Protecting L3 chains from L2 censorship

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research.arbitrum.io

TL;DR:

The Arbitrum community is actively discussing the risks of censorship attacks by a malicious L2 sequencer and the implications of the current 24-hour force-inclusion delay, with proposals to reduce it and enhance the protocol's security through measures like a multi-sequencer system. Despite the positive engagement from key members, concerns persist about the integrity of the challenge game, the complexity of enforcing transaction inclusion, and the reliance on the Security Council to address censorship.

What is this about?

The community's focus remains on the Arbitrum challenge protocol and the potential for worst-case censorship attacks on L3 Orbit chains, particularly in the context of a malicious L2 sequencer. The discussion has evolved to include the implications of the L2 sequencer's ability to delay transaction inclusion and the current 24-hour force-inclusion delay, which some propose reducing to 8 hours. Concerns are centered around the possibility of a malicious sequencer exploiting this delay to disrupt the challenge game. Additionally, the rarity of L2 reorgs on Arbitrum and the role of the Arbitrum Security Council in replacing a problematic L2 sequencer have been highlighted.

How is the community reacting?

Key community members, including Edfelten and CTrain, continue to be actively involved in proposing solutions and discussing the nuances of the protocol. Edfelten has emphasized the Security Council's role in intervening during prolonged censorship attacks and the need for a proposal on the enforcement mechanism for delayed-inbox transactions by L2 sequencers. CTrain has questioned the necessity of the 24-hour delay and suggested an L1 contract to enforce transaction inclusion. Sam.ng has joined the conversation, questioning the rarity of L2 reorgs and proposing a multi-sequencer system to mitigate censorship risks, suggesting a round-robin or turn-based approach to sequencer selection.

Why this is positive?

The community's proactive engagement and the contributions from knowledgeable members like Edfelten, CTrain, and Sam.ng are positive signs. Their deep understanding and commitment to improving the protocol's functionality and security could lead to significant enhancements. The idea of a multi-sequencer system and the discussion on optimizing the force-inclusion delay demonstrate the community's dedication to addressing potential vulnerabilities and ensuring the robustness of the Arbitrum challenge protocol.

Why this is negative?

The ongoing threat of censorship attacks by a malicious L2 sequencer remains a significant concern. The potential for repeated delays due to the current force-inclusion delay is a risk to the integrity of the challenge game and the overall performance of the Arbitrum protocol. The discussion about enforcing the inclusion of delayed-inbox transactions adds complexity and underscores the importance of carefully weighing the costs and benefits of any new mechanism. The reliance on the Security Council for censorship issues and the lack of information on backup sequencers also highlight areas that require further attention and potential improvement.

Posted 2 months ago

Last reply 17 days ago

Summary updated 17 days ago

Last updated 09/12 13:53