Convincing people to use apps such as Signal is hard work and most can’t be convinced. But with those you manage to convince, do you feel happy to talk to them on Signal?
The problem is these people use Signal on Android/IOS which can’t be trusted and IOS has recently been in the news for having a backdoor. And it has also been revealed that american feds are able to read everyone’s push notifications and they do this as mass surveillance.
So not only do you have to convince people to use Signal which is an incredibly difficult challenge. You also have to convince them to go into settings to disable message and sender being included in the push notifications. And then there’s the big question is the Android and IOS operating systems are doing mass surveillance anyway. And many people find it taking a lot of effort to type on the phone so they install Signal on the computer which is a mac or Windows OS.
So I don’t think I feel comfortable sending messages in Signal but it’s better than Whatsapp.
These were some thoughts to get the discussion started and set the context.
There are indeed shades of grey. Not only the presence of encryption itself matters, but the metadata, as well as details of the implementation. For example, Signal has all the messages encrypted - but it has the capability to know the identities of everyone and to build their social graph due to centralization.