BoE-数字英镑：技术篇（下）.pdf

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1、 The digital pound:Technology Working Paper February 2023 The digital pound:Technology Working Paper February 2023 Bank of England 2023 Page 2 Contents Executive summary 3 1:Introduction 8 2:Functional requirements 14 3:Technology design considerations 19 3.1:Privacy 20 3.2:Security 25 3.3:Resilienc

2、e 33 3.4:Performance 39 3.5:Extensibility 42 3.6:Energy usage 44 4:Illustrative conceptual model 45 4.1:Core ledger 48 4.2:Analytics 53 4.3:Alias service 54 4.4:API layer 57 4.5:Devices and payments 62 4.6:Interoperability 68 4.7:Programmability 70 4.8:Offline payments 78 5:Next steps and discussion

3、 questions 81 Glossary 84 Page 3 Executive summary This paper accompanies the digital pound Consultation Paper(CP),The digital pound:a new form of money for households and businesses?,and outlines the Bank of Englands(the Banks)thinking on the technical requirements and design considerations for a U

4、K central bank digital currency(CBDC).This paper sets out the Banks emerging thinking on CBDC technology and seeks feedback on the potential approach to important technology considerations.This paper does not set out a final design for CBDC.Rather,it sets out one possible approach to CBDC architectu

5、re.The Banks thinking on these matters will evolve as our work accelerates.This paper and the digital pound CP are products of the research and exploration phase of CBDC development,and mark the start of the design phase(Figure 2).In the design phase,the Bank will conduct experimentation which will

6、inform an evaluation of the technology feasibility of CBDC and help to determine the optimal design and technology architecture.This paper builds on the functional and economic design choices for CBDC,which are outlined in the digital pound CP.The Bank and His Majestys Treasury(HM Treasury)have iden

7、tified two primary motivations for a UK CBDC:sustaining access to,and promoting the usefulness of,central bank money;and promoting innovation,choice and efficiency in domestic payments.These motivations have informed the functional and economic design choices for CBDC,which are set out in the digita

8、l pound CP.The platform model is currently the preferred model for offering a UK CBDC(Figure 4).In this model,the Bank hosts the core ledger and an application programming interface(API)layer.The API layer would allow private sector firms,known as Payment Interface Providers(PIPs)and External Servic

9、e Interface Providers(ESIPs),access to the core ledger functionality in order to provide user services.Access to the core ledger would be subject to approval by the Bank,based on objective and transparent criteria,and subject to PIPs and ESIPs having appropriate regulatory status.This paper explores

10、 six technology design considerations,which help to organise and guide the Banks work on CBDC technology.The design considerations outlined in this paper are privacy,security,resilience,performance,extensibility and energy usage.These considerations guide the Banks current thinking on the technology

11、 requirements for a UK CBDC and will likely have significant impact on the design choices for CBDC.Page 4 Privacy:The privacy design considerations are informed by the Bank and HM Treasurys public policy objectives related to privacy.The CBDC system would be designed to protect user privacy,while al

12、lowing PIPs and ESIPs the minimum necessary access to transaction data needed to provide CBDC services and to fulfil their legal and regulatory obligations.The Bank considers that privacy-enhancing technologies(PETs)might assist in meeting these requirements.However,it is important to be mindful of

13、the complexities that PETs may introduce and the impact they might have on the other technology design considerations.Security:It is critical that any CBDC design identifies and guards against security risks.A CBDC may be a potential target for cyber threats from a range of threat actors.The securit

14、y risks could increase due to additional functionality of a CBDC,as well as the number of ecosystem participants.To manage new and existing risks,the CBDC system could be designed to support the rapid adoption of new cryptographic algorithms,use secure access management,and incorporate a comprehensi

15、ve security assurance programme.The Bank might also employ a layered security approach,which involves multiple layers of security controls.Resilience:The CBDC system should be resilient to disruption.Disruption may have far-reaching consequences for user confidence,data integrity and financial stabi

16、lity.Resilience might be achieved through containment and redundancy mechanisms.The Bank has established preliminary resilience requirements for a CBDC,including operating 24/7.Current RTGS and CHAPS services have a target uptime of at least 99.95%,and that would constitute a minimum expectation for

17、 Bank-managed CBDC infrastructure.However,we will also explore whether an uptime target of closer to 100%would be appropriate and deliverable(in particular 99.999%).Performance:The CBDC system should be able to handle a high number of transactions and confirm and settle these transactions as quickly

18、 as possible.The Bank estimates that throughput of approximately 30,000 transactions per second,and confirmation and settlement in under one second,might be needed.To enable high performance,the system might utilise certain techniques,including horizontal scaling,multi-destination payments and offli

19、ne payments.Extensibility:Extensibility refers to the ability to add new functionality to a system.The CBDC system should have an extensible design,allowing PIPs and ESIPs to implement additional functionality without affecting user services.There are several factors to consider in designing an exte

20、nsible CBDC system,including using a composable architecture,which focuses on defining building blocks that can be combined to achieve the required functionality of the CBDC system.The Bank might also examine the implications of using open-source components,and any vulnerabilities that may arise due

21、 to third-party dependencies.Energy usage:The CBDC system should be energy efficient and designed in a way which minimises any impact on the environment.Therefore,Bank-managed CBDC infrastructure Page 5 would,at the very least,need to be as energy efficient as existing payment infrastructures.The Ba

22、nk will evaluate the CBDC architecture for opportunities to optimise energy efficiency.The paper sets out an illustrative conceptual model,which is based on the platform model of CBDC.The conceptual model includes a number of different components,including the core ledger,analytics,alias service and

23、 API layer.This paper outlines how these components might operate and assesses some of the ways that ecosystem participants the Bank,PIPs,ESIPs,and users would interact with these components.This includes the devices and payments a CBDC might need to enable,as well as interoperability,programmabilit

24、y and offline payments.Core ledger:The core ledger would provide the minimum necessary functionality for CBDC,and must meet the Banks performance,resilience and privacy requirements,while maintaining consistency at all times.Distributed ledger technologies and blockchain-based solutions might have a

25、dvantages in guaranteeing consistency and resilience,but they also present privacy,scalability and security challenges.Centrally governed,distributed database technologies might achieve the ledger requirements without such limitations.Therefore,these technologies might be appropriate for the core le

26、dger design.Analytics:The Bank may need to collect operational metadata for analysis of system status and performance.This would allow the Bank to maintain the core ledger and the API layer.The Bank could also collect aggregate data,subject to effective anonymisation and privacy protections,in order

27、 to undertake economic and policy analysis.These analytics would take place in a data platform,away from the core systems,and would not involve the collection or analysis of personal data.Alias service:The alias service would manage the range of different identifiers that might be used to route tran

28、sactions between users.The CBDC system might also use aliases to interoperate with existing payment infrastructures.This would allow users to choose between using well-known aliases and disposable aliases.In addition to enabling interoperability,aliases would also conceal the core wallet identifier.

29、The initial alias design might include phone numbers,a primary account number(PAN),account number and sort code,and wallet aliases.API layer:The API layer would allow PIPs and ESIPs to access core ledger functionality in order to offer services to users.The API layer would include an API gateway,whi

30、ch is an entry point for API calls,and an API service,which would implement the core functionality.There are several matters to consider in designing this,including using security controls to prevent denial of service attacks and implementing authentication or authorisation functionality in a standa

31、rdised manner.API specifications might standardise data and information exchange by orchestrating CBDC payment flows.Page 6 Devices and payments:CBDC should be widely available and accepted in-store,online and peer-to-peer.Users should be able to make and receive payments using smart devices,smart c

32、ards,ecommerce websites and applications,and existing point-of-sale technologies.The Bank would need to establish standards to ensure a consistent minimum level of functionality and security.User balances would be recorded on the core ledger,but it might be necessary to store some balances locally t

33、o support offline payments.PIPs and ESIPs would carry out user authentication.Interoperability:CBDC would be interoperable,allowing conversion between CBDC and other forms of money,particularly cash and bank deposits.Subject to further evaluation and taking account of wider developments,this might b

34、e enabled through utilising existing payment infrastructure,such as Faster Payments System,New Payments Architecture or LINK.Further integrations might be added later to support specific payment or settlement needs.Programmability:The Bank will not pursue central bank-initiated programmable function

35、s.This means that the Bank will not program CBDC to restrict its use.But PIPs could,with user consent,implement programmability features which are designed to give users greater functionality from their wallets and CBDC holdings.These could include automated payments or programmable wallets.The CBDC

36、 system might also enable a wide range of other programmable features,including payment-versus-payment,delivery-versus-payment and smart contract functionality,by implementing locking mechanisms,which PIPs and ESIPs can access through the API layer.Offline payments:The CBDC system might enable offli

37、ne payments.This could be useful in increasing system resilience in the event of network disruption.However,offline payments could also increase the risk of double spend,and create challenges in verifying the authenticity of funds.Additionally,offline payments could introduce complexities that affec

38、t system security and performance.The considerations raised in this paper will be examined further in the design phase.This paper represents our high-level approach to some of the key technology considerations and technical requirements for a UK CBDC.They will be examined further and adjusted iterat

39、ively during the next phase of our work.The Bank is seeking feedback on the matters presented in this paper,particularly on the specific questions outlined in Section 5.This will feed into our work on CBDC and ensure that feedback and challenge from stakeholders is taken into account at an early sta

40、ge of our technology work.Page 7 How to respond Written responses to any of the questions outlined in Section 5,or any other relevant observations,are requested by 7 June 2023.Please respond via this survey.If you have any comments or enquiries,please address them to:CBDC Unit Bank of England Thread

41、needle Street London EC2R 8AH CBDCbankofengland.co.uk Page 8 1:Introduction This Technology Working Paper(TWP)focuses on the technical requirements and design considerations related to a digital pound.By setting out,at an early stage,a high-level approach to key technology considerations,and by prop

42、osing an illustrative technology model,the Bank aims to generate feedback and challenge that can inform our future technology work.The digital pound Consultation Paper(CP)explains that although no final decision can be taken at this stage,the Bank of England(the Bank)and His Majestys Treasury(HM Tre

43、asury)judge that a digital pound(hereafter central bank digital currency(CBDC)is likely to be needed in the future,and the Bank and HM Treasury are proposing to accelerate work on its architecture.The digital pound CP is consulting on the policy objectives and high-level design for a UK CBDC.It sets

44、 out why there is a likely need for a CBDC,its implications for the Banks objectives of monetary and financial stability,the proposed public-private partnership to provide a CBDC,and the model of CBDC the Bank intends to examine further in the next stage of our work.This paper considers the technolo

45、gy implications of the Bank and HM Treasurys policy objectives for a UK CBDC,and the economic and functional design choices set out in the digital pound CP,using the platform model of CBDC outlined in that paper.This paper accompanies the digital pound consultation.This paper is not a consultative d

46、ocument as we are not making a decision on a specific proposition.Instead,it sets out the Banks early stage thinking on CBDC technology and seeks feedback on the potential approaches to important technology considerations.By setting out an illustrative conceptual model for a UK CBDC,which builds on

47、the platform model,this paper offers a basis for further discussion and exploration.We invite stakeholders and technology experts to provide feedback and challenge on the matters set out in this paper,including the specific questions listed in Section 5.Page 9 Figure 1:Overview of the digital pound

48、CP and the TWP The Banks thinking on the technology implications of CBDC will mature and evolve as our work develops.It is too early to take a decision on whether to build a UK CBDC.As such,it is not yet necessary to make firm decisions on any options for the architectural design or technology solut

49、ion for a UK CBDC.The Bank and HM Treasurys priority is to accelerate CBDC development work to be in a position to build a CBDC,in the event that a decision is made to do so.The functional requirements,technology considerations and illustrative technology model in this paper represent the Banks emer

50、ging thinking on these matters.The technology implications discussed are not exhaustive and will be tested and developed further in the next phase of work.Page 10 The Banks CBDC roadmap A UK CBDC would be a major project,involving distinct phases of work.Figure 2:Indicative CBDC roadmap The digital