Learning Digital Identity

Chapter 14. Cryptographic Identifiers

As you learned in Chapter 10, identifiers are meaningful within a specific namespace. We need namespaces to confer context to the identifiers, because the same string of characters might be a phone number in one system and a product ID in another.

Take an email address like [e-mail], for example. The identifier windley is contextualized by the mail domain example.com. If I just gave you the string windley, without any further context, you’d have a tough time associating it with anything in particular. If I said @windley, you might guess it was a Twitter handle—but the convention of putting @ before identifiers has become standard in other applications, so you can’t be sure. Before you can be certain that I’m talking about a Twitter identifier, I must give you the entire URL: http://twitter.com/windley.

The context makes the identifier meaningful. You can use my Twitter identifier to view my profile or follow me. Most of the identifiers in common use are context first: the context (Twitter, in this example) already exists and the identifier gets created within that context, usually when someone creates an account and specifies an identifier. Because they are context first, traditional identifiers are controlled by the organization that controls the namespace. Twitter, for example, can suspend any account, making the identifier unusable or even assigning it to someone else. You have little recourse if that happens.

This becomes a ...