Quote Originally Posted by schlongfingers
rename mp3 to to xyz.zip for example - the only way of tracking the actual physical contents of files would be to keep a copy at the isp, which would be completely unworkable.
Well, that's not true, strictly speaking...

There's a lot of research going into hashing media files, so that you can uniquely identify files using a combination of values to create a key. You could easily maintain a central database of hashes... though someone would have to pay for it.

Where it does fall to pieces is the moment someone starts encrypting their internet sessions, unless you've got a supercomputer handy to break the cipher.

... and breaking a cipher is particularly non-trivial with binary data, as it doesn't contain English-language words which can be used to identify potential keys.

It'll be a sad day that I feel I have to encrypt all of the IP traffic coming out of my machine as a matter of course.