Privacy for Financial Services Workshop

The main barrier to scaling private payments is state growth due to an ever increasing nullifier set. We build Bonsai: a private payment system where validator state only grows with the number of accounts. User state only grows with the number of transactions they receive, but it can be pruned efficiently and avoids relying on third party services. When instantiated with the zk-pari proof system, we show that a million proofs can be verified in a second on a MacBook Pro.

We present the first secure group messaging schemes with probable worst case sublinear communication and computational complexity. This resolves the main open question in the area of secure group messaging. 

Aggregate signatures play an important role in proof-of-stake systems, where many validators must sign a block, and it is thus beneficial to aggregate all such signatures into one short signature that is fast to verify.  Since all validators know the block number they are signing, this setting is well suited for synchronous (a.k.a stateful) signatures. We present a new lattice-based approach to constructing a synchronous aggregate signature scheme where resulting signatures are asymptotically shorter than existing schemes and concretely shorter for some parameter choices.

 Tokenized assets will only scale across institutions if they can move between platforms without exposing sensitive data along the way. Bryan Bodner, Head of Business and Corporate Development at OpenAssets, will share the thinking behind OTAS, an early Lab program within LFDT focused on interoperable tokenized assets, including how it approaches privacy requirements and which questions are still unresolved. He will close with where the work goes next and how institutions and builders can help shape it. 

The session will explore Banque de France’s work on wholesale CBDC within the Eurosystem context, focusing on protecting sensitive transaction data while preserving authorized oversight. It presents the layered privacy approach used in the ESYDLT solution for Pilot Pontes and ongoing explorations, highlighting the challenges of end-to-end privacy.

Privacy has always been part of the blockchain vision, and now we are finally at the precipice where it is both a real requirement for institutional onchain finance and where we have the technology to make it practical. Most discussion focuses on the technologies used to enable private execution, such as encrypted mempools, TEEs, SNARKs, etc. This talk will instead focus on how wide-scale private execution changes the requirements of the blockchain infrastructure underneath, and how we can address these requirements to create fluidly interconnected, private applications.  

This talk explores the cryptography behind CLPR, Hashgraph’s protocol for secure communication between blockchains. We will show how weighted threshold signatures and succinct proofs allow one ledger to efficiently verify another’s state, even as validators and their stakes change, without introducing trusted intermediaries 

AI agents are starting to pay for inference, data and compute on their own, settling on public EVM chains where every record can be seen and linked. Using Mastercard Agent Pay for Machines (AP4M) and a live inference transaction, we show how a payment network can enforce spend limits on-chain while keeping commercial relationships, principal identity and spending scope off the public record. We will share our current commitment-based design, where it falls short, and the open problems we would like to solve with the privacy community.