Work Around for New DVD Format Protections

An anonymous reader writes "For the new Blu-ray and HD-DVD formats, Hollywood implemented a complete copy protection scheme; almost everything has to be encrypted and authenticated. Despite the crypto-stuff in Advanced Access Content System and High Bandwidth Digital Content Protection, they left the backdoor wide open — they forgot about the PrintScreen button. Using this function you can create exact digital copies of a film picture-by-picture and reassemble them into a stream."

Comments

hrmm

[paradigmdream]

thats quite a bit of work to copy a movie

Real pirates DUPLICATE

[erroneus]

To make "other" copies is too troublesome. As always, real pirates will use the means they always have. They will work "off hours" at DVD publishing sites making uncounted copies indistinguishable from the counted copies. They will have the production equipment in their homes to make exact duplicates.

This is not about stopping piracy because these measures to nothing to address the two primary methods. What it does thrwart is casual consumer copying to better ensure that the consumers will buy multiple copies of the same stuff.

What I am saying is not new and has been repeated since the creation of the first DVD format.

Those Idiots

[frogstar_robot]

Now was not the time to splatter this information all over the world. If they had waited for wider deployment, this hole could have been kept wedged open as closing it on hundreds of thousands of clients wouldn't have been terribly practical.

Remember would be DVD-Jons, if you find DRM holes in new media tech SHUT YOUR YAP UNTIL EVERYBODY AND HIS DOG HAS BOUGHT SOME. THEN RELEASE THE INFO. When you do release the information, do so complete with "mom friendly" utilities and use warez "spreaders" to be sure everybody and his dog can start using it right away. This also complicates shutting the hole in various social and technical ways.

Does HDCP solve this?

[MasterC]

High-Bandwidth Digital Content Protection (HDCP) "protects" DVI & HDMI interfaces but for this to work on a regular PC then the OS has to be in on the deal as well, right? So if a drive and video card support the devil that is HDCP, does this "back door" work if the OS is in on the HDCP? I would venture a "no" on that one.

Taking print screens is a weak solution, but a solution nonetheless. All it takes is one person to have the patience or scripting skills to automate this for a copy to hit the internet. One. That's the problem with DRM in that it may deter most people but to be totally effective it requires determent of everyone. Feeding millions of individual frames to an encoder is not beyond some people, I'm sure. Especially since hollywood raised the stakes.

If this is a back door, then it's one of those miniature clown doors. When someone figures out a way to completely strip out AACS (like what was done with CSS) then we can call AACS hacked and laugh again at the never-winable battle that is DRM.

DRM is unwinable because you have to give the decryption key to the user so that they can use the product. If you don't give them the key then they can't use it. So DRM gives the encrypted data and the decryption key to the user every time.

Not so much, really

[Weaselmancer]

It would be a lot of work, if you did it manually. The print screen button is really just a proof of concept idea. Remember that the device is a computer and they excell at repetition.

For example, it wouldn't be too hard to write a DirectX driver for a virtual display device that simply passes every frame it sees into a filter for recording. Same should work for audio, really. Just take the inbound stream and stash it somehwere. As long as you've got the bandwidth inside the machine to move the data and the space to store it, why not?

This is why MS is pushing so hard for that "driver verification" thing. User created drivers can bypass the DRM just before the media gets pushed out to the hardware. The Windows box simply isn't built for DRM level trust at all points in a broadcast. Yet, anyways. It's still possible to break the chain somewhere and extract content. I'm guessing that'll always be the case too, at least for a good long while. Only way to get around that with what we have today would be if MS started selling PCs that are welded shut.

Re:Not really a backdoor

[ratboy666]

This *is* a backdoor. The digital data is in the frame buffer, but cannot be extracted (programs that are not trusted cannot be run). The Print Screen function is trusted, and so can run even with end-to-end crypto. The Print Screen function has access to the entire frame buffer. I don't know of another way to do this -- this one is actually brilliant.

And, Print Screen can be scripted. The player can ALSO be "scripted". As in, pause, and single step ("consumer" features). As to the speed of such a utility -- I would estimate that the re-encode process for a typical movie would take around 400 minutes (on a "typical" high end PC, see next paragraph for the amount of data involved). Ripping the audio track is more difficult (especially in full 5.1+ glory), but the technology for that is known. Time for that is real-time. Pulling a figure out of my ass, I would think a usable rip would take 800 minutes.

It's not "2 trillion" screen captures. It is a lot of data, though. At maximum resolution (1920x1080p) its 2 million pixels per frame. At 24bpp, that's 672 GB per hour (108,000 frames). The data HAS to be jammed through an encoder right away. This, of course, introduces new artifacts (its not going to be a "perfect" first generation copy). But its still going to be better than DVD quality.

I believe that the keys for this software will be revoked, and the current users (if any) "upgraded".

The point that this attack makes is that "DRM" is actually rather laughable. Your audience needs the decrypt keys, and yet can't be trusted with the decrypt keys... It just isn't stable.

Ratboy.