Atomic Crosschain Transactions for Ethereum Private Sidechains

The Atomic Crosschain Transaction for Ethereum Private Sidechains protocol allows composable programming across permissioned Ethereum blockchains. It allows for inter-contract and inter-blockchain function calls that are both synchronous and atomic: if one part fails, the whole call tree of function calls is discarded. The protocol is not based on existing techniques such as Hash Time Locked Contracts, relay chains, block header transfer, or trusted intermediaries. It uses (a) threshold signatures to prove values across blockchains, (b) coordination contracts to manage the state of crosschain transactions, and (c) a function call tree commitment scheme to allow users to commit to a call tree and then later check that the correct function calls have been executed. This paper analyses the processing overhead of using this technique compared to using multiple standard non-atomic single blockchain transactions. The additional processing is analysed for four scenarios involving multiple blockchains: a Trade–Finance system, the Hotel–Train problem, a Supply Chain with Provenance, and an Oracle. The protocol is shown to have both safety and liveness properties.