SUI Move官方示例合约实践——游戏类:基于drand随机数的刮刮卡游戏(drand_based_scratch_card)

  • rzexin
  • 更新于 2024-02-15 17:26
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SUI Move官方示例合约实践——游戏类:基于drand随机数的刮刮卡游戏(drand_based_scratch_card)

SUI Move官方示例合约实践——游戏类:基于drand随机数的刮刮卡游戏(drand_based_scratch_card)

rzexin 2024.02.15

1 合约说明

1.1 功能介绍

  • 本合约是基于drand随机数的 刮刮卡 游戏合约。drand是分布式随机数信标,提供可验证、不可预测和无偏的随机数即服务。(Distributed randomness beacon. Verifiable, unpredictable and unbiased random numbers as a service.

    drand所在的quicknet chain每3秒产生一个可验证的随机32字节,任何人都可以检查给定的32字节是否确实是drand的第i个输出。故可以使用drand作为随机性来源实现需要不可偏倚且不可预测的随机性的链上游戏。即:每次游戏需要随机性时,它从drand接收下一个32字节(作为交易的一部分或从现有对象中读取),并相应地进行操作。然而,在某些情况下,这种简单的流程可能不安全,因为区块链不知道drand的最新轮次,因此可能依赖已经公开的随机性。)

  • 管理员可以 创建(create 刮刮卡游戏,该接口会创建不可变的游戏对象(Game 和一个 共享的奖励对象(Reward

  • 玩家可以 购买刮刮卡(buy_ticket ,购买刮刮卡,只能在游戏创建的同一世代里购买,购买需要支付reward/reward_factor数量的SUI,支付代币会转给游戏创建者,游戏玩家会获得 刮刮卡(ticket

  • 游戏结束,玩家可以自行 刮卡和开奖(evaluate ,若中奖,刮刮卡的持有人将会获得 赢家对象(Winner ,并销毁刮刮卡对象(Ticket

  • 赢家对象(Winner)持有人可以去 领奖(take_reward ,如果奖励未被领取,将会获得所有奖励SUI后,在销毁冠军对象(Winner),若奖励已经被其他中奖者领取,将只会销毁冠军对象(Winner),其他什么也不会发生:(

  • 如果奖励在几个epoch内没有被提取,游戏管理员(创建者)可以 赎回奖励(redeem

1.2 官方合约示例代码

1.2.1 合约源码地址

https://github.com/MystenLabs/sui/blob/main/sui_programmability/examples/games/sources/drand_based_scratch_card.move

1.2.2 数据结构说明

(1)游戏对象定义
  • 游戏对象是一个不可变对象,包括购买刮刮卡时要使用的所有参数
  • 参数有:
    • creator:游戏创建者
    • reward_amount:奖励SUI代币数量
    • reward_factor:奖励因子,reward/reward_factor为刮刮卡(ticket)价格
    • base_epoch:当前世代
    • base_drand_round:当前drand轮次
      /// Game represents a set of parameters of a single game.
      struct Game has key {
      id: UID,
      creator: address,
      reward_amount: u64,
      reward_factor: u64,
      base_epoch: u64,
      base_drand_round: u64,
      }
(2)奖励对象定义
  • 奖励是一个共享对象,任何获胜者都可以提取,先到先得
  • 如果在几个epoch内没有被提取,可以退还给游戏创建者。
    /// Reward that is attached to a specific game. Can be withdrawn once.
    struct Reward has key {
        id: UID,
        game_id: ID,
        balance: Balance<SUI>,
    }
(3)奖票对象定义
    /// Ticket represents a participant in a single game.
    /// Can be deconstructed only by the owner.
    struct Ticket has key, store {
        id: UID,
        game_id: ID,
    }
(4)冠军对象定义
    /// Winner represents a participant that won in a specific game.
    /// Can be consumed by the take_reward.
    struct Winner has key, store {
        id: UID,
        game_id: ID,
    }

1.2.3 对外接口说明

(1)创建刮刮卡游戏(create
  • 该接口会创建不可变的游戏对象(Game)和一个共享的奖励对象(Reward
  • 奖励金额(reward)需要能够整除奖励因子(reward_factor
    /// Create a new game with a given reward.
    ///
    /// The reward must be a positive balance, dividable by reward_factor. reward/reward_factor will be the ticket
    /// price. base_drand_round is the current drand round.
    public entry fun create(
        reward: Coin<SUI>,
        reward_factor: u64,
        base_drand_round: u64,
        ctx: &mut TxContext
    ) {
        let amount = coin::value(&reward);
        assert!(amount > 0 && amount % reward_factor == 0 , EInvalidReward);

        let game = Game {
            id: object::new(ctx),
            reward_amount: coin::value(&reward),
            creator: tx_context::sender(ctx),
            reward_factor,
            base_epoch: tx_context::epoch(ctx),
            base_drand_round,
        };

        let reward = Reward {
            id: object::new(ctx),
            game_id: object::id(&game),
            balance: coin::into_balance(reward),
        };

        transfer::freeze_object(game);
        transfer::share_object(reward);
    }
(2)购买刮刮卡(buy_ticket
  • 购买刮刮卡,只能在游戏创建的同一世代里购买
  • 购买需要支付reward/reward_factor数量的SUI
  • 支付代币会转给游戏创建者
  • 游戏玩家会获得刮刮卡(ticket
    /// Buy a ticket for a specific game, costing reward/reward_factor SUI. Can be called only during the epoch in which
    /// the game was created.
    /// Note that the reward might have been withdrawn already. It's the user's responsibility to verify that.
    public entry fun buy_ticket(coin: Coin<SUI>, game: &Game, ctx: &mut TxContext) {
        assert!(coin::value(&coin) * game.reward_factor == game.reward_amount, EInvalidDeposit);
        assert!(tx_context::epoch(ctx) == game.base_epoch, EInvalidEpoch);
        let ticket = Ticket {
            id: object::new(ctx),
            game_id: object::id(game),
        };
        transfer::public_transfer(coin, game.creator);
        transfer::public_transfer(ticket, tx_context::sender(ctx));
    }
(3)刮卡&开奖(evaluate
  • 游戏结束时间为游戏创建后的2天时间,以确保所有游戏玩家都能至少在参加游戏后的一个纪元进行开奖
  • 传入游戏开始后一个纪元+1小时时间后的drand签名随机数
  • 选出赢家的方法是:
    • 计算drand_sigsha2_256哈希
    • 将上述哈希拼接上ticket字节码后,计算其hmac_sha3_256消息认证码
    • 使用上述消息认证码挑选出奖励因子序号
    • 注意:直接检查(random_key % reward_factor) == (ticket id % reward_factor)是不安全的,因为攻击者可以操控ticket id的值
  • 若中奖,刮刮卡的持有人将会获得赢家对象(Winner),并销毁刮刮卡对象(Ticket
    public entry fun evaluate(
        ticket: Ticket,
        game: &Game,
        drand_sig: vector<u8>,
        ctx: &mut TxContext
    ) {
        assert!(ticket.game_id == object::id(game), EInvalidTicket);
        drand_lib::verify_drand_signature(drand_sig, end_of_game_round(game.base_drand_round));
        // The randomness for the current ticket is derived by HMAC(drand randomness, ticket id).
        // A solution like checking if (drand randomness % reward_factor) == (ticket id % reward_factor) is not secure
        // as the adversary can control the values of ticket id. (For this particular game this attack is not
        // devastating, but for similar games it might be.)
        let random_key = drand_lib::derive_randomness(drand_sig);
        let randomness = hmac_sha3_256(&random_key, &object::id_to_bytes(&object::id(&ticket)));
        let is_winner = (drand_lib::safe_selection(game.reward_factor, &randomness) == 0);

        if (is_winner) {
            let winner = Winner {
                id: object::new(ctx),
                game_id: object::id(game),
            };
            transfer::public_transfer(winner, tx_context::sender(ctx));
        };
        // Delete the ticket.
        let Ticket { id, game_id:  _} = ticket;
        object::delete(id);
    }

    public fun end_of_game_round(round: u64): u64 {
        // Since users do not know when an epoch has began, they can only check if the game depends on a round that is
        // at least 24 hours from now. Since the creator does not know as well if its game is created in the beginning
        // or the end of the epoch, we define the end of the game to be 24h + 24h from when it started, +1h to be on
        // the safe side since epoch duration is not deterministic.
        round + 20 * 60 * (24 + 25)
    }
(4)领奖(take_reward)
  • 赢家对象(Winner)持有人可以去领奖
  • 如果奖励未被领取,将会获得所有奖励SUI后,在销毁冠军对象(Winner
  • 若奖励已经领取,将只会销毁冠军对象(Winner
    public entry fun take_reward(winner: Winner, reward: &mut Reward, ctx: &mut TxContext) {
        assert!(winner.game_id == reward.game_id, EInvalidTicket);
        let full_balance = balance::value(&reward.balance);
        if (full_balance > 0) {
            transfer::public_transfer(coin::take(&mut reward.balance, full_balance, ctx), tx_context::sender(ctx));
        };
        let Winner { id, game_id:  _} = winner;
        object::delete(id);
    }
(5)赎回(redeem
  • 如果奖励在几个世代,游戏创建者可以赎回奖励
    /// Can be called in case the reward was not withdrawn, to return the coins to the creator.
    public entry fun redeem(reward: &mut Reward, game: &Game, ctx: &mut TxContext) {
        assert!(balance::value(&reward.balance) > 0, EInvalidReward);
        assert!(object::id(game) == reward.game_id, EInvalidGame);
        // Since we define the game to take 24h+25h, a game that is created in epoch x may be completed in epochs
        // x+2 or x+3.
        assert!(game.base_epoch + 3 < tx_context::epoch(ctx), ETooSoonToRedeem);
        let full_balance = balance::value(&reward.balance);
        transfer::public_transfer(coin::take(&mut reward.balance, full_balance, ctx), game.creator);
    }

2 前置准备

2.1 帐号准备及角色分配

别名 地址 角色
Jason 0x5c5882d73a6e5b6ea1743fb028eff5e0d7cc8b7ae123d27856c5fe666d91569a 游戏创建者:创建刮刮卡游戏
Alice 0x2d178b9704706393d2630fe6cf9415c2c50b181e9e3c7a977237bb2929f82d19 游戏参与者:购买刮刮卡
Bob 0xf2e6ffef7d0543e258d4c47a53d6fa9872de4630cc186950accbd83415b009f0 游戏参与者:购买刮刮卡
  • 将地址添加到环境变量
export JASON=0x5c5882d73a6e5b6ea1743fb028eff5e0d7cc8b7ae123d27856c5fe666d91569a
export ALICE=0x2d178b9704706393d2630fe6cf9415c2c50b181e9e3c7a977237bb2929f82d19
export BOB=0xf2e6ffef7d0543e258d4c47a53d6fa9872de4630cc186950accbd83415b009f0

2.2 获取开奖轮次

(1)查看当前轮次

curl -s https://drand.cloudflare.com/52db9ba70e0cc0f6eaf7803dd07447a1f5477735fd3f661792ba94600c84e971/public/latest | jq
{
  "round": 5061055,
  "randomness": "51412539d9d3ff693301e4e12b68d3e030ded71604c60857561d97d226d01553",
  "signature": "98a5d4633c62b9d573f6ca46055d19097c3a64224d8fc17062dd092824b20922ffe2be96f4f81318b9a8e74df9900b4e"
}

export BASE_ROUND=5061055

(2)获取游戏结束的开奖轮次

游戏结束的轮次为部署合约后的2天的轮次为开奖轮次,由于时间太长,实践阶段将其改小为合约部署后的10分钟

5061055 + 20 * 10 = 5061255
export END_ROUND=5061255

3 合约部署

切换到Jason账号

sui client publish --gas-budget 100000000
  • 命令输出关键信息截图

image.png

  • 将关键的对象ID记录到环境变量,方便后续调用使用
export PACKAGE_ID=0x2ac5cbd1b5eca10c1e7275e40fcc2ac094285e247ae05943d8471b10f088c5bb

4 合约交互

4.1 创建刮刮卡游戏(create

切换到Jason

export REWARD_COIN=0x84da8da6e8e8cb5fa4d9bd8393f94cfd357d80ee783931f30cd034f07a51a369  # 100
export REWARD_FACTOR=2

sui client call --function create --package $PACKAGE_ID --module drand_based_scratch_card --args $REWARD_COIN $REWARD_FACTOR $BASE_ROUND --gas-budget 10000000
  • 创建游戏对象和奖励对象

image.png

  • 记录游戏对象ID和奖励对象ID
# PACKAGE_ID::drand_based_scratch_card::Game
export GAME=0x3c26c40da8875654a8f9cae9e75546991c2fa02af77ded03a5370853151496cd

# PACKAGE_ID::::drand_based_scratch_card::Reward
export REWARD=0xe5dd8b85ca6821d6a9d13b62d9eb05cbb68c8d0346bf0d5c9b55159cd3863e80
  • 查看游戏
sui client object $GAME

image.png

  • 查看奖励对象
sui client object $REWARD

image.png

4.2 Alice购买2张刮刮卡(buy_ticket

切换到Alice

可以通过split命令准备好Alice购买刮刮卡所需的代币数量:

sui client split-coin --coin-id $COIN --amounts 50 --gas-budget 10000000
export ALICE_COIN1=0xd7e29460a4cefa03c896bb1d944b32760559207577a96b5913f922718cfe2d5d # 50
sui client call --function buy_ticket --package $PACKAGE_ID --module drand_based_scratch_card --args $ALICE_COIN1 $GAME --gas-budget 10000000

image.png

export ALICE_COIN2=0x84f60e84ffb0d95dd155bdb710dbed12f04df55ea8cb99e57f64f855251bcccc # 50
sui client call --function buy_ticket --package $PACKAGE_ID --module drand_based_scratch_card --args $ALICE_COIN2 $GAME --gas-budget 10000000

image.png

  • 记录Ticket对象
export TICKET_ALICE1=0xeafedcb7d2b1708a25ce9d31a6c339f24c222c6d18764221339e1c30df81a5df
export TICKET_ALICE2=0x216ea8c4e2763e58e1624b103cce5a9667646adfdca08626d2a0a7688201d8d8
  • 查看Ticket对象
sui client object $TICKET_ALICE1

image.png

4.3 Bob购买1张刮刮卡(buy_ticket

切换到Bob

export BOB_COIN=0xc073e29cfa5e4512b7625975f8f81f256aa7a928e024a00c826729aee3f9cf14 # 50

sui client call --function buy_ticket --package $PACKAGE_ID --module drand_based_scratch_card --args $BOB_COIN $GAME --gas-budget 10000000

image.png

  • 记录Ticket对象
export TICKET_BOB=0xb9bd1551775fab2f81c60a61d45d0404b200adf30ee5c087e1d2f3e80ff1fa27
  • 查看Ticket对象
sui client object $TICKET_BOB

image.png

4.4 刮卡&开奖(evaluate

(1)获取游戏结束轮次的随机数签名

curl -s https://drand.cloudflare.com/52db9ba70e0cc0f6eaf7803dd07447a1f5477735fd3f661792ba94600c84e971/public/$END_ROUND  | jq
{
  "round": 5061255,
  "randomness": "869866bfa289042d0b63f300b22efed9163fd453ba395defeb12f6f1682c4387",
  "signature": "8b2a28613f736f2676ee0e63194b4767fc0c5d635231ff8424f989530d8624b965d283ba3f24f9db3f6567a3d481b161"
}

(2)Alice刮卡&开奖

任何Ticket的持有人都可以进行刮卡&开奖

切换到Alice

  • 刮第一张卡,未中奖
export DRAND_SIG=0x8b2a28613f736f2676ee0e63194b4767fc0c5d635231ff8424f989530d8624b965d283ba3f24f9db3f6567a3d481b161
sui client call --function evaluate --package $PACKAGE_ID --module drand_based_scratch_card --args $TICKET_ALICE1 $GAME $DRAND_SIG --gas-budget 10000000
  • 刮第二张卡,中奖
sui client call --function evaluate --package $PACKAGE_ID --module drand_based_scratch_card --args $TICKET_ALICE2 $GAME $DRAND_SIG --gas-budget 10000000

image.png

export WINNER_ALICE=0x3464c09617cf978f1c59682b68ec5cdfbf32b169d003244c78e594d50daf4f5b

image.png

(3)Bob刮卡&开奖

任何Ticket的持有人都可以进行刮卡&开奖

切换到Bob

export DRAND_SIG=0x8b2a28613f736f2676ee0e63194b4767fc0c5d635231ff8424f989530d8624b965d283ba3f24f9db3f6567a3d481b161
sui client call --function evaluate --package $PACKAGE_ID --module drand_based_scratch_card --args $TICKET_BOB $GAME $DRAND_SIG --gas-budget 10000000
  • 中奖

image.png

export WINNER_BOB=0x729b15308d3885fc42c50fa089b55b1b51d5fde23e73a2aa229fe97534f021ad

image.png

4.5 领奖(take_reward)

切换到中奖者Bob,去领奖

sui client call --function take_reward --package $PACKAGE_ID --module drand_based_scratch_card --args $WINNER_BOB $REWARD --gas-budget 10000000
  • Bob领奖,获得Reward中的所有代币

image.png

$ sui client object 0xb83960c12070b57c44f157e0ea50833eed9bf2d8078aaa34f9c28d94457db2b2

image.png

  • Alice领奖,因为奖池已空,将无法获得任何奖励:(

切换到Alice

sui client call --function take_reward --package $PACKAGE_ID --module drand_based_scratch_card --args $WINNER_ALICE $REWARD --gas-budget 10000000

接口成功调用,除了Winner对象被删除,什么也没有发生:

$ sui client object  $WINNER_ALICE

Internal error, cannot read the object: Object has been deleted object_id: 0x3464c09617cf978f1c59682b68ec5cdfbf32b169d003244c78e594d50daf4f5b at version: SequenceNumber(17681447) in digest o#7gyGAp71YXQRoxmFBaHxofQXAipvgHyBKPyxmdSJxyvz

4.6 赎回(redeem

如果奖励在几个世代内没有被提取,游戏创建者可以赎回奖励。调用比较简单,略。

5 更多

🚀参与星航计划 开启你的 Sui Move 之旅!🚀

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rzexin
rzexin
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江湖只有他的大名,没有他的介绍。