Atomic Crosschain Transactions White Paper
This addresses the challenge of secure and reliable composable programming for users of private Ethereum blockchains, representing a novel approach rather than an incremental improvement.
The paper tackles the problem of enabling atomic and synchronous cross-chain transactions across private Ethereum blockchains, achieving this without relying on existing techniques like Hash Time Locked Contracts or trusted intermediaries, using methods such as BLS Threshold Signatures and Coordination Contracts to ensure rollback on failure.
Atomic Crosschain Transaction technology allows composable programming across private 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 graph of function calls is rolled back. It is not based on existing techniques such as Hash Time Locked Contracts, relay chains, block header transfer, or trusted intermediaries. BLS Threshold Signatures are used to prove to validators on one blockchain that information came from another blockchain and that a majority of the validators of that blockchain agree on the information. Coordination Contracts are used to manage the state of a Crosschain Transaction and as a repository of Blockchain Public Keys. Dynamic code analysis and signed nested transactions are used together with live argument checking to ensure execution only occurs if the execution results in valid state changes. Contract Locking and Lockability enable atomic updates.