链上信息、资产标准与协议拓展

Tinaaa · October 16, 2023, 3:46am

Hacker Dōjo Workshop：
研究种类：课题研究
资助金额：120 USDT
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现 Web3 专注研究Market、DeFi、Geth ，技术向周更博主，公众号《十四君》
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从公开私钥的陷阱说起

https://etherscan.io/address/0xb89d8a7c56241b550A6f8a0938BBBB2E2fe3166F

问答

获得私钥真能转走这30W刀吗？

不能，有USDT 黑名单

转走与否和我手速快慢有关系吗？

无关，以太坊出块15s，内存池是公开的
- 传统抢购，先到先得，演出票等要么是内鬼，要么是近距离服务器秒杀。
- 链上抢购，价高者得，内存池内是基本公开，矿工可以排序交易。

谁是最终受益者，他赚了多少？
拓展问题

后来资金确实被转走了，如何做到？

区块链的信息

从一个实时动画小游戏开始

https://txstreet.com/v/eth-btc

问题：他为什么能画出来这样的动画图？

1. 如何得知交易与左侧应用的关系
2. 交易签名是没有时间的，那如何统计出下方长期panding的交易？
3. 每个车厢为什么会有出来的交易？

区块信息详解

问题：

1. 该笔交易失败，该笔交易涉及的数据就会全部回滚吗？
2. MethodId 是如何算出来？

标准资产协议

ERC20标准是什么？

ERC-20: Token Standard

接口概览

// SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

}

完整实现-OpenZeppelin

/**
 *Submitted for verification at testnet.bscscan.com on 2023-08-13
*/

// File: @openzeppelin/contracts/utils/Context.sol

// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol

// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol

// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the default value returned by this function, unless
     * it's overridden.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(address from, address to, uint256 amount) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

// File: contracts/erc20PublicMint.sol

pragma solidity ^0.8.0;

contract MyToken is ERC20 {
    constructor() ERC20("xkh666", "xkh") {
    }
    function mint(address to,uint256 num) public  {
        _mint(to, num);
    }
}

本地体验

Remix - Ethereum IDE

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC20 {
    constructor() ERC20("xkh666", "xkh") {
    }
    function mint(address to,uint256 num) public  {
        _mint(to, num);
    }
}

上链体验
- bsc测试网与水龙头领取
  
  chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/home.html#settings/networks
  
  https://testnet.bscscan.com/
  
  Discord
  
  领取方式即加入服务器后在testnet-faucet频道，发送!faucet 你的地址
  Discord
- 小狐狸添加bsc测试网
  
  https://endpoints.omniatech.io/v1/bsc/testnet/public
- 已部署的erc20
  
  https://testnet.bscscan.com/address/0x8a1786a2b8101b1fb334d49e4ace69ad24ca63d4#code
问题
1. Gas消耗：Mint 99999 和 Mint 1e18 哪个消耗Gas多？为什么？
2. 我可以转入到任意地址吗？会有什么风险？
3. Mint不是一个标准的要求，那如何发现Mint的交易

协议应用层拓展

erc721代码

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyNFT is ERC721URIStorage {
    constructor(string memory _tokenName, string memory _tokenSymbol) 
        public ERC721(_tokenName, _tokenSymbol) {
    }
    //https://avatars.githubusercontent.com/u/13358272?v=4
    //https://ipfs.io/ipfs/bafybeieldy3ybghe5aqtby6y62jahtetizhaagycem4dzgwofmphlkzsde/1375.json
    function mint(address to, uint256 tokenId,string memory uri) public {
        _safeMint(to, tokenId);
        _setTokenURI(tokenId,uri);
    }
}

为什么有租赁的需要？
1. 原生协议的局限：只能证明所有权，代扣与所有权趋同
2. 市场应用的需求：分离NFT的资产价值和使用价值，释放出NFT的市场流动性
3. 链上安全的威胁：盗签致使资产流失
租赁的技术挑战
1. 链上是无法信任的
2. 租赁双方如何撮合？
3. 信任依据为何？
4. 历史协议的兼容性
5. 世面应用的兼容性

ERC4907-无强制性的租赁声明

如何设置

function setUser(uint256 tokenId, address user, uint64 expires) public virtual{
  require(_isApprovedOrOwner(msg.sender, tokenId),"ERC721: transfer caller is not owner nor approved");
  UserInfo storage info =  _users[tokenId];//新增存储登记信息
  info.user = user;   
  info.expires = expires;
  emit UpdateUser(tokenId,user,expires); //发出事件通知链下应用
}

如何查询

function userOf(uint256 tokenId)public view virtual returns(address){
  if( uint256(_users[tokenId].expires) >=  block.timestamp){
      return  _users[tokenId].user; 
  };//执行此函数，在未到期的情况下，返回此ID的当前用户地址
  else{return address(0);
  }//到期情况下，则返回0地址，意未占用
}

如何评价
1. 无法向前兼容
2. 原所有者权限极高，租赁者的维权能力薄弱（哪怕租赁期无法售卖和重置也好）
3. Dapp应用层的兼容需增加识别方法

ERC5058-强制性的租赁声明

请注意

只有对NFT有持有权的地址，才可以给与别人锁定权。

只有对NFT有锁定权的地址，才有权解锁该 NFT（或通过到期解锁）。

锁定期可以产生（未实现）Bound NFT，来代表约束权
- 给与锁定权
```
function _lockApprove(address owner,address to,uint256 tokenId
    ) internal virtual {
        _lockApprovals[tokenId] = to;
        emit LockApproval(owner, to, tokenId);
    }
```
- 执行锁定
```
function _lock(
        address operator,
        uint256 tokenId,
        uint256 expired
    ) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenLock(operator, owner, tokenId, expired);

        lockedTokens[tokenId] = expired;
        _lockApprovals[tokenId] = operator;

        emit Locked(operator, owner, tokenId, expired);

        _afterTokenLock(operator, owner, tokenId, expired);
    }
```
- 如何评价
  
  总之：用户一部分权利给与一定信任，dapp也让渡一部分权益给与一定的服务。
  1. 锁定权难以定价，难以转化成应用场景。
  2. 流动性反而降低，Bound NFT本身无实物的交割权。
  什么是更合适的拓展？
  
  质（可取回，偏保管性质）、押（可变现，高利贷性质)。
  
  典（属官营，偏不动产）、当（属民营，偏可动产）。
  
  以上都是在期限内交换所有权、使用权，如果可以过期即具备强制转移，类似当铺思路则可以具有一定社会契约层牟利的动机。
ERC6147-半强制性的租赁声明

- 如何评价
    
    改进点：
    
    1. 减低4907的应用层兼容性要求，租赁给你，实际上是直接转给你，但自己还是守卫者（可以取回），但由于dapp更多使用owner，而不是userof，所以兼容性更好。
    2. 降低应用耦合难度的同时，更偏用户的管理权。
    
    局限性
    
    1. 时间点非强制性，致使售卖定价缺乏信任。如按挂牌价租1个月，但我可以反悔。
    2. 能清除授权的转移是非标准方法，为transferRemove，则opensea等无法兼容。

综合点评

挑战	4907	5058	6147
概述	定义租赁角色，由所有者任意控制，到期自动解除关系	强制链上锁定，出卖转移权，仅可提前解除，用作质押类Defi场景。	定义守卫角色，所有者转为守卫，租赁方获得所有权，守卫可随时解除关系
链上信任	非强制	强制	半强制
定价撮合	无（需自研平台）	无（需自研平台）	中（借助os）
信任依据	双方自觉	强行锁定	用户自觉
往前兼容	差	差	差
应用兼容	差（要识别租赁角色）	差（要识别锁定状态）	中（复用所有权）

6551才是往前兼容好的典范：拓展阅读https://km.woa.com/articles/show/583323