They don&#x27;t have to block every user using unlawful encryption -- they just have to have a law that lets the penalty be enough that a few high profile convictions will deter enough law-abiding people that it isn&#x27;t worth the risk.<p>At that point, they can simply listen to all traffic and, if there are packets that aren&#x27;t listenable due to encryption, assume ill intent, then be free to react appropriately.<p>Assuming high enough signal ratios in detecting encryption, it might actually prove that encoded messages, or steganography proves to be more effective at preventing state-level eavesdropping... they won&#x27;t prevent a determined state from getting your secret content, but it could be enough that, if the messages looked unencrypted, they would be passed over for the more obviously encrypted messages -- hiding in plain sight, as it were.<p>Note, this is not an endorsement of any privacy invasions whatsoever, but musings on what a post-4th-amendment-obliteration world might look like for the privacy-minded.