How high-latency can a gnunet-conversation be? It seems once you do the initial ECDH handshake to get a shared secret, you could keep that secret around pretty much forever. I was thinking of a UI where conversations were like email exchanges, where you could compose it at your leisure, and reply whenever. Is that feasible?
I know in theory if we both have a shared secret, then if I publish a gnunet-fs://ksk record with that secret as the keyword, then you're the only one who can find it, the only one who can decrypt it, and we might not even have to be online at the same time because intermediate nodes can cache it. But I don't think gnunet-conversation uses ksk records? It just sends encrypted data through temporary tunnels that require low latency and simultaneous presence online, right?
If so, would it be good to augment gnunet-conversation to use KSK records as a backup to synchronize unsent messages, when tunnel establishment fails? Or would it be better to have a different "private message" service entirely, that only used gnunet-fs? Can a diffie-hellman key exchange be performed over gnunet-fs without some crippling security failure?