Information Dispersal with Provable Retrievability for Rollups

The ability to verifiably retrieve transaction or state data stored off-chain is crucial to blockchain scaling techniques such as rollups or sharding. We formalize the problem and design a storage- and communication-efficient protocol using linear erasure-correcting codes and homomorphic vector commitments. Motivated by application requirements for rollups, our solution Semi-AVID-PR departs from earlier Verifiable Information Dispersal schemes in that we do not require comprehensive termination properties. Compared to Data Availability Oracles, under no circumstance do we fall back to returning empty blocks. Distributing a file of 22 MB among 256 storage nodes, up to 85 of which may be adversarial, requires in total ~70 MB of communication and storage, and ~41 seconds of single-thread runtime (