Benchmarking the performance of a self-custody, non-ledger-based, obliviously managed digital payment system

TL;DR

This paper benchmarks a privacy-preserving, self-custody digital payment system for retail CBDCs, comparing a new streamlined ledger with a legacy system to support scalable, real-time transactions.

Contribution

It introduces a novel, fast verification technique and a streamlined digital ledger for privacy-preserving retail CBDC transactions, benchmarking against existing systems.

Findings

Significantly faster Proof of Provenance verification

Enhanced transaction validation speed and scalability

Maintained user privacy and data integrity

Abstract

As global governments intensify efforts to operationalize retail central bank digital currencies (CBDCs), the imperative for architectures that preserve user privacy has never been more pronounced. This paper advances an existing retail CBDC framework developed at University College London. Utilizing the capabilities of the Comet research framework, our proposed design allows users to retain direct custody of their assets without the need for intermediary service providers, all while preserving transactional anonymity. The study unveils a novel technique to expedite the retrieval of Proof of Provenance, significantly accelerating the verification of transaction legitimacy through the refinement of Merkle Trie structures. In parallel, we introduce a streamlined Digital Ledger designed to offer fast, immutable, and decentralized transaction validation within a permissioned ecosystem. The ultimate objective of this research is to benchmark the performance of the legacy system formulated by the original Comet research team against the newly devised system elucidated in this paper. Our endeavour is to establish a foundational design for a scalable national infrastructure proficient in seamlessly processing thousands of transactions in real-time, without compromising consumer privacy or data integrity.