The introduction of Bitcoin fueled the development of blockchain-based resilient data management systems that are resilient against failures, enable federated data management, and can support data provenance. The key factor determining the performance of such resilient data management systems is the consensus protocol used by the system to replicate client transactions among all participants. Unfortunately, existing high-throughput consensus protocols are costly and impose significant latency on transaction processing, which rules out their usage in responsive high-performance data management systems. In this work, we improve on this situation by introducing the Proof-of-Execution consensus protocol ( PoE ), a consensus protocol designed for high-performance low-latency resilient data management. PoE introduces speculative execution , which minimizes latency by starting execution before consensus is reached, and PoE introduces proof-of-executions to guarantee successful execution to clients. Furthermore, PoE introduces a single-round check-commit protocol to reduce the overall communication costs of consensus. Hence, we believe that PoE is a promising step towards flexible general-purpose low-latency resilient data management systems.

Decentralized systems built around blockchain technology promise clients an immutable ledger. They add a transaction to the ledger after it undergoes consensus among the replicas that run a Proof-of-Stake (PoS) or Byzantine Fault-Tolerant (BFT) consensus protocol. Unfortunately, these protocols face a long-range attack where an adversary having access to the private keys of the replicas can rewrite the ledger. An existing solution to this problem forces each committed block from these protocols to undergo another consensus, Proof-of-Work (PoW) consensus; POW protocol wastes computational resources as miners compete to solve complex puzzles. In this paper, we present the design of our Power-of-Collaboration (POC) protocol, which guards existing POS/BFT blockchains against long-range attacks and requires miners to collaborate rather than compete. POC guarantees fairness and accountability and only marginally degrades the throughput of the underlying system.