On the role of blockchain for self-sovereign identity

Self-sovereign identity (SSI) is a model for digital identity in which users control their identity. Users are issued with credentials and can use such credentials to construct verifiable proofs of identity to a third party. Typically, blockchain technologies are leveraged to implement a verifiable data registry, which is a constituent part of the SSI architecture. It is often suggested that blockchain enables the decentralised and trusted ecosystem required for an SSI system. We evaluate whether blockchain can provide the necessary decentralisation and trust. We argue that blockchain has the potential to enable this ecosystem, but this is dependent on the type of blockchain used to implement an SSI system. Moreover, with respect to trust, we argue that blockchain alone is not sufficient and must be accompanied with other mechanisms to provide a trusted ecosystem for SSI systems.