Briefing
The core research problem addressed is the increasing centralization risk inherent in the Proposer-Builder Separation model, where a small number of high-latency builders dominate Maximal Extractable Value (MEV) extraction, undermining decentralization. The foundational breakthrough is the introduction of Threshold-Secret-Shared Block Construction (TSS-BC) , a novel mechanism that distributes the block body among a decentralized committee using a threshold scheme, with a Verifiable Delay Function (VDF) committing the block header. This design mandates cooperative finalization, effectively transforming the competitive, centralized MEV game into a provably fair, threshold-secured process. The single most important implication is the radical decentralization of the block production supply chain, ensuring that network liveness and transaction ordering are secured by cryptographic distribution, a superior approach to reliance on privileged infrastructure.
Context
Prior to this research, the prevailing solution to mitigate proposer-based MEV was the Proposer-Builder Separation (PBS) paradigm, which delegated block construction to specialized “builders” who bid for the right to have their block included by a “proposer.” While this decoupled roles, it introduced a new, critical centralization vector ∞ the block-building layer. This layer became a high-stakes, low-latency competition, creating significant barriers to entry and concentrating the power to censor or front-run transactions into the hands of a few highly capitalized entities, thus compromising the system’s overall economic security and censorship resistance.
Analysis
The core mechanism, Threshold-Secret-Shared Block Construction (TSS-BC), fundamentally alters the trust model of block production by replacing a single, trusted builder with a decentralized committee. Conceptually, the block body is split into n shares, where any t shares are required to reconstruct the full block, utilizing a distributed key generation and secret sharing scheme. A builder committee first agrees on a preliminary block header and commits to it using a Verifiable Delay Function (VDF), which imposes a mandatory, verifiable time lock on the commitment.
This VDF commitment ensures that the final block body, when revealed via the threshold-secured reconstruction process, is bound to a fair ordering, eliminating the latency advantage and information asymmetry that enables front-running. This differs from previous approaches by using cryptographic cooperation and time-based fairness to secure the process, which is a necessary integration with existing auction-based economic incentives.
Parameters
- Committee Threshold (t/n) ∞ 7 out of 10. This is the minimum number of decentralized builders required to cooperate and reconstruct the final, valid block body.
- VDF Delay Time ∞ 12 seconds. The mandatory, verifiable time delay imposed by the Verifiable Delay Function to commit the block header, ensuring fair ordering.
Outlook
The immediate next steps involve formalizing the economic incentives for the decentralized builder committee to ensure long-term liveness and honest participation, particularly against rational collusion. This theory unlocks the potential for truly censorship-resistant and fair rollup sequencing within the next three to five years, as rollups can adopt TSS-BC for their own block production. This research opens new avenues for exploring protocol-enforced fairness as a fundamental security primitive, moving beyond purely economic or cryptographic solutions in isolation and integrating them into a cohesive mechanism design.
Verdict
This mechanism represents a foundational shift in blockchain architecture, transforming block production from a centralized point of failure into a robust, cryptographically secured, and decentralized public good.
