> This is not a theoretical argument. Disabling E2E encryption has already happened, although hardly anyone knows about it. In 2019 WhatsApp imposed forwarding limits on messages in order to “slow down the spread of rumors, viral messages, and fake news”. This represents a total defeat of the Signal protocol’s cryptographic objectives: a basic goal of any modern cryptographic scheme is to ensure the same message encrypted twice doesn’t encrypt to the same bytes. The point of this is to stop the adversary knowing when you’re repeatedly sending the same message and encryption modes that get this wrong (like AES/ECB) are discredited. Yet once Facebook — the adversary — became dominated by authoritarians who see unlimited communication as chaotic, they simply changed the client to include a forwarding counter outside the encrypted part of the message. There was nothing anyone could do about this. It just showed up one day, and all the fancy mathematics designed to stop this “attack” were irrelevant.