2 Understanding digital identity

 

This chapter covers

  • How identity supports digital relationships
  • Why naming matters for authorization
  • What centralized, federated, and decentralized models are
  • Tradeoffs among privacy, authenticity, and confidentiality
  • Why trust and confidence both matter

Imagine you’re a regular at a neighborhood café. Every morning, you walk in and the barista greets you by name. She remembers your usual order—a double espresso, no sugar. This recognition isn’t just about knowing your name; it’s about the relationship you’ve built through repeated interactions.

One day, the café switches to a new self-service kiosk for ordering. The machine doesn't know you, and it doesn't remember your order. It asks you to sign up, create an account, and log in. Suddenly, the familiar experience of being recognized is gone, replaced by a system that knows you only through an identifier and a set of attributes.

What changed? Your identity at the café was once relational and human, tied to memory, interaction, and trust. Now, in the digital system, you have been reduced to credentials and stored preferences. The system recognizes your account, not you. Depending on its sophistication, the digital system may give the impression it knows you, but its personalization efforts will often fall short. This scenario illustrates a fundamental question in digital identity: Are we just a set of attributes, or does identity mean something more?

2.1 What is digital identity?

2.2 The problems of digital identity

2.2.1 The proximity problem

2.2.2 The interoperability problem

2.2.3 The flexibility problem

2.2.4 The privacy problem

2.2.5 The consent problem

2.2.6 The scale problem

2.2.7 How identity problems affect authorization

2.3 Identity and digital relationships

2.3.1 Types of digital relationships

2.3.2 Digital relationship properties

2.4 Naming and discovery

2.4.1 The role of names in digital identity

2.4.2 Tradeoffs in identity naming

2.4.3 Namespaces and their role in identity

2.5 Identity system models

2.5.1 Centralized identity: single authority, high control

2.5.2 Federated identity: the backbone of modern identity systems

2.5.3 Decentralized identity: shifting control to users

2.6 Trust and confidence

2.6.1 The difference between trust and confidence

2.6.2 Trust and confidence in digital relationships

2.6.3 Technical confidence in identity systems

2.6.4 The limits of technical confidence

2.7 Privacy, authenticity, and confidentiality

2.7.1 Distinguishing privacy from confidentiality

2.7.2 Managing tradeoffs

2.7.3 Functional privacy

2.8 From identity to authentication

2.9 Summary