央行数字货币：银行与匿名性

StaffWorkingPaper/Documentdetravaildupersonnel—2024-9 Lastupdated:March22,2024 CBDC:BankingandAnonymity byYutengCheng1andRyuichiroIzumi2 1BankingandPaymentsDepartmentBankofCanadaycheng@bankofcanada.ca 2WesleyanUniversityrizumi@wesleyan.edu BankofCanadastaffworkingpapersprovideaforumforstafftopublishwork-in-progressresearchindependentlyfromtheBank’sGoverningCouncil.Thisresearchmaysupportorchallengeprevailingpolicyorthodoxy.Therefore,theviewsexpressedinthispaperaresolelythoseoftheauthorsandmaydifferfromofficialBankofCanadaviews.NoresponsibilityforthemshouldbeattributedtotheBank. DOI:https://doi.org/10.34989/swp-2024-9|ISSN1701-9397©2024BankofCanada Acknowledgements WethankYuAwaya,MatteoBenetton,NarayanBulusu,JonathanChiu,MohammadDavoodalhosseini,GiovanniDell’Ariccia,ScottHendry,KeiichiHori,DaisukeIkeda,CharlesKahn,ToddKeister,ThorstenKoeppl,JoëlMarbet,CyrilMonnet,MaartenvanOordt,ChristineParlour,DavidRappoport,FranciscoRivadeneyra,HajimeTomura,RobertTownsend,AlexandrosVardoulakis,YuZhu,andseminarparticipantsatthefirstannualconferenceoftheCentralBankofBrazil,theBankofCanada,theFederalReserveBoard,theJapaneseEconomicAssociation,RutgersUniversity,LACFinanceWorkshop,theSocietyforEconomicDynamics,theSummerWorkshoponMoney,Banking,Payments,andFinance,theCEPR-BocconiConferenceonDigitalAssets,ToyoUniversity,andWasedaUniversity.TheviewsexpressedinthispaperarethoseoftheauthorsandnotnecessarilytheviewsoftheBankofCanada. Abstract Weexaminetheoptimalamountofuseranonymityinacentralbankdigitalcurrency(CBDC)inthecontextofbanklending.Anonymity,definedasthelender’sinabilitytodiscernanentrepreneur’sactionsthatenablefunddiversion,influencesthechoiceofpaymentinstrumentduetoitsimpactonabank’slendingdecisions.WeshowthatmoderateanonymityinCBDCleadstoaninefficientpoolingequilibrium.Toavoidthis,CBDCanonymityshouldbeeitherlow,reducingattractiveness,orhigh,discouragingbanklending.Specifically,theanonymityshouldbehighwhenCBDCsignificantlybenefitssales,andlowotherwise.However,competitionbetweendepositsandCBDCmayhindertheimplementationoflowanonymity. Topic:DigitalcurrenciesandfintechJELcodes:E42,E58,G28 Résumé Nousexaminonsledegréoptimald’anonymatdesutilisateursd’unemonnaienumériquedebanquecentrale(MNBC)dansuncontextedecréditbancaireauxentreprises.L’anonymat–entenducommel’impossibilitépourlabanqueprêteusededétecterdesmesuresprisesparunemprunteurquipourraientnuireàl’examendesesfonds–influesurlechoixdesinstrumentsdepaiement,etce,enraisondesonincidencesurlesdécisionsdelabanqueenmatièredeprêts.Nousmontronsqu’undegrémodéréd’anonymatassociéàlaMNBCentraîneuneinefficacitédel’équilibrenonséparateur.Pourévitercettesituation,ledegréd’anonymatliéàlaMNBCdevraitêtresoitfaible,cequilarendraitmoinsattrayante,soitélevé,cequidécourageraitlecréditbancaire.Plusprécisément,ledegréd’anonymatdevraitêtreélevélorsquelaMNBCesttrèsavantageusepourlesventes,etfaibledanslesautrescas.Toutefois,laconcurrenceentrelesdépôtsbancairesetlaMNBCpourraitrendredifficilel’applicationd’unfaibledegréd’anonymat. Sujet:MonnaiesnumériquesettechnologiesfinancièresCodesJEL:E42,E58,G28 1Introduction Thepossibilityofissuingacentralbankdigitalcurrency(CBDC)hingesonthecurrency’sdesign.CentralbankshaveawiderangeofchoicesindesigningpublicmoneyintheformofaCBDC.Thisflexibilityhassparkedactivediscussionsthathaveevaluatedthebenefitsandcostsfromvariousperspectives.Amajorpolicyconcernisuserprivacy:GovernorBowmanoftheFederalReserveBoardemphasizedinherspeechthat“safeguardingprivacyisatopconcern...weneedtothinkabouthowtoprotecttheprivacyofconsumersandbusinesses”(Bowman,2023).Whilemuchoftheexistingliteraturefocusesonconsumerprivacy,theprivacyofbusiness,whichwecall“anonymity,”hasbeenlessthoroughlyexplored.En-trepreneursmightindeedfavoranonymity,butthispreferencemayintroducechallengestothebankingsector.Thislackofinformationemergesasakeyfrictioninbanklending,andhistoricalrecordsoftransactionsandcashflowscanprovidevaluabledataforbankswhenscreeningentrepreneurs.Toaddresssuchaconflictofdesires,thispaperasks:TowhatextentshoulduseranonymitybeincorporatedinthedesignofaCBDC? Banklendingdecisionsindeedutilizethetransactionhistoriesofborrowingentrepreneurs.Forexample,thefintechinnovatorSquarereliesonsuchdatainscreeningfirmstomakeloans.Squarewasoriginallyfoundedtoprovidepoint-of-sale(PoS)terminaldevices.However,asitsbusinessmodelevolved,SquareexpandedintolendingunderthenameSquareCapital andhassincere-brandeditselfasSquareLoans,whichhasfacilitatedmorethan$9billion insmallbusinessloansby2021.SquaremakesrefinancingdecisionsbasedonsalesdatareportedbyitsPoSdevices.Consider,forexample,asmallbusinessentrepreneur,likeaconveniencestoreowner,borrowingfromSquare.Theycouldacceptcashfromtheircustomers,whichoffersmoreanonymity,butsuchtransactionswouldnotberecordedonthePoSmachine,potentiallyimpactingtheirrefinancingprospects.Withtheissuanceof aCBDC,thepossibilityarisesforcentralbankstocollaboratewithentitieslikeSquaretodevelopterminaldevices,formingpublic-privatepartnerships.1However,itisnottrivialwhethertheseentitiesshouldbeallow