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：基于有向无环图（DAG）的拜占庭容错（BFT）共识协议因其高吞吐量和抗异步性，在不可信环境下实现一致复制的分布式数据管理系统中引起了广泛关注。然而，现有协议仍存在通信开销高、提交延迟长的问题。同时，引入最小化硬件信任已被证明能有效降低BFT共识的复杂度。受这些工作启发，我们提出Fides—一种基于DAG的异步BFT共识协议。据我们所知，这是首批利用可信执行环境（TEE）同时提升可扩展性与效率的协议之一。Fides能容忍少数拜占庭副本，并借助定制化TEE辅助可靠广播（T-RBC）原语（该原语在单步广播中具有线性通信复杂度），实现了$O(κn^2 + n^3)$元数据通信复杂度。基于T-RBC，Fides通过将连续顶点间的引用要求从$2f+1$降低至$f+1$，重新定义了DAG构建规则。这一新型结构削弱了DAG连接性，并使得传统提交规则失效，因此我们形式化地抽象了该问题，并推导出新的活性理论界。我们进一步提出一种四轮提交规则，实现了理论最低的提交延迟。此外，我们还设计了两个附加原语T-RoundCert和T-Coin，用于高效认证DAG引用并替代先前协议中昂贵的密码学公共硬币。在地理分布式及本地测试平台上的全面评估表明，Fides在保持强安全性与活性保证的同时，显著优于现有最先进协议（包括Tusk、Bullshark、Mysticeti、RCC、Damysus、Achilles及HybridSet），实现了更低延迟与更高吞吐量。