Both WhatsApp and Signal allow verification of the keys. Signal will error out if you change devices - contacts must manually OK it to continue. I think WA has

Both WhatsApp and Signal allow verification of the keys. Signal will error out if you change devices - contacts must manually OK it to continue. I think WA has this too, maybe? Signal also had some sort of work towards preventing contact list disclosure. At a state level, there's also traffic analysis. If you find Target A then look at their traffic, you might be able to time-coordinate messages sent to other users. (Target->Signal Servers->Recipient) Guess they could take the Signal source and run their own copy of it, too, eh? I'd also add a time-based auto-wipe function to Signal, which is useful if your are suddenly captured. Doing it by hand is tedious, so people don't. Signal doesn't do this because they don't want people to think it implements a secure remote wipe. But they should consider the problem of an activist having their phone recovered. If the app would delete on time, it'd mitigate some damage. Telegram shouldn't be touched.