Blockchain Kyoto #1 〜サトシ・ナカモト論文を読む〜

Transcript

1. Blockchainษڧձ in Kyoto #01
2. ατγ࿦จΛಡΉ λΠτϧɿ
 Bitcoin: A Peer-to-Peer Electronic Cash System ஶऀɿ
 Satoshi Nakamoto
3. Abstract ར༻ऀؒͷΦϯϥΠϯࢧ෷͍ʹ͓͍ͯͷଟॏ࢖༻໰ ୊Λ P2P ωοτϫʔΫͰղܾ͢Δํ๏ΛఏҊ͢Δɻ
4. ໨࣍ 1. Introductionʢ͸͡Ίʹʣ 2. Transactionsʢిࢠ௨՟ͷ΍ΓऔΓʣ 3. Timestamp ServerʢλΠϜελϯϓαʔόʣ 4. Proof-of-Workʢԋࢉྔূ໌ʣ 5. NetworkʢωοτϫʔΫʣ 6. IncentiveʢωοτϫʔΫࢀՃऀ΁ͷใुʣ 7. Reclaiming Disk Space ʢ࢖༻σΟεΫεϖʔεͷઅ໿ʣ 8. Simplified Payment Verification ʢऔҾͷ؆қݕূ๏ʣ 9. Combining and Splitting ValueʢίΠϯͷ༥߹ͱ෼཭ʣ 10. PrivacyʢϓϥΠόγʔʣ 11. Calculationsʢ਺ֶతࠜڌʣ 12. Conclusionʢ݁࿦ʣ
5. 1. Introduction ඞཁͳͷ͸ɺୈࡾऀػ͕ؔແ͘ͱ΋ೋऀ͕औҾΛߦ͑Δ͜ͱͰ͋Δɻ ͦͷͨΊʹ͸ɺ ৴པͰ͸ͳ͘҉߸ٕज़ʹج͍ͮͨࢧ෷͍γεςϜ͕͋Ε͹ྑ͍ɻ ʢͦΕΛՄೳʹ͢Δͷ͕BitcoinͰ͢ɻʣ ΠϯλʔωοτΛհͨ͠طଘͷऔҾ͸ɺࢧ෷͍Λిࢠతʹ࣮ߦ͢ΔͨΊʹɺ৴པͰ ͖ΔୈࡾऀػؔΛඞཁͱ͢Δɻ
6. 2. Transactions ίΠϯͷଟॏ࢖༻νΣοΫΛ৴པͰ͖Δػؔແ͠Ͱ࣮ݱ͢Δʹ͸ɺऔҾ͕ެ։͞ ΕɺͦΕΛݩʹͨ͠ಉҰͷऔҾཤྺΛར༻ऀશһ͕ڞ༗͍ͯ͠ΔΑ͏ͳγεςϜ ͕ඞཁͰ͋Δɻ
7. 3. Timestamp Server λΠϜελϯϓαʔόͱ͸ɺϒϩοΫΛड͚औͬͯϋογϡ஋Λܭࢉ͠ɺҰൠతʹ ͸৽ฉ΍ωοτχϡʔεͷΑ͏ͳ ࢓૊ΈͰ഑৴͢ΔαʔόͰ͋Δɻ σʔλΛϋογϡԽ͠λΠϜελϯϓʹ૊ΈࠐΉ͜ͱʹΑΓɺͦͷσʔλ͕ͦͷ࣌ ఺Ͱଘࡏͨ͜͠ͱΛ໌֬ʹূ໌͢Δɻ ·ͨɺλΠϜελϯϓ͸Ұͭલͷஈ֊ͷλΠϜελϯϓΛϋογϡԽͨ͠΋ͷΛ૊ ΈࠐΈνΣʔϯΛ࡞Δɻ ͦͷͨΊɺλΠϜελϯϓ͕ޙํʹ࿈ͳΔʹैͬͯɺ৴པੑ͕૿ͯ͠ߦ͘͜ͱʹͳ Δɻ ʮϒϩοΫνΣʔϯʯͷ͜ͱͰ͢Ͷɻ
8. 4. Proof-of-Work SHA-256ͷΑ͏ͳϋογϡؔ਺Λ࢖ͬͯɺ࠷ॳͷnϏοτ͕̌ʹͳΔΑ͏ͳ ϋογϡΛ୳͢ɻ ͜ͷΑ͏ͳԋࢉʹ͔͔Δฏۉ࣌ؒ͸nʹରͯ͠ࢦ਺ؔ਺తʹ૿Ճ͢Δɻ ߈ܸऀ͕աڈͷϒϩοΫͷ৘ใΛվ᜵͢Δʹ͸શͯͷϒϩοΫΛԋࢉ͠௚͢ඞཁ ͕͋Δɻ ϊʔυ਺ͷ૿Ճ΍̍ϊʔυ͋ͨΓͷԋࢉೳྗ޲্Λ૝ఆ͠ɺԋࢉྔূ໌ͷ೉қ ౓ʢdifficultyʣΛಋೖ͓ͯ͘͠
9. 5. Network ຊωοτϫʔΫ͸ɺ࣍ʹࣔ͢εςοϓͰಈ࡞͢Δɻ 1. औҾΛߦ͏ͱͦͷ৘ใ͕͢΂ͯͷϊʔυʹ޿ΊΒΕΔɻ 2. ֤ϊʔυ͸औҾ৘ใΛूΊͯϒϩοΫΛੜ੒͢Δɻ 3. ֤ϊʔυ͸ϒϩοΫʹର͢Δԋࢉྔূ໌Λ։࢝͢Δɻ 4. ԋࢉྔূ໌ʹ੒ޭͨ͠࠷ॳͷϊʔυ͸ɺͦͷϒϩοΫΛશϊʔυʹ޿ΊΔɻ 5. ֤ϊʔυ͸ϒϩοΫΛଟॏ࢖༻͕ແ͘ਖ਼͍͠औҾ͚ͩΛؚΉ͜ͱΛ֬ೝͯ͠ड ͚෇͚Δɻ 6. ֤ϊʔυ͸ड͚෇͚ͨϒϩοΫͷϋογϡ஋ΛຒΊࠐΈɺ࣍ͷϒϩοΫΛੜ੒ ࢝͠ΊΔɻ͜Ε͕ϒϩοΫΛड͚෇͚ͨ͜ͱͷද໌ͱ΋ͳΔɻ
10. 6. Incentive ϒϩοΫੜ੒ऀ͸ίΠϯΛड͚औΔɻ ϒϩοΫੜ੒ऀ͸औҾͷख਺ྉΛ΋Β͑Δɻ ߈ܸऀ΋σʔλΛվ͟Μ͢ΔΑΓɺਖ਼߈๏Ͱϒϩο ΫΛੜ੒͢Δํ͕ݡ໌ɻ ωοτϫʔΫࢀՃऀͷใु
11. 7. Reclaiming Disk Space ϋογϡ໦ʢϚʔΫϧπϦʔʣ
12. 8. Simplified Payment Verification औҾΛݕূ͢Δ͚ͩͳΒશͯͷσʔλ͸ෆཁͰɺ࠷ ௕νΣʔϯͷϒϩοΫϔομʔΛ࣮֬ʹ͍࣋ͬͯΔ ϊʔυʹཁٻ͓͚ͯ࣋ͬͯ͠͹ྑ͍ɻ
13. 9. Combining and Splitting Value Πϯϓοτ͸աڈͷෳ਺ͷࣗ෼Ѽͯ΁ͷऔҾΛ࢖͏ɻ Ξ΢τϓοτ͸ૹΓઌͱࣗ෼΁ͷ͓௼Γͱ͢Δɻ
14. 10. Privacy ϒϩοΫνΣʔϯ͸શͯͷऔҾΛެ։͍ͯ͠ΔͷͰɺϓϥΠ όγʔ͕໰୊ɻ ެ։伴Λಗ໊ʹ͢Δɻ ͋ΔֹΛ୭͔͕୭͔ʹૹ ۚͨ͜͠ͱ͸શࢀՃऀʹ஌ΒΕΔ͕ɺ ۩ମతʹͲ͏͍ͬͨਓ෺͕औҾʹؔΘ͔ͬͨ͸෼͔Βͳ͍ɻ औҾʹ࢖͏ϏοτίΠϯΞυϨε͸औҾຖʹมߋ͢Δɻ
15. 11. Calculations Gambler’s Ruin problemʢΪϟϯϒϥʔഁ࢈໰୊ʣ ֬཰઴Խࣜ ϙΞιϯաఔ
16. 12. Conclusion ৴པؔ܎Λඞཁͱ͠ͳ͍ిࢠऔҾγεςϜΛఏҊ͠ ͨɻ
17. ·ͱΊ