BIS-零售角度的央行数字货币技术（英文）-2020.12-16页_475kb

Summary of "The Technology of Retail Central Bank Digital Currency"

Core Content

Central Bank Digital Currencies (CBDCs) are being explored as a means to provide a cash-like alternative for peer-to-peer payments, combining safety, convenience, privacy, and cross-border functionality. The design of such a currency involves several key trade-offs, particularly between direct and indirect claims on the central bank, the use of distributed ledger technology (DLT) versus conventional infrastructure, and the choice between account-based and token-based access.

Main Viewpoints

• CBDC as a Cash Alternative: CBDCs aim to offer the same level of safety and convenience as cash, while enabling digital transactions.
• Consumer Needs Drive Design: The design of CBDCs must address consumer needs such as security, accessibility, privacy, and ease of use in cross-border payments.
• Trade-offs in Design: Each technical design of a CBDC has its own set of advantages and disadvantages, requiring careful evaluation of the balance between privacy, access, and law enforcement capabilities.
• Infrastructure Considerations: The choice of infrastructure (conventional or DLT) affects the resilience and scalability of the CBDC system.
• Cross-border Potential: CBDCs could support both wholesale and retail cross-border linkages, potentially improving efficiency in international payments.

Key Design Choices

The CBDC pyramid outlines four key design layers:

1. Legal Structure and Operational Roles

   • Indirect CBDC: Consumers have a claim on an intermediary, with the central bank only tracking wholesale accounts.
   • Direct CBDC: Consumers have a direct claim on the central bank, with the central bank maintaining all retail balances.
   • Hybrid CBDC: Combines direct claims on the central bank with a private sector messaging layer, enabling portability and resilience.

2. Infrastructure Type

   • Conventional Infrastructure: Centralized databases, which are more resilient to certain types of attacks but less scalable.
   • DLT Infrastructure: Distributed ledgers offer decentralization and transparency but face challenges in transaction throughput and consensus mechanisms.
   • DLT is not always the best choice: Permissioned DLT is more likely to be used due to lower costs and better scalability compared to permissionless DLT.

3. Access Technology

   • Account-based Access: Ties ownership to an identity, which can enhance security but may reduce privacy and complicate universal access.
   • Token-based Access: Uses cryptographic schemes to allow anonymous transactions, offering better privacy but increasing the risk of loss and complicating AML/CFT frameworks.

4. Cross-border Payments

   • Wholesale Linkages: May be implemented using existing systems, but offer limited consumer benefits.
   • Retail Linkages: Could allow consumers to hold foreign currencies directly, separating payment from foreign exchange transactions. This requires careful design and coordination across jurisdictions.

Privacy and Security Considerations

• Privacy is not solely about the access method but also about the data collected during transactions.
• Transaction-level data can reveal sensitive personal information, so data minimisation and anonymisation are crucial.
• Token-based systems can offer privacy by default but require robust safeguards against data breaches and loss of private keys.

Ongoing CBDC Projects

• Many central banks are exploring various CBDC designs, with no clear consensus on the optimal approach.
• Only a few projects focus on conventional infrastructure, while more are experimenting with DLT.
• The majority of projects are still in early stages, with a wide range of technical and legal considerations being tested.

Conclusion

• The design of a retail CBDC involves a complex hierarchy of decisions, each with its own trade-offs.
• Central banks are investigating a broad spectrum of technical solutions, and the optimal design may vary depending on the specific needs and circumstances of each jurisdiction.
• International collaboration and the sharing of experimental results could help clarify which technological choices are most suitable for CBDCs.