Earlier quoted context omitted.
> and it's ok to leak metadata? How could Signal (or other client-server protocol) not leak metadata? It is true that OpenPGP leaks more metadata than necessary (e.g. Subject), but seems to me that any efficient message protocol needs to leak at least three most important metadata - source, destination, time. One could avoid leaking destination by broadcasting encrypted to many receivers (when only the true one can d…
Signal has been working on features like "sealed sender", which encrypts the source metadata: https://signal.org/blog/sealed-sender/ I don't know if they can do anything about destination or time, but even hiding the source seems like a significant advancement.
The post mentions some kind of "short-lived" pseudo-sender, which is vulnerable to the same metadata analysis.