Briefing
The core research problem is the systemic centralization risk inherent in Layer 2 rollup architectures due to their reliance on a single, trusted sequencer for transaction ordering and a separate, often optional, Data Availability Committee (DAC). This paper introduces the Decentralized Arranger , a unified service that cryptographically combines the sequencer and DAC roles into a single, fault-tolerant entity. The arranger leverages an extension of Set Byzantine Consensus (SBC) , a protocol that achieves agreement on a subset of proposed values, to guarantee a provably correct and fully decentralized implementation of both sequencing and data availability. The single most important implication is the creation of a foundational architectural primitive for L2s that secures the rollup’s liveness and censorship resistance without compromising its scaling efficiency.
Context
Before this work, the dominant model for Layer 2 scaling separated the execution layer from the ordering and data availability layers. While rollups successfully offloaded computation to improve throughput, they introduced a central point of control → the single, centralized sequencer. This centralized entity determined transaction order, creating a vulnerability to censorship and Maximal Extractable Value (MEV) exploitation, fundamentally compromising the decentralized nature of the underlying blockchain. Furthermore, the reliance on an optional, separate DAC for data availability added complexity and a distinct trust assumption.
Analysis
The core mechanism is the Set Byzantine Consensus (SBC) -based Arranger. Conceptually, the Arranger functions as a single, distributed network of nodes that collectively process and commit rollup data. Unlike traditional Byzantine Fault Tolerance (BFT) which agrees on a single value, SBC allows participants to propose sets of values (i.e. transaction batches and their corresponding data availability proofs), and the protocol guarantees consensus on a subset of the union of all proposed sets.
This extension enables the Arranger to simultaneously agree on the final, serialized transaction hash and the commitment that the underlying data is available to the network. This unification fundamentally differs from previous approaches by collapsing two separate, trust-dependent roles (sequencer and DAC) into one provably decentralized, consensus-driven primitive.
Parameters
- Core Consensus Primitive → Set Byzantine Consensus (SBC) – The underlying protocol used to reach decentralized agreement on the transaction set and its data availability.
- Combined L2 Roles → Sequencer and Data Availability Committee (DAC) – The two centralized components unified into the single Decentralized Arranger service.
- Arranger Output → Posted Hashes to L1 – The minimal data committed to the Layer 1 chain to guarantee correctness and security.
Outlook
This foundational work immediately opens new avenues for modular blockchain design, moving beyond the fragmented model of independent sequencers and DACs. In the next three to five years, this theory is likely to underpin the architecture of fully decentralized, cross-rollup shared sequencing services. The next research step involves optimizing the communication complexity of the SBC-based arranger to ensure its throughput remains competitive with centralized sequencers, potentially through cryptographic aggregation techniques. Ultimately, this approach promises to unlock a truly trustless, composable Layer 2 ecosystem where censorship resistance is guaranteed by the protocol’s design, not by the benevolence of a single operator.
Verdict
The Decentralized Arranger provides a foundational, game-theoretic solution that elevates rollup security by cryptographically enforcing decentralization across the entire transaction lifecycle.
