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スマートコントラクトと分散ファイナンス / Smart Contracts and Decen...
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Kenji Saito
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June 28, 2025
Technology
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スマートコントラクトと分散ファイナンス / Smart Contracts and Decentralized Finance
早稲田大学大学院経営管理研究科「フィンテック ─ 金融革新とインターネット」2025 夏の第7-8回で使用したスライドです。
Kenji Saito
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June 28, 2025
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Transcript
Light and Shadow — Generated by Stable Diffusion 3.5 —
2025 7-8 (WBS) — 2025 7-8 — 2025-06-30 – p.1/75
https://speakerdeck.com/ks91/collections/fintech-2025-summer — 2025 7-8 — 2025-06-30 – p.2/75
( ) 1 6 9 (1) • 2 6 9
(2) • 3 6 16 Web3 (1) • 4 6 16 Web3 (2) • 5 6 23 (1) • 6 6 23 (2) • 7 6 30 (1) • 8 6 30 (2) • 9 7 7 (1) 10 7 7 (2) 11 7 14 (1) 12 7 14 (2) 13 7 21 (1) 14 7 21 (2) W-IOI ( ) — 2025 7-8 — 2025-06-30 – p.3/75
( 20 ) 1 ↑ 2 ↓ 2025 3 4
(TCP/IP ) 5 6 7 8 ↑ 9 ↓ 2024 ( ) 10 World Wide Web 11 Web API 12 * 13 git GitHub 14 (6/23 ) / (2 ) OK / — 2025 7-8 — 2025-06-30 – p.4/75
( ) Web3 (1) — Web3 (2) — — 2025
7-8 — 2025-06-30 – p.5/75
Ethereum — 2025 7-8 — 2025-06-30 – p.6/75
(+ ) — 2025 7-8 — 2025-06-30 – p.7/75
ϒϩοΫ൪߸O ϒϩοΫ൪߸O ϒϩοΫ൪߸O ϒϩοΫ൪߸O ϒϩοΫ൪߸O ϒϩοΫ൪߸O
ϒϩοΫ൪߸O ϒϩοΫ൪߸O ͍ͪΜهɾॻ͖͑ͷίετ͕ߴ͍ྺ࢙ ࠷վ͟Μ͠ʹ͍͘ྺ࢙ ͕༗ޮ ͻͱͭखલͷϒϩοΫͷ ʮμΠδΣετʯ σδλϧॺ໊͞Εͨ ʮτϥϯβΫγϣϯ औҾ ʯ ϒϩοΫΛ࡞ΔͨΊʹɺͦͷʮμΠδΣετʯ͕͋ΔҎԼͱ͍͏݅Λຬͨͨ͠Γ 1SPPGPG8PSL ҉߸ࢿ࢈ͷσϙδοτʹԠͨ͡ݖརΛͬͨථͰউͬͨΓ 1SPPGPG4UBLF ͢Δඞཁ͕͋Δ ίετ͕͔͔Δ ϒϩοΫΛ࡞ΔਓͦͷதʹࣗʹѼͯͨ ҉߸ࢿ࢈ͰͷใुΛॻ͖ࠐΉ͜ͱ͕Ͱ͖ɺ ͦͷϒϩοΫ͕༗ޮͳྺ࢙ͷதʹ͋Δ߹ʹ ݶΓใु༗ޮͱͳΔ τϥϯβΫγϣϯͷଘࡏΛ֬ೝ͢Δ ͨΊͷޮతͳํ๏͕ఏڙ͞ΕΔ ਖ਼ੑ ଘࡏੑ །Ұੑ Proof of Work ( ) (Proof of Stake ) . . . → — 2025 7-8 — 2025-06-30 – p.8/75
0 and/or Bitcoin “The Times 03/Jan/2009 Chancellor on brink of
second bailout for banks” 2009 1 3 2 https://www.blockchain.com/explorer 0 BTC Block “Hex to ASCII Text Converter” — 2025 7-8 — 2025-06-30 – p.9/75
: ( ( ) ) ( ) — 2025 7-8
— 2025-06-30 – p.10/75
(Hyperledger ) ( ) ( ) ( ) ( )
IoT / / ( , ) — 2025 7-8 — 2025-06-30 – p.11/75
: Bitcoin . . . : Proof of Existence, Everledger,
. . . ( ) ( ) × = NFT (Non Fungible Token) — 2025 7-8 — 2025-06-30 – p.12/75
( ) จ ॻ จ ॻ จ ॻ
จ ॻ จ ॻ O μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ حͷ߹ ෳ͢Δ ɾจॻ ΛಘͨΫϥΠΞϯτɺಉ࣌ʹূ໌ཁૉͱͯ͠ɺϒϧʔͰࣔ͞ΕΔμΠδΣετͱ֤ʑ͕ࠨӈͷͲͪΒʹҐஔ͢Δ͔Λड͚औΔɻ ɾΫϥΠΞϯτจॻ ͷμΠδΣετ͔Β࢝Ίͯɺ࿈͖݁͢Ұ࿈ͷμΠδΣετΛΔ͜ͱʹͳΔͷͰɺϚʔΫϧϧʔτʹࢸΔ·Ͱͷ ɹܭࢉΛ࠶ݱͰ͖ɺಘΒΕͨϚʔΫϧϧʔτ͕ϒϩοΫνΣʔϯʹه͞Ε͍ͯΔͱҰக͢Δ͜ͱΛ֬ೝͰ͖Δɻ ɾͦͷܭࢉݪཧͷཧղͱඞཁͳใ͕͋Ε୭Ͱ࠶ݱͰ͖Δ จॻ ͷଘࡏͱͦͷ༰ূ໌͞ΕΔɻ ˞μΠδΣετݩͷσʔλ͕ ɹϏοτͰҟͳΔͱશ͘ҟͳΔ ɹͱͳΓɺ·ͨɺμΠδΣετ ɹ͔ΒݩͷσʔλΛਪଌ͢Δ͜ͱ ɹͰ͖ͳ͍ɻ ˞ઍɾສͷจॻΛϚʔΫϧʹͯ͠ ɹͦͷͷߴ͞ߴʑʙ ఔ ه͢Δ ಡΈग़ͤΔ ূ໌Λ ඞཁͱ͢Δऀʹ ։ࣔ͞ΕΔใ ެ։͞ΕΔใ ϚʔΫϧϧʔτ Ϛ ồ Ϋ ϧ γ ε ς Ϝ ͕ อ ͠ ֤ Ϣ ồ β ʹ ෦ త ʹ ͑ Δ ʜʜ ʜʜ ʜʜ ʜʜ ʜʜ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ ϒϩοΫνΣʔϯ ʜ ʜ — 2025 7-8 — 2025-06-30 – p.13/75
: ⇒ LINE → → → ( ) ( )
⇒ ( ) → → → . . . — 2025 7-8 — 2025-06-30 – p.14/75
( ( )) ( ) / / — 2025 7-8
— 2025-06-30 – p.15/75
— 1. ( ) 2. ( ) 3. ( )
— 2025 7-8 — 2025-06-30 – p.16/75
— 2025 7-8 — 2025-06-30 – p.17/75
Bitcoin (2009 1 ∼2025 6 ) 2 → 2 2
→ → — 2025 7-8 — 2025-06-30 – p.18/75
( ) -12 -9 -7 -5 -3 -1 1 3
5 7 9 11 Time Zone (UTC-relative) Capacity (GW) Bitcoin 0 20 40 60 80 100 120 140 ( — Bitcoin 19GW) Solar power by country ( ) 17GW (13 ) Bitcoin 13 Bitcoin 1 4 4.25GW 29 UTC — 2025 7-8 — 2025-06-30 – p.19/75
10 ATM 1 ATM 1 : http://www.slideshare.net/yamaz2/ss-58813038 ⇒ ( (
) ) — 2025 7-8 — 2025-06-30 – p.20/75
— 2025 7-8 — 2025-06-30 – p.21/75
The DAO ( ) Ethereum The DAO Split ( )
360 ETH (50∼60 ) (2016/6/17) ( ) ( ; ) (2016/7/20 ) — 2025 7-8 — 2025-06-30 – p.22/75
(Ethereum (?); ) ( ) ( ) ( vs. )
( ) ( ) ( ) ⇒ ( : BBc-1, BBc-2) : : — 2025 7-8 — 2025-06-30 – p.23/75
SF — 2025 7-8 — 2025-06-30 – p.24/75
3. (1) SF (2) 2025 6 26 ( ) 23:59
JST ( ) Waseda Moodle — 2025 7-8 — 2025-06-30 – p.25/75
. . . . . . 17 13 (6/27( )
) ( ) ( ) ( ) ( Moodle ) H N Y H (← B. ) I Y M — 2025 7-8 — 2025-06-30 – p.26/75
A ⇒ — 2025 7-8 — 2025-06-30 – p.27/75
( )( ) ະདྷͷܦࡁࣾձ աظͷܦࡁࣾձ ࣌ؒ ݱঢ়ͷܦࡁࣾձ ՟ฎγεςϜ ͷϋοΫ ҉߸ࢿ࢈ͷࢢՁ֨ʹ
ґଘ͢ΔΈ ؆୯ʹͭͿͤΔͥ "* ʹΑͬͯॻ͖͑ΒΕͳ͍ ਅਖ਼ͳهΛԼࢧ͑ ҉߸ࢿ࢈ͷࢢՁ֨ʹґଘ͠ͳ͍ ҉߸ࢿ࢈ແؔͳ ٛͷݕӾهج൫ ՟ฎͷ ΠϯηϯςΟϒͰ ۦಈ "* ΤʔδΣϯτ ϩϘςΟΫε γϯɾ%"0 "* ͕ਓؒͷ࿑ಇྗΛར༻͢Δ ϝλɾωΠνϟʔ ਓؒͷ࿑ಇྗ ՟ฎͷ ΠϯηϯςΟϒͰ ۦಈ ࿑ಇͰͳ͍Կ͔ ϒϩοΫνΣʔϯ ҉߸ࢿ࢈ͱ͔ ·͋ͦ͏͍ͬͨͷ ҉߸ࢿ࢈·͋ؔͳͯ͘ 0, ࣮ࡍʹࣾձͷʹཱͭϑΟϯςοΫ — 2025 7-8 — 2025-06-30 – p.28/75
H ⇒ Bitcoin bitcoin ( ) ( . . .
) — 2025 7-8 — 2025-06-30 – p.29/75
A ( ) ⇒ Bitcoin Proof of Work ( )
( ) Bitcoin Litecoin, Litecoin Monacoin Ethereum Proof of Stake ( ) Ethereum Proof of Stake — 2025 7-8 — 2025-06-30 – p.30/75
S DAO ( : ) ⇒ DAO — 2025 7-8
— 2025-06-30 – p.31/75
S ( ) ⇒ 12 24 (Hierarchical Deterministic (HD) Wallet)
(Social Recovery Wallet) — 2025 7-8 — 2025-06-30 – p.32/75
Y (= ) “ ” ⇒ X ( ) https://x.com/gassimanga/status/1878478764679586124
— 2025 7-8 — 2025-06-30 – p.33/75
M ⇒ AI — 2025 7-8 — 2025-06-30 – p.34/75
N DAO Pros and Cons ⇒ DAO DAO — 2025
7-8 — 2025-06-30 – p.35/75
Ethereum Ethereum ( ) — 2025 7-8 — 2025-06-30 –
p.36/75
— 2025 7-8 — 2025-06-30 – p.37/75
Ethereum · → · → · → — 2025 7-8
— 2025-06-30 – p.38/75
↑ — 2025 7-8 — 2025-06-30 – p.39/75
(by ) 1. 2. ( ) ( ) . .
. cf. by McLuhan cf. by McLuhan → — 2025 7-8 — 2025-06-30 – p.40/75
by ⇒ ⇒ — 2025 7-8 — 2025-06-30 – p.41/75
by SNS AI AI ⇒ ( ) ⇒ — 2025
7-8 — 2025-06-30 – p.42/75
Ethereum EVM (Ethereum Virtual Machine) — 2025 7-8 — 2025-06-30
– p.43/75
Ethereum Vitalik Buterin, “Ethereum White Paper: A NEXT GENERATION SMART
CONTRACT & DECENTRALIZED APPLICATION PLATFORM” (Dec. 2013∼) 12 ( ) (= ) = = ( ) CPU ⇒ DApps DApps = / — 2025 7-8 — 2025-06-30 – p.44/75
= ( ) run = → — 2025 7-8 —
2025-06-30 – p.45/75
[Lamport 1984][Schneider 1990] ( ) (1) 0 ( ) (2)
(3) (4) ( ) ← — 2025 7-8 — 2025-06-30 – p.46/75
Ether (ETH) Ethereum EOA : Externally-Owned Account ( ) (
) ( ) ( ) ← Ether ( ) EVM EVM = Ethereum = — 2025 7-8 — 2025-06-30 – p.47/75
EVM : Ethereum Virtual Machine ঢ়ଶ ֎෦ΞΫλʔ ΞΧϯτ &7. ίʔυ
&UIFSˠ(BT ىಈ ίϯτϥΫτ ϝοηʔδ͔ɺ৽͍ࣗ͠ಈΦϒδΣΫτ ΞΧϯτؒͰΓऔΓ͞ΕΔσʔλ&UIFS ετϨʔδ ঢ়ଶ` τϥϯβΫγϣϯ ηοτ σδλϧॺ໊ &7. ਓؒͱ͔ ࣗಈ ΦϒδΣΫτ ( ) Gas ( EVM = ( burn)) — 2025 7-8 — 2025-06-30 – p.48/75
/ / (1) Ethereum Bitcoin ( OK) 1 — 2025
7-8 — 2025-06-30 – p.49/75
/ / (2) 3 ( ) · ( ) (
) 1 — 2025 7-8 — 2025-06-30 – p.50/75
/ / (3) ( ) ( ) 1 ( )
1,500 3,000 (← . . . ) Ethereum 2022 9 — 2025 7-8 — 2025-06-30 – p.51/75
/ / (4) Gwei Gwei ETH 32 ETH ( )
ETH ETH · 32 ETH ( OK) · 16 ETH ( ) 12 ( ) ( ) 1 — 2025 7-8 — 2025-06-30 – p.52/75
/ / (5) 32 1 (384 ) ( ) (
) 2 3 ( ) 256 512 — 2025 7-8 — 2025-06-30 – p.53/75
/ / (6) ( ) 5 2 3 (36 )
— 2025 7-8 — 2025-06-30 – p.54/75
/ / (7) ( ) ( ) DAO (RANDAO) 1
— 2025 7-8 — 2025-06-30 – p.55/75
Ethereum ߹ҙ͞Εͨཤྺ ϩʔΧϧʹෳΛҡ࣋
ϒϩοΫ εϩοτ ඵִؒ εϩοτͰ ΤϙοΫ ҉߸ֶతμΠδΣετ ϒϩοΫνΣʔϯͷҡ࣋ࢀՃऀ͕ϩʔΧϧʹཧ͢Δσʔλۭؒ ࣌ؒ ΑΓ৽͍͠ه ΦϒδΣΫτ τʔΫϯγεςϜͷεϚʔτίϯτϥΫτ ֤Ϣʔβͷ ߴͷঢ়ଶ ঢ়ଶ` ঢ়ଶ`` τϥϯβΫγϣϯ ΦϒδΣΫτͷੜ ·ͨঢ়ଶભҠͷࢦࣔ ແޮͳཤྺ ω ỽ τ ϫ ồ Ϋ Λ ௨ ͠ ͯ ૹ ड ৴ ͞ Ε Δ ϩ ồ Χ ϧ ʹ ࣋ ͭ ܨ͙ͨΊʹ&5) Ͱͷσϙδοτͱ σϙδοτ૯ֹͷ ♤ ૬ͷϢʔβʹΑΔ ΤϙοΫͷূݴ͕ඞཁ શΦϒδΣΫτͷભҠޙͷঢ়ଶ ͕ϋογϡ˞ʹू͞Ε ͦͷ ϧʔτ͕ϒϩοΫʹॻ͔ΕΔ ঢ়ଶભҠ ˞ϋογϡσʔλ܈ͷ҉߸ֶతμΠδΣετ ϋογϡ ɹΛߏʹදݱͨ͠ͷͰ ෆ߹ͷݕग़ʹ༻͍ΒΕΔ ETH ( ) ⇒ ETH = Ethereum Virtual Machine (EVM) 2 3 ETH ⇒ ETH — 2025 7-8 — 2025-06-30 – p.56/75
Ethereum (ex. ) (ex. ) ⇒ → — 2025 7-8
— 2025-06-30 – p.57/75
— 2025 7-8 — 2025-06-30 – p.58/75
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 ( ) — 2025 7-8 — 2025-06-30 – p.59/75
ERC-20 ERC-20 ← ( ) ( ) ⇒ ERC-20 (
ERC-20 ) ERC-20 ⇒ — 2025 7-8 — 2025-06-30 – p.60/75
(fungible) ERC-20 → ERC-223 (draft) or ERC-777 ( )( )
(non-fungible) ERC-721 ( ) ( ) ERC-1155 ( ) ERC-3525 (SLOT ) — 2025 7-8 — 2025-06-30 – p.61/75
— τʔΫϯ ସ՟ฎ εϚʔτίϯτϥΫτ ݕূՄೳͳঢ়ଶϚγϯ ϓϩϏφϯε དྷྺূ໌ ସՄೳ ঈؐෆೳ
ସՄೳ ঈؐՄೳ ସෆೳ ঈؐՄೳ ସෆೳ ঈؐෆೳ ূ໌͢Δ ಉఆ͢Δ ࢧ͍ ࠷ॳͷԠ༻ *%Χʔυ ηΩϡϦςΟ τʔΫϯ ূ݊ ηϯαʔ ྲྀɾ Ҩݴॻ อݥਃ ͢Δ ײ͢Δ தԝۜߦ σδλϧ௨՟ ҭήʔϜ ൿີ伴Λ͑Δ͔Βຊਓʁ ෛ࠴ Ξηοτͷ දݱΛҠసͰ͖Δʁ ొ͞Εͨίʔυͱ ͦͷ࣮ߦϩάͱ݁Ռͷ ਅਖ਼ੑΛ୲อͰ͖Δʁ ݖҖ͕ Կ͔ͷ༰Λূ໌͢Δʁ ࣋ଓ͢Δଘࡏʹ͍ͭͯ هΛΞοϓσʔτՄʁ ओମ͕͍ͳ͘ͳͬͯ աڈͷσʔλ༗ޮʁ /'5 Ұൠతͳ ೝࣝ ػೳͷ ੳ݁Ռ — 2025 7-8 — 2025-06-30 – p.62/75
— 2025 7-8 — 2025-06-30 – p.63/75
transfer settle, retrieve asset, retrieve token 3 — 2025 7-8
— 2025-06-30 – p.64/75
( ( )) ( ) / / — 2025 7-8
— 2025-06-30 – p.65/75
— 1. ( ) 2. ( ) 3. ( )
— 2025 7-8 — 2025-06-30 – p.66/75
token (ERC-20 ) $ brownie bake token GitHub git clone
$ git clone https://github.com/ks91/sample-smart-contracts.git sample-smart-contracts contracts, scripts tests token Token — 2025 7-8 — 2025-06-30 – p.67/75
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 — 2025 7-8 — 2025-06-30 – p.68/75
(1) from brownie import * import pytest seller = accounts[0]
buyer = accounts[1] 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") — 2025 7-8 — 2025-06-30 – p.69/75
(2) token.transfer(buyer, 300, {’from’: accounts[0]}) escrow = accounts[0].deploy(OneTimeEscrow, token, buyer,
asset, seller, 300) accounts[0]/seller accounts[1]/buyer 300 300 TX buyer seller 300 bake Token 300 ETH wei — 2025 7-8 — 2025-06-30 – p.70/75
(3) token.transfer(escrow, 300, {’from’: buyer}) asset.transfer(escrow, {’from’: seller}) assert token.balanceOf(seller)
== 999999999999999999700 assert token.balanceOf(buyer) == 0 assert token.balanceOf(escrow) == 300 assert asset.getOwner() == escrow buyer ( ) 300 seller ( ) — 2025 7-8 — 2025-06-30 – p.71/75
(4) escrow.settle({’from’: seller}) assert token.balanceOf(seller) == 1000000000000000000000 assert token.balanceOf(buyer) ==
0 assert token.balanceOf(escrow) == 0 assert asset.getOwner() == buyer settle() seller OK — 2025 7-8 — 2025-06-30 – p.72/75
— 2025 7-8 — 2025-06-30 – p.73/75
4. (1) × OK (2) 2025 7 3 ( )
23:59 JST ( ) Waseda Moodle — 2025 7-8 — 2025-06-30 – p.74/75
— 2025 7-8 — 2025-06-30 – p.75/75