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; hence, the main cross-chain use case is token transfer. By-design platform transparency, tamper-resistance, and auditability make blockchains an infrastructure candidate for Central Bank Digital Currencies (CBDCs), but bridging CBDCs is an important missing piece in general. In this paper, we leverage an asset transfer protocol, ODAP/SATP, to define an extendable and dependable blockchain interoperability middleware that can bridge CBDC from Hyperledger Fabric to 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 implement our design for the CBDC use case utilizing Hyperledger Cactus. Through a preliminary performance evaluation, we show that the underlying ledgers heavily influence the latency of the solution, not the bridging components.