|
|
Posted by Ablang on 04/15/07 01:54
Sparring Begins Over High-Def Movie Hacks
Vendors revamp copy-protection schemes as hackers descramble each in
turn.
Martyn Williams, IDG News Service
Monday, April 09, 2007 07:00 AM PDT
A cat-and-mouse game between the guardians of the copy-protection
system on next-generation DVDs and those intent on hacking it has
kicked off with the first revocation of a descrambling key used in a
popular software application.
Last week the Advanced Access Content System Licensing Administrator
LLC said it was expiring a key used in Corel Corp.'s InterVideo WinDVD
8 application after the key was discovered and posted on the Internet.
Writing on the Doom 9 message board, a user with the name "Atari
Vampire" said that he or she had managed to find the device key for
the software. The device key is used in conjunction with individual
keys on each movie title to decrypt the data on the disc.
In response Corel is updating WinDVD 8 with a new device key and
warning users that they won't be able to watch HD DVD or Blu-ray Disc
titles unless they upgrade.
"Our decision stems from recent reports that hackers have illegally
obtained certain software licensing keys and have used them to
duplicate copyrighted content without prior authorization," Corel said
in a statement.
The discovery of the device key is the latest in a string of attacks
on AACS, which is used on both HD DVD and Blu-ray Disc.
The first to be disclosed was a title key for Stanley Kubrick's 1987
film, "Full Metal Jacket." A user with the name "Muslix64" posting to
the same discussion board said he or she began attacking the copy-
protection system after it prevented the viewing of the movie on a
high-definition monitor. As an anti-piracy measure the system only
allows high-definition video output over a monitor connection that
supports copy protection.
Then on Feb. 13 an additional key, called a processing key, was also
published online.
AACSLA downplayed the impact of both attacks, saying of the first that
it "does not represent an attack on the AACS system itself" and of the
second that it "represents no adverse impact on the ability of the
AACS ecosystem to address the attack."
Ironically technical documentation on AACSLA's own Web site appears to
be lending a hand to people like Atari Vampire who are looking for
weaknesses in the copy-protection system.
"I even printed out all 70 pages of the AACS Introduction and Common
Cryptographic Elements document, painfully reading through this
material," wrote Atari Vampire before explaining how an analysis of
memory contents was conducted using data "per page 13 of the AACS
Common Crypto doc."
The attacks to date have all involved exploiting weaknesses in PC
software used to play the discs and in this respect they bear a close
resemblance to the downfall of the CSS (content scrambling system)
used on DVDs. The first attacks on that system were through badly
written software rather than a brute-force attack on the encrypted
data. The cracking of CSS has led to the widespread availability of
software that can copy DVDs.
The architects of AACS learned from the mistakes of CSS and built into
the system several different types of keys and the ability to change
keys whenever attacks were successful. In this way they can re-
establish the security of the system once details of an attack are
public.
This situation is very similar to one currently being played out by
manufacturers of other connected consumer electronics devices like the
PlayStation Portable or recently-released Apple TV. Developers are
finding ways to get around restrictions in the software of the devices
and typically the developers are quickly responding with security
patches that block the exploits of weaknesses in their code.
For an indication of how long this might last, the Decrypting forum on
the Doom 9 message board is well worth a look. It's already home to a
community of people who are spending vast amounts of time pulling out
various keys from high-definition movie discs and anticipating the
next move of AACSLA and how they might get around it.
http://www.pcworld.com/article/130505-1/article.html?tk=nl_dnxnws
Navigation:
[Reply to this message]
|