Fast intensive validation on blockchain with scale-out dispute resolution

Abstract

Blockchain heralds the dawn of decentralized applications that coordinate proper computations without requiring prior trust. Existing blockchain solutions, however, are incapable of dealing with intensive validation. Duplicated execution results in limited throughput and unacceptably high costs. Furthermore, the absence of secure incentive mechanisms derives undesired dilemmas among rational verifiers.

In this work, we present Lever-FS, a practical blockchain validation framework that makes intensive validation cost-efficient and incentive-compatible among rational verifiers. It is faster than previous constructions since full-fledged scalability is achieved over optimistic execution, dispute resolution, and backbone confirmation of every potential workload. Lever-FS first curtails the scale of each validation to a single node and introduces novel challenge-response games between potential adversaries and rational participants, optimistically optimizing validation redundancy according to the practical adversarial capability confronted. When there is a rich and stubborn adversary, the backstop protocol is then activated to resolve intricate disputes via a threshold voting supported by concurrent redundant executions. Throughout the game, compelling incentive design efficiently transfers the adversary’s budget to proliferated task rewards for subsequent executions, therefore allowing the user to lever sufficient endorsements for the correct verdict with minimum expense. In addition, fair incentive distribution mechanisms are designed to circumvent the well-known Verifier’s Dilemma. Finally, we accelerate Lever-FS with sharding to enable scale-out backbone confirmation, seamless workload balancing, and optimized unanimous assertion across multiple independent validation instances.

Experiments reveal that Lever-FS significantly improves the throughput while lowering expenses of intensive validation with a slight tradeoff in latency. Compared to state-of-the-art alternatives, it removes their brittle reliance on altruism, dense interactions, or massive computational power. It is also robust to conceivable attacks on validation and performs distinguishable ability to purify Byzantine participants.