Seven-line program beats DVD crypto

The Motion Picture Association of America is taking a closer look at a seven-line Perl script claimed by its authors to show just how "trivial" DVD encryption really is.

The algorithm was written by Keith Winstein and Marc Horowitz - one an MIT undergraduate, the latter a former student at the Institute - as part of a two-day course into the implications of the US' Digital Millennium Copyright Act.

The DMCA makes illegal any attempt to circumvent a copyright protection system. The pair wrote the code to prove to course attendees just how easy it is to fall foul of the law.

Of course, by doing so you'd think Winstein and Horowitz put themselves in hazard. Not so, they claim, the pair are protected by the First Amendment. Their free speech is guaranteed because the code was not created to crack DVD's Content Scrambling System (CSS), simply to illustrate copyright issues.

Good luck, we say. They may need it. The MPAA said it is looking into the code, which was published on the Web last week, courtesy of Carnegie Mellon University professor David Touretzky, having escaped from Winstein and Horowitz' course.

If it doesn't like what is sees, the MPAA might pursue the coders through he courts as it has done with authors and distributors - even one company that printed the code on a T-shirt - of the controversial DVD-on-Linux DVD decryption utility, DeCSS.

The movie industry has been able to keep a lid on DeCSS - just - but it's hard to see it preventing the spread of a seven-line chunk of code that, according to Winstein, "you can write these seven lines of code on a piece of paper and give it to someone".

It's certainly an elegant piece of programming, and is apparently efficient enough to enable realtime decryption and playback. ®

Related Link

Horowitz and Winstein's Perl code

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