I just reviewed all open and closed bugs in TextSecure's Issues page and didn't see a single crypto protocol bug. Admittedly, I looked quickly and casually. Could you point us to one?
You could not have reviewed all open and closed bugs in 8 minutes ;)
Issue 1073: https://github.com/WhisperSystems/TextSecure/issues/1073
Another one: Just sent an encrypted photo to someone? The photo is stored unencrypted on your phone.
Edit: group messages were also sent unencrypted, but this was fixed. https://github.com/WhisperSystems/TextSecure/issues/32
Edit2: ok, I see your point. Maybe they do crypto well as you say, but they don't seem to do software engineering well, or UI design for secure text messaging well. Sending messages unencrypted, and leaving messages unencrypted on the phone is a big fail in overall security of the app. It's meant to encrypt things, and it doesn't. That it doesn't put in tests for these things, and that it did not publish the independent security audit should cause everyone to reconsider using the TextSecure app for its stated purpose.
A crypto protocol bug is something like "TextSecure tried to implement secure file transfer, used the CTR block cipher mode, and managed to make the keystreams collide, so that passive attackers could recover file contents from encrypted streams".
The general point you made, that all applications have bugs (and thus security bugs) is valid. I'm drawing a line that you're not drawing, between design flaws in cryptosystems and random iOS/Android mistakes.
It's also true that until recently we didn't have an encrypted group chat protocol, but at no point in the past did TextSecure ever indicate that group chat was encrypted. Just the opposite.
It's important to realize that TextSecure is simultaneously a standard unencrypted SMS app as well as an encrypted chat app.
Sorry to bother, but is there any article/blog post/something to read about that?
As XMPP MUCs don't seem to have E2E encryption, mpOTR seems to be in infancy, and I'm unaware of anything else, this sounds really interesting.
I will agree with you about the UI design until the revamp in the latest release, though.