At least we have to agree on what we mean when we say that "end-to-end encryption works". I think there are `shades' of "working" if you will -- for instance, I know I mostly ignore when the key material changes in a Signal conversation, and this could be used to fool me. But then we have to talk about attack vectors and what we want to be protected from. I think it's mostly large-scale data collection and analysis rather than targeted attacks (like the CIA might do).

At any rate, thanks for setting me straight. I will read the paper!