Briefing
The core research problem is the critical centralization risk inherent in Layer 2 rollup architectures, which currently rely on a single, trusted sequencer for transaction ordering and a separate Data Availability Committee (DAC). This paper introduces the Decentralized Arranger , a novel service that cryptographically unifies the sequencer and DAC functions into a single, fully decentralized entity. The foundational breakthrough is an extension of Set Byzantine Consensus (SBC) , where nodes agree on a set of valid transaction batches rather than a total linear order, thereby decoupling sequencing from centralized control. The single most important implication is the creation of a credibly neutral, scalable, and fully decentralized L2 foundation, fundamentally securing the rollup ecosystem against single-point-of-failure and undue influence.
Context
The prevailing challenge in Layer 2 scaling is the centralization of the sequencer, which is responsible for collecting, ordering, and committing transaction batches to Layer 1. While rollups achieve high throughput by moving computation off-chain, the sequencer’s singular control over transaction flow introduces censorship risk, potential for malicious Maximal Extractable Value (MEV) extraction, and a liveness vulnerability, directly undermining the core decentralization ethos of the underlying Layer 1 blockchain. The reliance on a centralized Data Availability Committee (DAC) for data retrieval further compounds this single-point-of-failure vulnerability.
Analysis
The proposed Decentralized Arranger operates by extending the principles of Set Byzantine Consensus (SBC), a protocol where participants propose sets of values and the final consensus is reached on a subset of the union of all proposed values. This differs from traditional Byzantine Fault Tolerance (BFT) protocols, which enforce a strict, global, and linear order. The Arranger leverages this set-based agreement to simultaneously sequence a set of transaction batches (via posting their hashes to L1) and ensure their corresponding data availability (via the DAC function), achieving a single, atomic operation for both critical L2 services. This mechanism fundamentally replaces the single, centralized point of trust with a robust, cryptographically-secured committee.
Parameters
- Consensus Foundation ∞ Set Byzantine Consensus (SBC) is the novel protocol extension used to achieve decentralized agreement on the set of transaction batches.
- Decentralization Target ∞ Fully Decentralized Arranger is the end state, eliminating the single centralized sequencer and DAC, thereby achieving maximal credible neutrality.
- Core Function Unification ∞ Sequencer and Data Availability Committee are combined into a single atomic service, simplifying the L2 security model.
Outlook
This research establishes a new theoretical primitive ∞ the Decentralized Arranger ∞ that will serve as the foundational blueprint for all future L2 architectures aiming for credible neutrality. The next steps involve the empirical implementation and stress-testing of the SBC extension to validate its performance characteristics under high-throughput conditions. The potential real-world application is the unlocking of truly trustless, permissionless L2 systems in the next 3-5 years, enabling synchronous composability across multiple rollups without relying on a central coordinator. This work opens new avenues for research into mechanism design for shared sequencing and generalized set-consensus protocols.
Verdict
The formalization and implementation of the Decentralized Arranger via Set Byzantine Consensus is a decisive, foundational step toward resolving the critical centralization paradox of Layer 2 rollup scaling.
