基于区块链的毕业设计1. Fallback – 1退路

本文提供基于区块链的毕业设计国外最新区块链项目源码下载,包括solidity,eth,fabric等blockchain区块链,基于区块链的毕业设计1. Fallback – 1退路 是一篇很好的国外资料

1. Fallback

Look carefully at the contract’s code below. You will beat this level if

  1. you claim ownership of the contract
  2. you reduce its balance to 0

Things that might help

  • How to send ether when interacting with an ABI
  • How to send ether outside of the ABI
  • Converting to and from wei/ether units -see help() command-
  • Fallback methods

2. Fallout

Claim ownership of the contract below to complete this level. Things that might help:

  • Solidity Remix IDE

3. Coin Flip

This is a coin flipping game where you need to build up your winning streak by guessing the outcome of a coin flip. To complete this level you’ll need to use your psychic abilities to guess the correct outcome 10 times in a row.

4. Telephone

Claim ownership of the contract below to complete this level. Things that might help

  • See the Help page above, section “Beyond the console”

5. Token

The goal of this level is for you to hack the basic token contract below. You are given 20 tokens to start with and you will beat the level if you somehow manage to get your hands on any additional tokens. Preferably a very large amount of tokens. Things that might help:

  • What is an odometer?

6. Delegation

The goal of this level is for you claim ownership of the instance you are given. Things that might help

  • Look into Solidity’s documentation on the delegatecall low level function, how it works, how it can be used to delegate operations to on-chain libraries, and what implications it has on execution scope.
  • Fallback methods
  • Method ids

7. Force

Some contracts will simply not take your money ¯_(ツ)_/¯ The goal of this level is to make the balance of the contract greater than zero. Things that might help:

  • Fallback methods
  • Sometimes the best way to attack a contract is with another contract.
  • See the Help page above, section “Beyond the console”

8. Vault

Unlock the vault to pass the level!

9. King

The contract below represents a very simple game: whoever sends it an amount of ether that is larger than the current prize becomes the new king. On such an event, the overthrown king gets paid the new prize, making a bit of ether in the process! As ponzi as it gets xD Such a fun game. Your goal is to break it. When you submit the instance back to the level, the level is going to reclaim kingship. You will beat the level if you can avoid such a self proclamation.

10. Re-entrancy

The goal of this level is for you to steal all the funds from the contract. Things that might help:

  • Untrusted contracts can execute code where you least expect it.
  • Fallback methods
  • Throw/revert bubbling
  • Sometimes the best way to attack a contract is with another contract.
  • See the Help page above, section “Beyond the console”

11. Elevator

This elevator won’t let you reach the top of your building. Right? Things that might help:

  • Sometimes solidity is not good at keeping promises.
  • This Elevator expects to be used from a Building.

12. Privacy

The creator of this contract was careful enough to protect the sensitive areas of its storage. Unlock this contract to beat the level. Things that might help: Understanding how storage works Understanding how parameter parsing works Understanding how casting works Tips: Remember that metamask is just a commodity. Use another tool if it is presenting problems. Advanced gameplay could involve using remix, or your own web3 provider.

13. Gatekeeper One

Make it past the gatekeeper and register as an entrant to pass this level. Things that might help:

  • Remember what you’ve learned from the Telephone and Token levels.
  • You can learn more about the msg.gas special variable, or its preferred alias gasleft(), in Solidity’s documentation (see here and here).

14. Gatekeeper Two

This gatekeeper introduces a few new challenges. Register as an entrant to pass this level. Things that might help:

  • Remember what you’ve learned from getting past the first gatekeeper – the first gate is the same.
  • The assembly keyword in the second gate allows a contract to access functionality that is not native to vanilla Solidity. See here for more information. The extcodesize call in this gate will get the size of a contract’s code at a given address – you can learn more about how and when this is set in section 7 of the yellow paper.
  • The ^ character in the third gate is a bitwise operation (XOR), and is used here to apply another common bitwise operation (see here). The Coin Flip level is also a good place to start when approaching this challenge.

15. Naught Coin

NaughtCoin is an ERC20 token and you’re already holding all of them. The catch is that you’ll only be able to transfer them after a 10 year lockout period. Can you figure out how to get them out to another address so that you can transfer them freely? Complete this level by getting your token balance to 0. Things that might help

  • The ERC20 Spec
  • The OpenZeppelin codebase

16. Preservation

This contract utilizes a library to store two different times for two different timezones. The constructor creates two instances of the library for each time to be stored. The goal of this level is for you to claim ownership of the instance you are given. Things that might help

  • Look into Solidity’s documentation on the delegatecall low level function, how it works, how it can be used to delegate operations to on-chain. libraries, and what implications it has on execution scope.
  • Understanding what it means for delegatecall to be context-preserving.
  • Understanding how storage variables are stored and accessed.
  • Understanding how casting works between different data types.

17. Recovery

A contract creator has built a very simple token factory contract. Anyone can create new tokens with ease. After deploying the first token contract, the creator sent 0.5 ether to obtain more tokens. They have since lost the contract address. This level will be completed if you can recover (or remove) the 0.5 ether from the lost contract address.

18. MagicNumber

To solve this level, you only need to provide the Ethernaut with a “Solver”, a contract that responds to “whatIsTheMeaningOfLife()” with the right number. Easy right? Well… there’s a catch. The solver’s code needs to be really tiny. Really reaaaaaallly tiny. Like freakin’ really really itty-bitty tiny: 10 opcodes at most. Hint: Perhaps its time to leave the comfort of the Solidity compiler momentarily, and build this one by hand O_o. That’s right: Raw EVM bytecode. Good luck!

19. Alien Codex

You’ve uncovered an Alien contract. Claim ownership to complete the level. Things that might help

  • Understanding how array storage works
  • Understanding ABI specifications
  • Using a very underhanded approach

20. Denial

This is a simple wallet that drips funds over time. You can withdraw the funds slowly by becoming a withdrawing partner. If you can deny the owner from withdrawing funds when they call withdraw() (whilst the contract still has funds) you will win this level.

21. Shop

Сan you get the item from the shop for less than the price asked? Things that might help:

  • Shop expects to be used from a Buyer
  • Understanding how gas() options works

1。回退

仔细看下面的合同代码。如果有可能有助于你完成这一级别的工作,你将击败这一级别。可能有用的事情:

  1. 您声明合同的所有权
  2. 您将其余额减少为0

这是一个掷硬币游戏,你需要通过猜测掷硬币的结果来建立你的连胜记录。为了完成这一关,你需要使用你的心灵能力连续10次猜出正确的结果。

  • 如何在与ABI交互时发送乙醚
  • 如何在ABI外部发送乙醚
  • 转换为/从乙醚单元-请参阅help()命令-
  • 回退方法

2。沉降物。投币4。电话

要求拥有以下合同以完成此级别。可能有帮助的事情

  • Solidity Remix IDE

5。代币6。代表团7。力

这个级别的目标是让你破解下面的基本代币契约。你有20个代币开始,如果你设法得到任何额外的代币,你将击败水平。最好是大量的代币。可能有帮助的事情:

8。保险库9。国王10。重新进入

此级别的目标是让您声明对给定实例的所有权。有些合同根本不会拿走你的钱,这个级别的目标是使合同的余额大于零。可能有帮助的事情:

  • 请参阅在上面的“帮助”页的“超越控制台”部分中,

11。电梯12。隐私13。守门员一号14。看门人2个15。零币16。保存17。恢复18。MagicNumber

解锁保险库以通过关卡!

  • 什么是里程表?

19。外星人法典20。拒绝21。Shop

下面的合同代表了一个非常简单的游戏:谁给它发送的乙醚量大于当前的奖品,谁就成为新的国王。在这样的事件中,被推翻的国王得到了新的奖品,在这个过程中制造了一点乙醚!像庞氏骗局一样有趣的游戏。你的目标是打破它。当您将实例提交回该级别时,该级别将收回王权。如果你能避免这种自我宣示的话,你将超越这个等级。

  • 查看Solidity关于delegatecall低级函数的文档,了解它是如何工作的,如何使用它将操作委托给链上库,以及它对执行范围的影响。
  • 回退方法
  • 方法ID

7. Force

此级别的目标是让您从合同中窃取所有资金。可能有用的事情:

  • 回退方法
  • 有时攻击契约的最佳方法是使用另一个契约。
  • 请参阅上面的“帮助”页的“超越控制台”部分

8. Vault

这部电梯不能让你到达楼顶。正确的?一些可能有用的事情:

9. King

这个合同的创建者非常小心地保护了它存储的敏感区域。解除此合同以打破水平。可能有帮助的事情:了解存储是如何工作的了解参数解析是如何工作的了解转换是如何工作的提示:记住metamask只是一种商品。如果出现问题,请使用其他工具。高级游戏可能涉及使用混音,或您自己的web3提供商。

10. Re-entrancy

通过守门人并注册为进入者以通过此级别。可能有帮助的事情:

  • 不受信任的契约可以在您最不期望的地方执行代码。
  • 回退方法
  • 抛出/还原冒泡
  • 有时攻击契约的最佳方法是使用另一个契约。
  • 请参阅上面的帮助页“超越控制台”一节

11. Elevator

这个看门人介绍了一些新的挑战。注册为通过此级别的参赛者。可能有用的东西:

  • 有时,坚定不善于信守承诺。
  • 这部电梯预计在建筑物内使用。

12. Privacy

Noutcoin是一个ERC20代币,您已经拥有了所有的代币。问题是你只能在10年的禁赛期后才能转移他们。你能想出办法把他们送到另一个地址,这样你就可以自由地把他们转走吗?通过使您的令牌余额达到0来完成此级别。可能有用的东西

13. Gatekeeper One

这个合同使用一个库来存储两个不同时区的两个不同时间。构造函数为每次要存储的库创建两个实例。这个级别的目标是让您声明对给定实例的所有权。可能有用的事情

  • 记住从电话和令牌级别学到的知识。
  • 您可以进一步了解味精煤气特殊变量,或其首选别名gasleft(),在Solidity的文档中(请参阅此处和此处)。

14. Gatekeeper Two

契约创建者构建了一个非常简单的令牌工厂契约。任何人都可以轻松地创建新令牌。部署第一个令牌契约后,创建者发送0.5以太以获取更多令牌。他们后来失去了合同地址。如果您可以从丢失的合同地址中恢复(或删除)0.5乙醚,则此级别将完成。

  • 记住你从第一个守门人那里学到的东西——第一个门是一样的。
  • 第二个gate中的assembly关键字允许契约访问非vanilla Solidity本机的功能。更多信息请参见此处。此gate中的extcodesize调用将获得给定地址处合同代码的大小—您可以在黄皮书的第7节中了解更多关于如何以及何时设置的信息。
  • 第三个门中的^字符是位运算(XOR),在这里用于应用另一个常见的位运算(请参阅此处)。投币水平也是一个很好的开始,当接近这个挑战。ERC20规范OpenZeppelin代码库查看Solidity关于delegatecall低级函数的文档,它是如何工作的,如何用于将操作委派给on-chain。库,以及它对执行范围的影响。

15. Naught Coin

要解决这个级别,您只需要向Ethernaut提供一个“Solver”,一个用正确的数字响应“whatIsTheMeaningOfLife()”的契约。很简单吧?好。。。有个陷阱。解算器的代码必须非常小。真的很小。像个小东西:最多10个操作码。提示:也许是时候暂时离开Solidity编译器的舒适性了,手工构建这个编译器了。祝你好运!

  • 了解delegatecall保持上下文的含义。
  • 了解如何存储和访问存储变量。

16. Preservation

你发现了一个外星人的合同。声明所有权以完成级别。可能有用的东西

  • 了解不同数据类型之间的转换工作原理。了解阵列存储的工作原理
  • Understanding what it means for delegatecall to be context-preserving.
  • Understanding how storage variables are stored and accessed.
  • Understanding how casting works between different data types.

17. Recovery

这是一个简单的钱包,随着时间的推移,它会把资金滴进去。你可以通过成为提款合伙人来慢慢地提取资金。如果你可以拒绝所有者在调用draw()时提取资金(同时合同仍有资金),你将赢得此级别。

18. MagicNumber

你能以低于要求的价格从商店买到这件商品吗?可能有用的东西:

19. Alien Codex

You’ve uncovered an Alien contract. Claim ownership to complete the level. Things that might help

  • Understanding how array storage works
  • Understanding ABI specifications
  • Using a very underhanded approach

20. Denial

This is a simple wallet that drips funds over time. You can withdraw the funds slowly by becoming a withdrawing partner. If you can deny the owner from withdrawing funds when they call withdraw() (whilst the contract still has funds) you will win this level.

21. Shop

Сan you get the item from the shop for less than the price asked? Things that might help:

  • Shop expects to be used from a Buyer
  • Understanding how gas() options works

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www.interchains.cc

https://www.interchains.cc/20773.html

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