CBDC Bridging between Hyperledger Fabric and Permissioned EVM-based Blockchains

The last few years have seen a steep increase in blockchain interoperability research. Most solutions connect public blockchains, where the main cross-chain use case is token transfer. By-design platform transparency, tamper resistance, and auditability make blockchains a candidate infrastructure for Central Bank Digital Currencies (CBDCs), but bridging CBDCs is an important missing piece in that scenario. In this paper, we leverage an asset transfer protocol, SATP, to define an extendable and dependable blockchain interoperability middleware that can bridge CBDC between Hyperledger Fabric and EVM-based permissioned blockchains. The key interoperation enabler in the solution is a shared asset definition enforced by both sides of the bridge, accompanied by a mapping between Fabric identities and Ethereum addresses for identity management. We implemented our design using Hyperledger Cacti. A preliminary evaluation shows that latency is more influenced by the ledgers than the bridging components.