this is a review i found on another site. very detailed.
Disabling of Functionality
--------------------------
Vista's content protection mechanism only allows protected content to be sent
over interfaces that also have content-protection facilities built in.
Currently the most common high-end audio output interface is S/PDIF
(Sony/Philips Digital Interface Format). Most newer audio cards, for example,
feature TOSlink digital optical output for high-quality sound reproduction,
and even the latest crop of motherboards with integrated audio provide at
least coax (and often optical) digital output. Since S/PDIF doesn't provide
any content protection, Vista requires that it be disabled when playing
protected content [Note E]. In other words if you've sunk a pile of money
into a high-end audio setup fed from an S/PDIF digital output, you won't be
able to use it with protected content.
Say you've just bought Pink Floyd's "The Dark Side of the Moon", released as a
Super Audio CD (SACD) in its 30th anniversary edition in 2003, and you want to
play it under Vista. Since the S/PDIF link to your amplifier/speakers is
regarded as insecure for playing the SA content, Vista disables it, and you
end up hearing a performance by Marcel Marceau instead of Pink Floyd.
Similarly, component (YPbPr) video will be disabled by Vista's content
protection, so the same applies to a high-end video setup fed from component
video. What if you're lucky enough to have bought a video card that supports
HDMI digital video with HDCP content-protection? There's a good chance that
you'll have to go out and buy another video card that really *does* support
HDCP, because until quite recently no video card on the market actually
supported it even if the vendor's advertising claimed that it did. As the
site that first broke the story put it in their article "The Great HDCP
Fiasco" (http://www.firingsquad.com/hardware/..._hdcp_support/) puts
it:
"None of the AGP or PCI-E graphics cards that you can buy today support HDCP
[...] If you've just spent $1000 on a pair of Radeon X1900 XT graphics cards
expecting to be able to playback HD-DVD or Blu-Ray movies at 1920x1080
resolution in the future, you've just wasted your money [...] If you just
spent $1500 on a pair of 7800GTX 512MB GPUs expecting to be able to play
1920x1080 HD-DVD or Blu-Ray movies in the future, you've just wasted your
money".
(The two devices mentioned above are the premium supposedly-HDCP-enabled cards
made by the two major graphics chipset manufacturers ATI and nVidia). ATI was
later subject to a class-action lawsuit by its customers over this deception.
As late as August of 2006, when Sony announced its Blu-Ray drive for PCs, it
had to face the embarrassing fact that its Blu-Ray drive couldn't actually
play Blu-Ray disks in HD format ("First Blu-ray disc drive won't play Blu-ray
movies",
http://www.cnet.com.au/desktops/dvdb...91720,00.htm):
"Since there are currently no PCs for sale offering graphics chips that
support HDCP, this isn't yet possible".
In order to appropriately protect content, Vista will probably have to disable
any special device features that it can't directly control. For example many
sound cards built on C-Media chipsets (which in practice is the vast majority
of them) support Steinberg's ASIO (Audio Stream I/O), a digital audio
interface that completely bypasses the Windows audio mixer and other audio-
related driver software to provide more flexibility and much lower latency
than the Windows ones. ASIO support is standard for newer C-Media hardware,
see for example http://www.cmedia.com.tw/?q=en/PCI/CMI8788. Since ASIO
bypasses Windows' audio handling, it would probably have to be disabled, which
is problematic because audiophiles and professional musicians require ASIO
support specifically because of its much higher quality than the standard
Windows channels.
Indirect Disabling of Functionality
-----------------------------------
As well as overt disabling of functionality, there's also covert disabling of
functionality. For example PC voice communications rely on automatic echo
cancellation (AEC) in order to work. AEC requires feeding back a sample of
the audio mix into the echo cancellation subsystem, but with Vista's content
protection this isn't permitted any more because this might allow access to
premium content. What is permitted is a highly-degraded form of feedback that
might possibly still sort-of be enough for some sort of minimal echo
cancellation purposes.
The requirement to disable audio and video output plays havoc with standard
system operations, because the security policy used is a so-called "system
high" policy: The overall sensitivity level is that of the most sensitive data
present in the system. So the instant any audio derived from premium content
appears on your system, signal degradation and disabling of outputs will
occur. What makes this particularly entertaining is the fact that the
downgrading/disabling is dynamic, so if the premium-content signal is
intermittent or varies (for example music that fades out), various outputs and
output quality will fade in and out, or turn on and off, in sync. Normally
this behaviour would be a trigger for reinstalling device drivers or even a
warranty return of the affected hardware, but in this case it's just a signal
that everything is functioning as intended.
Decreased Playback Quality
--------------------------
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 if premium content is present. 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 [Note F]. In fact the specification specifically still allows for
old VGA analog outputs, but even that's only because disallowing them would
upset too many existing owners of analog monitors. In the future even analog
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"
[Note G].
Amusingly, the Vista content protection docs say that it'll be left to
graphics chip manufacturers to differentiate their product based on
(deliberately degraded) video quality. This seems a bit like breaking the
legs of Olympic athletes and then rating them based on how fast they can
hobble on crutches.
The Microsoft specs say that only display devices with more than 520K pixels
will have their images degraded, but conveniently omit to mention that this
resolution, roughly 800x600, covers pretty much every output device that will
ever be used with Vista. The abolute minimum requirement for Vista Basic are
listed as 800x600 resolution (and an 800MHz Pentium III CPU with 512MB of RAM,
which seems, well, "wildly optimistic" is one term that springs to mind).
However that won't get you the Vista Aero interface, which makes a move to
Vista from XP more or less pointless. The minimum requirements for running
Aero on a Vista Premium PC are "a DX9 GPU, 128 MB of VRAM, Pixel Shader 2.0,
and minimum resolution 1024x768x32", and for Aero Glass it's even higher than
that. In addition the minimum resolution supported by a standard LCD panel is
1024x768 for a 15" LCD, and to get 800x600 you'd have to go back to a 10-year-
old 14" CRT monitor or something similar. So in practice the 520K pixel
requirement means that everything will fall into the degraded-image category.
Beyond the obvious playback-quality implications of deliberately degraded
output, this measure can have serious repercussions in applications where
high-quality reproduction of content is vital. For example the field of
medical imaging either bans outright or strongly frowns on any form of lossy
compression because artefacts introduced by the compression process can cause
mis-diagnoses and in extreme cases even become life-threatening. Consider a
medical IT worker who's using a medical imaging PC while listening to
audio/video played back by the computer. This scenario is already very
common, the CDROM drives installed in workplace PCs inevitably spend most of
their working lives playing music or MP3 CDs to drown out workplace noise.
Now obviously CDs aren't (yet) regarded as premium content and so won't
trigger Vista's content-protection measures, that's merely an example to
illustrate how common it is for users to play back audio/video content while
working. Let's say that instead of listening to music while they work, the
user may have a humorous video that a workmate sent them, or that they grabbed
from YouTube, playing in the background that, and that unbeknownst to them
this video is protected premium content. As a result, the video image will be
subtly altered by Vista's content protection, potentially creating exactly the
life-threatening situation that the medical industry has worked so hard to
avoid. The scary thing is that there's no easy way around this - Vista will
silently modify displayed content under certain (almost impossible-to-predict
in advance) situations discernable only to Vista's built-in content-protection
subsystem [Note H][Note I].
Elimination of Open-source Hardware Support
-------------------------------------------
In order to prevent the creation of hardware emulators of protected output
devices, Vista requires a Hardware Functionality Scan (HFS) that can be used
to uniquely fingerprint a hardware device to ensure that it's (probably)
genuine. In order to do this, the driver on the host PC performs an operation
in the hardware (for example rendering 3D content in a graphics card) that
produces a result that's unique to that device type.
In order for this to work, the spec requires that the operational details of
the device be kept confidential. Obviously anyone who knows enough about the
workings of a device to operate it and to write a third-party driver for it
(for example one for an open-source OS, or in general just any non-Windows OS)
will also know enough to fake the HFS process. The only way to protect the
HFS process therefore is to not release any technical details on the device
beyond a minimum required for web site reviews and comparison with other
products.
This potential "closing" of the PC's historically open platform is an
extremely worrying trend. A quarter of a century ago, IBM made the momentous
decision to make their PC an open platform by publishing complete hardware
details and allowing anyone to compete on the open market. Many small
companies, the traditional garage startup, got their start through this. This
openness is what created the PC industry, and the reason why most homes
(rather than just a few offices, as had been the case until then) have one or
more PCs sitting in a corner somewhere. This seems to be a return to the bad
old days of 25 years ago when only privileged insiders were able to
participate.
Elimination of Unified Drivers
------------------------------
The HFS process has another cost involved with it. Most hardware vendors have
(thankfully) moved to unified driver models instead of the plethora of
individual drivers that abounded some years ago. Since HFS requires unique
identification and handling of not just each device type (for example each
graphics chip) but each variant of each device type (for example each stepping
of each graphics chip) to handle the situation where a problem is found with
one variation of a device, it's no longer possible to create one-size-fits-all
drivers for an entire range of devices like the current
Catalyst/Detonator/ForceWare drivers. Every little variation of every device
type out there must now be individually accommodated in custom code in order
for the HFS process to be fully effective.
If a graphics chip is integrated directly into the motherboard and there's no
easy access to the device bus then the need for bus encryption (see
"Unnecessary CPU Resource Consumption" below) is removed. Because the
encryption requirement is so onerous, it's quite possible that this means of
providing graphics capabilities will suddenly become more popular after the
release of Vista. However, this leads to a problem: It's no longer possible
to tell if a graphics chip is situated on a plug-in card or attached to the
motherboard, since as far as the system is concerned they're both just devices
sitting on the AGP/PCIe bus. The solution to this problem is to make the two
deliberately incompatible, so that HFS can detect a chip on a plug-in card vs.
one on the motherboard. Again, this does nothing more than increase costs and
driver complexity.
Further problems occur with audio drivers. To the system, HDMI audio looks
like S/PDIF, a deliberate design decision to make handling of drivers easier.
In order to provide the ability to disable output, it's necessary to make HDMI
codecs deliberately incompatible with S/PDIF codecs, despite the fact that
they were specifically designed to appear identical in order to ease driver
support and reduce development costs.
Denial-of-Service via Driver/Device Revocation
----------------------------------------------
Once a weakness is found in a particular driver or device, that driver will
have its signature revoked by Microsoft, which means that it will cease to
function. Details on exactly what happens are a bit vague here, the specs
contain sentences like "the related driver would have to be revoked and a new
driver would have to be deployed", however presumably some minimum
functionality like generic 640x480 VGA support will still be available in
order for the system to boot.
What this means is that a report of a compromise of a particular driver or
device will cause all support for that device worldwide to be turned off until
a fix can be found [Note J]. Again, details are sketchy, but if it's a device
problem then presumably the device turns into a paperweight once it's revoked.
If it's an older device for which the vendor isn't interested in rewriting
their drivers (and in the fast-moving hardware market most devices enter
"legacy" status within a year or two of their replacement models becoming
available), all devices of that type worldwide become permanently unusable.
An example of this might be nVidia TNT2 video cards, which are still very
widely deployed in business environments where they're all that you need to
run Word or Outlook or Excel (or, for that matter, pretty much any non-gaming
application). The drivers for these cards haven't been updated for quite some
time for exactly that reason: You don't need the latest drivers for them
because they're not useful with current games any more (if you go to the
nVidia site and try and install any recent drivers, the installer will tell
you to go back and download much older drivers instead). If a TNT2 device
were found to be leaking content, it seems unlikely that nVidia would be
interested in reviving discontinued drivers that it hasn't touched for several
years, creating instant orphanware of the installed user base.
The threat of driver revocation is the ultimate nuclear option, the crack of
the commissars' pistols reminding the faithful of their duty [Note K]. The
exact details of the hammer that vendors will be hit with is buried in
confidential licensing agreements, but I've heard mention of multi-million
dollar fines and embargoes on further shipment of devices alongside the driver
revocation mentioned above.
This revocation can have unforeseen carry-on costs. Windows' anti-piracy
component, WGA, is tied to system hardware components. Windows allows you to
make a small number of system hardware changes after which you need to renew
your Windows license (the exact details of what you can and can't get away
with changing has been the subject of much debate). If a particular piece of
hardware is deactivated (even just temporarily while waiting for an updated
driver to work around a content leak) and you swap in a different video card
or sound card to avoid the problem, you risk triggering Windows' anti-piracy
measures, landing you in even more hot water. If you're forced to swap out a
major system component like a motherboard, you've instantly failed WGA
validation. Revocation of any kind of motherboard-integrated device
(practically every motherboard has some form of onboard audio, and all of the
cheaper ones have integrated video) would appear to have a serious negative
interaction with Windows' anti-piracy measures.
The details of what will happen if a motherboard contains unused onboard audio
capabilities and an additional sound card alongside it, and the motherboard
drivers are revoked, is unknown. Windows can't tell that there's nothing
connected to the onboard audio because the user prefers to use their M-Audio
Revolution 7.1 Surround Sound card instead, so it'll probably have to revoke
the motherboard drivers even though they're not used for anything. Since
virtually all motherboards contain onboard audio, this could prove quite
problematic.
An entirely different DoS problem that applies more to HDMI-enabled devices in
general has already surfaced in the form of, uhh, "DVI amplifiers", which take
as input an HDMI signal and output a DVI signal, amplifying it in the process.
Oh, and as a side-effect they forget to re-apply the HDCP protection to the
output. These devices are relatively simple to design and build using off-
the-shelf HDMI chips. Beyond the commercially-available models, individual
hardware hackers have built their own protection-strippers using chip samples
obtained from chip vendors. If you have the right credentials you can even
get hardware evaluation boards designed for testing and development that do
this sort of thing. And I won't even get into the territory of HD players
with non-HDMI digital outputs, for example ones that contain an HD-SDI (SMPTE
292M) interface. HD-SDI is an unencrypted digital link typically used in TV
studios but also available from various non-US sources as after-market
sidegrades for standard HD players, providing better-than-HDMI image quality
without the hassle of HDCP.
Now assume that the "DVI amplifier" manufacturer buys a truckload of HDMI
chips (they'll want to get as many as they can in one go because they probably
won't be able to go back and buy more when the chip vendor discovers what
they're being used for). Since this is a rogue device, it can be revoked...
along with hundreds of thousands or even millions of other consumer devices
that use the same chip. If they're feeling particularly nasty, they can
recycle the HDMI chips from junked TVs to ensure that the maximum possible
damage to the consumer base occurs. Engadget have a good overview of this
scenario at
http://www.engadget.com/2005/07/21/t...ny-red-button/.
(Exactly what will happen when a key is leaked depends on how the attackers
handle it. The way HD-DVD/Blu-Ray keying works is that a per-device key is
used to decrypt the title key on the disk, and the title key is then in turn
used to decrypt the content. So the chain of custody is Device key -> Title
key -> Content. This level of indirection allows an individual device to be
disabled by revoking the device key without making the disk unplayable on all
devices, since other device keys can still decrypt the title key and thus the
content (I've simplified this a bit to cut down the length of the explanation,
see the AACS specification for more details).
The device key is tied to a particular device/player/vendor, but the title key
is only tied to the content on disk. You can probably see where this is
going... by publishing the device key, the attacker can cause general mayhem
by forcing device revocation. On the other hand by publishing the title key
the attacker can release the content in an untraceable manner, since it's not
known which device key was used to leak the title key. In addition since
there's no way to un-publish the title key (encrypted content + title key =
unencrypted content), at that point it's game over for the content).
Decreased System Reliability
----------------------------
"Drivers must be extra-robust. Requires additional driver development to
isolate and protect sensitive code paths" -- ATI.
Vista's content protection requires that devices (hardware and software
drivers) set so-called "tilt bits" if they detect anything unusual. For
example if there are unusual voltage fluctuations, maybe some jitter on bus
signals, a slightly funny return code from a function call, a device register
that doesn't contain quite the value that was expected, or anything similar, a
tilt bit gets set. Such occurrences aren't too uncommon in a typical
computer. For example starting up or plugging in a bus-powered device may
cause a small glitch in power supply voltages, or drivers may not quite manage
device state as precisely as they think. Previously this was no problem - the
system was designed with a bit of resilience, and things will function as
normal. In other words small variances in performance are a normal part of
system functioning. Furthermore, the degree of variance can differ widely
across systems, with some handling large changes in system parameters and
others only small ones. One very obvious way to observe this is what happens
when a bunch of PCs get hit by a momentary power outage. Effects will vary
from powering down, to various types of crash, to nothing at all, all
triggered by exactly the same external event.
With the introduction of tilt bits, all of this designed-in resilience is
gone. Every little (normally unnoticeable) glitch is suddenly surfaced
because it could be a sign of a hack attack, with the required reaction being
that "Windows Vista will initiate a full reset of the graphics subsystem, so
everything will restart". The effect that these tilt bits will have on system
reliability should require no further explanation.
Content-protection "features" like tilt bits also have worrying denial-of-
service (DoS) implications. It's probably a good thing that modern malware is
created by programmers with the commercial interests of the phishing and spam
industries in mind rather than just creating as much havoc as possible. With
the number of easily-accessible grenade pins that Vista's content protection
provides, any piece of malware that decides to pull a few of them will cause
considerable damage. The homeland security implications of this seem quite
serious, since a tiny, easily-hidden piece of malware would be enough to
render a machine unusable, while the very nature of Vista's content protection
would make it almost impossible to determine why the denial-of-service is
occurring. Furthermore, the malware authors, who are taking advantage of
"content-protection" features, would be protected by the DMCA against any
attempts to reverse-engineer or disable the content-protection "features" that
they're abusing.
Even without deliberate abuse by malware, the homeland security implications
of an external agent being empowered to turn off your IT infrastructure in
response to a content leak discovered in some chipset that you coincidentally
happen to be using is a serious concern for potential Vista users. Non-US
governments are already nervous enough about using a US-supplied operating
system without having this remote DoS capability built into the operating
system. And like the medical-image-degradation issue, you won't find out
about this until it's too late, turning Vista PCs into ticking time bombs if
the revocation functionality is ever employed.
Like the medical-imaging degradation example given earlier, it's possible to
imagine all sorts of scenarios in which the tilt bits end up biting users.
Consider a warship operating in a combat zone and equipped with Vista PCs for
management of the vessel's critical functions which does nothing more wrong
that to suffer a severe jolt from a near miss, scrambling the bus just enough
to activate the tilt bits (without causing any other real damage). In one
famous incident in September 1997, Windows NT managed to disable the Aegis
missile cruiser USS Yorktown ("NT Leaves Navy "Smart Ship" dead in the water",
Government Computer News, 13 July 1998). Now Windows Vista can do the same
thing via a by-design feature of the OS [Note L]. This issue, unless it can
be clearly resolved, would make the use of Vista PCs unacceptable for any
applications that have any hint of unusual environmental conditions such as
high altitude, environmental variations, shock, and so on.
Increased Hardware Costs
------------------------
"Cannot go to market until it works to specification... potentially more
respins of hardware" -- ATI.
"This increases motherboard design costs, increases lead times, and reduces
OEM configuration flexibility. This cost is passed on to purchasers of
multimedia PCs and may delay availability of high-performance platforms" --
ATI.
Vista includes various requirements for "robustness" in which the content
industry, through "hardware robustness rules", dictates design requirements to
hardware manufacturers. The level of control the content producers have over
technical design details is nothing short of amazing. As security researcher
Ed Felten quoted from Microsoft documents on his freedom-to-tinker web site
about a year ago (http://www.freedom-to-tinker.com/?p=882):
"The evidence [of security] must be presented to Hollywood and other content
owners, and they must agree that it provides the required level of security.
Written proof from at least three of the major Hollywood studios is
required".
So if you design a new security system, you can't get it supported in Windows
Vista until well-known computer security experts like MGM, 20th Century-Fox,
and Disney give you the go-ahead (this gives a whole new meaning to the term
"Mickey-Mouse security"). It's absolutely astonishing to find paragraphs like
that in what are supposed to be Windows technical documents, since it gives
Hollywood studios veto rights over Windows security mechanisms.
As an example of these "robustness rules", only certain layouts of a board are
allowed in order to make it harder for outsiders to access parts of the board.
Possibly for the first time ever, computer design is being dictated not by
electronic design rules, physical layout requirements, and thermal issues, but
by the wishes of the content industry. Apart from the massive headache that
this poses to device manufacturers, it also imposes additional increased costs
beyond the ones incurred simply by having to lay out board designs in a
suboptimal manner. Video card manufacturers typically produce a one-size-
fits-all design (often a minimally-altered copy of the chipset vendor's
reference design, as illustrated by
http://www.trustedreviews.com/images...ine/2685-2.jpg, which shows
five virtually identical cards from different vendors with the only noticeable
difference being the logo on the heatsink), and then populate different
classes and price levels of cards in different ways. For example a low-end
card will have low-cost, minimal or absent TV-out encoders, DVI circuitry,
RAMDACs, and various other add-ons used to differentiate budget from premium
video cards. You can see this on the cheaper cards by observing the
unpopulated bond pads on circuit boards, and gamers and the like will be
familiar with cut-a- trace/resolder-a-resistor sidegrades of video cards.
An example of omitting components from a high-end card to create a mid-range
card is shown at
http://images.infoteldistributors.co...53-out3-hl.jpg.
Note the large red rectangular area to the far left of the card, this is where
the manufacturer has omitted a component to produce a lower-cost model. The
same thing is visible in the card at
http://techreport.com/reviews/2006q4...650xt/card.jpg. Conversely,
http://www.xbitlabs.com/images/video...card-front.jpg shows an (at
the time it was released) top-of-the-line card with optional components
fitted, the chip to the left of the large square heatsink+fan handles video
encoding and can be added or removed (along with other optional components) to
create different levels of cards at different price points. The automotive
industry does the same thing, you have one basic model of each car type and
10,000 extras and options to suit everyone's needs and pockets.
Vista's content-protection requirements eliminate this one-size-fits-all
design, banning the use of separate TV-out encoders, DVI circuitry, RAMDACs,
and other discretionary add-ons because feeding unprotected video to these
optional external components would make it too easy to lift the signal off the
bus leading to the external component. So everything has to be custom-
designed and laid out so that there are no unnecessary accessible signal links
on the board. This means that a low-cost card isn't just a high-cost card
with components omitted, and conversely a high-cost card isn't just a low-cost
card with additional discretionary components added, each one has to be a
completely custom design created to ensure that no signal on the board is
accessible.
This extends beyond simple board design all the way down to chip design.
Instead of adding an external DVI chip, it now has to be integrated into the
graphics chip, along with any other functionality normally supplied by an
external chip. So instead of varying video card cost based on optional
components, the chipset vendor now has to integrate everything into a one-
size-fits-all premium-featured graphics chip, even if all the user wants is a
budget card for their kid's PC.
Increased Cost due to Requirement to License Unnecessary Third-party IP
-----------------------------------------------------------------------
"We've taken on more legal costs in copyright protection in the last six to
eight months than we have in any previous engagement. Each legal contract
sets a new precedent, and each new one builds on the previous one" -- ATI.
Protecting all of this precious premium content requires a lot of additional
technology. Unfortunately much of this is owned by third parties and requires
additional licensing. For example HDCP for HDMI is owned by Intel, so in
order to send a signal over HDMI you have to pay royalties to Intel, even
though you could do exactly the same thing for free over DVI. Similarly,
since even AES-128 on a modern CPU isn't fast enough to encrypt high-bandwidth
content, companies are required to license the Intel-owned Cascaded Cipher, an
AES-128-based transform that's designed to offer a generally similar level of
security but with less processing overhead.
The need to obtain unnecessary technology licenses extends beyond basic
hardware IP. In order to demonstrate their commitment to the cause, Microsoft
have recommended as part of their "robustness rules" that vendors license
third-party code obfuscation tools to provide virus-like stealth capabilities
for their device drivers in order to make it difficult to interfere with their
operations or reverse-engineer them. Vendors like Cloakware and Arxan have
actually added "robustness solutions" web pages to their sites in anticipation
of this lucrative market. This must be a nightmare for device vendors, for
whom it's already enough of a task getting fully functional drivers deployed
without having to deal with adding stealth-virus-like technology on top of the
basic driver functionality.
The robustness rules further complicate driver support by disallowing features
such as driver debugging facilities in shipping drivers. Most Windows XP
users will at one time or another have encountered a Windows crash message
indicating that some application that they were using has terminated
unexpectedly, and would they like to send debugging information to Microsoft
to help fix the problem. Some device vendors even implement their own custom
versions of this debugging support in their drivers, an example being ATI's
VPU Recover, which captures graphics diagnostic and debugging information to
send to ATI when a graphics device problem occurs. Since this debugging
functionality could leak content or content-related security information, it
can no longer be used with audio or video components, considerably
complicating vendors' driver support and software enhancement processes (the
ATI product manager referenced in the "Sources" section lists these additional
testing and support costs as "potentially the highest cost of all").
Unnecessary CPU Resource Consumption
------------------------------------
"Since [encryption] uses CPU cycles, an OEM may have to bump the speed grade
on the CPU to maintain equivalent multimedia performance. This cost is
passed on to purchasers of multimedia PCs" -- ATI.
In order to prevent tampering with in-system communications, all communication
flows have to be encrypted and/or authenticated. For example content sent to
video devices has to be encrypted with AES-128. This requirement for
cryptography extends beyond basic content encryption to encompass not just
data flowing over various buses but also command and control data flowing
between software components. For example communications between user-mode and
kernel-mode components are authenticated with OMAC message authentication-code
tags, at considerable cost to both ends of the connection. Needless to say,
this extremely CPU-intensive mechanism is a very painful way to provide
protection for content, and this fact has been known for many years. Twenty
years ago, in their work on the ABYSS security module, IBM researchers
concluded that the use of encrypted buses as a protection mechanism was
impractical (see their paper from the 1987 IEEE Symposium on Security and
Privacy).
In order to prevent active attacks, device drivers are required to poll the
underlying hardware every 30ms to ensure that everything appears kosher. This
means that even with nothing else happening in the system, a mass of assorted
drivers has to wake up thirty times a second just to ensure that... nothing
continues to happen. In addition to this polling, further device-specific
polling is also done, for example Vista polls video devices on each video
frame displayed in order to check that all of the grenade pins (tilt bits) are
still as they should be. We already have multiple reports from Vista
reviewers of playback problems with video and audio content, with video frames
dropped and audio stuttering even on high-end systems [Note M]. Time will
tell whether this problem is due to immature drivers or has been caused by the
overhead imposed by Vista's content protection mechanisms interfering with
playback. An indication of the level of complexity added to the software can
be seen by looking at a block diagram of Vista's Media Interoperability
Gateway (MIG). Of the eleven components that make up the MIG, only two (the
audio and video decoders) are actually used to render content. The remaining
nine are used to apply content-protection measures.
On-board graphics create an additional problem in that blocks of precious
content will end up stored in system memory, from where they could be paged to
disk. In order to avoid this, Vista tags such pages with a special protection
bit indicating that they need to be encrypted before being paged out and
decrypted again after being paged in. Vista doesn't provide any other
pagefile encryption, and will quite happily page banking PINs, credit card
details, private, personal data, and other sensitive information, in
plaintext. The content-protection requirements make it fairly clear that in
Microsoft's eyes a frame of premium content is worth more than (say) a user's
medical records or their banking PIN [Note N].
In addition to the CPU costs, the desire to render data inaccessible at any
level means that video decompression can't be done in the CPU any more, since
there isn't sufficient CPU power available to both decompress the video and
encrypt the resulting uncompressed data stream to the video card. As a
result, much of the decompression has to be integrated into the graphics chip.
At a minimum this includes IDCT, MPEG motion compensation, and the Windows
Media VC-1 codec (which is also DCT-based, so support via an IDCT core is
fairly easy). As a corollary to the "Increased Hardware Costs" problem above,
this means that you can't ship a low-end graphics chip without video codec
support any more.
The inability to perform decoding in software also means that any premium-
content compression scheme not supported by the graphics hardware can't be
implemented. If things like the Ogg video codec ever eventuate and get used
for premium content, they had better be done using something like Windows
Media VC-1 or they'll be a non-starter under Vista or Vista-approved hardware.
This is particularly troubling for the high-quality digital cinema (D-Cinema)
specification, which uses Motion JPEG2000 (MJ2K) because standard MPEG and
equivalents don't provide sufficient image quality. Since JPEG2000 uses
wavelet-based compression rather than MPEG's DCT-based compression, and
wavelet-based compression isn't on the hardware codec list, it's not possible
to play back D-Cinema premium content (the moribund Ogg Tarkin codec also used
wavelet-based compression). Because *all* D-Cinema content will (presumably)
be premium content, the result is no playback at all until the hardware
support appears in PCs at some indeterminate point in the future. Compare
this to the situation with MPEG video, where early software codecs like the
XingMPEG en/decoder practically created the market for PC video. Today,
thanks to Vista's content protection, the opening up of new markets in this
manner would be impossible.
The high-end graphics and audio market are dominated entirely by gamers, who
will do anything to gain the tiniest bit of extra performance, like buying
Bigfoot Networks' $250 "Killer NIC" ethernet card in the hope that it'll help
reduce their network latency by a few milliseconds. These are people buying
$500-$1000 graphics and sound cards for which one single sale brings the
device vendors more than the few cents they get from the video/audio portion
of an entire roomful of integrated-graphics-and-sound PCs. I wonder how this
market segment will react to knowing that their top-of-the-line hardware is
being hamstrung by all of the content-protection "features" that Vista hogties
it with?
Unnecessary Device Resource Consumption
---------------------------------------
"Compliance rules require [content] to be encrypted. This requires
additional encryption/decryption logic thus adding to VPU costs. This cost
is passed on to all consumers" -- ATI.
As part of the bus-protection scheme, devices are required to implement
AES-128 encryption in order to receive content from Vista. This has to be
done via a hardware decryption engine on the graphics chip, which would
typically be implemented by throwing away a GPU rendering pipeline or two to
make room for the AES engine.
Establishing the AES key with the device hardware requires further
cryptographic overhead, in this case a 2048-bit Diffie-Hellman key exchange
whose 2K-bit output is converted to a 128-bit AES key via a Davies-Meyer hash
with AES as its block transformation component. In programmable devices this
can be done (with considerable effort) in the device (for example in
programmable shader hardware), or more simply by throwing out a few more
rendering pipelines and implementing a public-key-cryptography engine in the
freed-up space.
Needless to say, the need to develop, test, and integrate encryption engines
into audio/video devices will only add to their cost, as covered in "Increased
Hardware Costs" above, and the fact that they're losing precious performance
in order to accommodate Vista's content protection will make gamers less than
happy.
Final Thoughts
--------------
"No amount of coordination will be successful unless it's designed with the
needs of the customer in mind. Microsoft believes that a good user
experience is a requirement for adoption" -- Microsoft.
"The PC industry is committed to providing content protection on the PC, but
nothing comes for free. These costs are passed on to the consumer" -- ATI.
At the end of all this, the question remains: Why is Microsoft going to this
much trouble? Ask most people what they picture when you use the term
"premium-content media player" and they'll respond with "A PVR" or "A DVD
player" and not "A Windows PC". So why go to this much effort to try and turn
the PC into something that it's not?
In July 2006, Cory Doctorow published an analysis of the anti-competitive
nature of Apple's iTunes copy-restriction system ("Apple's Copy Protection
Isn't Just Bad For Consumers, It's Bad For Business", Cory Doctorow,
Information Week, 31 July 2006). The only reason I can imagine why Microsoft
would put its programmers, device vendors, third-party developers, and
ultimately its customers, through this much pain is because once this copy
protection is entrenched, Microsoft will completely own the distribution
channel. In the same way that Apple has managed to acquire a monopolistic
lock-in on their music distribution channel (an example being the Motorola
ROKR fiasco, which was so crippled by Apple-imposed restrictions that it was
dead the moment it appeared), so Microsoft will totally control the premium-
content distribution channel. Not only will they be able to lock out any
competitors, but because they will then represent the only available
distribution channel they'll be able to dictate terms back to the content
providers whose needs they are nominally serving in the same way that Apple
has already dictated terms back to the music industry: Play by Apple's rules,
or we won't carry your content. The result will be a technologically enforced
monopoly that makes their current de-facto Windows monopoly seem like a velvet
glove in comparison.
The onerous nature of Vista's content protection also provides a perverse
incentive to remove the protection measures from the content, since for many
consumers that'll be the only way that they can enjoy their legally-acquired
content without Vista's DRM getting in the way. This is already illustrated
in the "Quotes" and "Footnotes" sections, where the people bypassing HD-DVD
protection measures aren't hardcore video pirates but ordinary consumers who
can't even play their own legitimately-acquired content. The sheer
obnoxiousness of Vista's content protection may end up being the biggest
incentive to piracy yet created. Even without overt "piracy" (meaning
bypassing restrictions in order to play legally-purchased media), it makes
very sound business sense for companies to produce hardware that bypasses the
problem, just as they have already with region-free play-anything DVD players.
Perhaps Hollywood should heed the advice given in one of their most famous
productions: "The more you tighten your grip, the more systems will slip
through your fingers".
Overall, Vista's content-protection functionality seems like an astonishingly
short-sighted piece of engineering, concentrating entirely on content
protection with no consideration given to the enormous repercussions of the
measures employed. It's something like the PC equivalent of the (hastily
dropped) proposal mooted in Europe to put RFID tags into high-value banknotes
as an anti-counterfeiting measure, completely ignoring the fact that the major
users of this technology would end up being criminals who would use it to
remotely identify the most lucrative robbery targets.
To add insult to injury, consider what this enormous but ultimately wasted
effort could have been put towards. Microsoft is saying that Vista will be
the most secure version of Windows yet, but they've been saying that for every
new Windows release since OS security became a selling point. I don't think
anyone's under any illusions that Vista PCs won't be crawling with malware
shortly after the bad guys get their hands on them. But what if the Vista
content-protection technology had instead been applied towards malware
protection? Instead of a separate protection domain for video playback, we
might have a separate protection domain for banking and credit card details.
Instead of specialised anti-debugging technigues to stop users getting at even
one frame of protected content, we could have those same techniques combatting
malware hooking itself into the OS. The list goes on and on, with all of the
effort being misapplied to DRM when it could have been used to combat malware
instead. What a waste. What a waste.
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 O]) 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. Because
Windows dominates the market and device vendors are unlikely to design and
manufacture two different versions of their products, non-Windows users will
be paying for Windows Vista content-protection measures in products even if
they never run Windows on them.
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 P], will you in exchange withhold this poison from the computer
industry? Please?
all credit goes to original author Peter Gutmann from this site
Originally Posted by Kaistar 
He's too young otherwise.