A Practical Rollup Escape Hatch Design

Rollups are "Layer 2" blockchain networks that separate execution of transactions from other aspects like con- sensus, processing transactions off of a "Layer 1" blockchain, and posting data to it for security. While rollups offer significant scalability advantages, they often rely on centralized operators for transaction ordering and inclusion, which introduces risks. If the operator fails to build rollup blocks or propose new state roots to the underlying layer, users may lose access to digital assets on the rollup. An escape hatch allows users to bypass the failing operator and withdraw assets directly on the Layer 1. We propose using a time-based trigger, Merkle proofs, and new resolver contracts to implement a practical escape hatch for rollups. The use of novel resolver contracts allow user owned assets to be located in the Layer 2 state root, including those owned by smart contracts, in order to retrieve them. This design ensures safe and verifiable escape of assets, including Ether and tokens, from the rollup.