Hackers europeus descobrem maneira de burlar o alogaritmo de criptografia dos discos de DVD

Variety.com has an article on the DVD encryption being cracked, and MPAA and Hollywood reaction. You'll also find the article on Yahoo. Yes, as the article mentions, "the MPAA tapped Bill Hunt to the newly created post of chief technology officer, charged with coordinating the group's Internet and optical media antipiracy efforts". And no, that Bill Hunt ISN'T me. Just a funny coincidence, don't you think? FYI, the Washington Post also has an article about the crack up today.

By now, you may have heard that Wired has run a story - by our friend Andy Patrizio no less - that digital pirates have managed to find a way to crack DVD's CSS encryption scheme. And I've received several panicked e-mails, from people fearing that this is "the end of DVD". So I'm gonna address this issue, and try to calm the waters a bit. First of all, some explanation as to how the pirates were able to do this.

DVD's CSS (Content Scrambling System) works like this: all of the audio and video content on a DVD disc is encrypted using a 40-bit encryption scheme. The keys for decrypting this content are stored on the same disc (and are also encrypted, using the same 40-bit scheme). Each player (be it a software DVD-ROM player, or a stand-alone hardware DVD player) then has its own activation key (also encrypted) coded into its decoder, which ensures that the device is authorized to read the disc's content. This is an oversimplification, but basically what happens, is that when the encrypted content data on the DVD disc is discovered, the player decoder's activation key is authenticated, which in turn activates the decryption key on the disc, thus allowing the decryption of the program content.

The CSS algorithm and keys are supposed to be secret, but as Jim Taylor (author of the Official DVD FAQ) says in his book DVD Demystified, "anyone who thinks it will remain secret for long is delusional." And such as come to pass. Being the clever chaps that they are, a group of hackers in Scandinavia started looking at the many software DVD players (for computer DVD-ROM drives) available. All of these players are supposed to encrypt their built-in activation keys, so hackers can't get at them. This is yet to be confirmed, but according to Patrizio, apparently one (the XingDVD player) didn't do this properly, and the activation key was easily extracted from the program's code. The result is a small utility, now available on the Net, which strips away the CSS encryption, leaving an unencrypted (and massive) audio/video file on your hard drive. This knowledge in hand, these hackers were then able to successfully guess at other activation keys.

Now before everyone starts panicking, and thinking this is the end of the world, let's get a few things straight. First of all, these tools have apparently been available on the Net for several months at least, on pages loaded with "DVD Ripper" utilities. And no one is churning out perfect DVD copies, that you can spin in your DVD players. These files are 600 MB+ in size. So what some people have done, is to convert this audio/video file (the .vob file) into more traditional Internet movie file formats (.avi or .mpg, for example), at a substantial reduction in quality, and copy them onto VCD-formatted CD-R discs. In most cases, this is little better quality than you can get from doing the same thing from a VHS or laserdisc source. If you tried to copy the .vob file itself, and run it in your DVD player, you'd need like 10+ CD-R discs per movie. It also begs the question, why would you want to do this in the first place? What's the advantage of taking a DVD movie, and turning it into a VCD of much less quality? Or simply splitting a DVD movie in higher quality into 10+ discs? Well, there isn't really any reason, unless you're a Hong Kong pirate, and you routinely make lots of illegal VCD movies anyway - this just gives you another tool to do so.

The real problem, will be DVD-R drives, and recordable stand-alone DVD-R players (expected in the first few months of next year), which generate discs that can be played in all current DVD players. These would allow people to copy complete .vob files onto one disc. Now keep in mind, that this hacked software doesn't copy and emulate all of the authoring, so there's no menus and interactivity. But sooner or later, these hackers will probably create their own custom authoring software (if they haven't already), remedying this problem. It remains to be seen how the Hollywood studios will react to all this. This isn't the end of DVD as we know it, folks - I'm told by reliable industry sources that there are a number of measures that can be taken to solve this problem. But I would be surprised if the first move Hollywood makes isn't to put the brakes on the introduction of recordable DVD, until such a time as stronger safeguards can be put in place to prevent this kind of piracy.

Rest assured, we're working closely with some of the players involved in this issue, and we'll have in-depth follow-up in the coming weeks. And we'll be back later today with more, so stay tuned...

Bill Hunt Nov.99

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