> I question whether one could ever design an identity system, or whether it just "happens"
I'm with you. We're trying to get over most of that in Persona by using email address as identifiers, which most people already view as proxies for identities (home, school, work, etc), but time will tell whether or not that belief pans out.
On the other hand, designing authentication systems seems completely tractable. To that end, Mozilla already relies heavily on Persona, so it will continue to exist and work for authentication even if external traction is slow.
I know Persona allows a user to attach multiple email addresses to their Persona identity, but can a user log into a third party service with any of those email addresses and get their same third party account? Alternately, can a user create separate accounts on a third party service that are associated with different email addresses of the single Persona identify?
Persona tries to support the notion of one address == one identity, so the only information you transmit to a site when logging in is "my email address is [email protected], and here's the proof."
To help people manage identities, the Persona UI does allow you to pre-load a bunch of your addresses, but the connections there are never revealed to outside parties. In the future, that information will be managed completely locally in your browser if it has native support for Persona.
I'm with you. We're trying to get over most of that in Persona by using email address as identifiers, which most people already view as proxies for identities (home, school, work, etc), but time will tell whether or not that belief pans out.
On the other hand, designing authentication systems seems completely tractable. To that end, Mozilla already relies heavily on Persona, so it will continue to exist and work for authentication even if external traction is slow.