For open source messengers, you can check whether they actually encrypt your messages and whether the server has access to your encryption keys but what about WhatsApp? Since it's not open source, you can't be sure that the encryption keys aren't sent to the server, right? Has there been a case where a government was able to access WhatsApp chats without reading them from the phone itself?
You bet your ass they can. Since when has Facebook taken anybody's privacy seriously? And you remember all the Snowden leaks? Like how AT&T has been a government apparatus for spying for decades? Or how about the way that the USA taps under sea cables to monitor data, causing China to build totally parallel backbone infrastructure
The better question is whether Signal, despite being open source, is actually secure. It's very plausible that the govt has backdoors somewhere, for either encryption, the OS, the programming language, the app store, or some random dependency lib
The answer is yes, the US government spies on everything, and has a complete profile of everyone
Well, in my comment I describe quite a number of methods. It doesn't matter how secure or reviewed signal is, if the feds have a keylogger at the OS or compiler level. It's really unbelievable how much code is involved in day to day security
Nah, the OS has proprietary overlays that vendors put in there. And it's not like you're reviewing and compiling your own software - you're dependent on your provider to be honest with the software they actually installed. But factually you have no idea if the android phone you purchased has been modified. And Android itself is so huge that backdoors can be sneaky. We have already caught several instances of attempted backdoors in Linux - but there's always the fear we didn't find them all
If this all sounds way too paranoid, then review Snowden leaks