Zipline - A Fault-Proof Blocker Header Oracle

Abstract

Zipline is a protocol for trustless relaying of sync committee attested block roots from an Ethereum beacon chain to the execution layer of another blockchain. These in turn can be used to prove transactions or state to support crosschain applications. Zipline's operation is similar to that of an optimistic rollup but rather than updating a blockchain state via transactions it updates a beacon chain light client state. Under normal operation Zipline is able to maintain an updated view of the beacon chain block roots with minimal execution. In the case of relayer fraud it borrows from state-of-the-art fault proving strategies to identify and revert fraudulent blocks under an honest minority assumption.