Decentralized Identity Management and Blockchains: Design Patterns and Architectures

Securely and efficiently managing digital identities is a pre-requisite to enabling prosperous digital service economy underpinned by trust. The concept of digital identity goes beyond just providing a credential for logins. A truly effective digital identity scheme should be able to model the observations that people, throughout their life, tend to carry many different senses of “identities” (or personas) and each identity is fused with different sets of personal artefacts overtime. Of course, digitizing all aspects of a person’s identity must be supported by the highest level of security and privacy protection possible. A decentralized identity management aims to provide an individual with a platform to manage multiple identities and associated artefacts for different contexts. More importantly, the users will exert full control over their identities in terms of when and with whom the identity is formed and shared with others, without having to rely on a centralised identity provider. A distributed ledger technology like blockchain can play a vital role in the design and implementation of a decentralised identity management scheme. Indeed, a decentralised identity management scheme such as self-sovereign identity (SSI) has been acclaimed the “killer app of Blockchain”. This chapter aims to introduce the foundational concept and motivation of decentralised identity management, examine the current state of the art and present a set of software design patterns that could help guide the designers and developers of decentralised identity management systems.