I use telegram on a day to day basis, but calling it "secure" is quite a bit of a stretch. But it is quite possibly the best app I have used in regards to user expetience.
But until signal actually produced a usable (to the average person) app, people will continue to use telegram and other insecure chat platforms.
But until signal actually produced a usable (to the average person) app, people will continue to use telegram and other insecure chat platforms.