In various messengers, we have end-to-end encryption, making it hard to know what the message said.
But do these messengers have to pad the message to some maximum length every time, in order to hide the length of the message?
In a block cipher, there is a minimum length that you have to pad to, right?
My question is how do WhatsApp, Telegram, and Signal actually do this? How effective are they are hiding the length of the message?
And are there good ways to hide this type of metadata (length of the message and how often it is being sent) by doing some sort of steganography (eg posting message chunks to different endpoints depending on a hash of some variables available only to the participants, and sometimes also posting decoy garbage prefixed with “disregard:” in order to obfuscate patterns, etc.)