OK...so public encryption gets banned...
....and privacy-minded guys (good and bad) just get on with their own business using modest, unknown, home-brewed ciphers. Here's a sample of what the so-called white hats at the NSA will read when they "decrypt" a message sent across their now insecure public channel.
There's also the assumption that all this is going on via point-to-point channels (email, mobile phones, etc) where the white hats can identify the sender and the recipient. Of course, communication by USENET, or using the good offices of The Register (as here), all make that assumption moot too!
(P.S. the key is "brain678")