[antisyzygy]

Estonia has a system for this using blockchains. However, it requires a government agency and proper legislation to implement.

For example, if a hospital wants your health information, you have to manually approve their access over there. The same is true for other information the government stores. Government agencies likewise have to ask for access to information, for example, the equivalent of a DMV would request some personal info before they can obtain it.

[beders]

Yes, nothing here requires blockchains and I do want to manually approve giving my healthcare information to a new provider.

Once given though, all bets are off. They could be selling it. There's no technological solution for that. Just laws.