スマートコントラクトデザイン / Smart Contract Design

慶應義塾大学大学院メディアデザイン研究科「サービスデザインプロジェクトB」2024秋 第4回にて使用したスライドです。

Transcript

1. Generated by Stable Diffusion XL v1.0 B 2024 4 ( ) B 2024 — 4 — 2024-10-28 – p.1/58
2. https://speakerdeck.com/ks91/collections/service-design-project-b-2024-fall ( ) ( ) Discord Discord ( / / ) Zoom URL ( ) B 2024 — 4 — 2024-10-28 – p.2/58
3. ( ) 1 10 7 • 2 10 14 • 3 10 21 • 4 11 28 • 5 11 4 1 6 11 11 2 7 11 18 8 11 25 ( ) ( ) 4 ( 3 ) ↓ B 2024 — 4 — 2024-10-28 – p.3/58
4. Ethereum ( ) (1) : ERC20 ( ) (2) : (3) : Web3 B 2024 — 4 — 2024-10-28 – p.4/58
5. Ethereum ( ) B 2024 — 4 — 2024-10-28 – p.5/58
6. Ethereum Vitalik Buterin, “Ethereum White Paper: A NEXT GENERATION SMART CONTRACT & DECENTRALIZED APPLICATION PLATFORM” 12 (= ) = ⇒ → Dapps ( / / ) B 2024 — 4 — 2024-10-28 – p.6/58
7. ( ) B 2024 — 4 — 2024-10-28 – p.7/58
8. . . . B 2024 — 4 — 2024-10-28 – p.8/58
9. vs. Ethereum (Ether ) 13 13 B 2024 — 4 — 2024-10-28 – p.9/58
10. = run B 2024 — 4 — 2024-10-28 – p.10/58
11. Ether Ethereum EOA : Externally-Owned Account ( ) Ether EVM EVM B 2024 — 4 — 2024-10-28 – p.11/58
12. EVM : Ethereum Virtual Machine ঢ়ଶ ֎෦ΞΫλʔ ΞΧ΢ϯτ &7. ίʔυ &UIFS
    ˠ
    (BT ىಈ ίϯτϥΫτ ϝοηʔδ
    ͔ɺ৽͍ࣗ͠ಈΦϒδΣΫτ ΞΧ΢ϯτؒͰ΍ΓऔΓ͞ΕΔσʔλ΍
    &UIFS ετϨʔδ ঢ়ଶ` τϥϯβΫγϣϯ ηοτ σδλϧॺ໊ &7. ਓؒͱ͔ ࣗಈ ΦϒδΣΫτ Gas ( ( )) . . . B 2024 — 4 — 2024-10-28 – p.12/58
13. EVM : : ← : Solidity — JavaScript LLL — Lisp Vyper — Python Fe — Vyper Rust ← NEW! Solidity Vyper Python B 2024 — 4 — 2024-10-28 – p.13/58
14. Solidity ( ) pragma solidityˆ0.7.0; 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 2024 — 4 — 2024-10-28 – p.14/58
15. ( , ) (constructor) (deploy) = ( ) ( ) ETH Trusted Actor Model B 2024 — 4 — 2024-10-28 – p.15/58
16. Ethereum B 2024 — 4 — 2024-10-28 – p.16/58
17. (1) : ERC20 $ brownie bake token B 2024 — 4 — 2024-10-28 – p.17/58
18. pragma solidity ˆ0.6.0; /* 0.8.x */ contract Token { ( ) : (EVM ) : constructor (...) public { /* */ : } function balanceOf(...) { /* ( ) */ : } : } constructor C (/* */ // ) B 2024 — 4 — 2024-10-28 – p.18/58
19. ERC-20 ERC (Ethereum Request for Comments) 20 https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md (EIP: Ethereum Improvement Proposal) ← EIP ( ) 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 ERC-777 ( ) B 2024 — 4 — 2024-10-28 – p.19/58
20. ERC20 ERC20 ( ) ⇒ ERC20 ( ERC20 ) ERC20 ⇒ B 2024 — 4 — 2024-10-28 – p.20/58
21. (fungible) ERC-20 → ERC-223 (draft) or ERC-777 ( )( ) (non-fungible) ERC-721 ( ) ERC-1155 ( ) ERC-3525 (SLOT ) B 2024 — 4 — 2024-10-28 – p.21/58
22. 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 2024 — 4 — 2024-10-28 – p.22/58
23. Token ( ) event Transfer(address from, address to, uint256 value); Token function emit Transfer() ( ) B 2024 — 4 — 2024-10-28 – p.23/58
24. 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 2024 — 4 — 2024-10-28 – p.24/58
25. Token balanceOf() function balanceOf(address _owner) public view returns (uint256) { return balances[_owner]; } B 2024 — 4 — 2024-10-28 – p.25/58
26. 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 2024 — 4 — 2024-10-28 – p.26/58
27. (2) : B 2024 — 4 — 2024-10-28 – p.27/58
28. GitHub git clone $ git clone https://github.com/ks91/sample-smart-contracts.git sample-smart-contracts contracts, scripts tests token Token Solidity 0.5 0.6/0.7 (Token ) Solidity B 2024 — 4 — 2024-10-28 – p.28/58
29. (m2 ) 1 1 B 2024 — 4 — 2024-10-28 – p.29/58
30. IndivisibleAsset string public _name_; string public _symbol_; uint256 public _quantity_; address public _owner_; _name_ ( ) _symbol_ _quantity_ (m2 ) _owner_ ‘_’ Solidity . . . B 2024 — 4 — 2024-10-28 – p.30/58
31. IndivisibleAsset event Transfer(address indexed from, address indexed to); from to indexed B 2024 — 4 — 2024-10-28 – p.31/58
32. IndivisibleAsset constructor (string name, string symbol, uint256 quantity) public { _name_ = name; _symbol_ = symbol; _quantity_ = quantity; _owner_ = msg.sender; } B 2024 — 4 — 2024-10-28 – p.32/58
33. IndivisibleAsset getOwner() function getOwner() public view returns (address) { return (_owner_); } B 2024 — 4 — 2024-10-28 – p.33/58
34. 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 B 2024 — 4 — 2024-10-28 – p.34/58
35. scripts/indivisible asset.py from brownie import * def main(): accounts[0].deploy(IndivisibleAsset, "5322 Endo, Fujisawa", "mˆ2", 300) SFC (300m2 ) ( ) B 2024 — 4 — 2024-10-28 – p.35/58
36. 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 2024 — 4 — 2024-10-28 – p.36/58
37. $ pytest tests/test_indivisible_asset.py B 2024 — 4 — 2024-10-28 – p.37/58
38. (3) : B 2024 — 4 — 2024-10-28 – p.38/58
39. transfer settle, retrieve asset, retrieve token 3 B 2024 — 4 — 2024-10-28 – p.39/58
40. 1. ( ) 2. ( ) 3. ( ) B 2024 — 4 — 2024-10-28 – p.40/58
41. 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 2024 — 4 — 2024-10-28 – p.41/58
42. (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 2024 — 4 — 2024-10-28 – p.42/58
43. (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 2024 — 4 — 2024-10-28 – p.43/58
44. (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 2024 — 4 — 2024-10-28 – p.44/58
45. (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 2024 — 4 — 2024-10-28 – p.45/58
46. $ pytest tests/test_one_time_escrow.py : settle() ⇒ Discord B 2024 — 4 — 2024-10-28 – p.46/58
47. B 2024 — 4 — 2024-10-28 – p.47/58
48. 1. (1) (2) Ethereum 2024 10 26 ( ) 23:59 JST B 2024 — 4 — 2024-10-28 – p.48/58
49. . . . . . . 3 2 ( ) ( ) ( ) B 2024 — 4 — 2024-10-28 – p.49/58
50. N SFC ⇒ ( ) ( ) B 2024 — 4 — 2024-10-28 – p.50/58
51. L Ethereum ⇒ B 2024 — 4 — 2024-10-28 – p.51/58
52. ⇒ 20 Discord . . . B 2024 — 4 — 2024-10-28 – p.52/58
53. Web3 Web3 HTTPS B 2024 — 4 — 2024-10-28 – p.53/58
54. B 2024 — 4 — 2024-10-28 – p.54/58
55. miro ( ) ( ) B 2024 — 4 — 2024-10-28 – p.55/58
56. B 2024 — 4 — 2024-10-28 – p.56/58
57. 2. API (1) ( ) (2) Web API 2024 11 2 ( ) 23:59 JST B 2024 — 4 — 2024-10-28 – p.57/58
58. B 2024 — 4 — 2024-10-28 – p.58/58