Case studies for the necessity of the blockchain in self-sovereign identity

Identity management technology has gradually developed and has now evolved into a self-sovereign identity in that the user has all control over his/her authentication information. Blockchain is one of the main technologies to realize SSI, and various SSI services using blockchain have been studied and created. However, it is still ambiguous whether using blockchain for SSI is the best option. Therefore, it is necessary to evaluate whether blockchain is required in SSI and figure out whether there is a better alternative. In this paper, we will analyze and compare two representative blockchain-based SSI systems, uPort and Sovrin, investigate the need for blockchain in those services, and suggest alternatives if necessary.