The current Self-Sovereign Identity (SSI) ecosystem is rapidly changing and ill-defined. Manifold actors, projects, and initiatives produce different SSI solutions, frameworks, protocols, and distributed ledgers. Even though some patterns exist among SSI ecosystem members, no elaborate systematization has been made. This paper conducts a systematic gray literature review to structure the SSI ecosystem. Specifically, we derive a four-dimensional taxonomy that portrays members of the SSI ecosystem. Then, we classify the ecosystem members into eight archetypes. The goals are to allow researchers to describe SSI ecosystem members, help new and existing members locate themselves within the SSI ecosystem, and provide an overview of members’ functionalities. We find that SSI ecosystem members either govern the SSI ecosystem and/or networks, implement SSI offerings, or support governing and/or implementing members. The study suggests that, as the SSI ecosystem grows, the number of governing members will grow slower than the number of implementing and supporting members.

The Self-Sovereign Identity (SSI) paradigm postulates global unique identities that are controlled by the user. To achieve a widespread applicability, the emphasized interoperability principle supports the proclaimed ambition. Furthermore, identity portability enables the transfer of the identity to another SSI solution. These axioms gain additional momentum due to the development of numerous implementations. In this paper, we examine interoperability and portability concepts for SSI. Initially, we define these principles regarding the blockchain-based SSI model. Subsequently, we outline assessment criteria considering functional scope, governance/ trust, scalability and further characteristics. For interoperability, we evaluate the concepts of protocol and standard, broker, hub and pairing. Besides that, we assess the transformer and auxiliary solutions for portability. We can conclude that all interoperability schemes provide the maximum functional level theoretically. In contrast, portability patterns are fragmented in this regard. Nonetheless, protocol and standards can only be applied in the design phase, whereas broker, hub, pairing, transformer and auxiliary solutions enable interoperability, respectively portability post-deployment of the SSI system.

The self-sovereign identity management model emerged with the rise of blockchain technology. This paradigm focuses on user-centricity and strives to place the user in full control of the digital identity. Numerous implementations embrace the self-sovereign identity concept, leading to a fragmented landscape of solutions. At the same time, traditional identity and access management protocols are largely disregarded and facilities to issue verifiable claims as attributes are not available. Therefore, service providers barely adopt these solutions. We propose a component-based architecture for integrating self-sovereign identity solutions into web applications to foster their adoption by service providers. Furthermore, we outline a sample implementation as a gateway that enables uPort and Jolocom for authentication, via the OpenID Connect protocol, as well as the retrieval of email address attestations for these solutions.