Somehow, nearly every article on the subject completely misses this, and instead keeps moving goalposts on reasonable endpoint security.
Somehow, nearly every article on the subject completely misses this, and instead keeps moving goalposts on reasonable endpoint security.
It also means that an adversary can't go in long after the fact and dig up a message history from a server god knows where.
A lot of the eavesdropping scenarios concocted around key change in particular are fanciful. Practically speaking, end-to-end encrypted chat is often replacing email, not trying to protect secret agents hiding from the Reptilian Council.
Mass surveillance no, but if everybody blindly trusts any key provided (which seems to be the default "setting" for Signal and WhatsApp) then it's easy to start MITM'ing any connection at any point. You'll just get an innocuous-looking "your safety number has changed" and nothing else.
I do agree that it's still much better than nothing but I also agree with TFA when they say that "Signal cut a big corner by not planning device management properly", there are many ways Signal could make it massively easier for users to transfer their keys from one device to an other (for instance by deriving the master key from a passphrase bitcoin-wallet-style, or simply by making it easier to transfer your keys and history from device to device).
Because they didn't do this they probably considered that having an SSH-style intrusive "SOMETHING IS GOING WRONG HERE" message was too annoying and got rid of it. But really, they're fixing the symptom, not the problem.