Like FB implemented as Signal on steroids, when I add a friend I exchange keys to open up a channel with him to enable him to see posts/photos etc from my life, but the org (say FB) itself cannot see any of this data.
Not sure how blockchain will fit in here though or enhance this
All of these things can be done with trusted intermediaries, but when you start considering use cases such as - being in china and needing to allow a chinese hospital to access your records back in the USA, suddenly these things become important.
For example, how are you defining trustless? Personal data systems needs to be based on trust and reputation (otherwise you’ll have a bunch of 4chaners spamming claims about you) so are you simply thinking tamper-evidence and non-repudiation? That’d raise the questions of why this would be better than PKI, Merkel trees, etc.
All of the other claims hit similar problems: e.g. you can’t store the data in a blockchain and make any of those promises, and it’s not clear how useful a shared index or log would be when you can’t trust all of the participants.
Another fatal flaw is the lost of control and inability to correct mistakes. If there’s ever a vulnerability all of that data is irrecoverably public. What organization is going to turn control of something they get sued for over to an entity they don’t control? “They told us the software was perfect” doesn’t seem like a good HIPAA defense tactic to me.