Briefing
The core problem addressed is the centralization risk inherent in Layer Two (L2) rollups, where a single, permissioned sequencer controls transaction ordering, creating vectors for censorship and Maximal Extractable Value (MEV) extraction. The foundational breakthrough is the concept of Based Rollups , a paradigm that delegates the L2 sequencing function to the Layer One (L1) block producer, effectively turning the L1 consensus into the L2’s transaction ordering mechanism. This architecture dictates that the L1 block producer is the only entity authorized to post a corresponding L2 block to the L1 settlement layer. The most important implication is that L2s can immediately inherit the L1’s robust decentralization and censorship resistance guarantees, fundamentally transforming the L2 security model from one based on fraud/validity proofs to one based on L1 consensus security.
Context
Before this research, the prevailing model for L2 rollups relied on a dedicated, often centralized or federated, sequencer to collect, order, and batch transactions before posting them to the L1. This design was necessary for achieving fast pre-confirmations and high throughput, but it created a critical single point of failure. The centralized sequencer had unilateral control over which transactions were included and in what order, leading to potential censorship of user transactions and the ability to extract MEV by front-running or reordering trades, thereby compromising the core trustlessness of the decentralized system.
Analysis
The Based Rollups mechanism introduces a primitive where the L2’s block is inextricably linked to the L1’s block production process. Conceptually, the L1 block producer (e.g. an Ethereum validator) for a given L1 slot is granted the exclusive right to propose the corresponding L2 rollup block. This process, termed L1-Sequencing or Base Sequencing , ensures that the L2’s transaction ordering is determined by the same highly decentralized and permissionless process that secures the L1. By aligning the L2 block with the L1 block, the rollup’s liveness and censorship resistance are no longer dependent on a small set of L2-specific operators but are instead secured by the entire L1 validator set, making censorship prohibitively expensive and economically non-viable.
Parameters
- L2 Block Time Floor ∞ L1 Block Time. The L2 block time is constrained by the L1 block time, as the L1 block producer determines the L2 block.
- Sequencer Set Size ∞ L1 Validator Set Size. The L2 sequencer set is effectively the entire L1 validator set, providing maximum decentralization.
- Censorship Resistance ∞ L1 Consensus Security. The L2 inherits the L1’s high security threshold against malicious block inclusion or exclusion.
Outlook
The Based Rollups model is a strategic inflection point for the entire L2 ecosystem, shifting the focus from custom L2 sequencer solutions to leveraging the L1 as a shared sequencing layer. This will unlock new avenues of research focused on optimizing L1-L2 communication and achieving atomic composability across multiple L2s that share the same L1 sequencing mechanism. Within 3-5 years, this architecture is projected to become the canonical, permissionless endgame for L2s, standardizing a high-security, low-trust model that dramatically improves user experience by guaranteeing transaction fairness and eliminating the current centralization-based MEV extraction at the sequencing layer.
Verdict
The Based Rollups paradigm is a foundational re-architecture of the Layer Two security model, providing the definitive, cryptographically enforced path to rollup decentralization and censorship resistance.
