DeCloak: Enable Secure and Cheap Multi-Party Transactions on Legacy Blockchains by a Minimally Trusted TEE Network

The crucial blockchain privacy and scalability demand has boosted off-chain contract execution frameworks for years. Some have recently extended their capabilities to transition blockchain states by off-chain multi-party computation while ensuring public verifiability. This new capability is defined as acrfull mpt. However, existing MPT solutions lack at least one of the following properties crucially valued by communities: data availability, financial fairness, delivery fairness, and delivery atomicity. This paper proposes a novel MPT-enabled off-chain contract execution framework, Decloak. Using TEEs, Decloak solves identified properties with lower gas costs and a weaker assumption. Notably, Decloak is the first to achieve data availability and also achieve all of the above properties. This achievement is coupled with its ability to tolerate all-but-one Byzantine parties and TEE executors. Evaluating 10 MPTs in different businesses, Decloak reduces the gas cost of the SOTA, Cloak, by 65.6%. This efficiency advantage further amplifies with an increasing number of MPT's parties. Consequently, we establish an elevated level of secure and cheap MPT, being the first to demonstrate the feasibility of achieving gas costs comparable to Ethereum transactions while evaluating MPTs.