Minutes

Date of meeting: 16 July 2024

Item 1: Welcome

Tom Mutton (Chair) welcomed Members to the thirteenth meeting of the CBDC Technology Forum

The Chair stated that the Technology Forum was important to the Bank, and they were grateful for Members’ hard work in the subgroups which had been established on a time limited basis to help explore technology considerations relevant to the digital pound architecture.

The Chair noted the agenda for the meeting would comprise a presentation from the Bank on recommendations made by the subgroups. The Chair noted that this meeting was an opportunity to bring together work from the subgroups.

Item 2: Recap of subgroup discissions

The Bank stated that they would play back their understanding of the recommendations made by each subgroup.

The Bank recalled recommendations from each subgroup, starting with Subgroup 1 which explored technology options to ensure privacy in a digital pound and design of the alias service. The Bank highlighted the different roles of potential actors in a digital pound ecosystem, including payer, payee, Payer PIP and Payee PIP. The Bank also noted the separation of the role of a core ledger operator and an alias operator, as described by Subgroup 1, although there were no assumptions about who the operators would be.

The Bank played back other considerations from Subgroup 1, such as adopting techniques from other solutions including using multiple accounts or addresses to create noise.

In their hypothetical privacy model, Subgroup 1 had considered that the alias service would provide a mapping from aliases to identifiers, preventing the ledger from seeing personal data. The Bank asked Members to consider whether aliases could be mapped to the wallet provider rather than identifiers, to support greater levels of privacy. One Member stated that it would be possible to map to wallet providers instead of identifiers, but putting discoverability at the PIP level has both advantages and disadvantages.

The Bank then played back discussions from Subgroup 2, which focused on models of interaction between PIPs. The Bank recalled the three models of interaction proposed by Subgroup 2. The Bank highlighted other recommendations from Subgroup 2, including the need for standards to enable communication and support interoperability; and enabling payer and payee signature checking without revealing identity. The Bank stated that Subgroup 1 and 2’s work seemed to suggest that the communication model that allowed direct interaction between PIPs might be the most privacy preserving.

The Bank then played back work from Subgroups 3, which focused on core ledger technology, and Subgroup 4, which focused on requirements for providing a platform for innovation. Both Subgroups had discussed experiments for the Bank to consider.

The Bank stated that there were questions in Subgroup 3’s work about comparing decentralised ledger technologies and centralised ledger technologies in the areas of scalability, finality, availability and resilience and security.

The Bank stated that Subgroup 4 had suggestions for experimenting with a smart contact platform. The Bank acknowledged the potential need to experiment with an application programming interface (API) platform and a smart contract platform to the compare capabilities of both.

The Bank then played back possible options for integration between the API platform and smart contract system to examine subgroup 4’s suggestion. The first model exposed locks, such as HTLC locks, on the ledger and allowed firms to access it via APIs. The second model created a native implementation of the token CBDC, and the third smart contract logic hosted at the PIP layer and executed via the standard ledger interaction APIs.

The Bank recalled the list of experiment proposals from the subgroups, including decentralised finance style use cases, private amount and balances, interoperability, and tap and go. The Bank stated that these proposals might result in an architecture that supports capabilities such as locks/escrow and smart contracts. The Bank stated that they were minded to do such an experiment

Item 3: Next steps for the Technology Forum

The Bank asked Members to share their experience working in their subgroups.

One Member stated that there were strong leaders across groups and deadlines set by the Bank helped to push delivery. A few Members stated that they would have liked more support from the Bank in terms of administration and tooling.

The Bank thanked Members for their feedback and noted that the Bank would reach out soon with further information.

Item 4: Closing remarks

The Chair closed the meeting and thanked Members for contributions.

Attendees

Bank of England

Tom Mutton (Chair)

Danny Russell

Will Lovell

Members

Adrian Field, OneID

Alain Martin, Thales

Ashley Lannquist, IMF

Bejoy Das Gupta, eCurrency

David MacKeith

Dominic Black, Ledgerz

Edwin Aoki, Paypal

Gary King, Lloyds

Geoff Goodell, UCL

Georgios Samakovitis, University of Greenwich

Inga Mullins, Fluency

Joshua Jeeson Daniel, JP Morgan

Julia Demidova, FIS

Keith Bear, Cambridge Centre for Alternative Finance

Kene Ezeji-Okoye, Millicent Labs

Lars Hupel, Giesecke+Devrient

Lauren Del Giudice, Idemia

Lee Braine, Barclays

Michael Adams, Quali-Sign

Paul Lucas, IBM

Richard Brown, R3

Sarah Meiklejohn, IC3

Vikram Kimyani, Oracle

Will Drewry, Google

Apologies

Alan Ainsworth, Open Banking

Andrew Flatt, Archax

James Whittle, Pay.UK

Paul Carey, Stripe

Mark Shaw, Spotify

Simon Brayshaw, Motorway

Tom Beresford, Starling

Tim Moncrieff, Visa