Exploring Retail CBDC with Cash-Like Anonymity: The Project Tourbillon

Project Tourbillon, developed by the Bank for International Settlements (BIS) Innovation Hub Swiss Centre, aims to explore privacy, security, and scalability for retail central bank digital currencies (CBDCs). The project introduces a new privacy paradigm that focuses on payer anonymity, providing cash-like anonymity to the payer. This concept addresses the concern of privacy, which is consistently ranked highly among users’ concerns according to surveys conducted by the Bank of England and the European Central Bank. The project tested the concept of payer anonymity, ensuring that consumers can make payments using CBDCs without disclosing personal information to anyone, including the merchant, banks, and the central bank. However, the identity of the merchant is disclosed to the merchant’s bank for payment purposes. The project also emphasizes the importance of privacy protection technologically and preventing potential abuse. Additionally, the project explores quantum-safe cryptography for future security, although further research is needed to enhance its speed and scalability. The final report provides insights into the experimental work and discusses technical and operational considerations for central banks. Project Tourbillon serves as an initial step in understanding the trade-offs between privacy, security, and scalability in retail CBDC design, and further research is required to improve quantum-safe cryptography and explore additional use cases.

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