Yeah, identity is a very crucial and difficult topic, which I did ignore in that post. Reason being: in my experience, as soon as you start about identity, it takes up everything. So I have made a couple of assumptions about authentication and identity; this is what we could build on top of that.
Here are some excellent links about the subjects:
http://www.moxytongue.com/2016/02/self-sovereign-identity.ht... http://www.lifewithalacrity.com/2016/04/the-path-to-self-sov... https://en.wikipedia.org/wiki/Digital_identity https://blog.cryptographyengineering.com/2017/07/02/beyond-p... https://pages.nist.gov/800-63-3/ https://www.forgerock.com/