# 3 Example scenarios of how SSI works

by Drummond Reed and Daniel Hardman

In chapter 2 we examined the core building blocks of SSI. In this chapter we’ll show you how these building blocks are put together to implement SSI in seven example scenarios that progress from the very simple to the reasonably complex:

- Alice and Bob form a connection after meeting in person at a conference.
- Alice and Bob form a connection via Alice’s blog.
- Bob logs into Alice’s blog to leave a comment.
- Alice and Bob form a connection by meeting through an online dating site.
- Alice applies for a bank account.
- Alice buys a car.
- Alice sells the car to Bob.

Each scenario illustrates basic patterns of SSI usage that you will see repeated in the many industry--specific SSI scenarios we will be exploring in Part Two.

## 3.1 A simple notation for SSI scenario diagrams

First, we want to introduce a simple notation for the diagrams in this chapter—a notation that illustrates how conceptually easy it is to apply SSI technology to standard business problems (even though there is real rocket science in the underlying cryptography and protocols). Our notation is inspired by the simple connector-style toys that can be found in almost any child’s playroom.