The metaverse refers to a virtual world that mirrors the real world, constructed based on technologies such as the Internet, extended reality, blockchain, and artificial intelligence. To enter the metaverse, users must have a digital avatar, i.e., a virtual identity. In metaverse services, identity authentication is a crucial element to ensure the trustworthiness of services. However, the virtual avatars or physical devices in the metaverse cannot determine the uniqueness of an entity’s identity. Moreover, the diversity of services in the metaverse makes it difficult to link identities across different scenarios, leading to the need for repeated authentication. Therefore, this paper proposes a distributed digital identity authentication scheme for the metaverse. We construct a dual-factor metaverse identity model based on Self-Sovereign Identity (SSI) and propose a scalable chain-based identity identifier using the Chameleon Signature Algorithm. Finally, we design a simulation experiment to test the efficiency and security of the scheme.