Dr. Dobb's Journal October 2002
My curiosity has a request. You may be able to satisfy it, but please don't e-mail me about this without first carefully reading the last paragraph below. I'd rather remain curious than get either of us in trouble. The War to Save the Entertainment Industry Middlemen rages on, with our Misrepresentatives in Washington entertaining creative ideas on how to prevent anyone from stealing the rightful income of movie studios and music publishing companies by sharing or porting or backing-up copies of their copyrighted works without paying for the privilege, and on how to find and punish those nefarious IP pirates without the hassle of a trial. Think they're pirating your intellectual property? Sure, go ahead and hack their system, trash their files, say Misrepresentatives Howard Berman and Howard Coble.
(For those of you not from the United States, here's a brief primer on our federal system. We have three branches of government: the Supreme Corpse, which is the unelected and unrepresentative body of senile ex-judges, bureaucrats, and John Holmes fans that makes most of the important laws in the country; the House of Misrepresentatives, which turns wishlists written by oil-company lawyers and other special-interest lobbyists into rough drafts for the Supreme Corpse to copyedit and sanctify; and the unpopularly dislected Chief Executioner, who does, to the best of his ability, whatever they tell him to do. There's also something called the Senate, but it doesn't do anything. Hope this helps.)
The latest landmine in the War to Save the Entertainment Industry Middlemen is something called "MacroSafe" from Macrovision. The problem with copy-protection techniques is that they are digital and we are analog. (Okay, okay, if Ed Fredkin is right, then that's not true. But it wouldn't hurt you to humor me. At least I hope not.) At some point, the patterns of light and sound have to be beamed to us as, well, patterns of light and sound; and at that point, they can be recorded onto a noncopy-protected medium. (Assuming that our government does not outlaw the manufacture of all noncopy-protected media, which is by no means a safe assumption.)
So Macrovision has invented a technology to allow it to find the copiers who are able to thwart its copy-protection technology. When a copy is made, that copy will contain, in addition to the movie or music recorded on the original, all sorts of personal identifying information about the owner of the original, including e-mail address and credit-card details, information that MacroSafe snooped around and found on the owner's hard disk.
Any copy then remains tagged with this ID information about the original purchaser. The assumption will, of course, be made that it was the original purchaser who made the copy, and the copyright owner, on coming across such an illegal copy, will go after the original purchaser. "Go after" could, the record shows, involve anything from threatening letters to doors smashed down in the middle of the night and guns brandished in children's faces. Not an attractive prospect.
So the enemy—which the entertainment industry pretty much defines as all of us—needs to consider its response. Finding and reading that hidden ID information would presumably be a tough decryption problem. But how difficult would it be simply to make the ID information unreadable? Couldn't you do that without even knowing where it was, especially if you were willing to accept a slight degradation of the movie or music on the disc? I'm looking for a precise mathematical characterization of the difficulty of making such a hidden ID code unreadable without ruining the disc's content. I hope some DDJ reader can help.
I'm pretty sure that merely characterizing the difficulty would not violate the Digital Millennium Copyright Act, but please don't send me code or a detailed algorithm. Seriously. I'm not interested in having federal storm troopers break down my door and seize my computers. It's unbelievable and unacceptable that I have to say this, but that's life in America under the DMCA.
Michael Swaine
editor-at-large
mike@swaine.com