Proofs of Writing for Efficient and Robust Storage
The authors 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. Furthermore, 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 they show optimal).