@Alex I have encryption and authentication working now. See https://github.com/mirage/capnp-rpc#networking for the current state.
It’s not clear exactly what the persistence API should look like. I’ve asked on the capnp group at https://groups.google.com/forum/#!topic/capnproto/d6uPbXf9e4E for suggestions. If there isn’t a standard yet, I’ll define a basic SturdyRef structure and a restorer interface that can be used as your bootstrap service.