Wednesday, January 10, 2007

Windows VISTA corporate tyranny


A Cost Analysis of Windows Vista Content Protection





Peter Gutmann, pgut001@cs.auckland.ac.nz

http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html

Last updated 7 February 2007

Distributed under the
Creative Commons
license (see Appendix)



(A note to readers: The reaction to what started out as an obscure technical
post to a security mailing list has been rather unexpected and overwhelming,
so I'm totally buried in Vista email at the moment. Please be patient when
expecting replies, and apologies if I can't reply to all messages).





Executive Summary



Windows Vista includes an extensive reworking of core OS elements in order
to provide content protection for so-called “premium content”,
typically HD data from Blu-Ray and HD-DVD sources. Providing this protection
incurs considerable costs in terms of system performance, system stability,
technical support overhead, and hardware and software cost. These issues
affect not only users of Vista but the entire PC industry, since the effects
of the protection measures extend to cover all hardware and software that will
ever come into contact with Vista, even if it's not used directly with Vista
(for example hardware in a Macintosh computer or on a Linux server). This
document analyses the cost involved in Vista's content protection, and the
collateral damage that this incurs throughout the computer industry.



Executive Executive Summary



The Vista Content Protection specification could very well constitute the
longest suicide note in history [Note A].



Table of Contents





Introduction



This document looks purely at the cost of the technical portions of Vista's
content protection [Note B]. The political issues (under the
heading of DRM) have been examined in exhaustive detail elsewhere and won't be
commented on further, unless it's relevant to the cost analysis. However, one
important point that must be kept in mind when reading this document is that
in order to work, Vista's content protection must be able to violate the laws
of physics, something that's unlikely to happen no matter how much the content
industry wishes that it were possible [Note C]. This
conundrum is displayed over and over again in the Windows content-protection
requirements, with manufacturers being given no hard-and-fast guidelines but
instead being instructed that they need to display as much dedication as
possible to the party line. The documentation is peppered with sentences
like:




“It is recommended that a graphics manufacturer go beyond the strict
letter of the specification and provide additional content-protection
features, because this demonstrates their strong intent to protect premium
content”.



This is an exceedingly strange way to write technical specifications, but
is dictated by the fact that what the spec is trying to achieve is
fundamentally impossible. Readers should keep this requirement to display
appropriate levels of dedication in mind when reading the following analysis
[Note D].



A second point to note is that the term “premium content”, or
in more recent statements by Microsoft, “commercial content” (I've
used “premium content” throughout this writeup for consistency)
goes well beyond the HD-DVD and Blu-Ray examples that I've used above and
encompasses not just the obvious definition of “HD content in any
form” but even non-HD content, or

as
Microsoft put it “commercial content generally, independent of
resolution”. While premium content is currently still somewhat scarce,
in five years' time it'll be hard to find a movie or similar content that
isn't HD or similar premium content. So although Microsoft have tried to
downplay the perceived impact of Vista's content-protection by stating that
it'll only apply when premium/commercial content is present, this conveniently
sidesteps the fact that Microsoft hopes that this situation will become
universal in the near future. The whole future of Vista's content protection
is predicated on this fact, because without near-universal premium content
there's no point in having content-protection features in the first place.



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. But 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 in their article
The
Great HDCP Fiasco 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:




“Since there are currently no PCs for sale offering graphics chips that
support HDCP, this isn't yet possible”.


In fact so far no-one has been able to identify any
Windows system that will actually play HD content in HD quality, in all
cases any attempt to do this produced either no output or a message that it
was blocked by content protection. While it's not possible to prove a
negative in this manner, it's certainly an indication that potential buyers
may be in for a shock when they try and play premium content on their shiny
new Vista PC.



The same issue that affects graphics cards also goes for high-resolution
LCD monitors. One of the big news items at CES 2007 was Samsung's 1920x1200
HD-capable 27" LCD monitor, the
Syncmaster 275T,
released at a time when everyone else was still shipping 24" or 25" monitors
as their high-end product [Note F]. The only problem with
this amazing HD monitor is that Vista won't display HD content on it because
it doesn't consider any of its many input connectors (DVI-D, 15-pin D-Sub, S-
Video, and component video) secure enough. So you can do almost anything with
this HD monitor except view HD content on it.



If you have even more money to burn, you can go for the largest
(conventional) computer monitor made, the Samsung's stupidly large (for a
computer monitor) 46"
SyncMaster
460PN. Again though, Vista won't display HD content on it, turning your
$4,000 purchase into a still-image picture frame (oddly enough, this monitor
has been advertised as “HDTV ready” by retailers even though you
can't display HD images on it, although in practice the term
“HD-ready” has been diluted close to meaninglessness).



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 like the CMI
8788. 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 (you can get more information on Vista's
audio architecture and the changes from XP in
this
post from Creative Labs).



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. Echo cancellation is used to prevent
sound from a loudspeaker or headphones interfering with a microphone in the
vicinity. This is rather tricky because the sound will be modified by the
speaker and the surroundings that it's operating in, so it requires fairly
sophisticated signal processing to remove, as well as a high-quality copy of
the signal (if you get a degraded copy the signal, it becomes much harder to
use it to cancel out the echo with it). Although it's not visible, echo
cancellation is very widely used in applications like hands-free car phones,
standard phones used in hands-free mode, and conference calling systems.



AEC in a PC 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 that 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 (see the
Quotes for real-world examples of this). 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 (there's even a special status code for
this, STATUS_GRAPHICS_OPM_RESOLUTION_TOO_HIGH), 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.



(A lot of this OPM stuff seems to come straight from the twilight zone.
It's normal to have error codes indicating that there was a disk error or that
a network packet got garbled, but I'm sure Windows Vista must be the first OS
in history to have error codes for things like “display quality too
high”).



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. Vista's content-protection
means that video images of premium content can be subtly altered, and there's
no safe 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 (Philip Dorrell has
created a neat
cartoon that illustrates this problem). Microsoft claim that this hidden
image manipulation will only affect the portions of the display that contain
the protected content, but since no known devices currently implement this
“feature” it's hard to say how it'll work out in practice (what
happens currently is that Vista just refuses to play premium content rather
than downgrading it).



An interesting potential security threat, suggested by Karl Siegemund,
occurs when Vista is being used to run a security monitoring system such as a
video surveillance system. If it's possible to convince Vista that what it's
communicating is premium content, the video (and/or audio) surveillance
content will become unavailable, since it's unlikely that a surveillance
center will be using DRM-enabled recording devices or monitors. I can just
see this as a plot element in Ocean's Fifteen or Mission Impossible Six,
“It's OK, their surveillance system is running Vista, we can shut it
down with spoofed premium content”.



(The silly thing about the industry's obsession with image quality is that
repeated studies have shown that what really matters to viewers (rather than
what they think matters) is image size and not quality. Sure, if you take the
average consumer into a store and put them in front of the latest plasma panel
they'll be impressed by the fact that they can count each individual hair in
Gandalf's beard, but once he's leaping about wrestling with the balrog this
detail becomes lost and the only differentiator is image size. You can find a
good discussion of this in
The
Media Equation by Stanford professors Byron Reeves and Clifford Nass. In
one experiment on visual fidelity they showed a film using the best equipment
they could get their hands on, and again using a fifth-generation copy on bad
tape and poor equipment. There were no differences in users' responses to the
two types of images (see the book for more details on this). You can see an
example of this effect yourself if you can set up a machine with a CRT and an
LCD monitor. Use the CRT monitor for awhile, then switch to the LCD monitor
for a minute or two. When you go back to the CRT monitor, does it seem
faulty? Did you notice this before you looked over at the LCD monitor?



Conversely, image size is a huge differentiator: The bigger the better. So
in practice a degraded image on a huge VGA monitor (or by extension anything
with a lower-quality analog input) will rate better than a non-degraded image
on a much smaller LCD monitor, assuming you can find an example of the latter
that Vista will actually output an HD image to. Of course convincing
consumers of this is another matter).



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 (in the bad old days it used
to be necessary to identify individual device types and download specific
drivers for them, something that was more or less impossible for non-geek
users). 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, resulting
in a re-balkanisation of drivers that have only just become available in a
clean, unified form in the last few years. This is more a concern for device
vendors and driver developers than users, since they don't see any of this
artifically-created extra complexity. As far as the user is aware it's still
a “unified” driver since the internal re-balkanisation isn't
visible in the driver bundle (although the “unified” driver
suddenly becomes a lot larger). The indirect cost to the user (longer driver
development cycles and higher cost) is mostly hidden from them.



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 no longer be
fed anything considered to be premium content. What this means is that a
report of a compromise of a particular driver or device will cause all premium
content-handling ability for that device worldwide to be turned off until a
fix can be found. To quote the content-protection specs, “Vista will
[...] revoke any driver that is found to be leaking premium content [...] if
the same driver is used for all the manufacturer's chip designs, then a
revocation would cause all that company's products to need a new
driver”. 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 unable to handle premium content.



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. 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 (or in Vista's case its successor
Software
Protection Platform, SPP), 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 affected by a driver revocation (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.



Another unforeseen consequence of the potential for a downgrade disguised
as an upgrade (that is, a driver being revoked by Windows Update) is that the
whole process of updating your machine is supposed to provide benefits to the
user in the form of enhanced functionality or, more pragmatically, bugfixes
and security patches. Since malware attacks are invisible but a loss of
playback capability isn't, if the only visible effect of an update is to
reduce system functionality it incentivises users to disable updates in order
to avoid this issue.



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 cheap 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. Amusingly enough, precisely this approach
has been

recommended
by a Westinghouse (large US TV manufacturer) VP of Marketing to resolve
problems with Sony's interpretation of HDCP in the Playstation 3 and
Westinghouse's interpretation in their 1080p televisions, who told consumers
to “purchase an HDMI to DVI adapter to bypass HDCP”. The hardware
vendors seem to have come to the same conclusion about content protection as
the computer in Wargames
did about global thermonuclear war: “A strange game. The only winning
move is not to play”.



HDCP strippers 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. Even more accessible than that are 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. This
cannibalisation process is actually fairly common among TV servicemen. When a
major component like the picture tube or yoke (which is often only sold as an
integral part of the picture tube) fails, it's often not worth repairing the
TV any more, at which point it gains a second life as a source of spare parts
of other TVs. In particular components like the jungle IC (which integrates a
large amount of discrete circuitry into a single device) can cost as much as
$50-100 to replace, so it makes sense to recycle some of the parts rather than
buy new ones, particularly when it's not obvious whether this is the problem
component. Lifting an HDMI chip from such a TV set isn't nearly as exotic as
it sounds. Engadget have a

good
overview of the ensuing doomsday scenario.



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 (from the spec) “Windows Vista will initiate a full reset of the
graphics subsystem, so everything will restart”. According to Microsoft
this will only take a few seconds and will only affect the graphics subsystem
(so it's not a complete restart of Vista), but the true impact of this
mechanism remains to be seen. In addition even if it's relatively quick,
systems with high availability requirements probably won't appreciate the
overhead of periodic soft-reboots of the graphics subsystem. So 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 unusably unstable, 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, could claim
protection under the DMCA against any attempts to reverse-engineer or disable
the content-protection “features” that they're abusing.



Going beyond deliberate denial-of-service attacks, 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
infamous 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 H].
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.



Some contributors have commented that they can't see the revocation system
ever being used because the consumer backlash would be too enormous, but then
the legal backlash from not going ahead could be equally extreme. The only
real indication that we have for how committed Microsoft really are to this is
the amazing speed with which Microsoft released a patch for the WMDRM (Windows
Media DRM) vulnerability, which they

rushed out at a speed that even the most virulent worm never produced.
This would seem to indicate that they're pretty serious about this, since they
prioritised it above any conventional non-DRM-related security problem.



Can these protection mechanisms be inadvertently triggered? There's plenty
of real-world evidence to show that this happens all the time. One example
that I recently encountered in my friends-and-neighbours computer support work
involved a retired filmmaker who has a 50-year collection of educational films
made for teaching in schools. Recently he's been transferring his entire
collection to DVD to make them more accessible to newer audiences.
Unfortunately some component of Windows' content-protection has decided that
some protection requirement isn't being met somewhere, and as a result 50
years of educational film-making have been reduced to an error message
indicating that Macrovision can't be enabled and therefore the content can't
be played. Since it plays just fine on a variety of non-Windows platforms
including a range of standard DVD players, it's not a problem with the DVDs
but is due to the malfunctioning of a Windows content-protection mechanism
around a technology called Macrovision.



Macrovision
is a basic analog signal-protection technique that's applied to TV-out ports
on computer video cards. Strangely, his computer doesn't actually have any
TV-out capability. What it does have is a video chipset that, in theory, can
provide TV-out (most video chipsets have this capability, but it's only used
on some types of video cards, see the section Increased
Hardware Costs for details on their use in different variations of video
cards). However, since no actual TV-out capability exists, it's not possible
to enable Macrovision for it. This leads to a farcical situation where
Windows is prohibiting playback due to the absence of copy protection on a
nonexistent output
(here's one of
many examples of other users running into the same problem). As a result,
in the name of content protection, the film-maker is prevented from playing
back his own content!



This isn't just an isolated incident. A quick
Google
search of the error message that comes up reveals thousands upon thousands
of users that have encountered this very problem, and this in turn is merely
the tip of the iceberg, since few of those affected — home users wanting
to play back movies — will have enough know-how to seek out the far-
flung technical forums where this is being discussed (in fact to get a better
estimate of the number of affected users you need to make multiple searches
using variations of the error message, since it's reported in a variety of
different ways). In any event even if they do get this far, it's a pointless
effort because there's no known solution to the problem (although random
poking around like wiping the computer clean and reinstalling Windows have
reportedly helped in some cases).



This in turn is just one single way in which Windows' content-protection
can malfunction. A Google search for various other playback-prevention error
messages
(here's
one example of such a message) reveals further unfortunate communities of
users united by the fact that they've been prevented from viewing content by
malfunctioning Windows content protection.



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:




“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 this 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 one product review 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
clearly shows the large red rectangular area to the far left of the card,
which is where the manufacturer has omitted a component to produce a lower-
cost model. The same thing is visible in
another
card. Conversely, an (at the time it was released) top-of-the-line card
with
optional components fitted shows an additional chip to the left of the
large square heatsink+fan that 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.



In some cases the addition of extra circuitry isn't merely a convenient
price-differentiation mechanism but is required for the device to function.
Most newer video cards have dual video outputs, and the higher-end ones tend
to have dual-DVI out. However, many devices only provide have a single TMDS
(Transition Minimized Differential Signaling, a high-speed serial data format)
output for DVI signalling. The second output is provided by a DVO (Digital
Video Out, not to be confused with Intel's similarly-named SVDO) port in
combination with an external TMDS transmitter. In addition some high-
resolution displays require multiple DVI/TMDS links because single-channel DVI
doesn't have enough bandwidth to support very high resolutions, requiring
external TMDS transmitters. You can see this in the first image on a review
of Macintosh video cards, which shows
the dual-link
DVI output used to drive Apple's 30" Cinema Display (this actually
requires two dual-link TMDS transmitters to support a second display, but I'll
spare you the technical details of that one). The important point in all of
this is the phrase “external TMDS transmitter”, none of which meet
the robustness requirements since they have direct access to the high-quality
digital signal. Perversely enough, it's mostly the high-resolution displays
advertised as suitable for HD content that require the external TMDS circuitry
that makes them unable to meet the robustness requirements.



This problem is a nasty catch-22 from which there's no escape. In theory
it would be possible to add a DVI-to-HDMI (with HDCP) encoder to bypass this
(a typical example would be the Silicon Image Sil139x or Sil193x devices,
which were specifically designed for this application. Silicon Image TMDS
transmitters are widely used on graphics cards), but HDMI doesn't have the
bandwidth to carry the high-definition images that this monitor displays. Even
without explicit image degradation via constriction, the requirement to use
the lower-quality HDMI link to carry what should be a DVI signal means that
image quality is lost, and to make it even more painful the resulting graphics
cards will be more expensive because it costs extra to add the quality-
downgrading HDMI transmitter. In other words consumers will be paying extra
in order to get a lower-quality image.



Even with lower-resolution monitors, the fact that the data signal is
present in unprotected form when it enters the external encoder means that it
probably won't meet the robustness requirements. (Exactly how this is meant
to work is unspecified in any documentation that I've been able to get my
hands on. It appears to be impossible to output a content-provider approved
protected signal from a PC while also meeting the robustness requirements).



Vista's content-protection requirements eliminate the ability to accomodate
different feature sets in a 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/TMDS chip, it now has to be integrated into
the graphics chip, along with any other functionality normally supplied by an
external device. 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 (although given the popularity of graphics-
intensive computer games, it's more likely that they'd be getting the budget
card for their own PC).



A further example of external meddling in hardware vendors' product
development and distribution can be found in the document that specifies what
happens when a product is compromised in some way even though it's previously
been found to be fully compliant with the robustness requirements:





“Company shall promptly redesign the affected product [...] if such
redesign is not possible or practical, cease manufacturing and selling such
product”.


This indicates that no matter how much dedication you show to the party
line, it still won't help you when the chips are down. Some years ago a
friend of mine was working for a company that was building a custom IT
solution for a government department. When the day came time to sign off on
it, everyone in the entire department who had signing authority called in sick
rather than end up being the one who put their name to it. I can just imagine
the corporate sick day at ATI, nVidia, Intel, VIA, SiS, when it came time to
put someone's name to this gem, which gives Hollywood veto rights over your
production lines and sales and distribution channels.



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
(actually you could do it better, since DVI is provides a higher-quality link
than HDMI). 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 (for example the spec
requires “use of techniques of obfuscation to disguise and hamper
attempts to discover the approaches used”). 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. In fact the
sorry state of some of Vista's still-not-finished-yet graphics drivers have
already prompted a class-action
lawsuit against nVidia for deceptive advertising because many devices
using nVidia hardware and advertised as "Vista Ready" don't actually work
because the drivers aren't ready (the situation with 64-bit drivers,
ostensibly a major reason for switching to Vista in the first place, is
particularly dire).



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. The initial crypto handshake is:




  driver -> application: cert + nonce
  application -> driver: RSA-OAEP-SHA512( nonce || key || seqNo1 || seqNo2 )


In this step the driver supplies its certificate to the calling application
via DxgkDdiOPMGetCertificate() and a 128-bit nonce via
DxgkDdiOPMGetRandomNumber(). This is either a COPP or an OPM certificate,
with COPP being the older Windows XP content protection and OPM being the
newer Windows Vista one. There's also a third type of certificate which the
driver uses if it has a UAB (User-Accessible Bus). The certificates contain a
2048-bit RSA key which is used to encrypt a 40-byte payload containing the
nonce provided by the driver, a 128-bit session key, and two 32-bit initial
sequence numbers (they start at random values), the first number is for status
messages via DxgkDdiOPMGetInformation() and the second for command messages
via DxgkDdiOPMConfigureProtectedOutput().



Once the keys are set up, each function call is:




  in = OMAC( nonce || seqNo || data )
  out = OMAC( nonce || seqNo || data )



(I've used conventional bits-on-the-wire notation for this, the values are
actually fields in a structure so for example the sequence number is provided
in the ulSequenceNumber member). This is very similar to the protocol used in
SSL or SSH (in practice some steps like cipher suite negotiation are omitted,
since there's a hardcoded set of ciphers used). Finding SSL being run inside
a PC from one software module to another is just weird.



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.



In order to prevent active attacks, device drivers are required to poll the
underlying hardware every 30ms for digital outputs and every 150 ms for analog
ones 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
(Leo Laporte in his Security Now podcast with
Steve Gibson calls Vista “an operating system that is insanely
paranoid”). 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 I]. 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 J].



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?



Looking at this from the point of view of the typical user rather than
high-end gamers, the problem is rather different. It's not uncommon to find
PCs so infested with malware (spyware, viruses, trojans, bots, and so on) that
they can barely perform their normal tasks, let alone handle the overhead of
content protection (depending on whose surveys you believe, the typical
Internet-connected PC averages 20-30 pieces of malware). Despite the fact
that, on paper, they may have plenty of system resources to throw around for
content protection, in practive the overhead of hosting an entire zoo of
malware means that any added overhead due to content protection renders them
more or less unusable for content playback (while users don't seem to mind
waiting around for their botnet-hosting PC to open a Word document, they'll be
less happy when it drops frames or produces stuttering audio output).



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.



(The burden that the content-protection overhead places on resources is
even more severe for portable, battery-powered devices. As a
CNET review of
portable devices found, “DRM not only slows down an MP3 player but
also sucks the very life out of them”, with the extra overhead of
processing DRM'd content shortening the battery life by about 25% across a
whole range of products. This burden extends beyond DRM'd music into games as
well. For example the content-protected version of the game
Flatout 2 runs
15% slower than the same game
without content protection).



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
which looked at the benefits of restrictive DRM for the company that controls
the DRM. 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 restrictions that a Fortune magazine senior editor reviewed
it as the STNKER), so Microsoft will totally control the premium-content
distribution channel. In fact examples of this Windows content lock-in are
already becoming apparent as people move to Vista and find that
their legally-purchased content
won't play any more under Vista (the example given in the link is
particularly scary because the content actually includes a self-destruct after
which it won't play any more, so not only do you need to re-purchase your
content when you switch from XP to Vista, but you also need to re-purchase it
periodically when it expires. In addition and since the media rights can't be
backed up, if you experience a disk crash you get another opportunity to re-
purchase the content then). It's obvious why this type of business model
makes the pain of pushing content protection onto consumers so worthwhile for
Microsoft since it practically constitutes a license to print money.



Microsoft have been saying for some years now that they'd really like the
PC to go away, to turn into a kind of media center and content-distribution
center for consumers. Windows MCE has been the tail and of a long line of
(unsuccessful) attempts to achieve this (the only reason why MCE seems to sell
at all is because it's the cheapest version of Windows that vendors can pre-
install on a PC). If “premium content” ever takes off, Microsoft
wants to be the central controller of all content distribution and playback
— only Windows can secure the content, therefore only Windows can
distribute it. Even the term “premium content” is misleading: in
a few years' time, most audio and video will be produced in some form of HD
format, at which point “premium content” becomes normal, and so
everything is subject to content protection.



Paul Stimpson submitted an excellent analysis of this situation in which he
points out that “Microsoft are being clever by releasing these
protection 'features' now; The average user who goes to a computer store will
get Vista but won't have either premium content or get 'premium ready' PC
hardware; The ordinary person in the street can't afford a top-of-the-line
machine and display. They will have a 'Vista capable' machine; Vista will
look nice and not cause too much trouble or suffer from the protection
overhead too much; They won't have any choice or know any different and it
will be accepted. These people will dismiss any complaints they hear about
these problems as a geek thing. They got their computer at the right price
and it does everything they ask of it. They will only find out the truth in a
few years when they buy their next computer and all machines are 'premium
ready' (and fast enough to implement the protection) and every display has an
HDMI connector. By that time XP will be well into it's decline so there will
be no going back. It's impossible to keep off the upgrade treadmill if you
have Windows; Eventually you will either have to buy new hardware (with a new
copy of Windows) or your out-of-support version of Windows will become such a
target for malware that it will no longer be useable.”



“In today's environment these content protection features are indeed
a nonsense. I don't think, however that MS are thinking about today's
environment beyond keeping these features low-key for most users in order to
avoid rejection. In their heads MS see the 'connected home' where everyone
has a network and displays around the house that integrate everything from TV
to email, Internet, telephone, lighting and heating. In order to do these
things on your TV you need a computer attached to it and MS want that computer
to run Windows.”



So not only will Microsoft 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.
And as the example above shows, they'll also be able to dictate terms to
consumers in order to ensure a continual revenue flow. The result will be a
technologically enforced monopoly that makes their current de-facto Windows
monopoly seem like a velvet glove in comparison [Note K].



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 (there were already Vista
exploits up for sale before the OS even hit the shelves). 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 L]) 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 M], will you in exchange withhold this poison
from the computer industry? Please?



Acknowledgements



This document was put together with input from various sources, including a
number that requested that I keep their contributions anonymous (in some cases
I've simplified or rewritten some details to ensure that the original,
potentially traceable wording of non-public documents isn't used). Because it
wasn't always possible to go back to the sources and verify exact details,
it's possible that there may be some inaccuracies present, which I'm sure I'll
hear about. No doubt Microsoft (who won't want a view of Vista as being
broken by design to take root) will also provide their spin on the details.



In addition to the material present here, I'd be interested in getting
further input both from people at Microsoft involved in implementing the
content protection measures and from device vendors who are required to
implement the hardware and driver software measures. I know from the
Microsoft sources that contributed that many of them care deeply about
providing the best possible audio/video user experience for Vista users and
are quite distressed about having to spend time implementing large amounts of
anti-functionality when it's already hard enough to get things running
smoothly without the intentional crippling. I'm always open to further input,
and will keep all contributions confidential unless you give me permission to
repeat something. If you're concerned about traceability, grab a disposable
account at Yahoo, Gmail, or some similar provider and contact me through that.
If you're worried about being identified via the machine you connect to the
email provider with, use an Internet cafe to send the message — just use
standard common-sense precautions. If you want to encrypt things, my PGP key
is linked from my home
page.



(In case the above hints aren't obvious enough, if you work for nVidia,
ATI, VIA, SiS, Intel, ..., I'd really like to get your comments on
how all of this is affecting you).



Sources



Because this writeup started out as a private discussion in email, a number
of the sources used were non-public. The best public sources that I know of
are:





An excellent analysis from one of the hardware vendors involved in this
comes from ATI, in the form of
Digital
Media Content Protection from WinHEC. This points out (in the form of
PowerPoint bullet-points) the manifold problems associated with Vista's
content-protection measures, with repeated mention of increased development
costs, degraded performance and the phrase “increased costs passed on to
consumers” pervading the entire presentation like a mantra.



In addition there have been quite a few writeups on this (although not
going into quite as much detail as this document) in magazines both online and
in print, one example being PC World's feature article
Will your PC run Windows
Vista? which covers this in the appropriately-titled section “
Multimedia in chains”, and ComputerWorld's article
Vista
and More: Piecing Together Microsoft's DRM Puzzle. Audience reactions to
these proposals at WinHEC are covered in
Longhorn:
tough trail to PC digital media published in EE Times, unfortunately you
need to be a subscriber to read this but you may be able to find accessible
cached copies using your favourite search engine. The EFF has an overview of
the effects of Vista's revocation mechanisms in
Protected Media
Path, Component Revocation, Windows Driver Lockdown.



Use, Modification, and Redistribution



This document is licensed under the
Creative Commons
Attribution 2.5 License. This means that you can copy, distribute,
display, and perform the work, and make derivative works, provided that you
credit the original author and provide a link back to the original work (at
the URL given in the title). To quote the Creative Commons site, “This
license lets others distribute, remix, tweak, and build upon your work, even
commercially, as long as they credit you for the original creation. This is
the most accommodating of licenses offered, in terms of what others can do
with your works”.





Appendices and Footnotes



The more formal section of the document ends here. The following sections
contain various informal comments, thoughts, and other odds and ends. For
people doing translations of this document, it's probably not worth trying to
translate these sections.



Mini-FAQ



This document seems to produce various reactions that come up repeatedly.
To respond to the more frequently-expressed views, I've added this mini-FAQ.



This is just Microsoft-bashing.



It's bad-technology bashing. If this had been done by Linus Torvalds,
Steve Jobs, Alan Cox, or Theo de Raadt, I'd have said the same thing about it.
As far as I'm concerned computers are tools to get a job done and not a
platform for religious wars, and if something's bad I'll say so regardless of
who's doing it. Just for the record I run various versions of Windows on ...
[counting] ... seven of my machines (the rest are a mixture of Linux, FreeBSD,
and occasionally Solaris), so I'd be a rather unlikely Microsoft detractor if
I have their software all over my machines.



This is a biased writeup.



Perhaps, but then I challenge anyone to read the specifications given in
the Sources section above and write a positive analysis
of Vista's content protection. Someone has to point out these problems, and
it happened to be me in this case, but I think anyone with technical skills
who reads the relevant documents would come to a similar conclusion.



This is all a pile of FUD.



The process that leads to comments like this tends to be (1) Quickly skim
through this document, (2) Decide that it sounds a bit implausible (possibly
even before performing step 1), (3) Post a rant saying it's FUD. To pick one
particular example, a Digg reader's reaction to the section of text that
states there isn't sufficient CPU power available for both decompression and
encryption was:




I'm sorry, where does this come from? You do realize that this is completely
uncited, and very likely wrong? Entire paragraphs that follow are based on
this magical detail pulled out of thin air. [...] I'm no fan of this asinine
DRM bullshit, but the scenarios and postulates put forth in this article are
complete rubbish.


Referring to the very first source listed in the
Sources section shows that this is picked not from thin
air but from Microsoft's own documentation:




The problem with regular AES is that it takes about 20 CPU clocks to encrypt
each byte. This is OK for compressed or semi-compressed video, but for the
multiple HD uncompressed case, it is too much even for a 2006 processor
[referring to the fastest CPU available at the time the document was written].


and then again:




In the case of premium content, whether video can play back smoothly when
using regular AES with uncompressed video will be a function of the resolution
of the uncompressed video and the power of the processor. It is unlikely to
work well in 2006 for uncompressed HD premium content


If you don't believe what you've read here, go back to Microsoft's own
documentation and read that (in fact read the Microsoft documents no matter
what you believe, because they're quite scary). If you still think it's FUD
then you can at least post informed comments about it.



Microsoft is only doing this because Hollywood/the music industry is
forcing them to.



“We were only following orders” has
historically worked
rather poorly as an excuse, and it doesn't work too well here either.
While it's convenient to paint an industry that sues 12-year-old kids and 80-
year-old grandmothers as the scapegoat, no-one's holding a gun to Microsoft's
head to force them do this. The content industry is desperate to get its
content onto PCs, and it would have been quite easy for Microsoft to say
“Here's what we'll do with Vista, take it or leave it. We won't
seriously cripple our own and our business partners' products just to suit
your whims”. In other words they could make it clear to Hollywood who's
the tail and who's the dog.



Here's an illustrative story about what can happen when the content-
industry tail tries to wag the dog. About 10-15 years ago, music companies
told a bunch of NZ TV stations that they had to pay fees in order to screen
music videos. The TV stations disagreed, saying that they were providing free
advertising for the music companies, and if they didn't like that then they'd
simply stop playing music videos. So they stopped playing all music videos.



After a few weeks, cracks stated to appear as the music companies realised
just how badly they needed the TV channels. One of the music companies bought
an entire prime-time advertising block (at phenomenal cost, this wasn't a
single 30-second slot but every slot in an entire prime-time ad break) just to
play one single new music video.



Shortly afterwards, music videos reappeared on TV. The details of the
settlement were never made public, but I imagine it consisted of a bunch of
music company execs on their knees begging the TV stations to start playing
music videos again and let's please never bring this matter up again.



It's the same with Microsoft, the content industry needs them as badly (or
more badly) than Microsoft needs the content industry. Claiming that they're
only following orders from Hollywood is a red herring — if Microsoft
declined to implement this stuff, Hollywood would have to give in because they
can't afford to lock themselves out of 95% of the market, in the same way that
the music companies couldn't afford to cut out their primary advertising
channel.



This overstates the potential risks.



I work in the field of computer security. It's my job to perform risk
assessments of computer technology and that's what this writeup is. If I
worked in marketing, it'd be my job to tell you how wonderful Vista's content
handling is. Since I don't work in marketing, what you're reading is an
analysis of the potential risks of Vista's content-protection technology.



If you go to a lawyer and say “I want to do X, what are the potential
risks from a legal point of view”, they'll tell you the potential risks
of X. If you go to a security person and ask the same question, they'll tell
you the potential risks from a security point of view. The intent is to
inform potential Vista users of possible risks and allow them to make their
own decisions. Some of the risks may seem obscure, but it's up to you to
decide what their impact on you might be and whether they apply to your field
of use or not.



You're just upset because you can no longer steal content under Vista.



Yes, someone really did send me email with this claim in it. It's silly
enough that I just had to include it for the amusement value :-).



Open Questions



There are a number of open questions about Vista's content protection that
probably won't be able to be answered until some months after its wide
deployment when users can report on real-life experiences, because no-one
seems to know how certain things will work.



Question 1.



How easy is it to get HD content around the outside of Vista's content-
protection? Looking at the block diagrams in the specification documents is:




       User-space application
              --------
  Vista content-protection interface
              --------
   Vista content playback subsystem
              --------
        Vista device drivers
              --------
           Device hardware


Reading the specs, user-space applications are expected to call down into
the Vista content-protection interface to play back content (one document
actually uses the metaphor of the user-space application simply acting as a
remote control for the Vista content-protection and playback subsystem). The
question is, can a user-space application that chooses to opt out perform an
end-run around the higher-level Vista interface and go directly to the low-
level interface to get its content out without Vista's content-protection
getting in the way?

User feedback on Microsoft's own forums indicates that even using third-
party playback software like the nVidia or Cyberlink decoders instead of the
Vista one will result in playback being disabled when (in this case) the Vista
Media Centre trial license expired.



Question 2.



How will all of this affect users who want to prepare HD content, protected
or not? Given that the intent of Vista's content-protection is to ensure that
no HD content ever leaves the system in usable form, how do you prepare the HD
content? More importantly, since Vista happens to be a multitasking OS, how
do you guarantee that as your HD content is being prepared, the presence of
some other protected content somewhere in the system doesn't cause it to be
silently degraded for “protection” purposes? Just how deep does
the protection extend? If it's on a per-task or even per-thread level then
any cross-task or cross-thread mechanism (e.g. process thread injection) can
be used to compromise the content protection. On the other hand if it's

“all your content are belong to us” whenever protected content is
present then innocent content will be degraded along with protected content.



Question 3.



If you build it, they will come. Once the DRM mechanisms are in place,
there's every reason to believe that any kind of content subject to any kind
of copyright will try and take advantage of it. After all, why not? The
tools are there, there's no reason not to use them. We already have so-called
Enterprise DRM (E-DRM) that's intended to control access to documents like
Microsoft Word, PDF documents, CAD files, and so on (about 20 years ago during
the heyday of the DoD Orange Book this stuff was known as ORCON, originator-
controlled access control). Now that DRM is integrated into Vista as a core
technology there's no knowing how far this can be taken in the future. Indeed
Bill Rosenblatt, managing editor of
Jupiter Media's “DRM Watch”
sees
enterprise
DRM as a major growth area for Vista's content-protection technology.
What will computing be like in a few years time?



Question 4.



I've both read on the web and received via email endless reports of people
unable to play HD-DVD and Blu-Ray content on Windows PCs, both Vista (beta)
and XP. Has anyone actually been able to play HD-DVD or Blu-Ray
content (i.e. the material that Vista classes as premium content) under
Windows at HD quality levels (i.e. without resorting to hooking up an analog
monitor or something similar)? If so, what HD drive, player software,
graphics card, and monitor did you use?



(So far alongside a great many reports of people being unable to play any
HD content at all I've received one report of someone who could play back HD-
DVDs. Equipment used was an XBox360 (functioning as the HD-DVD player), an
nVidia 8800GTX with HDCP (a top-of-the-line graphics card currently selling
for around $600), and a Westinghouse 37w3 with HDCP on the DVI input (a 37"
LCD display currently selling for around $1,200).



Microsoft's Response



In mid-January 2007,
Microsoft
responded to some of the points in this writeup. Some of the material was
new and interesting (for example clarifying just what actually gets revoked
when a driver revocation occurs), other parts seem more likely to have come
from Waggener Edstrom

(Microsoft's PR firm) than Program Manager Dave Marsh
(The
Inquirer wasn't too impressed by it either). I'll be updating the
body text based on some of the clarifications, but for things that aren't
directly relevant to the main text (which means the PR-spin items) I'll
comment on them here. The important technical clarifications that affect the
main body of the writeup are (1) exactly what happens when a driver is
revoked, (2) what happens when a tilt bit triggers, and (3) which portions of
the output are affected when content degradation takes place. The content-
protection specifications were previously somewhat unclear about these various
consequences of the protection mechanisms, so it's good to have this
clarification on exactly what occurs.



Since the portions that I'll comment on here are PR-related rather than
technical content, the following section is an attempt to respond directly and
try and unravel the PR spin. The technical comments have been integrated into
the main body of the writeup.



Do things such as HFS (Hardware Functionality Scan) affect the ability of
the open-source community to write a driver?




No. HFS uses additional chip characteristics other than those needed to write
a driver. HFS requirements should not prevent the disclosure of all the
information needed to write drivers.


This claim is directly contradicted by a

document by the same author which states:




Such tests could involve loading a surface with an image, and then getting the
chip to apply various visual effects to the image and reporting back the
resulting pixels.


and then later on:




The internal workings of the graphics chip must be kept secret, such that a
hacker building an emulator could not find out the required information.


So this document, the primary reference for Vista's content protection,
states exactly the opposite of what's said in Microsoft's response, namely
that standard chip functionality (in this case graphics rendering in a GPU) is
exercised for HFS, and that the device details have to be kept secret to
prevent someone emulating the functionality.



Will the Windows Vista content protection board robustness recommendations
increase the cost of graphics cards and reduce the number of build options?




Everything was moving to be integrated on the one chip anyway and this is
independent of content protection recommendations. Given that cost
(particularly chip cost) is most heavily influenced by volume, it is actually
better to avoid making things optional through the use of external chips.


While it's certainly tempting to quote the Slashdot response
“Whose
ass was this assertion pulled out of?”, I'll provide a bit more
context. This comment, that the overhead of Vista's content protection will
lead to cheaper hardware, comes from a Microsoft product manager resposible
for the content protection. An ATI product manager responsible for producing
the actual hardware says:





“These costs are passed on to the consumer”


“This cost is passed on to all consumers”


“This cost is passed on to purchasers of multimedia PC's”


“Costs are passed on to consumers”


“Costs are passed on to consumers, especially early adopters”




I'll let you decide who to believe.



(Another problem with this unification of hardware is that it leads to
problems like the erroneous triggering of content-protection measures that's
described in Decreased System Reliability).



Will Windows Vista content protection features increase CPU resource
consumption?




Yes. However, the use of additional CPU cycles is inevitable, as the PC
provides consumers with additional functionality.




Note the careful use of the term “additional functionality”
rather than “enhanced functionality”. Vista's content protection
actually provides reduced functionality (as the main body of the writeup goes
into in great detail), so the comment is pretty much confirming what's in the
writeup. Vista users have already
complained
about the excessive CPU usage of a Vista component called “Media
Foundation Protected Pipeline” (here's a

screenshot
of it in action), complaining of it pegging the CPU at 100% load on
startup and then staying at 10-20% CPU during playback. One user complained
of it
consuming
50% of the CPU on his 3GHz Pentium 4 machine under Vista, while there had been
no problems under XP. Another user observed that
this
process also runs for DivX and XviD files, implying that it's always
active even if no premium content is present.



The exact nature of this Media Foundation Protected Pipeline is somewhat
mysterious, the executable image is mfpmp.exe but there's no file of that name
present in Vista which implies it's being generated on the fly by another
executable. The process only shows up with Windows Media Player, not with
other players like VLC or WinAMP, and even then only when certain content like
MP3s or video is played. It doesn't show up for older/simpler content like
WAV files, but then again it does show up for non-protected content. Karel
Donk has done some further testing with this and reports that:




While playing an MP3 file in WMP, I ended the “mfpmp.exe” process,
and then sound stopped, but WMP still worked. I then pressed stop in WMP and
then Play again and the MP3 file started playing, but this time through
wmplayer.exe itself. It probably detected something wrong with the “

mfpmp.exe” and fell back to another playback path I think. Can't be
sure. A few seconds later, “mfpmp.exe” did appear again, but with
0 CPU usage as the file was playing through WMP. I had to restart WMP in order
for the MP3 to play again through “mfpmp.exe”.


(Can others confirm this? I don't run Vista, but if this is true then it
would seem to disconfirm Microsoft's claims that the content protection
doesn't interfere with playback and is only active when premium content is
present).



Another way of looking at this is to rephrase the question to “Will
viruses increase CPU resource consumption?”, to which the answer is also
“Yes. However, the use of additional CPU cycles is inevitable, as the PC
provides consumers with additional functionality” (like spamming,
phishing site hosting, and so on).



What about S/PDIF audio connections? [...] Will Component (YPbPr) video
outputs be disabled by Windows Vista's content protection?




Similar to S/PDIF, Windows Vista does not require component video outputs to
be disabled, but rather enables the enforcement of the usage policy set by
content owners or service providers, including with respect to output
restrictions and image constraint.


So that would be a “Yes” then. This is another one of the
sections that seems likely to have had Waggener Edstrom influence.



Will echo cancellation work less well for premium content?




We believe that Windows Vista provides applications with access to sufficient
information to successfully build high quality echo cancellation
functionality.


The reason why I brought up the issue of echo cancellation in the first
place is that a
document
by Dave Marsh, the same person who wrote the above text, states that
content protection interferes with echo cancellation. The above text says
that it doesn't. One of those two statements has to be wrong.



Will Windows Vista audio content protection mean that HDMI outputs can't
be shown as S/PDIF outputs?




It is better if they show as different codec types, as it allows the
difference to be reflected in the UI, thus providing the user help with their
configuration and creating a better user experience. The user wants to know
the difference between HDMI and S/PDIF, as they are different physical
connectors.


From reading the slashdot
comments on this, it's nice to see that I wasn't the only one who
immediately thought of Orwell when they read this reply:




War is peace!

Slavery is freedom!

We have always been at war with consume^H^H^H^H^H^Hpirates!




This is another one of these twilight-zone comments
that seem to crop up again and again when discussing Vista's content
protection. The HDMI designers had very good reasons for making HDMI's audio
S/PDIF-compatible, as discussed in the writeup.
Arguing that creating an artificial difference between the two because it
gives users more control is like arguing that manual gearboxes are better
because they provide more control — this may (technically) be the case,
but unless you're an F1 driver you're probably not going to appreciate this
very much. Less is more. War is peace.



Do content protection requirements mean that graphics chips have to
provide hardware acceleration for video decode?




No. The Windows Vista content protection requirements do not require that
graphics hardware include hardware acceleration for decode for many years, but
such support is highly recommended to improve the user experience for HD
content.


Like the comment about echo cancellation above, my source for this is also
the original
document
by Dave Marsh. Here's the text straight from the original document:




It is a PVP-UAB requirement that discrete graphics chips implement at least
iDCT and Motion Comp decode acceleration for MPEG2 and Windows Media® Version
9/VC-1.


As with the comments on HFS and echo cancellation, those statements can't
both be right.



There are other minor nits with Microsoft's response, but it's minor stuff
and not worth picking through here.



About the Author



I'm a researcher in the Department of
Computer Science at the University of
Auckland, New Zealand, working on the design and analysis of cryptographic
security architectures. In the past I've helped write the popular PGP
encryption program and have authored a number of
papers and RFC's on security
and encryption including the X.509 Style Guide for certificates, as well
as

Cryptographic
Security Architecture: Design and Verification (published by Springer-
Verlag). Most of my time is taken up with development and support of the open
source cryptlib
security toolkit. This gives me a lot
of exposure to industry practices and trends, so I'd say my background is a
50/50 mix of industry and academia.



In my spare time I engage my obsesssion with
photography,
and if I had just a little bit more spare time than that the link would
probably take you to a proper Flickr gallery rather than a bare web page. In
addition to this, I seem to have recently taken up a second full-time job as
spokesperson for Vista content security :-).



Glossary



This document was originally written for a technical audience and so used a
number of technical terms that would have been familiar to its target audience
but not to the general public. This glossary provides a few basic
definitions, for more details see your favourite online source, for example
Wikipedia.




DRM

“Digital Rights Management” or “Digital Restrictions
Management” or “Defective Recorded Media” (when applied to
CDs, since it deliberately introduces defects into the media). Combine all
three and you have a general idea of what DRM is.

HD

High definition, technically meaning video content of 1920 x 1080 (1080p)
resolution, but more generally anything with better than generic TV-quality
resolution. In their specs, Microsoft regard anything with more than 520K
pixels or 800x600 resolution as premium content that needs to be downgraded
before displaying it to the user.

HD-DVD


One of the proposed successors to DVDs, capable of storing HD content.

(More definitions to come).



AEC (automatic echo cancellation)

AES-128

AGP

CRT

DVI

DMCA

HDCP

HDMI

HFS (hardware functionality scan)

IDCT

IP (intellectual property)

JPEG2000

MPEG


OMAC

PCIe

RAMDAC

S/PDIF

TOSlink

VGA

VPU

WGA


Quotes



A few fun quotes, included for amusement value.



“I propose that each copy of the OS should ship with an
orange jumpsuit and sensory deprivation goggles, since all Vista users have
been unilaterally declared 'enemy combatants' by the content apparatchiki

” — Daniel Nevin.


“Windows Vista? And what a vista! All you see as you look
around your garden is a 60foot high brick wall” — Crosbie Fitch.


“When you download licenses for protected content, you agree
that Microsoft may include a revocation list with the licenses [...] content
owners may ask Microsoft to revoke the software's ability to use WMDRM to play
or copy protected content” — Windows Vista EULA.


“[Microsoft researcher] England has a bold plan to improve
the PC and make it a secure delivery system for audio and video. England's
solution involves making minor modifications to the PC's hardware to allow
Microsoft to make a secure version of the Windows Media Player. Essentially,
this would turn the PC into a record player as far as music is
concerned” — Microsoft Research News.

“This is obviously some strange use of the word 'improve' which I've
previously been unaware of” — Arthur dent.


“welcome to the new world of DRM where expensive pieces of
hardware across the world could potentially be remotely rendered useless by
over-zealous copyright holders. Way to go, Hollywood!” — Chip
Mulligan.


“I can not only say that the idea [of tilt bits] is
basically insane, but I can also see hardware manufacturers refusing to
implement tilt bits, or more likely, faking their functionality” —
Dave Walker.


“I purchased a new DVD/SACD player (w/HDMI out), surround-
sound receiver/amp (non-HDMI i/o — they're still too expensive for me),
& LCD TV with HDMI input. My DVD/SACD player was connected to the SSamp via a
nice single simple optical cable (& HDMI cable to the TV). I figured that
would be all I need, keeping a digital path all the way to the SSamp (& TV).
Wrong! It worked beautifully until I played my one & only SACD. No sound
came forth! Huh? I read the DVD/SACD player manual: in brief small print,
'When playing SACDs, audio is output only from the 5.1ch RCA analogue outputs'
” — Anthony May.


“This is SACD silence, the purest silence known to man
— It's premium and must be protected at all costs!” — Paul
Stimpson.


“I can't playback HD because I need to upgrade my 2 (SLI'd)
Nvidia Quadro 4500's (~$2000) to a $200 FX7600GT because it supports HDCP. I
can't wait till someone cracks this DRM/HDCP/AACS crap” —
“Sy”.


“I've just had my first experience with HD content being
blocked. I purchased an HP Media Center PC with a built-in HD DVD player,
together with a 24" 'high definition' 1920 x 1200 HP flat panel display (HP
LP2465). They even included an HD movie, 'The Bourne Supremacy'. Sure
enough, the movie won't play because while the video card supports HDCP
content protection, the monitor doesn't. (It plays if I connect an old 14"
VGA CRT using a DVI-to-VGA connector)” — Roger Strong.


“when I disable my HD monitor, I can watch the movie, on my
old VGA screen, but, what is the point of having a HD monitor and not being
able to watch a HD movie on it” — “muslix64” (muslix64
was so upset at not being able to play his legitimately-purchased movies on
his legitimately-purchased monitor attached to his legitimately-purchased
player that he broke the AACS protection just to be able to see his own
movies, see Note D).


“With the HD-DVD, I wasn't able to play my movie on my non-
HDCP HD monitor. Not being able to play a movie that I have paid for, because
some executive in Hollywood decided I cannot, made me mad... I'm just an upset
customer. My efforts can be called 'fair use enforcement'!” —
“muslix64”, author of the HD-DVD and Blu-Ray cracks.


“Thanks alot, Muslix64 [author of the HD-DVD crack] you're
not the only one with a monitor/vid card that doesn't support hdcp, your work
is greatly appreciated” — “yodoso”.


“The funny thing is that I cant see how HDCP will actually
even prevent piracy. In fact the only thing I can see it doing is encouraging
piracy because everyone whose bought a new computer/monitor/HDTV in the last
few years which don't have HDCP are now screwed out of the several thousand
dollar purchases. So instead of buying new products they will turn to
pirated/cracked Blu-ray/HD-DVDs which will work without the HDCP”
— “Gizza”.


“The HDCP scheme will serve to make the illegal product the
most full featured and least restrictive, and thus the most attractive to the
consumer. Add in the expense of buying new equipment to view the legal content
(when existing equipment is perfectly capable) and the performance drain
imposed by in-line encryption/decryption and they've put out the biggest
incentive to piracy yet” — “Greg”.


“The HDCP (high-definition content protection) overlords are
coming to get us. They are basically saying you can't watch video unless you
have a digital monitor and a special video card that supports the end-to-end
content protection they have built; So that you, the un-trusted-consumer-who-
bought-their-expensive-product, can't possibly make backup copies or anything
else with that fancy new HD-DVD or Blu-ray disc you have” —
“verifex”.


“Digital rights management technology will still fail to
prevent widespread infringement. In a related development, pigs will still
fail to fly. I predict that every year, and it turns out to be true every
year” — Ed Felten.


“Microsoft wasted no time; it issued a patch three days
after learning about the hack. There's no month-long wait for copyright
holders who rely on Microsoft's DRM. This clearly demonstrates that economics
is a much more powerful motivator than security” — Bruce Schneier
on Microsoft's DRM re-enabling patch for FairUse4WM.


“As a not-so-long-ago electronics design engineer, I can
imagine the rage & pain felt by engineers & their employers [...] This is
total insanity from anyone's perspective except the content providers, and
they don't care because it's everyone else who's picking up the tab for
it!” — Anthony May.


“Good job, industry! Spend an incredible amount of time and
effort developing the next generation of video quality only to step on it
BEFORE THERE'S EVEN A DECIDED UPON STANDARD in the name of Copy Protection
which will just be outflanked by a couple of 14 year old hackers and
distributed over BitTorrent anyway” — “SweetMercury”.


“By any standard, Vista's new DRM capabilities hardly
qualify as a selling point; after all, it's hard to sing the praises of
technology designed to make life harder for its users. — Matt McKenzie,
Computerworld.


“Sony, MS, movie studios... here's the deal. You've screwed
up so bad that i'm not buying either HD drive option until they're so cheap
that I end up getting one included with my computer because it was the minimum
optical drive” — “zweben”.


“I was reminded of a quote from a Disney executive that I
read a while ago [in the Economist]. The quote is:
If
consumers even know there's a DRM, what it is, and how it works, we've already
failed. If I went to play premium content and all that shows up on my
monitor is a message telling me that part of the display process isn't
supported by content protection, this would scream DRM to even the most
unsavvy users” — Steven Grueber.


“I could not be more skeptical about the viability of the
DRM included with Vista, from either a technical or a business standpoint.
It's so consumer-unfriendly that I think it's bound to fail — and when
it fails, it will sink whatever new formats content owners are trying to
impose” — Matt Rosoff, lead analyst, Directions On Microsoft.



“The [AACS] design prevents legitimate purchasers from
playing legitimately purchased content on legitimately purchased machines, and
fails to prevent people from ripping the content and sharing it through
bittorrent. The DRM people wanted something that could not be done, so
unsurprisingly they winded up buying something that does not do it”
— James Donald.


“The net effect of these concerns may constitute the real
Vista revolution as they point to an unprecedented loss of consumer control
over their own personal computers [...] Vista seemingly wrestles control of
the 'user experience' from the user ” — Michael Geist, Canada
Research Chair in Internet and E-commerce Law at the University of Ottawa,
Faculty of Law.


“I'm not sure how the company lost sight of what matters to
our customers, both business and home, the most, but in my view we lost our
way. I think our teams lost sight of what bug-free means, what resilience
means, what full scenarios mean, what security means, what performance means,
how important current applications are, and really understanding what the most
important problems our customers face are ” — Jim Allchin,
Platform Products and Services Group, Microsoft.


“There has to be a whole new division at Microsoft. The
'Office of Consumer Apology' or something. Responsible for 'I'm sorry your
content didn't PlayForSure. That isn't meant to be literal you know' and 'yes,
I know you're supposed to be able to play HD at full resolution, but you see,
your cable has a kink in it, which changed the electrical characteristics
slightly and, well, I guess I'm just sorry'” — Blake Ramsdell.


“DRM causes too much pain for legitimate buyers [...] There
are huge problems with DRM” — Bill Gates
(reported
by blogger Michael Arrington).


“your latest girly moan bitch rant is making the rounds on
every news site just about isn't it? are you on cnn yet? are women throwing
their panties at you?” — A friend (who requested anonymity).



Footnotes



Note A: This comment was inspired by Sir Gerald
Kaufman's similar comment about the British Labour Party's 1983 election
manifesto, which resulted in Labour turning in its worst election results
since its founding (it was so bad that Labour's opponents in the election
reprinted and distributed it themselves. Maybe Apple could take a hint from
this and use Microsoft's content-protection details in their advertising for
OS X). At 44 pages, Microsoft's “Output Content Protection and Windows
Vista” document squeezes out Labour's 37-page manifesto to take the
crown.



Note B: This document uses “cost” in the
sense of “penalty”, “damage”, “harm”,

“injury” and “loss” rather than the more financial
“expense”, “outlay”, and “price”. A full
financial analysis would require a top-to-bottom internal audit of the design,
development, production, distribution, support, and legal costs for each
vendor involved, something for which even the vendors themselves would have
difficulty producing a precise figure.



Note C: In order for content to be displayed to
users, it has to be copied numerous times. For example if you're reading this
document on the web then it's been copied from the web server's disk drive to
server memory, copied to the server's network buffers, copied across the
Internet, copied to your PC's network buffers, copied into main memory, copied
to your browser's disk cache, copied to the browser's rendering engine, copied
to the render/screen cache, and finally copied to your screen. If you've
printed it out to read, several further rounds of copying have occurred.
Windows Vista's content protection (and DRM in general) assume that all of
this copying can occur without any copying actually occurring, since the whole
intent of DRM is to prevent copying. If you're not versed in DRM doublethink
this concept gets quite tricky to explain, but in terms of quantum mechanics
the content enters a superposition of simultaneously copied and uncopied
states until a user collapses its wave function by observing the content (in
physics this is called quantum indeterminacy or the observer's paradox).
Depending on whether you follow the Copenhagen or many-worlds interpretation
of quantum mechanics, things then either get weird or very weird. So in order
for Windows Vista's content protection to work, it has to be able to violate
the laws of physics and create numerous copies that are simultaneously not
copies.



(Someone has pointed out that Microsoft is trying to implement a quantum
encryption channel in software that attempts to make premium content non-
observable, detecting problem states and discontinuing transmission if any are
observed).



Note D: I'll make a prediction at this point that,
given that it's trying to do the impossible, the Vista content protection will
take less than a day to bypass if the bypass mechanism is something like a
driver bug or a simple security hole that applies only to one piece of code
(and can therefore be quickly patched), and less than a week to
comprehensively bypass in a driver/hardware-independent manner. This doesn't
mean that it'll be broken the day or week that it appears, but simply that
once a sufficiently skilled attacker is motivated to bypass the protection,
it'll take them less than a day or a week to do so.



In a recent development, a sort of re-run of the DeCSS/Xing player story
from a few years ago has occurred in which someone appears to have figured out
how to extract HD-DVD and Blu-Ray keys from the PowerDVD player software,
allowing all(?) HD disk content to be decrypted and played back on any HD
display, without content-protection measures getting in the way. The
manufacturers of PowerDVD
claim
that they've done nothing wrong and won't be updating the player, and
muslix64 says that “they
[players] are all vulnerable [to a] different extent”.



Eric Rescorla has looked at this a bit further and concluded that this
problem is
more
or less unfixable as long as software players exist. A side-effect is
that if the content owners decide to address this by revoking the players, it
affects a huge number of innocent users, and because the problem as a whole is
unfixable, the attackers can force the content owners to do this whenever they
please and as often as they please, a fact that's unlikely to endear the
content providers to consumers if their players are constantly revoked (from a
chess-playing point of view, it appears that the content owners' threat
modelling never went any further than “Hey, I can move my rook over
there!”. There doesn't seem to have been any consideration of what could
happen during any subsequent moves, or maybe no-one wanted to think about it).
So even though the mechanisms to address this are in place, in practice it
looks like AACS is CSS all over again (see [Note C] for the
reasons why).



The AACS Licensing Authority in turn says that
AACS has not
been seriously compromised, which no doubt comes as a considerable
surprise to people busy decrypting HD-DVD and Blu-Ray content. Given the
legal implications for the various participants in AACS this finger-pointing
contest is to be expected (you could just
blame
Canada, for example), but it's unlikely that anyone but the lawyers will
care.

(In case the “blame Canada” comment is a bit obscure, it's a
reference to a
carefully-planted
story in the Canadian Globe and
Mail newspaper designed to influence Canadian lawmakers in their vote on
Bill C-60. Another Canadian paper calls the story
“mostly fiction
[...] much ado about nothing, featuring unsubstantiated and inconsistent
claims about camcording, exaggerations about its economic harm and misleading
critiques of Canadian law”, with further analysis showing that

“the
industry's own data reveals that the claims are based primarily on fiction
rather than fact”).



As a result, both HD-DVD and Blu-Ray content can now be decrypted and
played without image downgrading or blocking by the OS, and unprotected
content is already appearing in the usual locations like BitTorrent streams.
The fact that the legally-purchased content wouldn't play on a legally-
purchased player because the content protection got in the way was
the motivating factor for the
crack. The time taken was about a week, that information wasn't revealed
until after I made my prediction above. If you want to read more about the
AACS crack and its potential repercussions, Ed Felten has a long and detailed
analysis in his
Freedom to Tinker blog.



Note E: There is SCMS, but that has all the
effectiveness of a “Keep out” sign.



Note F: Incidentally, if anyone wants to send me one
of these amazing 27" monitors for, uh, evaluation purposes, I promise to
evaluate it and return it by 2012 :-).



Note G: The question of how content producers other
than the major studios who can afford expensive custom equipment are supposed
to create and manipulate high-definition content has been raised by a number
of readers. For example one contributor who works with people in the content
industry comments that “I have seen [smaller content producers] going
from just recording weddings and the like, to ones that have gone all the way
to make a full featured movie. They have gone through problems like where to
edit HD material, which cameras to use, which format, etc. Their decisions
have been based on availability of equipment to make their projects, not
really costs”. It has been suggested that the large content producers
are quite happy with this situation, since it prevents any competition from
more innovative, creative, and agile newcomers.



Note H: I see some impressive class-action suits to
follow if this revocation mechanism (“bricking”) is ever applied.
Perhaps Microsoft or the content providers will buy everyone who owns a device
that inadvertently leaks content and is then disabled by the revocation
process replacement hardware for their system, although that will in turn
trigger the WGA time-bomb.



For anyone who's read “Guns of August”, the situation seems a
bit like pre-WWI Europe with people sitting on step 1 of enormously complex
battle plans that can't be backed out of once they're triggered, no matter how
obvious it is that going ahead with them is a bad idea. Driver revocation is
a lose/lose situation for Microsoft, they're in for some serious pain whether
they do or they don't. Their lawyers must have been asleep when they let
themselves get painted into this particular corner — the first time some
“feature” of Vista's content protection inadvertently takes out a
hospital, foreign government department, air traffic control system, or
whatever, they've guaranteed themselves a front-row seat in court proceedings
for the rest of their natural lives.



(Several people have suggested that this was deliberate in order for the
lawyers to guarantee themselves lifetime employment, but this seems highly
unlikely. Firstly, lawyers have an obligation to protect their clients, so
deliberately getting a client into trouble in order to generate more work
would be a severely career-limiting move. Secondly, they're corporate in-
house counsel rather than independent counsel, so they'll get paid anyway.
Making more work for themselves would not be a big priority for them).



Note I: Some insider comments indicate that it'll be
mid-2007 at least before Vista's non-Microsoft graphics and sound drivers are
finished enough to be stable and reliable. Vendors are frantically rushing to
get drivers ready in time for Vista's release (they didn't even make it onto
the RTM media and will have to be downloaded after the install), but even
those have been described as 'beta-quality at best'. No doubt we'll hear more
of this at Vista's public release.



Note J: The Enterprise and Ultimate editions of
Vista do feature
this
type of encryption (BitLocker) (to quote Microsoft “all user and
system files are encrypted”), but the features of these high-end
versions will never get into the hands of typical users. What's really
important is to provide swap-file encryption for all users of all versions of
Vista (independent of whether they use BitLocker), since that's what contains
copies of sensitive in-memory data. The OpenBSD approach of
generating
a random swap-file encryption key at boot time and encrypting any memory data
that gets paged to disk is the correct way to handle memory protection.
Oddly enough,
Windows
Readyboost does encrypt all data swapped to a USB drive so the technology
is present and active in Vista, it just doesn't seem to be enabled when
exactly the same thing is done for disk swap files instead of USB swap.



Note K: Video and audio playback aren't the only
areas in which Vista's inner control freak comes to the fore. A Gamasutra
article

Vista
Casts A Pall On PC Gaming looks at Vista's new Game Explorer
“feature”, which subjects all games to parental controls. Any
games vendor who can't afford to obtain an extremely expensive ESRB rating has
their software treated as “Not Rated”, the equivalent of the
MPAA's X-rating for films which was originally intended to mean “Not
Rated” (the multiple Oscar-winning
Midnight Cowboy is an
example of an early X-rated film) but has since become synonymous with
hardcore porn (Midnight Cowboy was later re-rated R). Obviously any parent
would block Not-Rated content, which means that anyone who can't afford to pay
the ESRB (in other words any small, independent game producers, including the
ones most likely to produce free and low-cost family-rated games) can't work
with Vista's Game Explorer. This seems like yet another area of Vista in
which the words “anticompetitive ” and “class-action”

will feature prominently in the future.



Note L: The “kool-aid” reference may be
slightly unfamiliar to non-US readers, it's a reference to the 1978 Jonestown
mass-suicide in which Jim Jones' followers drank Flavor Aid laced with poison
in order to demonstrate their dedication to the cause. In popular usage the
term “kool-aid” is substituted for Flavor Aid because it has more
brand recognition. There's also an earlier, less well-known link to fruit
juice laced with LSD, I'll avoid the obvious comment linking that and some of
the thinking behind Vista's content protection.



Note M: If I do ever want to play back premium
content, I'll wait a few years and then buy a $50 Chinese-made set-top player
to do it, not a $1000 Windows PC. It's somewhat bizarre that I have to go to
communist China in order to find vendors who actually understand the
consumer's needs.



A reductio ad absurdum solution to the “premium-content
problem”, proposed by a Slashdot reader, is to add support to Windows
Vista for a black-box hardware component that accepts as input encrypted
compressed premium content and produces as output encrypted (or otherwise
protected) decoded premium content. In other words, move the entire mass of
hardware, driver, and software protection into a dedicated black box that's
only used in media PCs where it's (arguably) required.



Now compare this add-on black box to the canonical Chinese-made $50 media
player. Why would anyone buy the black box (which will almost certainly cost
more than $50) merely as an add-on to their already-expensive PC when they can
buy a complete dedicated media player that does the same thing and more? (A
BBC World Service
commentator agrees, people will just buy dedicated players instead of
using Vista).



(It's possible that people in countries conditioned to region-locked
minimal-functionality DVD devices may not understand the appeal of one of
these low-cost players. For about $50 you'll get a totally region-free PAL +
NTSC player with upscaling to 1080i that plays pretty much anything you can
get onto a CD or DVD, not just the usual DVD, VCD, and SVCD formats but also
MPEG4/DivX, XviD, and so on. Add another $10-20 and you get features like an
SD/CompactFlash card reader, a USB interface, 1080p, and DVI and HDMI output.
So with a slightly more expensive player and an external USB drive or SD card
to hold the content I get everything that Microsoft is promising us for Vista,
but without any crippling and without the high cost, size, and ungainliness of
a PC in my living room. It's really no contest).



http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html

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posted by u2r2h at Wednesday, January 10, 2007

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