A Practical Rollup Escape Hatch Design

2025-03-31

AI Summary

Rollups—the dominant Layer 2 scaling solution—rely on centralized sequencers for transaction ordering and state commitment, introducing a single point of failure: if the sequencer halts or becomes unresponsive, user assets are effectively locked on Layer 2. Method: This paper proposes a trustless escape mechanism enabling users to bypass the sequencer and directly withdraw ETH, ERC-20, and ERC-721 assets to Layer 1 under adversarial conditions. It introduces a novel three-layer architecture: (i) time-lock triggering, (ii) Merkle path verification, and (iii) a user-verifiable resolver contract. Contribution/Results: The mechanism achieves, for the first time, both *locatability* and *escapability* of smart-contract-held assets within the L2 state root. By performing on-chain state root parsing and fully on-chain verification, it eliminates reliance on operator trust, maintains compatibility with standard token interfaces, and ensures security, transparency, and auditability.

Technology Category

• Multiagent Systems: Mechanism Design
• Reasoning under Uncertainty: Sequential Decision Making
• Data Mining & Knowledge Management: Representing, Reasoning, and Using Provenance, Trust

Application Category

• Security and Privacy: Cryptocurrency and smart contracts
• Responsible Web: Social and technical mechanisms of refusal for web technologies and applications
• Economics, Online Markets and Human Computation: Trust and reliance of crowd workers and data experts on GenAI

Abstract

A rollup network is a type of popular"Layer 2"scaling solution for general purpose"Layer 1"blockchains like Ethereum. Rollups networks separate execution of transactions from other aspects like consensus, processing transactions off of the Layer 1, and posting the data onto the underlying layer for security. While rollups offer significant scalability advantages, they often rely on centralized operators for transaction ordering and inclusion, which also introduces potential risks. If the operator fails to build rollup blocks or propose new state roots to the underlying Layer 1, 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 these networks. 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 allow users to escape them. This design ensures safe and verifiable escape of assets, including ETH, ERC-20 and ERC-721 tokens, and more, from the Layer 2.

Problem

• Centralized rollup operators risk user asset access
• Escape hatch needed for failing rollup operators
• Secure asset withdrawal from Layer 2 to Layer 1

Innovation

• Time-based trigger for escape hatch
• Merkle proofs for asset verification
• Resolver contracts for Layer 2 assets