Briefing
The core research problem is the systemic centralization risk introduced by single-operator sequencers in Layer 2 rollup architectures, which undermines the foundational decentralization promise of blockchain systems. This paper proposes the “decentralized arranger,” a novel service primitive that cryptographically unifies the functions of transaction sequencing and the Data Availability Committee (DAC) into a single, cohesive, decentralized protocol. The breakthrough is the implementation of this arranger using an extension of Set Byzantine Consensus (SBC) , a mechanism where nodes reach consensus on a set of proposed transaction batches rather than a single block. The single most important implication is the establishment of a robust, censorship-resistant L2 infrastructure that achieves high throughput while maintaining the security and trustlessness derived from the underlying Layer 1.
Context
Before this research, Layer 2 rollups primarily relied on a single, centralized entity → the sequencer → to aggregate, order, and submit transaction batches to the Layer 1 chain. This established model, while efficient for scaling, introduced a critical single point of failure and control, creating a vector for censorship, unfair transaction ordering, and potential governance influence over the entire L2 ecosystem. The prevailing theoretical limitation was the lack of a robust, decentralized consensus mechanism capable of efficiently agreeing on a sequence of transactions while simultaneously guaranteeing the availability of the underlying data.
Analysis
The paper introduces the decentralized arranger as a new architectural component. Conceptually, the arranger replaces the centralized sequencer and DAC with a distributed committee that runs a modified Set Byzantine Consensus (SBC) protocol. Instead of voting on a single block, committee members propose sets of transaction batches.
The SBC mechanism then deterministically selects a subset of the union of all proposed batches, effectively achieving consensus on both the transaction order and the commitment to the data’s availability in a single step. This integration, achieved by committing only the hash of the batch to Layer 1 and using the decentralized arranger to guarantee the availability of the original data, fundamentally decouples the Layer 2’s security from reliance on a single, trusted operator.
Parameters
- Core Mechanism → Set Byzantine Consensus (SBC) – The core consensus mechanism extended to agree on transaction sets.
- Architectural Primitive → Decentralized Arranger Service – The new combined role replacing the centralized sequencer and DAC.
- L2 Component Unification → Sequencer and Data Availability Committee (DAC) – The two functions merged into a single decentralized service.
Outlook
This research establishes a new foundational standard for Layer 2 architecture, shifting the focus from simply scaling computation to ensuring decentralized sequencing and data integrity. The next steps involve the formal cryptoeconomic analysis of the SBC extension to bound adversarial profit and ensure liveness under various network conditions. In the next 3-5 years, this model could unlock a new generation of Layer 2s that are provably censorship-resistant, enabling a truly trustless modular blockchain ecosystem where transaction ordering fairness is a guaranteed protocol property, not a centralized policy.
Verdict
The decentralized arranger and its foundation in Set Byzantine Consensus represent a foundational shift toward provably trustless and censorship-resistant Layer 2 blockchain architecture.
