It is impossible to ban encryption, at least not the really good stuff,
because you don't even know the encryption is there; the message looks like
any other message. That's the whole *point* of cryptography. By its very
nature it will be secret and undetectable without the proper knowledge, which
is also secret. One day, we're going to be sending each other lots of music
and video footage through computer networks. It is fairly trivial to hide a
message in video by altering the bits of the pictures which have the least
effect on the appearance of the picture. Someone who knows which bits you
altered and how you altered them can pull your message out of the video. That
message can be encrypted as well, and so they have to run other algorithms on
the message to decipher the intended message. If someone had the original,
unaltered video, they could compare it to the one with the hidden message and
realize that a message had been hidden in it. But eventually people will be
sending each other videos which they recorded themselves, and then not leave
any unaltered originals. Then it would be impossible to even know that a
message was hidden in the video, just by examining the video itself. Video is
just one medium of many that are excellent for concealing messages in, and
clever, secretive people will use whatever they can to maintain privacy.
Encrypted messages will be flowing all over the place and they will be
completely invisible to anyone attempting to ban encryption. There's not much
we can do to prevent people from sending each other secret, encrypted
messages. For all you know, this sentence contains a hidden message, if you
only knew the deciphering algorithm.
- David Musick