# Central banks are building confidentiality themselves

> Central banks are building confidentiality themselves: What the people writing the rules do when they design money. Region: Global.

Part of the Soda Labs Privacy Hub regulation map, which reads the instruments
themselves rather than summarising the summaries: https://www.sodalabs.xyz/privacy-hub/regulation

## Key facts

- Entry type: Where privacy tech meets the rulebook
- Region: Global
- Subject: What the people writing the rules do when they design money
- Tags: CBDC, Project Tourbillon, payer anonymity, precedent
- Canonical page: https://www.sodalabs.xyz/privacy-hub/regulation/why-central-banks-build-privacy

## What it actually says

The strongest evidence that public authorities do not equate confidentiality with wrongdoing is that they keep building it. The BIS Innovation Hub's Tourbillon prototypes, developed with the Swiss National Bank, were designed around payer anonymity: a consumer pays without revealing personal information to the merchant, to the banks or to the central bank, while the payee remains identified to their own bank. The BIS presents this as compatible with anti-money-laundering aims rather than in tension with them, precisely because the receiving side stays legible. The Bank of England has run comparable work on offline digital pound payments. Read together with the digital euro's offline design, the pattern is consistent: asymmetric privacy, where the party being paid is known and the party paying is not, is a design regulators actively pursue.

## The instruments that matter

- **BIS Project Tourbillon (final report, November 2023)**: retail CBDC prototypes built around payer anonymity, where the central bank sees the amount but not the consumer or the merchant, while the payee stays identified to their own bank
- **Bank of England digital pound offline payments report (2025)**: assessed pseudonymisation, ephemeral key management and confidential computing with commercial partners

## Sources

- [BIS Project Tourbillon](https://www.bis.org/about/bisih/topics/cbdc/tourbillon.htm)
- [Bank of England offline payments experiment](https://www.bankofengland.co.uk/report/2025/digital-pound-experiment-report-offline-payments)

## Related entries

- [BIS Innovation Hub](https://www.sodalabs.xyz/privacy-hub/regulation/reg-bis-innovation-hub): Central bank prototypes that build privacy on purpose
- [Anonymity is not the same thing as confidentiality](https://www.sodalabs.xyz/privacy-hub/regulation/why-programmable-confidentiality): Why two privacy designs get treated differently
- [Erasure against an append-only ledger](https://www.sodalabs.xyz/privacy-hub/regulation/why-erasure): The one collision with no clean answer yet
- [Proving where funds did not come from](https://www.sodalabs.xyz/privacy-hub/regulation/why-privacy-pools): Association sets, and the Tornado Cash aftermath
- [Sanctions screening on a confidential ledger](https://www.sodalabs.xyz/privacy-hub/regulation/why-sanctions-screening): The genuinely open problem
- [Selective disclosure as a compliance primitive](https://www.sodalabs.xyz/privacy-hub/regulation/why-viewing-keys): Bilateral disclosure versus publishing to everyone