2017-11-13: I couldn’t convince anyone to try Surespot with me. I’m still using Whatsapp and Telegram regularly.
I am interested in encrypting as much of my communication as possible, so I looked for a Whatsapp alternative.
Note that since I began my little research Open WhisperSystems teamed up with Whatsapp and claims that the Android client already uses end-to-end encryption now. The issue of encryption in closed-source software remains. See the comments on the whispersystems blog.
A good overview from February was written by Roman Lehnhof. In the following, I mainly comment on his selection and add surespot to the list which I consider to be the only real option at this point.
Switzerland-based Threema uses the most promising protocol and I want to like it for that. It does charge a fee and most importantly, it is not open source or a standard of any kind. This makes security validation pretty much impossible.
Telegram, which is the second largest service after Whatsapp, is backed by a non-profit organization in the background. It’s free and available for both Android and iOS. It claims that it uses an open-source protocol, but - again - this cannot be verified by outsiders since the software overall is closed source.
TextSecure is the Android app from Open WhisperSystems and encrypts not only messages, but phone calls as well. It is open source and looks promising. I did not test it because it does not have an iOS version at the moment and I refuse to half my circle of friends for software reasons.
surespot is another open source alternative for both Android and iOS. We installed and tested it, but it felt clunky. The notifications don’t include what was written and the smileys are more tricky to access. Mostly, I guess I have just gotten used to Whatsapp, so it felt unfamiliar. Give this a bit more time however and it might grow into a real alternative.