
Some thoughts:

Has any work been done on encapsulating encrypted data inside "non-encrypted"
data files?  Many file formats can be written with "gaps" in them to hide
other data.  New file formats could be designed to have alternate data hidden
by dispersing it amongst the "legitimate" data.  The hidden data would only
show up with the right key(s), and a file with hidden data would be
indistinguishable from one without.  So, only the correct key(s) would reveal
the presence of an "illegal" document.

If I devise a custom file compression algorithm and only I and a friend have
the uncompressor, and otherwise the file appears to be total gigerish, do I
have the right to transmit the file?  Will we have to "escrow" all our data
file formats?  Are gangs required to escrow their hand signals, colors and
catch phrases?