2 The basic building blocks of SSI


Drummond Reed, Rieks Joosten, and Oskar van Deventer

    To help describe the core components of SSI architecture, we enlisted two of the leaders in SSI in Europe: Rieks Joosten and Oskar van Deventer of TNO, the Netherlands Organization for Applied Scientific Research. Rieks is a senior scientist focused on business information processes and information security. Oskar is a senior scientist for blockchain networking. Together, they are two of the founders of the European SSI Framework Laboratory (ESSIF-Lab).

    As we explained in chapter 1, SSI is relatively new, having only emerged onto the internet stage in 2016. At one level, SSI is a set of principles about how identity and personal data control should work across digital networks. At another level, SSI is a set of technologies that build on core concepts in identity management, distributed computing, blockchain or distributed ledger technology (DLT), and cryptography.

    In many cases, these core concepts have been established for decades. What’s new is how they are put together to create a new model for digital identity management. The purpose of this chapter is to quickly familiarize you from a conceptual point of view with seven basic building blocks of SSI before we show how they are applied to different example scenarios in chapter 3. These seven building blocks are as follows:

    2.1 Verifiable credentials

    2.2 Issuers, holders, and verifiers

    2.3 Digital wallets

    2.4 Digital agents

    2.5 Decentralized identifiers (DIDs)

    2.6 Blockchains and other verifiable data registries

    2.7 Governance frameworks

    2.8 Summarizing the building blocks