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サービスデザインプロジェクトB 第3回「スマートコントラクトプログラミング」 / Smart Contract Programming

サービスデザインプロジェクトB 第3回「スマートコントラクトプログラミング」 / Smart Contract Programming

2020年10月26日、慶應義塾大学大学院メディアデザイン研究科の「サービスデザインプロジェクトB (2020 秋)」第3回にて使用したスライドです。

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Kenji Saito
PRO

October 26, 2020
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  1. B 2020 3 ( ) B 2020 — 3 —

    2020-10-26 – p.1/62
  2. https://speakerdeck.com/ks91 Discord Discord ( / / ) Zoom URL (

    ) B 2020 — 3 — 2020-10-26 – p.2/62
  3. ( ) 1 10 12 • 2 10 19 •

    3 10 26 • 4 11 2 5 11 9 1 6 11 16 2 7 11 30 8 12 7 B 2020 — 3 — 2020-10-26 – p.3/62
  4. – : Ethereum – ( ) Ethereum (1) : ERC20

    (2) : (3) : B 2020 — 3 — 2020-10-26 – p.4/62
  5. – : Ethereum macOS (Catalina 10.15.7) + Homebrew Homebrew Linux

    (Ubuntu 18.04) Windows 10 + Windows Subsystem for Linux (Ubuntu 18.04 ) WSL Ethereum solidity brownie B 2020 — 3 — 2020-10-26 – p.5/62
  6. Solidity Ethereum http://solidity.readthedocs.io/en/latest/installing-solidity.html Linux (on Windows) “sudo apt”, macOS “brew”

    solc 0.7.3 (10/10 ) $ solc --version brownie py-solc-x solc (dependencies) ( solc py-solc-x ) B 2020 — 3 — 2020-10-26 – p.6/62
  7. Python3 macOS $ brew install python3 Linux $ sudo add-apt-repository

    ppa:deadsnakes/ppa $ sudo apt update $ sudo apt install python3.8 python3.8-dev python3.8-venv python3.8-tk 16.10 python3(.8) apt B 2020 — 3 — 2020-10-26 – p.7/62
  8. macOS : . . . macOS wget brew dyld: Library

    not loaded: /usr/local/opt/gettext/lib/libintl.8.dylib $ brew uninstall --force gettext $ brew install gettext B 2020 — 3 — 2020-10-26 – p.8/62
  9. Python (venv) macOS ‘python3.8’ ‘python3’ $ python3.8 -m venv bbc1env

    $ source bbc1env/bin/activate (bbc1env) $ pip install -U pip (bbc1env) $ pip install wheel bbc1env ( BBc-1 ) ( ) (bbc1env) $ deactivate B 2020 — 3 — 2020-10-26 – p.9/62
  10. Ganache CLI Ethereum RPC CLI : Command Line Interface npm

    ( ) macOS https://qiita.com/kyosuke5_20/items/c5f68fc9d89b84c0df09 Linux https://qiita.com/seibe/items/36cef7df85fe2cefa3ea npm Ganache CLI $ sudo npm install -g ganache-cli B 2020 — 3 — 2020-10-26 – p.10/62
  11. Brownie Python Ethereum https://eth-brownie.readthedocs.io Brownie $ pip install eth-brownie version

    1.11.8 (10/10 ) B 2020 — 3 — 2020-10-26 – p.11/62
  12. $ brownie init ( ERC-20 ) $ brownie bake token

    $ cd token ( ) $ brownie compile ( ) $ pytest tests B 2020 — 3 — 2020-10-26 – p.12/62
  13. Brownie $ brownie console Python >>> len(accounts) 10 >>> accounts[0].balance()

    100000000000000000000 >>> quit() B 2020 — 3 — 2020-10-26 – p.13/62
  14. – ( ) Ethereum ropsten B 2020 — 3 —

    2020-10-26 – p.14/62
  15. infura.io Brownie https://infura.io SIGN UP PROJECT ID infura Ethereum API

    infura . . . infura.io PROJECT ID WEB3_INFURA_PROJECT_ID PROJECT ID (∼/.bash_profile ) $ export WEB3_INFURA_PROJECT_ID= PROJECT ID B 2020 — 3 — 2020-10-26 – p.15/62
  16. ropsten ETH brownie console ropsten >>> network.disconnect() >>> network.connect(’ropsten’) >>>

    len(accounts) 0 >>> accounts.add() <LocalAccount object ’ 16 ’> >>> accounts[0].private_key 16 >>> quit() Ropsten Testnet ETH Faucet 5.0ETH https://faucet.dimensions.network/ ( ) https://metamask.io/ B 2020 — 3 — 2020-10-26 – p.16/62
  17. ropsten ETH brownie console ropsten ETH >>> network.disconnect() >>> network.connect(’ropsten’)

    >>> len(accounts) 0 >>> accounts.add( 16 ) <LocalAccount object ’ 16 ’> >>> accounts[0].balace() ETH >>> quit() ETH >>> accounts[0].transfer(accounts[1], "1 ether") B 2020 — 3 — 2020-10-26 – p.17/62
  18. Ethereum B 2020 — 3 — 2020-10-26 – p.18/62

  19. Ethereum Vitalik Buterin, “Ethereum White Paper: A NEXT GENERATION SMART

    CONTRACT & DECENTRALIZED APPLICATION PLATFORM” 15 (= ) = ⇒ → Dapps ( / / ) B 2020 — 3 — 2020-10-26 – p.19/62
  20. B 2020 — 3 — 2020-10-26 – p.20/62

  21. . . . B 2020 — 3 — 2020-10-26 –

    p.21/62
  22. vs. B 2020 — 3 — 2020-10-26 – p.22/62

  23. = run B 2020 — 3 — 2020-10-26 – p.23/62

  24. Ether Ethereum EOA : Externally-Owned Account ( ) Ether EVM

    EVM B 2020 — 3 — 2020-10-26 – p.24/62
  25. EVM : Ethereum Virtual Machine (validator) ⇒ Gas B 2020

    — 3 — 2020-10-26 – p.25/62
  26. EVM : : ← : Solidity — JavaScript LLL —

    Lisp Vyper — Python Fe — Vyper Rust ← NEW! Solidity Vyper Python B 2020 — 3 — 2020-10-26 – p.26/62
  27. Solidity ( ) pragma solidityˆ0.5.0; contract IndivisibleAsset { /* */

    string public _name; string public _symbol; uint256 public _quantity; address public _owner; constructor(string memory name, string memory symbol, uint256 quantity) public { _name = name; _symbol = symbol; _quantity = quantity; _owner = msg.sender; } function transfer(address to) public returns (bool) { require (_owner == msg.sender); _owner = to; return true; } } B 2020 — 3 — 2020-10-26 – p.27/62
  28. Ethereum B 2020 — 3 — 2020-10-26 – p.28/62

  29. (1) : ERC20 $ brownie bake token B 2020 —

    3 — 2020-10-26 – p.29/62
  30. Solidity JavaScript ( , ) (constructor) ( ) ( )

    Ether Ethereum B 2020 — 3 — 2020-10-26 – p.30/62
  31. pragma solidity ˆ0.5.0; contract Token { ( ) : (EVM

    ) : constructor (...) public { /* */ : } function balanceOf(...) { /* ( ) */ : } : } constructor C (/* */ // ) B 2020 — 3 — 2020-10-26 – p.31/62
  32. ERC20 ERC (Ethereum Request for Comment) 20 https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md contract ERC20

    { function totalSupply() constant returns (uint totalSupply); function balanceOf(address _owner) constant returns (uint balance); function transfer(address _to, uint _value) returns (bool success); function transferFrom(address _from, address _to, uint _value) returns (bool success); function approve(address _spender, uint _value) returns (bool success); function allowance(address _owner, address _spender) constant returns (uint remaining); event Transfer(address indexed _from, address indexed _to, uint _value); event Approval(address indexed _owner, address indexed _spender, uint _value); } name/ , symbol/ , decimals/ approve allowance ERC223 ( ), ERC721 (Non-Fungible) B 2020 — 3 — 2020-10-26 – p.32/62
  33. ERC20 ERC20 ( ) ⇒ ERC20 ( ERC20 ) ERC20

    ⇒ B 2020 — 3 — 2020-10-26 – p.33/62
  34. (fungible) ERC20 → ERC223 (draft) or ERC777 (non-fungible) ERC721 (

    ) (partially fungible) ERC1410 (draft) (ERC1400 ) B 2020 — 3 — 2020-10-26 – p.34/62
  35. Token ( ) string public symbol; string public name; uint256

    public decimals; uint256 public totalSupply; mapping(address => uint256) balances; . . . name, symbol decimals : 2 100 1.00 mapping balances B 2020 — 3 — 2020-10-26 – p.35/62
  36. Token ( ) event Transfer(address from, address to, uint256 value);

    Token function emit Transfer() ( ) B 2020 — 3 — 2020-10-26 – p.36/62
  37. Token ( ) constructor( string memory _symbol, string memory _name,

    uint256 _decimals, uint256 _totalSupply ) public { symbol = _symbol; name = _name; decimals = _decimals; totalSupply = _totalSupply; balances[msg.sender] = _totalSupply; } msg.sender _totalSupply B 2020 — 3 — 2020-10-26 – p.37/62
  38. Token balanceOf() function balanceOf(address _owner) public view returns (uint256) {

    return balances[_owner]; } B 2020 — 3 — 2020-10-26 – p.38/62
  39. Token transfer() function transfer(address _to, uint256 _value) public returns (bool)

    { balances[msg.sender] = balances[msg.sender].sub(_value); balances[_to] = balances[_to].add(_value); emit Transfer(msg.sender, _to, _value); return true; } OpenZeppelin https://openzeppelin.org B 2020 — 3 — 2020-10-26 – p.39/62
  40. (2) : B 2020 — 3 — 2020-10-26 – p.40/62

  41. GitHub git clone $ git clone https://github.com/ks91/sample-smart-contracts.git sample-smart-contracts contracts, scripts

    tests token Token B 2020 — 3 — 2020-10-26 – p.41/62
  42. (m2 ) 1 1 B 2020 — 3 — 2020-10-26

    – p.42/62
  43. IndivisibleAsset string public _name_; string public _symbol_; uint256 public _quantity_;

    address public _owner_; _name_ ( ) _symbol_ _quantity_ (m2 ) _owner_ ‘_’ Solidity . . . B 2020 — 3 — 2020-10-26 – p.43/62
  44. IndivisibleAsset event Transfer(address indexed from, address indexed to); from to

    indexed B 2020 — 3 — 2020-10-26 – p.44/62
  45. IndivisibleAsset constructor (string name, string symbol, uint256 quantity) public {

    _name_ = name; _symbol_ = symbol; _quantity_ = quantity; _owner_ = msg.sender; } B 2020 — 3 — 2020-10-26 – p.45/62
  46. IndivisibleAsset getOwner() function getOwner() public view returns (address) { return

    (_owner_); } B 2020 — 3 — 2020-10-26 – p.46/62
  47. IndivisibleAsset transfer() function transfer(address to) public returns (bool) { require(_owner_

    == msg.sender); _owner_ = to; emit Transfer(msg.sender, to); return true; } require (function ) ( ) $ brownie compile token Solidity 0.6.0 0.5.0 token B 2020 — 3 — 2020-10-26 – p.47/62
  48. scripts/indivisible asset.py from brownie import * def main(): accounts[0].deploy(IndivisibleAsset, "5322

    Endo, Fujisawa", "mˆ2", 300) SFC (300m2 ) ( ) B 2020 — 3 — 2020-10-26 – p.48/62
  49. from brownie import * import pytest def test_owner_and_transfer(IndivisibleAsset): asset =

    accounts[0].deploy(IndivisibleAsset, "5322 Endo", "mˆ2", 300) assert asset.getOwner() == accounts[0] asset.transfer(accounts[1], {’from’: accounts[0]}) assert asset.getOwner() == accounts[1] try: asset.transfer(accounts[0], {’from’: accounts[0]}) done = 1 except: done = 0 assert done == 0 accounts[0] accounts[1] B 2020 — 3 — 2020-10-26 – p.49/62
  50. $ pytest tests/test_indivisible_asset.py B 2020 — 3 — 2020-10-26 –

    p.50/62
  51. (3) : B 2020 — 3 — 2020-10-26 – p.51/62

  52. transfer settle, retrieve asset, retrieve token 3 B 2020 —

    3 — 2020-10-26 – p.52/62
  53. 1. ( ) 2. ( ) 3. ( ) B

    2020 — 3 — 2020-10-26 – p.53/62
  54. OneTimeEscrow settle() function settle() public returns (bool) { require(_token_.balanceOf(address(this)) >=

    _price_); /* this */ require(_asset_.getOwner() == address(this)); _token_.transfer(_seller_ , _price_); _asset_.transfer(_buyer_); emit Settled(); /* */ return true; } settle() transfer ( / ) $ brownie compile B 2020 — 3 — 2020-10-26 – p.54/62
  55. (1) from brownie import * import pytest def test_deploy_and_settle(Token, IndivisibleAsset,

    OneTimeEscrow): asset = accounts[0].deploy(IndivisibleAsset, "5322 Endo", "mˆ2", 300) token = accounts[0].deploy(Token, "Test Token", "TEST", 18, "1000 ether") B 2020 — 3 — 2020-10-26 – p.55/62
  56. (2) token.transfer(accounts[1], 300, {’from’: accounts[0]}) escrow = accounts[0].deploy(OneTimeEscrow, token, accounts[1],

    asset, accounts[0], 300) accounts[0] accounts[1] 300 300 TX accounts[1] accounts[0] 300 bake Token 300 ETH wei B 2020 — 3 — 2020-10-26 – p.56/62
  57. (3) token.transfer(escrow, 300, {’from’: accounts[1]}) asset.transfer(escrow, {’from’: accounts[0]}) assert token.balanceOf(accounts[0])

    == 999999999999999999700 assert token.balanceOf(accounts[1]) == 0 assert token.balanceOf(escrow) == 300 assert asset.getOwner() == escrow accounts[1] ( ) 300 accounts[0] ( ) B 2020 — 3 — 2020-10-26 – p.57/62
  58. (4) escrow.settle({’from’: accounts[0]}) assert token.balanceOf(accounts[0]) == 1000000000000000000000 assert token.balanceOf(accounts[1]) ==

    0 assert token.balanceOf(escrow) == 0 assert asset.getOwner() == accounts[1] settle() accounts[0] OK B 2020 — 3 — 2020-10-26 – p.58/62
  59. $ pytest tests/test_one_time_escrow.py : settle() ⇒ Discord B 2020 —

    3 — 2020-10-26 – p.59/62
  60. B 2020 — 3 — 2020-10-26 – p.60/62

  61. 1. (1) (2) Ethereum 1 2 2020 10 31 (

    ) 23:59 JST B 2020 — 3 — 2020-10-26 – p.61/62
  62. B 2020 — 3 — 2020-10-26 – p.62/62