POSE: Practical Off-chain Smart Contract Execution

TL;DR

POSE introduces a practical off-chain smart contract execution protocol utilizing Trusted Execution Environments to reduce costs, enhance privacy, and improve robustness compared to existing solutions.

Contribution

The paper presents POSE, a novel off-chain smart contract protocol that overcomes limitations of current solutions by using TEEs for secure, efficient, and resilient execution.

Findings

POSE reduces blockchain interaction costs significantly.

The protocol ensures strong security even with many corrupted parties.

Implementation shows high efficiency and robustness.

Abstract

Smart contracts enable users to execute payments depending on complex program logic. Ethereum is the most notable example of a blockchain that supports smart contracts leveraged for countless applications including games, auctions and financial products. Unfortunately, the traditional method of running contract code on-chain is very expensive, for instance, on the Ethereum platform, fees have dramatically increased, rendering the system unsuitable for complex applications. A prominent solution to address this problem is to execute code off-chain and only use the blockchain as a trust anchor. While there has been significant progress in developing off-chain systems over the last years, current off-chain solutions suffer from various drawbacks including costly blockchain interactions, lack of data privacy, huge capital costs from locked collateral, or supporting only a restricted set of applications. In this paper, we present POSE -- a practical off-chain protocol for smart contracts that addresses the aforementioned shortcomings of existing solutions. POSE leverages a pool of Trusted Execution Environments (TEEs) to execute the computation efficiently and to swiftly recover from accidental or malicious failures. We show that POSE provides strong security guarantees even if a large subset of parties is corrupted. We evaluate our proof-of-concept implementation with respect to its efficiency and effectiveness.