RaceTEE: A Practical Privacy-Preserving Off-Chain Smart Contract Execution Architecture

Abstract: Decentralized on-chain smart contracts enable trustless collaboration, yet their inherent data transparency and execution overhead hinder widespread adoption. Existing cryptographic approaches incur high computational costs and lack generality. Meanwhile, prior TEE-based solutions suffer from practical limitations, such as the inability to support inter-contract interactions, reliance on unbreakable TEEs, and compromised usability. We introduce RaceTEE, a practical and privacy-preserving off-chain execution architecture for smart contracts that leverages Trusted Execution Environments (TEEs). RaceTEE decouples transaction ordering (on-chain) from execution (off-chain), with computations performed competitively in TEEs, ensuring confidentiality and minimizing overhead. It further enhances practicality through three key improvements: supporting secure inter-contract interactions, providing a key rotation scheme that enforces forward and backward secrecy even in the event of TEE breaches, and enabling full compatibility with existing blockchains without altering the user interaction model. To validate its feasibility, we prototype RaceTEE using Intel SGX and Ethereum, demonstrating its applicability across various use cases and evaluating its performance.