 🚀 Advanced

Provably fair dice game with encrypted bets and random rolls

Overview

A dice game where bets are encrypted and dice rolls use verifiable randomness. Neither the house nor players can predict or manipulate outcomes. Uses FHE.mod for random range generation and encrypted bet comparisons.

Quick Start

# Create new project from this template
npx labz create dice-game my-project

# Navigate and install
cd my-project
npm install

# Run tests
npx hardhat test

Contract

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import { FHE, euint64, euint8, ebool, eaddress, externalEuint64, externalEuint8, externalEbool, externalEaddress } from "@fhevm/solidity/lib/FHE.sol";
import { ZamaEthereumConfig } from "@fhevm/solidity/config/ZamaConfig.sol";

/**
 * @title DiceGame
 * @notice Provably fair dice game with encrypted rolls
 * @dev Uses FHE.random() for fair dice generation
 *
 * Game Types:
 * - Over/Under: Bet on dice total being over or under a threshold
 * - Exact: Bet on exact dice sum
 * - High/Low: Bet on high (4-6) or low (1-3)
 *
 * FHE Operations Used:
 * - random: Generate unpredictable dice rolls
 * - rem: Map random to 1-6 range
 * - add: Sum multiple dice
 * - mul: Calculate payouts
 * - gt/lt/eq: Compare against bet predictions
 * - select: Determine win/loss
 */
contract DiceGame is ZamaEthereumConfig {
    // ============ Errors ============
    error InsufficientBet();
    error GameNotFound();
    error GameAlreadyRevealed();
    error GameNotRevealed();
    error NotGamePlayer();
    error InsufficientHouseFunds();
    error AlreadyClaimed();
    error InvalidDecryptionProof();
    

    // ============ Events ============
    event BetPlaced(uint256 indexed gameId, address indexed player, uint256 amount);
    event DiceRolled(uint256 indexed gameId);
    event ResultReadyForReveal(uint256 indexed gameId);
    event ResultRevealed(uint256 indexed gameId, address indexed player, bool won);
    event WinningsClaimed(uint256 indexed gameId, address indexed player, uint256 amount);
    

    // ============ Enums ============
    enum BetType { OverUnder, Exact, HighLow }

    // ============ Structs ============
    struct Game {
        address player;
        BetType betType;
        uint8 prediction;                // What player predicted
        uint256 betAmount;
        euint64 dice1;             // Encrypted first die
        euint64 dice2;             // Encrypted second die (optional)
        euint64 total;             // Encrypted sum
        ebool won;                       // Encrypted win status
        bool revealRequested;            // Has reveal been requested
        bool revealed;                   // Has result been revealed
        bool revealedWon;                // Decrypted win status
        bool claimed;                    // Has payout been claimed
        uint256 payout;
    }

    // ============ State Variables ============
    mapping(uint256 => Game) public _games;
    uint256 public _gameCount;

    uint256 public minBet;
    uint256 public maxBet;
    uint256 public houseEdge;            // In basis points (100 = 1%)

    // Payout multipliers (in basis points, 10000 = 1x)
    uint256 public constant OVER_UNDER_PAYOUT = 19500;  // 1.95x
    uint256 public constant EXACT_PAYOUT = 50000;        // 5x
    uint256 public constant HIGH_LOW_PAYOUT = 19000;     // 1.9x
    

    // ============ Modifiers ============
    modifier gameExists(uint256 gameId) {
        if (gameId >= _gameCount) revert GameNotFound();
        _;
    }

    modifier isPlayer(uint256 gameId) {
        if (_games[gameId].player != msg.sender) revert NotGamePlayer();
        _;
    }
    

    // ============ Constructor ============
    constructor(uint256 _minBet, uint256 _maxBet, uint256 _houseEdge) {
        minBet = _minBet;
        maxBet = _maxBet;
        houseEdge = _houseEdge;
        
    }

    // ============ External Functions ============

    /**
     * @notice Place a bet and roll dice
     * @param betType Type of bet (OverUnder, Exact, HighLow)
     * @param prediction Your prediction (threshold for OverUnder, exact sum for Exact, 0=low/1=high for HighLow)
     */
    function placeBet(BetType betType, uint8 prediction) external payable returns (uint256) {
        if (msg.value < minBet) revert InsufficientBet();
        if (msg.value > maxBet) revert InsufficientBet();

        uint256 gameId = _gameCount++;

        // Generate encrypted dice using FHE.random
        euint64 rand1 = FHE.randEuint64();
        euint64 rand2 = FHE.randEuint64();

        // Map to 1-6 range: (random % 6) + 1
        euint64 dice1 = FHE.add(FHE.rem(rand1, uint64(6)), FHE.asEuint64(1));
        euint64 dice2 = FHE.add(FHE.rem(rand2, uint64(6)), FHE.asEuint64(1));

        // Calculate total
        euint64 total = FHE.add(dice1, dice2);

        // Determine win based on bet type
        ebool won;
        if (betType == BetType.OverUnder) {
            // Win if total > prediction
            won = FHE.gt(total, FHE.asEuint8(prediction));
        } else if (betType == BetType.Exact) {
            // Win if total == prediction
            won = FHE.eq(total, FHE.asEuint8(prediction));
        } else {
            // HighLow: prediction 0 = low (2-6), prediction 1 = high (8-12)
            if (prediction == 0) {
                won = FHE.le(total, FHE.asEuint8(6));
            } else {
                won = FHE.ge(total, FHE.asEuint8(8));
            }
        }

        _games[gameId] = Game({
            player: msg.sender,
            betType: betType,
            prediction: prediction,
            betAmount: msg.value,
            dice1: dice1,
            dice2: dice2,
            total: total,
            won: won,
            revealRequested: false,
            revealed: false,
            revealedWon: false,
            claimed: false,
            payout: 0
        });

        // Allow contract to use encrypted values
        FHE.allowThis(dice1);
        FHE.allowThis(dice2);
        FHE.allowThis(total);
        FHE.allowThis(won);

        emit BetPlaced(gameId, msg.sender, msg.value);
        emit DiceRolled(gameId);

        return gameId;
    }

    /**
     * @notice Request result reveal via public decryption
     * @dev Step 1 of 3-step async public decryption pattern
     * @param gameId The game to reveal
     */
    function requestResultReveal(uint256 gameId)
        external
        gameExists(gameId)
        isPlayer(gameId)
    {
        Game storage game = _games[gameId];
        if (game.revealRequested) revert GameAlreadyRevealed();

        game.revealRequested = true;

        // Mark win status for public decryption
        FHE.makePubliclyDecryptable(game.won);

        emit ResultReadyForReveal(gameId);
    }

    /**
     * @notice Get encrypted win status handle for off-chain decryption
     * @dev Step 2 is off-chain: use relayer-sdk to decrypt
     * @param gameId The game to get handle for
     */
    function getWinHandle(uint256 gameId)
        external
        view
        gameExists(gameId)
        returns (ebool)
    {
        return _games[gameId].won;
    }

    /**
     * @notice Finalize result reveal with decryption proof
     * @dev Step 3 of 3-step async public decryption pattern
     * @param gameId The game to finalize
     * @param wonResult The decrypted win status
     * @param decryptionProof The proof from Zama KMS
     */
    function finalizeResultReveal(
        uint256 gameId,
        bool wonResult,
        bytes calldata decryptionProof
    )
        external
        gameExists(gameId)
    {
        Game storage game = _games[gameId];
        if (!game.revealRequested) revert GameNotRevealed();
        if (game.revealed) revert GameAlreadyRevealed();

        // Verify the decryption proof
        bytes32[] memory cts = new bytes32[](1);
        cts[0] = ebool.unwrap(game.won);

        bytes memory cleartexts = abi.encode(wonResult);

        // This reverts if proof is invalid
        FHE.checkSignatures(cts, cleartexts, decryptionProof);

        // Store revealed result
        game.revealed = true;
        game.revealedWon = wonResult;

        // Calculate payout if won
        if (wonResult) {
            uint256 multiplier;
            if (game.betType == BetType.OverUnder) {
                multiplier = OVER_UNDER_PAYOUT;
            } else if (game.betType == BetType.Exact) {
                multiplier = EXACT_PAYOUT;
            } else {
                multiplier = HIGH_LOW_PAYOUT;
            }
            game.payout = (game.betAmount * multiplier) / 10000;
        }

        emit ResultRevealed(gameId, game.player, wonResult);
    }

    /**
     * @notice Claim winnings after reveal
     * @param gameId The game to claim
     */
    function claimWinnings(uint256 gameId)
        external
        gameExists(gameId)
        isPlayer(gameId)
    {
        Game storage game = _games[gameId];
        if (!game.revealed) revert GameNotRevealed();
        if (game.claimed) revert AlreadyClaimed();

        game.claimed = true;

        if (game.revealedWon && game.payout > 0) {
            if (address(this).balance < game.payout) revert InsufficientHouseFunds();

            (bool success, ) = payable(msg.sender).call{value: game.payout}("");
            require(success, "Transfer failed");

            emit WinningsClaimed(gameId, msg.sender, game.payout);
        }
    }

    /**
     * @notice Fund the house (for payouts)
     */
    function fundHouse() external payable {}

    

    // ============ View Functions ============

    /**
     * @notice Get game info
     */
    function getGame(uint256 gameId) external view returns (
        address player,
        BetType betType,
        uint8 prediction,
        uint256 betAmount,
        bool revealRequested,
        bool revealed,
        bool revealedWon,
        bool claimed,
        uint256 payout
    ) {
        Game storage game = _games[gameId];
        return (
            game.player,
            game.betType,
            game.prediction,
            game.betAmount,
            game.revealRequested,
            game.revealed,
            game.revealedWon,
            game.claimed,
            game.payout
        );
    }

    /**
     * @notice Get total games played
     */
    function getGameCount() external view returns (uint256) {
        return _gameCount;
    }

    /**
     * @notice Get house balance
     */
    function getHouseBalance() external view returns (uint256) {
        return address(this).balance;
    }

    /**
     * @notice Calculate potential payout
     */
    function calculatePayout(BetType betType, uint256 betAmount) external pure returns (uint256) {
        uint256 multiplier;
        if (betType == BetType.OverUnder) {
            multiplier = OVER_UNDER_PAYOUT;
        } else if (betType == BetType.Exact) {
            multiplier = EXACT_PAYOUT;
        } else {
            multiplier = HIGH_LOW_PAYOUT;
        }
        return (betAmount * multiplier) / 10000;
    }

    

    // ============ Internal Functions ============
    

    receive() external payable {}
}

FHE Operations Used

FHE.mod()
FHE.add()
FHE.gt()
FHE.lte()
FHE.select()
FHE.allowThis()
FHE.allow()
FHE.fromExternal()

FHE Types Used

euint8
euint64
externalEuint64
ebool

Prerequisites

Before this example, you should understand:

encryption-single

Next Steps

After this example, check out:

poker

Generated with Lab-Z

PreviousBlind Matching NextPrivate Escrow

Last updated 1 month ago

Good morning

Dice Game

Overview

Quick Start

Contract

FHE Operations Used

FHE Types Used

Tags

Prerequisites

Next Steps

Good morning

hashtagOverview

hashtagQuick Start

hashtagContract

hashtagFHE Operations Used

hashtagFHE Types Used

hashtagTags

hashtagRelated Examples

hashtagPrerequisites

hashtagNext Steps

Overview

Quick Start

Contract

FHE Operations Used

FHE Types Used

Tags

Related Examples

Prerequisites

Next Steps