區(qū)塊鏈：新穎的溯源應(yīng)用

Blockchain:NovelProvenanceApplications

April12,2022

CongressionalResearchService

R47064

SUMMARY

R47064

April12,2022

KristenE.BuschAnalystinScienceandTechnologyPolicy

Blockchain:NovelProvenanceApplications

Blockchain,generally,isadatabasetechnologythatrecordsandstoresinformationinblocksofdatathatarelinked,or“chained,”together.Datastoredonablockchainarecontinuallyshared,replicated,andsynchronizedacrossthenodesinanetwork—individualcomputersystemsorspecializedhardwarethatcommunicatewitheachotherandstoreandprocessinformation.Thissystemenablestamper-resistantrecordkeepingwithoutacentralizedauthorityorintermediary.

Therearemultipletypesofblockchains,and,dependingonthetype,recordeddatamaybeaccessibletoallusersoronlyadesignatedsubset.Allblockchainssharecommoncharacteristics,

includingdecentralization(i.e.,nocentralizedauthority),immutability(i.e.,theblockchainrecordsareunalterable),andpseudonymity(i.e.,howusers’real-worldidentitiesarehandled).Certainblockchaintypesmayoffergreaterlevelsofdecentralizationandpseudonymitythanothers.Newblockchainapplications,suchassmartcontracts,non-fungibletokens,anddecentralizationautonomousorganizations,mayautomateprocessesorreplaceintermediariesinavarietyoffields.

Recentdevelopmentsinblockchaingovernanceprotocolsandconsensusmechanismshaveraisedconcernsabouttheenvironmentalimpact,oversight,andaccountabilityofblockchainnetworks.

Sinceitscreationin2008,blockchainhasbeenmostcommonlyassociatedwithcryptocurrencies—digitalcurrenciesthatusersexchangethroughdecentralizedcomputernetworks.Morerecently,publicandprivatesectoractorshaveusedblockchainapplicationsinfieldssuchassupplychainmanagement,identitymanagement,andassetregistration.Blockchaintechnologiesmayenableestablishingtheprovenanceofgoodsandtrackingtheirprogressionthroughasupplychain;identity-managementwithdigitalcredentials;recordingtheownershipofdigitalandphysicalobjects;andthetransferofproperty,rights,orgoodswithoutathird-partyintermediary.TheUnitedStatesisahubforprivate-sectorblockchaindevelopment,andmanystatesandfederalagenciesareexperimentingwithnovelblockchainprovenanceapplications,includingtheFoodandDrugAdministrationandDepartmentoftheTreasury.

Proponentsclaimthatblockchaincanincreasetransparencyandefficiencyinmanyfieldsbyenablingauditableandimmutablerecordkeeping.However,opponentshavesignificantconcerns.Blockchaintechnologiesarematuringandfullydevelopedusecasesoutsideofthefinancialsectorarerelativelylimited.Insomeapplications,blockchaintechnologiescanaddunnecessarycomplexitycomparedwithusingconventionaldatabasesorotheralternatives.Thetechnologymayalsoposesecurityandprivacyrisksifsensitiveinformationispermanentlyrecordedonablockchain,encryptionalgorithmsarebroken,smartcontractsmalfunction,ordigitalwalletsandotherblockchainapplicationsarehacked.Someblockchainsalsouseenergy-intensiveprocessestovalidatetransactions,whichcanconsumeasmuchenergyassmallnations.

Individualstateshavepassedlegislationorestablishedinitiativestodevelop,incentivize,andregulateblockchaintechnologies.Somestateshavetakenvastlydifferentapproachestoblockchaintechnologies,sothestate-levelregulationsthatdoexistvarywidely.Ahandfuloffederalagencieshavereleasedguidanceonblockchaintechnologiesinspecificsectors,suchasfinance,butthereislittleguidanceforblockchainapplicationsinotherfields,suchsupplychainlogistics,identitycredentialing,orintellectualpropertyandassetregistration.Inthemeantime,ChinaandtheEuropeanUnionhaveinvestedheavilyinblockchaintechnologiesanddevelopedtheirownrespectiveregulatoryframeworks,sointernationalregulationsmayalsoconflictwithoneanother.

Congressmayconsidertheappropriaterole,ifany,theU.S.governmentmayplayinthedevelopmentorregulationofblockchaintechnologiesandapplications.Congresscouldconsiderfundingresearchintoblockchaintechnologies,supportingstandardsdevelopment,ordirectingfederalagenciestocreateguidanceoncertainblockchainapplications,amongotheroptions.Congressmayalsoconsidertherolesofthepublicandprivatesectorsinaddressingthepotentialrisksassociatedwithblockchaintechnologiesgenerally,aswellaswithinspecificsectorsandwithspecificapplications.Forexample,Congressmightconsiderwhetherexistingprivacyregulationsareadequatetoaddresspotentialconcernsarisingfromtheuseofblockchaintechnologiesandblockchain-enabledprovenanceapplications.

CongressionalResearchService

Blockchain:NovelProvenanceApplications

CongressionalResearchService

Contents

Introduction 1

OverviewofBlockchain 2

BlocksofData 2

ChainingBlocks 3

DistributedNetworks 4

TypesofBlockchains 5

Public,Private,Hybrid,andConsortiumBlockchains 5

Permissionlessvs.Permissioned 5

ConsensusMechanisms 7

GovernanceandProtocols 9

SmartContracts 10

NFTs,dApps,andDAOs 10

BlockchaininProvenanceApplications 11

SupplyChainProvenance 11

IdentityandCredentialProvenance 13

RegistriesandAssetProvenance 14

OtherBlockchainApplications 16

DomesticandInternationalInitiativesandRegulatoryFrameworks 16

StateRegulatoryFrameworks 16

InternationalRegulatoryFrameworks 18

China 18

EuropeanUnion 19

ConsiderationsforCongress 19

RegulatoryAuthorityandFederalAgencies 19

PolicyConsiderationsandRisks 20

StandardsDevelopment 21

Conclusion 22

Figures

Figure1.DiagramofBlockchainandCryptographicLinking 3

Figure2.Centralizedvs.DistributedLedgerSystems 4

Tables

Table1.TypesofBlockchains 6

TableA-1.SelectedBlockchainLegislationIntroducedinthe115th-117thCongresses 23

Appendixes

AppendixA.SelectedLegislationandHearings 23

AppendixB.Glossary 25

Contacts

AuthorInformation 26

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Introduction

Blockchainisadatabasetechnologythatrecordsandstoresinformationinblocksofdatathatarelinked,or“chained,”together.Datastoredonablockchainarecontinuallyshared,replicated,andsynchronizedacrossthenodesinanetwork—individualcomputersystemsorspecializedhardwarethatcommunicatewitheachotherandstoreandprocessinformation.Thissystemenablestamper-resistantrecordkeepingwithoutacentralizedauthorityorintermediary.Allblockchainssharecommoncharacteristics,includingalevelofdecentralization(i.e.,nocentralizedauthority),immutability(i.e.,theblockchainrecordsareunalterable),andpseudonymity(i.e.,howusers’real-worldidentitiesarehandled).

Sinceitscreationin2008,blockchainhasbeenmostcommonlyassociatedwithcryptocurrencies—digitalcurrenciesthatusersexchangethroughdecentralizedcomputernetworks.Proponentsofblockchaintechnologieshaveidentifiedapplicationsthathelpestablishtheprovenanceofphysicalanddigitalitems.Provenanceistheabilitytoknowtheoriginandhistoryofaphysicalordigitalitem.Blockchaintechnologiesmayenableestablishingtheprovenanceofgoodsandtrackingtheirprogressionthroughasupplychain;identity-managementwithdigitalcredentials;recordingtheownershipofdigitalandphysicalobjects;andthetransferofproperty,rights,orgoodswithoutathird-partyintermediary.

Congressmayconsidertheappropriaterole,ifany,theU.S.governmentmayplayinthedevelopmentorregulationofblockchaintechnologiesandapplications.Congresscouldconsiderfundingresearchintoblockchaintechnologies,supportingstandardsdevelopment,ordirectingfederalagenciestocreateguidanceoncertainblockchainapplications,amongotheroptions.

Congressmayalsoconsidertherolesofthepublicandprivatesectorsinaddressingthepotentialrisksassociatedwithblockchaintechnologiesgenerally,aswellaswithinspecificsectorsandapplications.

Thisreportfocusesonblockchainprovenanceapplicationsinsupplychainmanagement,identitymanagement,andregistryandassettracking.Itprovidesanoverviewofblockchaintechnologiesandrecenttechnicaldevelopments.Thisreportdiscussesexamplesofinternationalanddomesticregulatoryframeworksandcongressionalconsiderationsforblockchaintechnologies.Formoreinformationoncryptocurrenciesandotherblockchainapplications,seethefollowinglistofexistingCRSproducts.

CRSProductsonBlockchainTechnologiesandApplications

BlockchainTechnologies

CRSReportR45116,Blockchain:BackgroundandPolicyIssues,byChrisJaikaran.

CRSTestimonyTE10025,BeyondBitcoin:EmergingApplicationsforBlockchainTechnology,byChrisJaikaran.CRSVideoWVB00200,UnderstandingBlockchainTechnologyandItsPolicyImplications,byChrisJaikaran.Non-FinancialBlockchainApplications

CRSReportR45863,Bitcoin,Blockchain,andtheEnergySector,byCorrieE.ClarkandHeatherL.Greenley.CRSInFocusIF11829,BlockchainTechnologyandAgriculture,byGenevieveK.Croft.

CRSInFocusIF10810,BlockchainandInternationalTrade,byRachelF.Fefer.

FinancialBlockchainApplications

CRSReportR46208,DigitalAssetsandSECRegulation,byEvaSu.

CRSReportR45427,Cryptocurrency:TheEconomicsofMoneyandSelectedPolicyIssues,byDavidW.Perkins.CRSReportR45440,InternationalApproachestoDigitalCurrencies,byRebeccaM.Nelson.

CRSReportR46486,Telegraphs,Steamships,andVirtualCurrency:AnAnalysisofMoneyTransmitterRegulation,by

AndrewP.Scott.

CRSReportR45664,VirtualCurrenciesandMoneyLaundering:LegalBackground,EnforcementActions,andLegislativeProposals,byJayB.SykesandNicoleVanatko.

CRSReportR46843,InternationalFinancialMessagingSystems,byLianaWongandRebeccaM.Nelson.

CRSReportR43339,Bitcoin:Questions,Answers,andAnalysisofLegalIssues,byEdwardV.MurphyandM.MaureenMurphy.

CRSInFocusIF10824,FinancialInnovation:“Cryptocurrencies”,byDavidW.Perkins.

CRSInFocusIF10825,DigitalCurrencies:SanctionsEvasionRisks,byRebeccaM.NelsonandLianaW.Rosen.CRSInFocusIF11004,FinancialInnovation:DigitalAssetsandInitialCoinOfferings,byEvaSu.

CRSInFocusIF11910,CryptocurrencyTransfersandDataCollection,byMarkP.KeightleyandAndrewP.Scott.

CRSInFocusIF11471,FinancialInnovation:CentralBankDigitalCurrencies,byMarcLabonte,RebeccaM.Nelson,andDavidW.Perkins.

CRSInFocusIF10513,FinancialInnovation:“Fintech”,byDavidW.Perkins.

CRSInFocusIF11195,FinancialInnovation:ReducingFintechRegulatoryUncertainty,byDavidW.Perkins,CherylR.Cooper,andEvaSu.

CRSInsightIN11709,DecentralizedFinance(DeFi)andFinancialServicesDisintermediation:PolicyChallenges,byEvaSu.CRSInsightIN11632,Pandemics,Payments,and(Digital)Property,byAndrewP.Scott.

CRSInsightIN11183,Libra:AFacebook-ledCryptocurrencyInitiative,byRebeccaM.NelsonandDavidW.Perkins.

CRSLegalSidebarWSLG1856,ForFirstTime,FinCENImposesPenaltyonForeign-BasedVirtualCurrencyExchangeforViolationsofAnti-MoneyLaunderingLaws,byM.MaureenMurphy.

CRSLegalSidebarLSB10227,CFTCandVirtualCurrencies:NewCourtRulingsandImplicationsforCongress,byNicoleVanatko.

OverviewofBlockchain

BlocksofData

Blockchainisasystemtokeeptrackofinformationandstoredata.1Inmanycases,blockchainsrecordtransactionaldata(e.g.,assetssentandreceivedbetweenparties).Transactionsoccurringataroundthesametimeonanetworkaregroupedtogetherandrecordedasblocksofdataontheblockchain.Atypicalblockontheblockchainmightincludethousandsoftransactions,eachwithitsowntransactiondata,listofsendersandrecipients,andtimestamp.2However,theexacttypeofinformationstoredinablockdependsonthespecificcase,suchastheexchangeofdigitalcurrency,saleandtransferoflandtitles,recordsofintellectualpropertyrights,oridentityinformation.

Forthisreport,theterm“blockchain”referstothedigitalledger(i.e.,record)oftransactions.A“blockchainnetwork”referstothecollectionofnodes(i.e.,computerorhardwaresystems)withinadistributednetwork,foraspecificblockchain.Eachnetworkhasitsownblockchainledger.A“blockchainplatform”isatechnicalinfrastructurethatsupportsblockchainoperationsanddevelopment,suchasEthereumorSolana,onwhichotherfeaturesorblockchain-basedapplicationscanbebuilt.Finally,“blockchaintechnologies”referstothemanydifferent

1Foranoverviewofblockchain,seeCRSReportR45116,Blockchain:BackgroundandPolicyIssues,byChrisJaikaran.

2Foranin-depthtechnicalexplanationofblockchain,seeDylanJ.Yaga,PeterM.Mell,andNikRoby,etal.,BlockchainTechnologyOverview,NationalInstituteofStandardsandTechnology,NISTInteragency/InternalReport(NISTIR)8202,Gaithersburg,MD,October3,2018,/10.6028/NIST.IR.8202.

implementationsandapplicationsofblockchains,suchasdecentralizedapps(DApps),decentralizedautonomousorganizations(DAO),non-fungibletokens(NFT),andsmartcontracts,whichareexploredinthe“DApps,DAOs,andNFTs”sectionofthisreport.

ChainingBlocks

Inablockchain,theblocksofdataarecryptographicallychainedtogetherthroughahashfunction,3whichreferstohoweachblockcontainsuniquedatafromthepreviousblock.Ahashfunctionproducesastringofcharactersasanoutputgivensomedataasinput.Thisisaone-wayfunction,meaningahashvaluemaybecreatedfromaninput,buttheinputcannotberecreatedfromthehash.4Anumberofblockchaintransactionsaregroupedtogethertomakeasingleblock,whichisthenhashed.Anychangestooneblockwouldchangethehashandimmediatelyshowinthesubsequentblock,therebycreatinganimmutableandtamper-resistantrecordoftransactions.5Asshownin

Figure1,

eachblockcontainsahashofthepreviousblock’sdataandthemaintransactiondata.Theconstantadditionofnewblocksiscriticaltomaintainingablockchain’ssecurity.6

Figure1.DiagramofBlockchainandCryptographicLinking

Source:CRS,adaptedfromDylanJ.Yaga,PeterM.Mell,andNikRoby,etal.,BlockchainTechnologyOverview,NationalInstituteofStandardsandTechnology,NISTInteragency/InternalReport(NISTIR)8202,Gaithersburg,MD,October3,2018,/10.6028/NIST.IR.8202.

Notes:Startingfromtheleftmostblockinthediagram,themainblockdata(suchasatransactionlist,etc.)ishashedandstoredinthecurrentblockheader(alongwithotherdatasuchasatimestamp)(Block1).Theentireblockheaderishashedandstoredinthenextblock’sheader(Block2).Theprocessrepeatsforeachblock(Block3).Thus,eachblockwillcontainahashfromthepreviousblock,whichcreatesachainofblocksthat

“reference”or“point”tooneanother.Ifablock’sdatawasretroactivelyaltered,itwouldautomaticallyresultinadifferenthash.

3Therearevariouskindsofhashfunctions,suchasSHA-256,Scrypt,andX11.Eachhashingfunctionhasitsownadvantagesanddisadvantagesfortheblockchain’sspeed,energy-efficiency,andthroughput.

4Formoreinformationonhashfunctions,seeCRSReportR45116,Blockchain:BackgroundandPolicyIssues,byChrisJaikaran.

5Ifanydatainapreviousblockischanged,itwillresultinadifferenthash,whichalertstheblockchainnetwork.Thismakestheblockchainimmutableandtamper-resistant.

6Inordertochangethedatainaparticularblock,theusermustalsochangeallsubsequentblocks.Ina“51%attack,”abadactorattemptstogain51%ofthecomputingpowerneededtogenerateblocksinapublic,permissionlessnetwork.Thistypeofattackisverydifficultbecausetheattackermustoutpacetheblockcreationrateoftherestofthenetworkwhilenewblocksarebeingcontinuouslyadded.

DistributedNetworks

Thechainedblocksoftransactiondataformadigitalledgerthatisstoredandmaintainedbymultiplepartiesinadistributed,peer-to-peercomputernetwork(i.e.,withoutcentralizedadministrationoruseofanintermediary’srepository).7Thetermledgerreferstoarecordorcollectionoftransactions,whichtrackthemovementofmoneyorgoodsfromoneentitytoanother.Conventionally,mostrecordsaredigitalandstoredonserversmaintainedbyasingleentityororganization.Blockchain,however,createsmultipleidenticalledgersonindividualcomputersystemsorspecializedhardwarecallednodes.8Throughcombiningpre-existingtechnologies,9blockchaintechnologiesenablepeer-to-peertransactionsandrecordkeepingbysharingeachupdatewithparticipatingnodesinthenetworkasarecordofactivityforverification.The“safetyinnumbers”approachreducesthelikelihoodoffraud.Blockchainisoneexampleofthelargercategoryofdistributedledgertechnologies(DLTs).10

Figure2

demonstratesthedifferencesbetweencentralizedanddistributedledgers.

Figure2.Centralizedvs.DistributedLedgerSystems

Source:CRS,adaptedfromU.S.GovernmentAccountabilityOffice,Blockchain&DistributedLedgerTechnologies,GAO-19-704SP,September16,2019,https:

//www.gao

.

gov/

p

roducts/gao-19-704sp.

7Blockchainwascreatedbyanindividualorgroupofpeopleoperatingunderthepseudonym“SatoshiNakamoto.”SatoshiNakamotopublishedawhitepaperoutliningapeer-to-peerdigitalpaymentssystem,whichwasthefoundationforBitcoin,thefirstapplicationofblockchain.SatoshiNakamoto,“Bitcoin:APeer-to-PeerElectronicCashSystem,”WhitePaper,2008,

http://satoshinakamoto.me/bitcoin.pdf.

8A“full”nodestoresthefullblockchaindataandverifiesblocks;a“l(fā)ight”nodeonlystoressomeoftheblockchaindata;a“publishingnode”isafullnodethatalsopublishesnewblocks.

9Blockchainscombinemanypre-existingtechnologies,includingasymmetrickeyencryption,hashvalues,Merkletrees,andpeer-to-peernetworks.Formoreinformationonthetechnologiesunderlyingblockchain,seeCRSReportR45116,Blockchain:BackgroundandPolicyIssues,byChrisJaikaran.

10Althoughdefinitionsmaydiffer,distributedledgertechnologies(DLT)areoftenreferredtoas“amulti-partysysteminwhichparticipantsreachagreementoverasetofshareddataanditsvalidity,intheabsenceofacentralcoordinator.WhatseparatesDLTsystemsfromtraditionaldistributeddatabasesarefeaturesrootedindesignscapableofsupportingdataandmaintainingdataintegrityinanadversarialenvironment.”MichelRauchs,AndrewGlidden,andBrianGordon,etal.,DistributedLedgerTechnologySystems:AConceptualFramework,UniversityofCambridgeCentreforAlternativeFinance,August2018,pp.19-20,https://

www.jbs.cam.ac.uk/wp-content/uploads/2020/08/2018-10-26-

conceptualising-dlt-systems.pdf.

Bypublishingallblockchaintransactionstoallparticipatingnodes,whichnodeoperatorsmaintainandcanconstantlyverify,proponentsbelieveblockchainmayenablemoresecureandtransparentrecordkeepingcomparedtotraditionaldatamanagementsystemsthatusecentralizeddatabasesmaintainedbyasingleorganization.Afundamentalideabehindblockchainisthatanindividualcantrustthesystemasawholewithoutnecessarilytrustinganyoftheparticipantssincethereisasharedrecordofalltransactions.

TypesofBlockchains

Therearemanydifferenttypesofblockchains,eachwithuniquecharacteristicsandapplications.Thefourmajortypesofblockchains—public,private,hybrid,andconsortiumblockchains—areshownin

Table1.

However,allblockchaintypessharecommoncharacteristics,includingimmutabilityandalevelofdecentralizationandpseudonymity.Thesecharacteristicsarenotprerequisitesforablockchain,butvaryingfeatures.Thebalanceamongthesecharacteristicsmayvarydependingonthetypeofblockchainandspecificimplementation.

Public,Private,Hybrid,andConsortiumBlockchains

Publicblockchainsallowanyonewithaninternetconnectiontoaccessand“read”theblockchainledger.Publicblockchainsfeatureadegreeofpseudonymitybyallowingparticipantstouseverifiablealiasesthroughpublic-privatekeycryptography.11Participantscanuseapublickeytoencryptdata,andaprivatekeytodecryptthedata.12Participantscanalsosignatransactionwiththeirprivatekey,andtherecipientcanverifythesignaturewiththepublickey.13Insuchsystems,linkingidentitiestopseudonymsiscomputationallyanddataintensive.Accesstoprivateblockchains,typicallyrunbyacompanyforthebenefitofthatcompanyorclients,isgenerallycontrolled.Unlikepublicblockchains,privateblockchainsrequiresomelevelofidentityverificationbeforeaccessisauthorized.Privateblockchainsrunbyagroupofentitiesarecalledconsortiumblockchains.

Hybridblockchainscombineelementsofbothpublicandprivatenetworks.Hybridblockchains,orsidechains,arecontrolled-accessblockchainsattachedtoalarger,publicblockchain.Sidechainsmayenablespecific,authorizeduserstoexchangesensitiveinformationoffthemainblockchain.Forexample,thepopularblockchainplatformEthereumenablesdeveloperstobuildprivatesidechains.

Permissionlessvs.Permissioned

Blockchainnetworksareeitherpermissionlessorpermissioned,whichisindependentofwhethertheblockchainispublicorprivate.

11Eachkeyisageneratedthroughacryptographicalgorithm.Formoreinformationonpublic-privatekeycryptographyandblockchain,seeCRSReportR45116,Blockchain:BackgroundandPolicyIssues,byChrisJaikaran.

12“Publickeyencryption,orpublickeycryptography,isamethodofencryptingdatawithtwodifferentkeysandmakingoneofthekeys,thepublickey,availableforanyonetouse.Theotherkeyisknownastheprivatekey.Dataencryptedwiththepublickeycanonlybedecryptedwiththeprivatekey,anddataencryptedwiththeprivatekeycanonlybedecryptedwiththepublickey.”Cloudflare,HowDoesPublicKeyEncryptionWork?PublicJeyCryptographyandSSL,https://

/learning/ssl/how-does-public-key-encryption-work/.

WhitfieldDiffieandMartinHellman,“NewDirectionsinCryptography,”IEEETransactionsonInformationTheory,vol.22,no.6(1976),pp.644-654,/iel5/18/22693/01055638.pdf.

13Formoreinformationonpublicandprivatekeys,aswellasencryption,seeCRSReportR44642,Encryption:FrequentlyAskedQuestions,byChrisJaikaran.

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Onpermissionlessblockchains,allnodeshaveequalrights,withanynodeabletoviewthefullblockchainandpotentiallyaddadditionalblocks.Permissionedblockchainsallowonlyauthorizednodestoviewtheblockchainandvalidateblocks.Permissionsmayalsobevariable,withsomenodesonlyabletoviewaportionoftheblockchain,othersabletoviewthewholeblockchain,andstillothersabletoaddandvalidateblocks.Inapermissionedsystem,administratorscontroltherightsofnodesontheblockchain,howmanynodesareneededtovalidateanewblock,andbywhatconsensusmechanism.Differenttypesofblockchainsmayoffervaryinglevelsofanonymity,speed,andefficiency.

Table1.TypesofBlockchains

AbilitytoValidateTransactions

AbilitytoReadandSubmitTransactions

Permissioned

Permissionless

PublicBlockchain

Allnodescanreadandsubmittransactions.Onlyauthorizednodescanvalidatetransactions.

Examples:Sovrin

Allnodescanread,submit,andvalidatetransactions.Nocentralentitymanagesblockchainmembership.

Examples:Ethereum,Bitcoin

PrivateBlockchain

Onlyauthorizednodescanread,submit,andvalidatetransactions.

NA(allprivateblockchainsarepermissionedbydefinition)

HybridBlockchain

Onlyauthorizednodescanaccesstheprivatechain,butallnodescanread,submit,andvalidatetransactionsonthepublicchain.Allhybridblockchainsareinpermissionedandpermissionlesscategories.

ConsortiumBlockchain

Onlynodesauthorizedbytheconsortiumcanaccessthechain,andsubmitandvalidatetransactions.

Examples:HyperledgerFabric

NA(allconsortiumblockchainsarepermissionedbydefinition)

Source:CRS,adaptedfromRomanBeck,ChristophMüller-Bloch,andJohnLeslieKing,“GovernanceintheBlockchainEconomy:AFrameworkandResearchAgenda,”JournaloftheAssociationforInformationSystems,vol.19,no.10(2018).

Blockchaintechnologiesareoftendescribedasdecentralizedbecauseoftheuseofdistributedledgersandlackofcentralizedservers.Decentralization,however,isnotaconditionofblockchain,butavaryingfeature,dependentonthetypeofblockchainandimplementation.Manycloudserviceproviders(CSP),suchasOracleandAmazonWebServices(AWS),offercloudservicesforblockchainplatforms.14Currently,AWSreportsthat25%ofallEthereumnodesrunontheirservices.15WhileaCSPmightnotactasacentralvalidatingauthority,itbecomesathirdpartytotransactionsonhostedblockchains.16However,inotherservices,aCSPmaybecomeakindofcentralauthority.Forexample,variouscompanieshavehiredIBM,aCSP,tobuildtheirblockchainsandhostthemintheIBMCloud,ratherthaneachindividualcompanydevelopingthenecessaryblockchaininfrastructureinternally.17

14FormoreinformationonOracle’sblockchainservices,see“OracleBlockchain,”https://

/

blockchain/.

15FormoreinformationonAmazon’sblockchainservices,see“BlockchainonAWS,”/blockchain/.

16Forinformationonpeer-to-peernetworksandCSPs,seeCRSReportR45116,Blockchain:BackgroundandPolicyIssues,byChrisJaikaran.

17FormoreinformationonIBM’sblockchainservices,seeIBM,“IBMBlockchainPlatform,”https://

/

cloud/blockchain-platform.

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Differentblockchainpermissionframeworksprioritizeandbalancefactorssuchastransparency,speed,andsecurity.Forexample,manycryptocurrencies,NFTs,anddecentralizedfinanceapplicationsusepublic,permissionless,orhybridblockchainnetworks.However,companiesthatadoptblockchainfortheirinternalservicestypicallyuseprivateorconsortiumblockchainnetworksduetotheirincreasedeffi