Polynomial Multiproofs for Scalable Data Availability Sampling in Blockchain Light Clients

TL;DR

This paper introduces polynomial multiproofs to reduce bandwidth, storage, and verification costs in blockchain light clients by aggregating proofs for multiple data samples, demonstrated in the Avail system.

Contribution

It proposes a novel polynomial multiproof mechanism that aggregates multiple cell evaluations into a single proof, improving efficiency in blockchain light clients.

Findings

Up to 45% reduction in proof bytes and verifier resource usage.

Lower infrastructure costs achieved through proof aggregation.

Trade-offs include grouped retrieval considerations.

Abstract

Light clients are essential for scalable blockchain systems because they verify data availability without downloading full blocks. In data availability sampling based systems, sampled cells are retrieved from a peer-to-peer network and verified against cryptographic commitments. A common deployment pattern associates each sampled cell with an independent Kate-Zaverucha-Goldberg (KZG) proof, creating substantial cumulative bandwidth, storage, and verification overhead. This paper studies polynomial multiproofs (PMP) as a mechanism for reducing these costs in blockchain light clients. We present a design in which multiple sampled cell evaluations are verified using a single aggregated proof over a shared evaluation micro-domain and describe the corresponding changes to proof generation, dissemination, retrieval, and verification in a peer-to-peer light-client stack. We instantiate and evaluate the design in Avail, a modular data availability layer for blockchains, as a case study. The results show lower proof bytes, lower verifier CPU and memory usage, and deployment-level infrastructure cost reductions of up to 45% relative to a per-cell baseline, while also clarifying the trade-offs introduced by grouped retrieval.