BUNGEE: Dependable Blockchain Views for Interoperability.

With the evolution of distributed ledger technology (DLT), several blockchains that provide enhanced privacy guarantees and features, including Corda, Hyperledger Fabric, and Canton, are being increasingly adopted. These distributed ledgers only provide partial consistency, meaning that participants can observe the same ledger differently, i.e., observe some transactions but not others, providing higher levels of privacy to the end-user. Choosing privacy instead of transparency leads to delicate trade-offs that are difficult to manage during runtime, hampering the development of applications that depend on reasoning about shared state, e.g., asset transfers across blockchains. We propose using the concept of blockchain view (view) – an abstraction of the state a participant can access at a certain point to address this problem. Views allow us to systematically reason about either state partitions within the same DLT or an integrated view spanning across several DLTs. We introduce BUNGEE (Blockchain UNifier view GEnErator), the first DLT view generator, to allow capturing snapshots, constructing views from these snapshots, and merging views according to a set of rules specified by the view stakeholders. Creating views and operating views allows new applications built on top of dependable blockchain interoperability, such as stakeholder-centric snapshots for audits, cross-chain analysis, blockchain migration, and combined on-chain-off-chain analytics.