ODYSSEY: Reestablishing Confidentiality in Confidential Blockchain via Delegated Execution

2026-06-03

AI Summary

This work addresses execution inference and replay attacks in consortium blockchains arising from side-channel leaks and state continuity within Trusted Execution Environments (TEEs). To mitigate these threats, the authors propose a delegated execution model wherein clients entrust transaction execution to a designated node while other nodes merely synchronize the resulting outputs. This architecture integrates location-aware concurrent execution with a robust delegation failure handling mechanism, significantly reducing the attack surface and preserving transaction confidentiality without compromising performance. A prototype implementation built on FISCO BCOS achieves approximately 4,000 transactions per second (TPS) throughput with latencies as low as 0.4–0.5 seconds in a three-node wide-area network deployment.

Abstract

Confidential blockchains leveraging Trusted Execution Environments (TEEs) have garnered extensive attention for transaction confidentiality. In this paper, we first taxonomize two classes of attacks against confidential blockchains, i.e., execution-inference and execution-replay attacks, which exploit TEEs' long-lasting side-channel and state-continuity issues to compromise the confidentiality of existing consortium blockchains. Then, we present ODYSSEY, a confidential blockchain that efficiently mitigates these attacks. The core innovations of ODYSSEY are the following: (1) Its delegation model: clients delegate transaction execution to their designated trustees, while other participants synchronize only the execution results, which significantly reduces the attack surface while preserving confidentiality and system performance. (2) Two novel techniques to improve ODYSSEY's efficiency and security: location-aware concurrent execution and delegation failure handler. Finally, we develop a prototype of ODYSSEY on FISCO BCOS, an enterprise-grade consortium blockchain platform. We have conducted various experiments, and our evaluation results show that in a WAN environment with 3 nodes, ODYSSEY can achieve about 4k throughput while keeping latency as low as 0.4-0.5s.

Problem

• confidential blockchain
• Trusted Execution Environments
• execution-inference attack
• execution-replay attack
• transaction confidentiality

Innovation

• Trusted Execution Environments
• Delegated Execution
• Confidential Blockchain
• Side-channel Attacks
• Concurrent Execution