The Security of Arbitrum’s optimistic roll-up implementation

Abstract

Arbitrum, a Layer 2 solution for Ethereum, has gained significant traction, surpassing Ethereum's mainnet in transaction volume. However, the security mechanisms underpinning Arbitrum, particularly the implementation of optimistic roll-ups, remain ambiguous. A unique feature of Arbitrum is its whitelisting process for challenges, which has sparked questions about its security robustness. Despite the surge in transactions, the full implementation of optimistic roll-ups, a critical security feature, is yet to be seen. This paper delves into the security implications of this non-implementation, focusing on potential vulnerabilities and risks it may introduce to users and the broader Ethereum ecosystem. Our approach involves an in-depth analysis of Arbitrum's architecture, with a focus on its challenge process and the role of whitelisting. We also scrutinize the optimistic roll-up mechanism, its intended security benefits, and the potential impact of its non-implementation. This analysis is supplemented by a comparative study of the transaction volumes on Arbitrum and the Ethereum mainnet, underscoring the growing reliance on Layer 2 solutions. The findings of this study offer valuable insights into the security implications of the non-implementation of optimistic roll-ups in Arbitrum. By illuminating potential vulnerabilities, we aim to contribute to the ongoing discourse on the security of Layer 2 solutions and their role in the future of the Ethereum ecosystem. This study emphasizes the importance of robust security measures in scaling solutions to ensure the safety and integrity of blockchain transactions.