Sober, MichaelMichaelSoberScaffino, GiuliaGiuliaScaffinoSchulte, StefanStefanSchulte2024-09-252024-09-252024-07-15ACM Distributed Ledger Technologies 3 (4): 27 (2024)https://hdl.handle.net/11420/49215The closed architecture of prevailing blockchain systems renders the usage of this technology mostly infeasible for a wide range of real-world problems. Most blockchains trap users and applications in their isolated space without the possibility of cooperating or switching to other blockchains. Therefore, blockchains need additional mechanisms for seamless communication and arbitrary data exchange between each other and external systems. Unfortunately, current approaches for cross-blockchain communication are resource-intensive or require additional lockchains or tailored solutions depending on the applied consensus mechanisms of the connected blockchains. Therefore, we propose an oracle with an off-chain aggregation mechanism based on Zero-Knowledge Succinct Non-interactive Arguments of Knowledge (zk-SNARKs) to facilitate cross-blockchain communication. The oracle queries data from another blockchain and applies a rollup-like mechanism to move state and computation off-chain. The zkOracle contract only expects the transferred data, an updated state root, and proof of the correct execution of the aggregation mechanism. The proposed solution only requires constant 378 kgas to submit data on the Ethereum blockchain and is primarily independent of the underlying technology of the queried blockchains.en2769-647220244Association for Computing Machineryhttps://creativecommons.org/licenses/by/4.0/Computer Science, Information and General Works::004: Computer SciencesJournal Articlehttps://doi.org/10.15480/882.1382510.1145/367818710.15480/882.138252405.08395Journal Article