  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.
