XML was probably a mistake. Strong, deniable, end-to-end encryption should be mandatory. The Axolotl ratchet is the current state-of-the-art: maybe it does asymmetric things we don't need, or maybe that's helpful.
Looking forward: metadata protection. This is a much more difficult-to-solve problem, but existing tools such as Tor are partially successful.
Looking forward: metadata protection. This is a much more difficult-to-solve problem, but existing tools such as Tor are partially successful.