[silentiumest]

This response is not valid as Tobias Boelter points out in his follow-up blog post: https://tobi.rocks/2017/01/there-is-a-whatsapp-backdoor/

>> Those "blocking" clients could instead retransmit a message of the same length that just contains garbage, i.e. instead of "Login with the password d98y289whcma0", they'd send "0000000000000000000000000000000000000" and this message would just not be displayed by the receiver's phone. By the guarantees of encryption, those two messages are indistinguishable in the encrypted form. Hence, this technique would make identifying users with the additional security enabled on a large scale impossible. <<