DRM behind lack of Windows Vista drivers... and fear the new content protection

, posted: 24-Dec-2006 16:24

VistaThe "professionally paranoid" Peter Gutmann at Auckland University has ripped into Windows Vista Content Protection (VCP) and written a paper, well, a web page then, called A Cost Analysis of Windows Vista Content Protection that makes for worrying reading. I've seen a number of pieces on the Digital Rights Management "features" that Microsoft has built into Vista but Gutmann's is probably the best so far. It references hardware vendors and Microsoft's own documentation and presents a not very appealing DRM vista.

Importantly, Gutmann looks into what VCP actually means for manufacturers as well as Vista users. Reading the long document made me realise that the likely culprits for apparent lack of Vista hardware drivers for graphics and sound devices aren't the vendors in question. Instead, it's VCP.

VCP is about protecting "Premium Content" on Vista, through a variety of technological measures, implemented in hardware and software. What does VCP mean in practical terms? Well, as soon as you play "protected content" the following components on your machine will be disabled dynamically:
  • S/PDIF (Sony/Philips Digital Interface Format) or TOSlink digital optical outputs.
  • Component Video
  • Automatic Echo Cancellation for PC voice communications
Vista may degrade your audio and video says Gutmann:
Alongside the all-or-nothing approach of disabling output, Vista requires that any interface that provides high-quality output degrade the signal quality that passes through it. This is done through a "constrictor" that downgrades the signal to a much lower-quality one, then up-scales it again back to the original spec, but with a significant loss in quality.

So if you're using an expensive new LCD display fed from a high-quality DVI signal on your video card and there's protected content present, the picture you're going to see will be, as the spec puts it, "slightly fuzzy", a bit like a 10-year-old CRT monitor that you picked up for $2 at a yard sale. [My emphasis]

In fact the spec specifically still allows for old VGA analogue outputs, but even that's only because disallowing them would upset too many existing owners of analogue monitors. In the future even analogue VGA output will probably have to be disabled. The only thing that seems to be explicitly allowed is the extremely low-quality TV-out, provided that Macrovision is applied to it.

The same deliberate degrading of playback quality applies to audio, with the audio being downgraded to sound (from the spec) "fuzzy with less detail".

Gutmann's paper also covers the headaches VCP creates for hardware vendors who are now faced with having to write far more complex drivers as a result, and have to use expensive, licensed third-party Intellectual Property.

Even the hardware designs of the devices have to be different now, to eliminate any unprotected signal paths. Hardware and the software drivers for devices must set "tilt bits" in case they notice anything unusual. Gutmann points out that this will lead to far less resilient hardware that may stop working if there's say a power surge that sets the "tilt bit".

Worse, malware writers could exploit the "tilt bits" in order to launch a huge Denial of Service attack.

Having to incorporate the vaguely specified VCP into hardware and software sounds like a nightmare so I'm frankly not surprised that device drivers for Vista are late or non-existent.

There's much more in Gutmann's document (it runs to almost 6,000 words) and it's definitely worth reading and creating some noise around because as he says:
The worst thing about all of this is that there's no escape. Hardware manufacturers will have to drink the kool-aid (and the reference to mass suicide here is deliberate [Note D]) in order to work with Vista: "There is no requirement to sign the [content-protection] license; but without a certificate, no premium content will be passed to the driver". Of course as a device manufacturer you can choose to opt out, if you don't mind your device only ever being able to display low-quality, fuzzy, blurry video and audio when premium content is present, while your competitors don't have this (artificially-created) problem.

As a user, there is simply no escape. Whether you use Windows Vista, Windows XP, Windows 95, Linux, FreeBSD, OS X, Solaris (on x86), or almost any other OS, Windows content protection will make your hardware more expensive, less reliable, more difficult to program for, more difficult to support, more vulnerable to hostile code, and with more compatibility problems.

I quite like his suggestion towards the end:
Here's an offer to Microsoft: If we, the consumers, promise to never, ever, ever buy a single HD-DVD or Blu-Ray disc containing any precious premium content [Note E], will you in exchange withhold this poison from the computer industry? Please?

Note E say Gutmann will wait a few years and then buy a $50 Chinese made set-top player if he ever wants to play back Premium Content - and not use a $1,000 Windows PC.

Other related posts:
Fighting with Windows 8
The Windows Phone 7.5 bouncing tiles bug
Windows Live Essentials betas seem good, but oh so flaky

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