ブロックチェーンと金融システム / Blockchain and Financial Systems

2020年12月8日(火)、東京大学大学院の授業 (システム創成特別演習 4C「近未来金融システムの創成」」) として実施された「近未来金融システム創造プログラム 第13 回 金融と技術 (各論 V)」にて使用したスライドです。

Transcript

1. Replicate the logs. – 13 ( V) ks91@sfc.wide.ad.jp / ks91@aoni.waseda.jp — 2020-12-08 – p.1/35
2. https://speakerdeck.com/ks91 — 2020-12-08 – p.2/35
3. ( ) SFC ( ) CSO (Chief Science Officer) 1993 ( ) 2006 ( ) SFC 20 P2P (Peer-to-Peer) ( 9 ) 2011 2018 2019 2019 2020 2020 → ( ) — 2020-12-08 – p.3/35
4. (2017) : SF + + SF (2048 ) 2048 — 2020-12-08 – p.4/35
5. 2020 9 60 (2020) : . . . ( ) . . . — 2020-12-08 – p.5/35
6. — 2020-12-08 – p.6/35
7. SAY NO TO BULLSHIT JOBS — 2020-12-08 – p.7/35
8. Alexa, ত࿨࣌୅
   
    ੈلޙ൒ ࣾձγεςϜ ࣾձ؀ڥ ػց ٕज़ ਓؒ ࣗಈγεςϜ ྩ࿨࣌୅
   
    ੈلલ൒ ిؾ͚ͭͯ ͸͍ ͸͍ ిؾ͚ͭͯ ͜ͷ৚݅ͷͱ͖ ٕज़Ͱ͋Γࣾձ؀ڥ
   ˠ
   ࣗવ؀ڥ ਓ ⇒ ( ) — 2020-12-08 – p.8/35
9. (4 ) ( ) — 2020-12-08 – p.9/35
10. . . . → → 30 — 2020-12-08 – p.10/35
11. — 2020-12-08 – p.11/35
12. ( ) ( ) (BP : Blockchain Property ) BP-1 : BP-2 : BP-3 : ( ) ( ) — 2020-12-08 – p.12/35
13. ( ) ( ) ( ) ( ) ( 16 ) SHA (Secure Hash Algorithm) ( ) 1bit — 2020-12-08 – p.13/35
14. ( ) ( ) < , > ( ) : < , > : : < , , > : OK NG — 2020-12-08 – p.14/35
15. BP-1 ( ), BP-2 ( ) BBc-1 f : → BP-3 ( ) ( ) ( ) ← BP-2 ← BP-3 ( ) ( ) ← BP-3 + ← BP-{1,2} — 2020-12-08 – p.15/35
16. [Lamport 1984][Schneider 1990] (1) (2) (3) (4) ( ) ← ↑ — 2020-12-08 – p.16/35
17. ( 4 TX ) SMRP (State Machine Replication Problem) SMRP-1 ( ) SMRP-2 : ← — 2020-12-08 – p.17/35
18. ( ) ( ) ϒϩοΫ൪߸
    
    O ϒϩοΫ൪߸
    
    O  ϒϩοΫ൪߸
    
    O  ϒϩοΫ൪߸
    
    O  ϒϩοΫ൪߸
    
    O  ϒϩοΫ൪߸
    
    O  ϒϩοΫ൪߸
    
    O  ϒϩοΫ൪߸
    
    O  ͍ͪ͹Μه࿥ɾॻ͖׵͑ͷίετ͕ߴ͍ྺ࢙ ࠷΋վ͟Μ͠ʹ͍͘ྺ࢙ ͕༗ޮ ͻͱͭखલͷϒϩοΫͷ ʮμΠδΣετʯ σδλϧॺ໊͞Εͨ ʮτϥϯβΫγϣϯ औҾ ʯ ϒϩοΫΛ࡞ΔͨΊʹ͸ɺͦͷʮμΠδΣετʯ͕͋Δ਺ҎԼͱ͍͏৚݅Λຬͨͨ͠Γ 1SPPG
    PG
    8PSL Ծ૝௨՟ͷ࣋ͪ෼ʹԠͨ͡ݖརΛ࢖ͬͨ౤ථͰউͬͨΓ 1SPPG
    PG
    4UBLF ͢Δඞཁ͕͋Δ ίετ͕͔͔Δ ϒϩοΫΛ࡞Δਓ͸ͦͷதʹࣗ෼ʹѼͯͨ Ծ૝௨՟ͰͷใुΛॻ͖ࠐΉ͜ͱ͕Ͱ͖ɺ ͦͷϒϩοΫ͕༗ޮͳྺ࢙ͷதʹ͋Δ৔߹ʹ ݶΓใु΋༗ޮͱͳΔ τϥϯβΫγϣϯͷଘࡏΛ֬ೝ͢Δ ͨΊͷޮ཰తͳํ๏͕ఏڙ͞ΕΔ ਖ਼౰ੑ ଘࡏੑ །Ұੑ Proof of Work ( ) . . . → — 2020-12-08 – p.18/35
19. (BP-3 ) ( : ) (BP-3 ) ( : ) BP-{1,2,3} BP-{1, 2} ⇒ — 2020-12-08 – p.19/35
20. (Confidentiality) BP-{1,2,3} ↑ ( = ) ( integrity ) (Integrity) BP-3 (Availability) BP-2 — 2020-12-08 – p.20/35
21. . . . 2009 ↑ 11 . . . — 2020-12-08 – p.21/35
22. BBc-1/Ethereum API/ https://github.com/beyond-blockchain/examples/tree/master/certify-web 1. ID ( ) 2. ID ID . . . ID ( ) — 2020-12-08 – p.22/35
23. ID { "id": "4445 4558 1689", "name": "Wednesday Addams", "born": "1980-02-12", "address": "0001 Cemetery Lane", "public-key": "04d49e0786a37efce8552d6fd1566d7cfd86f110d4d95f1...4edb", "algo": "ecdsa-p256v1", "sig": "609b390f9486110d1ba39fc59cc46f1c2aa31ae8e40d3454c05a42...48e2", "pubkey": "0479c6676de61b41b7d0291b338f3279671d649f0a71bbb495...4bd1", } (Merkle) Ethereum — 2020-12-08 – p.23/35
24. *%
    Χʔυจॻ JE
    
    JE OBNF8FEOFTEBZ
    "EEBNTOBNF 8FEOFTEBZ
    "EEBNT ͷ΋ͷ ࣏ࣗମͷ΋ͷ CPSOCPSO BEESFTT
    $FNFUFSZ
    -BOFBEESFTT QVCMJDLFZEFDFECQVCMJDLFZ *% Χʔυจॻ ͷμΠδΣετ ॺ໊෇͖ *% Χʔυจॻ ͷμΠδΣετ ࿈͔݁ͯ͠Β ܭࢉ͢Δ ॺ໊Λݕূ͠ɺ ੒ޭͨ͠Β ࿈͔݁ͯ͠Β ܭࢉ͢Δ EJHFTU EJHFTU EJHFTU BMHPSJUIN TJHOBUVSF QVCMJD
    LFZ EJHFTU EJHFTU EJHFTU EJHFTU
    +40/ σʔλߏ଄͸ɺ಺෦ॲཧͰ͸ 9.- ʹม׵͞Ε·͢
    ΋ͱ΋ͱ 9.- ༻ʹ࡞ͬͯ͋ΔϥΠϒϥϦΛ࢖༻͍ͯ͠·͢ ɻ
    ෦෼తʹӅ͞Ε͍ͯͯ΋ূ໌Ͱ͖ΔΑ͏ʹɺηΫγϣϯ͝ͱʹμΠδΣετΛܭࢉ͍ͯ͠·͢ɻ
    ྫ͑͹ɺ*% ΧʔυͰ೥ྸ΍ॅॴɺ͋Δ͍͸ެ։伴Λ֬ೝ͢Δ͚ͩͰ͋Ε͹ɺ*% ൪߸ΛݟΔ͜ͱ͕๏཯Ͱېࢭ͞Ε͍ͯΔ౳ͷ৔߹ɺ
    
    *% ൪߸ΛӅͯ͠ ͦͷ෦෼ΛରԠ͢ΔμΠδΣετͰஔ͖׵͑ͯ ఏࣔͯ͠΋࠷ऴతʹॺ໊෇͖ *% Χʔυจॻͷಉ͡μΠδΣετΛܭࢉͰ͖ΔͷͰɺଘࡏূ໌͕Ͱ͖·͢ɻ
    ʮμΠδΣετʯͱ͸ɺ҉߸ֶతϋογϡؔ਺ʢࠓճ͸ 4)"
    ʣʹΑͬͯܭࢉ͞Εͨ஋ͷ͜ͱͰ͢ɻ
    Θ͔ͣ  ϏοτͰ΋ݩͷσʔλ͕ҟͳΔͱɺฦͬͯ͘Δ஋͕શ͘ҟͳΓɺμΠδΣετ͔ΒݩͷσʔλΛ
    ਪଌ͢Δ͜ͱ͸Ͱ͖·ͤΜɻ — 2020-12-08 – p.24/35
25. API/ Merkle Proof จ
    
    ॻ  จ
    
    ॻ  จ
    
    ॻ  จ ॻ  จ
    
    ॻ O μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ μΠδΣετ ح਺ͷ৔߹͸ ෳ੡͢Δ ɾจॻ 
    Λಘͨ
    " ࢯ͸ɺಉ࣌ʹূ໌ཁૉͱͯ͠ɺϒϧʔͰࣔ͞ΕΔμΠδΣετͱ֤ʑ͕ࠨӈͷͲͪΒʹҐஔ͢Δ͔Λड͚औΔɻ ɾ" ࢯ͸จॻ  ͷμΠδΣετ͔Β࢝Ίͯɺ࿈݁͢΂͖Ұ࿈ͷμΠδΣετΛ஌Δ͜ͱʹͳΔͷͰɺϚʔΫϧϧʔτʹࢸΔ·Ͱͷ ɹܭࢉΛ࠶ݱͰ͖ɺಘΒΕͨϚʔΫϧϧʔτ͕ &UIFSFVN εϚʔτίϯτϥΫτʹه࿥͞Ε͍ͯΔ஋ͱҰக͢Δ͜ͱΛ֬ೝͰ͖Δɻ ɾͦͷܭࢉΛ୅ߦ͢Δͷ͕
    DFSUJGZXFC
    ͷαʔϏε
    ݪཧͷཧղͱඞཁͳ৘ใ͕͋Ε͹୭Ͱ΋࠶ݱͰ͖Δ  ূ໌͞ΕΔ ɻ ه࿥͢Δ ಡΈग़ͤΔ ূ໌Λ ඞཁͱ͢Δऀʹ ։ࣔ͞ΕΔ৘ใ ˞
    ##D
    ͸ɺ͜ͷߏ଄Λอଘ ɹ
    ͍ͯ͠Δ͕ɺαϒπϦʔΛ ɹ
    ূ໌ཁૉԽͯ͠౉ͨ͠ޙ͸ɺ ɹ
    ূ໌͢Δ্Ͱ͸
    ##D ͸ෆཁ ެ։͞ΕΔ৘ใ 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 &UIFSFVN
    ϒϩοΫνΣʔϯ ʜ ʜ ##D
    ϥΠϒϥϦ
    ূ໌ॻΞϓϦͰ࣮ݱ — 2020-12-08 – p.25/35
26. Merkle Proof ( ) { "proof": { "spec": { "subsystem": "ethereum", "network": "ropsten", "contract": "BBcAnchor", "contract_address": "0x609CD0aF4663bbA6c7105fd34BbCBCDd5e75067C", "block": 9186681 }, "subtree": [ { "position": "right", "digest": "bd7d8c62a483e23b8e4713699bec9ff036ead7f3a72a8ff70684cdec1e8b6aeb" }, : # ] } } — 2020-12-08 – p.26/35
27. BBcAnchor.sol ( ) contract BBcAnchor { mapping (uint256 => uint) public _digests; constructor () public { } function getStored(uint256 digest) public view returns (uint block_no) { return (_digests[digest]); } function isStored(uint256 digest) public view returns (bool isStored) { return (_digests[digest] > 0); } function store(uint256 digest) public returns (bool isAlreadyStored) { bool isRes = _digests[digest] > 0; if (!isRes) { _digests[digest] = block.number; } return (isRes); } } / — 2020-12-08 – p.27/35
28. Token ୅ସ՟ฎ Smart Contract ݕূՄೳͳঢ়ଶϚγϯ Provenance ग़ࣗূ໌
    Fungible Non-redeemable Fungible Redeemable Non-fungible Redeemable Non-fungible Non-redeemable Certifying Identifying payment ID card security token last will logistics insurance claim Tracking Sensing fiat money crypt pet ൿີ伴Λ࢖͑Δ͔Βຊਓʁ ෛ࠴  Ξηοτͷ ਺஋දݱΛҠసͰ͖Δʁ ొ࿥͞Εͨίʔυͱ ͦͷ࣮ߦϩάͱ݁Ռͷ ਅਖ਼ੑΛ୲อͰ͖Δʁ ݖҖ͕
    Կ͔ͷ಺༰Λূ໌͢Δʁ ࣋ଓ͢Δଘࡏʹ͍ͭͯ ه࿥ΛΞοϓσʔτՄʁ ओମ͕͍ͳ͘ͳͬͯ΋ աڈͷσʔλ͸༗ޮʁ Certify Web API — 2020-12-08 – p.28/35
29. ( ) — 2020-12-08 – p.29/35
30. IP (Internet Protocol) ( ) : IP : / (IP ) : : — 2020-12-08 – p.30/35
31. : ⇒ LINE → → ( ) ( ) ⇒ → → → — 2020-12-08 – p.31/35
32. ( ) . . . ( : ) (GitHub ← D.C. ) ( : ) ↑ P2P ( : Ethereum) ( ) — 2020-12-08 – p.32/35
33. ( ) ( ) . . . ← ( ) . . . — 2020-12-08 – p.33/35
34. ( ) (cyborg) = (cybernetic) (organism) 1 : ← 2 : ⇒ (1) (2) ⇒ ← — 2020-12-08 – p.34/35
35. 100 50 ( 50 ) ( ) . . . — 2020-12-08 – p.35/35