Chenyang Liu 刘晨阳

We present Quintus, information-theoretic BFT protocols for tolerating f < n/5 Byzantine faults among n parties. We present two protocols: The first protocol, Quintus-Fixed, is in a fixed view regime where views advance at a cadence 3∆time. This protocol incurs a good-case latency of 2δtime where δindicates actual network delay and message complexity of O(n^2) in a view. The second protocol, Quintus-Responsive, is an optimistically responsive protocol with good-case latency of 2δtime, O(n^2) message complexity, and 2∆+ 2δworst-case view latency where ∆denotes a pessimistic network delay parameter under synchrony.

Proposer-Builder Separation (PBS) in Ethereum aims to improve decentralization and scalability by offloading block construction to specialized builders, but its current MEV-Boost implementation relies on trusted relays, introducing centralization as well as security and performance concerns. We propose Decentralized Proposer-as-a-Service (DPaaS) to eliminate relays while preserving compatibility with Ethereum’s consensus layer by distributing the combined proposer and relay roles across Proposer Entities (PEs) running in independent Trusted Execution Environments (TEEs). DPaaS presents itself to Ethereum as a single validator using threshold BLS signatures, while a new Byzantine broadcast protocol decentralizes the auctioneer role with censorship-resistance and availability-backed guarantees. Our evaluation, deployed across four independent cloud hosts and driven by real-world traces, shows that DPaaS achieves ≤6 ms bid processing latency, 68.7 ms latency from the end of auction to block proposal, and 3.3% more MEV earnings, demonstrating that DPaaS can offer security, decentralization, and trustworthiness benefits while providing strong performance.

Trusted Execution Environments (TEE) have been widely adopted as a protection approach for security-critical applications. Although feature extensions have been previously proposed to improve the usability of enclaves, their provision patterns are still confronted with security challenges. This paper presents Palantir, a verifiable multi-layered inter-enclave privilege model for secure feature extensions to enclaves. Specifically, a parent-children inter-enclave relationship, with which a parent enclave is granted two privileged permissions, the Execution Control and Spatial Control, over its children enclaves to facilitate secure feature extensions, is introduced. Moreover, by enabling nesting parent-children relationships, Palantir achieves multi-layered privileges (MLP) that allow feature extensions to be placed in various privilege layers following the Principle of Least Privilege. To prove the security of Palantir, we verified that our privilege model does not break or weaken the security guarantees of enclaves by building and verifying a formal model named TAP^∞. Furthermore, We implemented a prototype of Palantir on Penglai, an open-sourced RISC-V TEE platform. The evaluation demonstrates the promising performance of Palantir in runtime overhead and startup latencies.