do you mean archive your contacts log? (their conversations with others) It could be a per user option with new layers of encryption applied to the log at some

do you mean archive your contacts log? (their conversations with others) It could be a per user option with new layers of encryption applied to the log at some slow interval. You would get something like a soft delete that would take n hours to decrypt even if you had the keys. Could gradually make stale conversations harder to decrypt with the oldest messages de hardest. you could have part of your data stored with each contact in decryptable form and the rest stored with them too but in increasingly unreasonable. If enough contacts preserve your data you can easily decode your logs, with less it takes increasingly more cpu cycles.