DAG-based BFT consensus has attracted growing interest in distributed data management systems for consistent replication in untrusted settings due to its high throughput and resilience to asynchrony. However, existing protocols still suffer from high communication overhead and long commit latency. In parallel, introducing minimal hardware trust has proven effective in reducing the complexity of BFT consensus. Inspired by these works, we present Fides, an asynchronous DAG-based BFT consensus protocol that, to our knowledge, is among the first to leverage TEEs to enhance both scalability and efficiency. Fides tolerates a minority of Byzantine replicas and achieves $O(κn^2 + n^3)$ metadata communication complexity through a customized TEE-assisted Reliable Broadcast (T-RBC) primitive with linear communication complexity in one-step broadcast. Building on T-RBC, Fides redefines the DAG construction rules by reducing the reference requirement from $2f+1$ to $f+1$ between consecutive vertices. This new structure weakens DAG connectivity and invalidates traditional commit rules, so we formally abstract the problem and derive new theoretical bounds of liveness. We further propose a four-round commit rule that achieves the theoretically minimal commit latency. Besides, we design two additional primitives, T-RoundCert and T-Coin, to efficiently certify DAG references and replace the costly cryptographic common coin used in prior protocols. Comprehensive evaluations on geo-distributed and local testbeds show that Fides substantially outperforms state-of-the-art protocols, including Tusk, Bullshark, Mysticeti, RCC, Damysus, Achilles and HybridSet, achieving lower latency and higher throughput while preserving strong safety and liveness guarantees.

翻译：DAG（有向无环图）拜占庭容错共识凭借其高吞吐量和异步环境下的鲁棒性，在非可信环境下的分布式数据管理系统一致性复制领域引起了广泛关注。然而现有协议仍面临通信开销高、提交延迟长的问题。与此同时，引入最小化硬件可信模块已被证明可有效降低拜占庭容错共识的复杂度。受此启发，我们提出Fides——据我们所知，这是首个利用可信执行环境提升可扩展性与效率的异步DAG拜占庭容错共识协议。Fides可容忍少于半数的拜占庭副本，通过定制化TEE辅助可靠广播原语（T-RBC）实现元数据通信复杂度$O(κn^2 + n^3)$，该原语在一次广播中具有线性通信复杂度。基于T-RBC，Fides重新定义DAG构建规则，将连续顶点间的引用需求从$2f+1$降至$f+1$。这种新结构削弱了DAG连通性并使传统提交规则失效，为此我们对该问题进行了形式化抽象，推导出新的活性理论界，并提出四轮提交规则以实现理论最优的提交延迟。此外，我们设计了T-RoundCert和T-Coin两个附加原语，用于高效认证DAG引用关系并替代先前协议中高成本密码学公共硬币。在地理分布式与本地测试平台上的综合评估表明，Fides在保持强安全性与活性保证的同时，相比Tusk、Bullshark、Mysticeti、RCC、Damysus、Achilles和HybridSet等最先进协议，显著实现了更低的延迟和更高的吞吐量。