For instance, if I wanted to run a private Mastodon instance for friends, I could read their PMs. Basically I want a social network where friends exchange keys and posts are encrypted between us. Surely this isn't a new idea.
Ooo. This maybe what is needed to build that. The properties described in the background are perfect for storing encrypted federated social network posts.
@ericmoritz Not only isn't this new, library support is stellar these days; most major languages have bindings to NaCl, which makes it really easy to make keys, encrypt, decrypt, etc: offers clear threat models and makes it hard to screw up. It's never been easier to do crypto correctly.