Proofs of Writing for Efficient and Robust Storage

TL;DR

PoWerStore is an efficient, robust storage protocol that guarantees linearizability and fault tolerance without digital signatures, using lightweight cryptography, erasure coding, and Proofs of Writing to optimize latency.

Contribution

It introduces PoWerStore, the first storage protocol combining optimal latency, robustness against Byzantine faults, and cryptographic proofs without digital signatures.

Findings

Achieves 2-round latency in single-writer variant, proven optimal.

Supports multi-writer variant with 3-round reads/writes, only invoked under attack.

Outperforms existing robust storage protocols in efficiency and fault tolerance.

Abstract

We present PoWerStore, the first efficient robust storage protocol that achieves optimal latency without using digital signatures. PoWerStore's robustness comprises tolerating asynchrony, maximum number of Byzantine storage servers, any number of Byzantine readers and crash-faulty writers, and guaranteeing wait-freedom and linearizability of read/write operations. PoWerStore's efficiency stems from combining lightweight authentication, erasure coding and metadata write-backs where readers write-back only metadata to achieve linearizability. At the heart of PoWerStore are Proofs of Writing (PoW): a novel storage technique based on lightweight cryptography. PoW enable reads and writes in the single-writer variant of PoWerStore to have latency of 2 rounds of communication between a client and storage servers in the worst-case (which we show optimal). We further present and implement a multi-writer PoWerStore variant featuring 3-round writes/reads where the third read round is invoked only under active attacks, and show that it outperforms existing robust storage protocols, including crash-tolerant ones.