Posted by Ablang on 01/10/07 06:50

Hack Will Help Kill HD DVD Copy Protection
New video decryption software is "the first step in the meltdown of
AACS," Princeton researchers say.
Robert McMillan, IDG News Service
Tuesday, January 09, 2007 07:00 AM PST

The recent release of software that can be used to decode encrypted HD
DVD and Blu-ray movies is the first step toward making the encryption
standard used by these next-generation video players obsolete,
Princeton University researchers said Monday.

Late last month, a hacker going by the name Muslix64 released software
that could be used to decrypt movies that were encoded using the AACS
(Advanced Access Content System) digital rights management
specification. AACS is supported by Hollywood and video player
manufacturers.

Introduced in April 2005, AACS is the copy protection system for HD DVD
and Blu-ray movies. It is supported by companies such as Microsoft,
Panasonic, Sony, Toshiba, Walt Disney and Warner Bros.
Arms Race

Muslix64's BackupHDDVD software did not crack AACS, but it will make it
easier for some technically adept users to decrypt movies, said Alex
Halderman, a Princeton computer science student who, along with noted
researcher Ed Felten, is calling the software "the first step in the
meltdown of AACS."

AACS devices use cryptographic techniques to read numeric codes, called
'keys,' from video discs. These keys are then used to unlock the
digital content, making it readable on the player. Muslix64's software
does not give users a way to discover these keys, but it does provide a
way to descramble content once the key is uncovered.

"This is the framework through which the arms race is going to be
fought," Halderman said. "They don't have the ammunition yet, but this
is the gun."
All You Need Is The Key

AACS is supposed to work better than the CSS (content scrambling
system) encryption system used to protect DVDs from unauthorized
copying. CSS was cracked just a few years after its release by three
hackers, including a 16-year-old Norwegian named Jon Johansen.

Unlike CSS, however, the AACS system gives movie companies a way of
"revoking keys"--changing new movies so that these keys cannot be read
on video players that have been cracked.

This system gives Hollywood a way of protecting new releases, but it
only works if hackers publicize their work and disclose which player
has been cracked. And even with key revocation, nothing can be done to
prevent disks whose keys have already been published from being
unlocked, Halderman said.

"What the future looks like to us is that some individuals will have
cracks that they don't publish and which Hollywood is unable to
revoke," he said. "Other people will have cracks that they do publish,
and which will work for all old disks."
Trouble For Hollywood?

This scenario may not be so bad for the movie studios, so long as they
are able to prevent widespread illegal distribution of their products
and keep movies from being widely available while they are still being
shown in theatres, said Mike McGuire, an analyst with Gartner Inc. "If
they can preserve the existing [theatrical] release windows, then
they're probably going to feel reasonably comfortable," he said.

Still, Halderman believes it's only a matter of time before the keys
that can be used with BackupHDDVD become public and Hollywood will be
faced with unauthorized copying of AACS-protected material. "There's
just no doubt that title keys are going to become available at some
point in the near future," he said.

http://www.pcworld.com/article/128469-1/article.html?tk=nl_dnxnws

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