Sadly the interesting stuff I found was behind paywalls. I just found it interesting in its approach.

I’ve done a few rounds of search on the topic as I see it as the base for a whole lot of stuff (in my case decentralized academic accreditation) but I’d say from what is available freely nobody has cracked it, and there are some pretty horrible ideas floating.

Probably the people having done the most work on this are cybersecurity firms, they looked at assessing the true nature of their online adversaires. Some seem quite satisfied with their models. But they have they own metrics, which do not translate well into other areas.