Decentralized storage systems face a fundamental trade-off between replication overhead, recovery efficiency, and security guarantees. Current approaches either rely on full replication, incurring substantial storage costs, or employ trivial erasure coding schemes that struggle with efficient recovery especially under high storage-node churn. We present Walrus, a novel decentralized blob storage system that addresses these limitations through multiple technical innovations. At the core of Walrus is RedStuff, a two-dimensional erasure coding protocol that achieves high security with only 4.5x replication factor, while enabling self-healing recovery that requires bandwidth proportional to only the lost data $(O(|blob|/n)$ versus $O(|blob|)$ in traditional systems). Crucially, RedStuff is the first protocol to support storage challenges in asynchronous networks, preventing adversaries from exploiting network delays to pass verification without actually storing data. Walrus also introduces a novel multi-stage epoch change protocol that efficiently handles storage node churn while maintaining uninterrupted availability during committee transitions. Our system incorporates authenticated data structures to defend against malicious clients and ensures data consistency throughout storage and retrieval processes. Experimental evaluation demonstrates that Walrus achieves practical performance at scale, making it suitable for a wide range of decentralized applications requiring high-integrity, available blob storage with reasonable overhead.

翻译：去中心化存储系统面临着复制开销、恢复效率与安全保证之间的根本性权衡。现有方法要么依赖完全复制，导致巨大的存储成本；要么采用简单的纠删码方案，难以实现高效恢复，尤其在存储节点高流失率的情况下。本文提出Walrus，一种新颖的去中心化块存储系统，通过多项技术创新解决了这些局限性。Walrus的核心是RedStuff——一种二维纠删码协议，仅需4.5倍复制因子即可实现高安全性，同时支持仅与丢失数据量成正比的自我修复恢复（$O(|blob|/n)$，而传统系统为$O(|blob|)$）。关键的是，RedStuff是首个支持异步网络中存储挑战验证的协议，可防止攻击者利用网络延迟通过验证却未实际存储数据。Walrus还提出了一种新颖的多阶段纪元切换协议，能高效处理存储节点流失，并在委员会切换期间保持服务不中断。本系统采用认证数据结构防御恶意客户端，并确保数据在存储与检索全过程中的一致性。实验评估表明，Walrus在大规模场景下具备实用性能，适用于各类需要高完整性、高可用性且开销合理的去中心化块存储应用。