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

2021年11月1日(月)、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」2021秋 第4回で使用されたスライドです。

Transcript

1. B 2021 4 ( ) B 2021 — 4 — 2021-11-01 – p.1/51
2. https://speakerdeck.com/ks91 ( ) Discord Discord ( / / ) Zoom URL ( ) B 2021 — 4 — 2021-11-01 – p.2/51
3. ( ) 1 10 11 • 2 10 18 • 3 10 25 • 4 11 1 • 5 11 8 1 6 11 15 2 7 11 22 8 11 29 ( ) 4 ( 3 ) ↓ B 2021 — 4 — 2021-11-01 – p.3/51
4. brownie (1) : ERC20 (2) : (3) : Web 3.0 B 2021 — 4 — 2021-11-01 – p.4/51
5. brownie ropsten B 2021 — 4 — 2021-11-01 – p.5/51
6. 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 2021 — 4 — 2021-11-01 – p.6/51
7. 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 2021 — 4 — 2021-11-01 – p.7/51
8. 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 2021 — 4 — 2021-11-01 – p.8/51
9. (1) : ERC20 $ brownie bake token B 2021 — 4 — 2021-11-01 – p.9/51
10. Solidity JavaScript ( , ) (constructor) ( ) ( ) Ether Ethereum B 2021 — 4 — 2021-11-01 – p.10/51
11. pragma solidity ˆ0.6.0; /* 0.8.x */ contract Token { ( ) : (EVM ) : constructor (...) public { /* */ : } function balanceOf(...) { /* ( ) */ : } : } constructor C (/* */ // ) B 2021 — 4 — 2021-11-01 – p.11/51
12. 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 2021 — 4 — 2021-11-01 – p.12/51
13. ERC20 ERC20 ( ) ⇒ ERC20 ( ERC20 ) ERC20 ⇒ B 2021 — 4 — 2021-11-01 – p.13/51
14. (fungible) ERC20 → ERC223 (draft) or ERC777 (non-fungible) ERC721 ( ) (partially fungible) ERC1410 (draft) (ERC1400 ) B 2021 — 4 — 2021-11-01 – p.14/51
15. 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 2021 — 4 — 2021-11-01 – p.15/51
16. Token ( ) event Transfer(address from, address to, uint256 value); Token function emit Transfer() ( ) B 2021 — 4 — 2021-11-01 – p.16/51
17. 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 2021 — 4 — 2021-11-01 – p.17/51
18. Token balanceOf() function balanceOf(address _owner) public view returns (uint256) { return balances[_owner]; } B 2021 — 4 — 2021-11-01 – p.18/51
19. 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 2021 — 4 — 2021-11-01 – p.19/51
20. (2) : B 2021 — 4 — 2021-11-01 – p.20/51
21. 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 2021 — 4 — 2021-11-01 – p.21/51
22. (m2 ) 1 1 B 2021 — 4 — 2021-11-01 – p.22/51
23. IndivisibleAsset string public _name_; string public _symbol_; uint256 public _quantity_; address public _owner_; _name_ ( ) _symbol_ _quantity_ (m2 ) _owner_ ‘_’ Solidity . . . B 2021 — 4 — 2021-11-01 – p.23/51
24. IndivisibleAsset event Transfer(address indexed from, address indexed to); from to indexed B 2021 — 4 — 2021-11-01 – p.24/51
25. IndivisibleAsset constructor (string name, string symbol, uint256 quantity) public { _name_ = name; _symbol_ = symbol; _quantity_ = quantity; _owner_ = msg.sender; } B 2021 — 4 — 2021-11-01 – p.25/51
26. IndivisibleAsset getOwner() function getOwner() public view returns (address) { return (_owner_); } B 2021 — 4 — 2021-11-01 – p.26/51
27. 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 2021 — 4 — 2021-11-01 – p.27/51
28. scripts/indivisible asset.py from brownie import * def main(): accounts[0].deploy(IndivisibleAsset, "5322 Endo, Fujisawa", "mˆ2", 300) SFC (300m2 ) ( ) B 2021 — 4 — 2021-11-01 – p.28/51
29. 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 2021 — 4 — 2021-11-01 – p.29/51
30. $ pytest tests/test_indivisible_asset.py B 2021 — 4 — 2021-11-01 – p.30/51
31. (3) : B 2021 — 4 — 2021-11-01 – p.31/51
32. transfer settle, retrieve asset, retrieve token 3 B 2021 — 4 — 2021-11-01 – p.32/51
33. 1. ( ) 2. ( ) 3. ( ) B 2021 — 4 — 2021-11-01 – p.33/51
34. 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 2021 — 4 — 2021-11-01 – p.34/51
35. (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") brownie console ropsten . . . ← accounts[0] seller, accounts[1] buyer buyer Ether (gas ) B 2021 — 4 — 2021-11-01 – p.35/51
36. (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 2021 — 4 — 2021-11-01 – p.36/51
37. (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 2021 — 4 — 2021-11-01 – p.37/51
38. (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 2021 — 4 — 2021-11-01 – p.38/51
39. $ pytest tests/test_one_time_escrow.py : settle() ⇒ Discord B 2021 — 4 — 2021-11-01 – p.39/51
40. B 2021 — 4 — 2021-11-01 – p.40/51
41. 1. (1) (2) Ethereum 1 2 2020 10 30 ( ) 23:59 JST B 2021 — 4 — 2021-11-01 – p.41/51
42. . . . . . . 5 3 ( ) ( ) (← ) (← ) ( ) ( ) B 2021 — 4 — 2021-11-01 – p.42/51
43. O ⇒ B 2021 — 4 — 2021-11-01 – p.43/51
44. K NFT ⇒ NFT SNS TikTok SNS ⇒ ( ) . . . B 2021 — 4 — 2021-11-01 – p.44/51
45. C ⇒ ( ) B 2021 — 4 — 2021-11-01 – p.45/51
46. Web 3.0 Web 3.0 HTTPS B 2021 — 4 — 2021-11-01 – p.46/51
47. NFT SNS ↑ B 2021 — 4 — 2021-11-01 – p.47/51
48. miro ( ) ( ) B 2021 — 4 — 2021-11-01 – p.48/51
49. B 2021 — 4 — 2021-11-01 – p.49/51
50. 2. API (1) ( ) (2) Web API 2020 11 6 ( ) 23:59 JST B 2021 — 4 — 2021-11-01 – p.50/51
51. B 2021 — 4 — 2021-11-01 – p.51/51