The emerging Self-Sovereign Identity (SSI) techniques, such as Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs), move control of digital identity from conventional identity providers to individuals and lay down the foundation for people, organizations, and things establishing rich digital relationship. The existing applications of SSI mainly focus on creating person-to-person and person-to-service relationships, whereas person-to-device and device-to-device interactions have been largely overlooked. In this paper, we close this gap by identifying a number of key challenges of applying SSI to the Internet of Things (IoT) and providing a comprehensive taxonomy and usage of VCs in the IoT context with respect to their validity period, trust and interoperability level, and scope of usage. The life-cycle management of VCs as well as various optimization techniques for realizing SSI in IoT environments are also addressed in great detail. This work is a noteworthy step towards massive adoption of SSI for securing existing and future IoT applications in practice.

翻译：新兴的自主主权身份（SSI）技术，例如去中心化标识符（DIDs）和可验证凭证（VCs），将数字身份的控制权从传统身份提供者转移至个人，为人员、组织及实体间建立丰富的数字关系奠定了基础。现有SSI应用主要聚焦于创建人与人、人与服务之间的关系，而人与设备、设备与设备之间的交互在很大程度上被忽视。本文通过识别将SSI应用于物联网（IoT）所面临的一系列关键挑战，并在有效期、信任与互操作级别以及使用范围方面，提供了物联网背景下VCs的综合分类与使用方法，从而弥补了这一空白。本文还详细探讨了VCs的生命周期管理以及实现物联网环境中SSI的各种优化技术。这项工作对于推动SSI大规模应用于保障现有及未来物联网应用安全具有里程碑意义。