This paper presents a novel reference architecture for blockchain-enabled federated learning (BCFL), a state-of-the-art approach that amalgamates the strengths of federated learning and blockchain technology.We define smart contract functions, stakeholders and their roles, and the use of interplanetary file system (IPFS) as key components of BCFL and conduct a comprehensive analysis. In traditional centralized federated learning, the selection of local nodes and the collection of learning results for each round are merged under the control of a central server. In contrast, in BCFL, all these processes are monitored and managed via smart contracts. Additionally, we propose an extension architecture to support both crossdevice and cross-silo federated learning scenarios. Furthermore, we implement and verify the architecture in a practical real-world Ethereum development environment. Our BCFL reference architecture provides significant flexibility and extensibility, accommodating the integration of various additional elements, as per specific requirements and use cases, thereby rendering it an adaptable solution for a wide range of BCFL applications. As a prominent example of extensibility, decentralized identifiers (DIDs) have been employed as an authentication method to introduce practical utilization within BCFL. This study not only bridges a crucial gap between research and practical deployment but also lays a solid foundation for future explorations in the realm of BCFL. The pivotal contribution of this study is the successful implementation and verification of a realistic BCFL reference architecture. We intend to make the source code publicly accessible shortly, fostering further advancements and adaptations within the community.

翻译：本文提出了一种面向区块链使能的联邦学习（BCFL）的新型参考架构，该架构融合了联邦学习与区块链技术的优势，代表了当前最先进的技术路线。我们明确定义了智能合约功能、利益相关方及其角色，以及星际文件系统（IPFS）作为BCFL关键组件的应用，并进行了全面分析。在传统集中式联邦学习中，本地节点的选取及各轮学习结果的收集均由中央服务器统一控制。相比之下，在BCFL中，所有这些流程均通过智能合约进行监控与管理。此外，我们提出了一种扩展架构，以同时支持跨设备与跨孤岛的联邦学习场景。更进一步，我们基于实际以太坊开发环境对架构进行了实现与验证。所提出的BCFL参考架构具备显著的灵活性与可扩展性，能够根据具体需求和应用场景集成各类附加组件，从而成为适用于广泛BCFL应用的适配性解决方案。作为可扩展性的典型案例，分散标识符（DIDs）被用作一种认证方法，为BCFL引入了实际应用价值。本研究不仅弥合了研究与实践部署之间的关键鸿沟，也为未来BCFL领域的探索奠定了坚实基础。本研究的核心贡献在于成功实现并验证了一个真实的BCFL参考架构。我们计划于近期公开源代码，以期促进社区内的进一步创新与适配。