Introduction
Digital rights management, as its name implies, applies
only to digital media. Digital media have gained
in popularity over analog media both because of technical
advantages associated with their production, reproduction,
and manipulation, and also because they are sometimes
of higher perceptual quality than their analog counterparts.
Since the advent of personal computers, digital media
files have become easy to copy an unlimited number
of times without any degradation in the quality of
subsequent copies. Many analog media lose quality
with each copy generation, and often even during
normal use. The popularity of the Internet and file
sharing tools have made the distribution of copyrighted
digital media files simple.
The availability of multiple perfect copies of copyrighted
materials is perceived by much of the media industry
as a threat to its viability and profitability, particularly
within the music and movie industries. Digital media
publishers typically have business models that rely
on their ability to collect a fee for each copy made
of a digital work, and sometimes even for each performance
of said work. DRM was created by and/or designed for
digital media publishers as a means to allow them to
control any duplication and dissemination of their
content.
Although technical control measures on the reproduction
and use of application software have been common since
the 1980s, the term DRM usually refers to the increasing
use of similar measures for artistic works/content.
Beyond the existing legal restrictions which copyright
law imposes on the owner of the physical copy of a
work, most DRM schemes can and do enforce additional
restrictions at the sole discretion of the media distributor
(which may or may not be the same entity as the copyright
holder).
DRM vendors and publishers coined the term digital
rights management to refer to the types of technical
measures discussed here. Because the "rights"—actually,
technical capabilities — that a content owner
grants are not the same as the legal rights of a content
consumer, DRM critics point out that the phrase "digital
rights management" is a misnomer and the term
digital restrictions management is a more accurate
characterization of the functionality of DRM systems.
DRM is an extension of Mandatory Access Control (as
opposed to Discretionary access control) wherein a
central policy set by an administrator is enforced
by a computer system. The well-studied theoretical
problems of Mandatory Access Control apply equally
to DRM. DRM is vulnerable to an additional class of
attacks due to its need to be run on tamper-resistant
hardware (DRM systems that do not run on tamper-resistant
hardware cannot ever be theoretically secure since
digital content can be copied on a hardware level).
Legal enforcement of DRM
DRM controls are sometimes proposed to be enforced
through so-called trusted computing. However, trusted
computing creates the prospect of a computer system
which cannot be trusted by its owner, but rather its
behavior can be remotely manipulated at any time, regardless
of the legal merits of such manipulation. Most opponents
have little faith that the courts or legislatures will
be able to limit such manipulation to only that which
is legally permitted.
Several laws relating to DRM have been proposed or
enacted in various jurisdictions (State, Federal, non-US).
Some of them would require all computer systems to
have mechanisms controlling the use of digital media.
(See Professor Edward Felten's freedom-to-tinker Web
site for information and pointers to the current debate
on these matters).
An early example of a DRM system is the Content
Scrambling System (CSS) employed by the DVD Forum on movie DVD
disks. The data on the DVD is encrypted so that it
can only be decoded and viewed using an encryption
key, which the DVD Consortium kept secret. In order
to gain access to the key, a DVD player manufacturer
was required to sign a license agreement with the DVD
Consortium which restricted them from including certain
desirable features in their players, such as a digital
output which could be used to extract a high-quality
digital copy of the movie. Since the only market hardware
capable of decoding the movie was controlled by the
DVD Consortium, they hoped to be able to impose whatever
restrictions they chose on the playback of such movies.
See also DIVX for a more restrictive and less commercially
successful variant of this scheme which is no longer
marketed. That name is also used (DivX), in ironic
tribute to the defunct disk "protection" scheme,
for an implementation of the MPEG-4 video compression
protocol.
To date, all DRM systems have failed to meet the challenge
of protecting the rights of the copyright owner while
also respecting the rights of the purchaser of a copy.
None have succeeded in preventing criminal copyright
infringement by organized, unlicensed, commercial pirates.
Flaws of some well known systems include:
Physical protection: Utilizes separate hardware to
ensure protection. Examples include hardware dongles
that had to be attached to the computer prior to using
the content, and USB and smart card devices working
in a similar fashion. Physical protection methods consistently
failed in consumer markets due to compatibility problems
and extra level of complexity in content use; however,
they did enjoy limited success with enterprise software.
DIVX: Required a phone line, inhibiting mobile
use. To take a work for which unlimited plays had been
purchased (called DIVX Silver) to a friend's home,
it was necessary to carry a 14 kg (30 lb) DVD player
as well as the light and compact disc; or to telephone
the DIVX service and have the player of the friend
transferred to the account of the purchaser of the
work, and then call again to have it switched back.
The system prevented certain legal uses such as the
creation of compilations, by the purchaser. The system
also prevented the sale or lending of purchased works,
by recording the account information of the original
purchaser on the DIVX Silver disk. Under copyright
law, the owner of a legally-obtained copy of a work
may create compilations, or re-sell the copy in the
secondary (used goods) market. By using these technical
measures, the DIVX system was able to thwart the buyer's
right of first sale and other fair use rights. DIVX
is a form of physical protection of the content (see
above).
CSS: It restricts fair use and first purchaser
rights, such as the creation of compilations or full
quality reproductions for the use of children or in
cars. It also prevents the user from playing CSS-encrypted
DVDs on any computer platform (although this restriction
can be easily circumvented). Recently, with the advent
of DeCSS and cryptographic analysis of the CSS algorithm
have demonstrated flaws in this system which can be
exploited to allow users to recover some of their fair-use
rights. Full quality digital copies can now be easily
made, making fair use by normal consumers easier. Although
it has been argued that programs like DeCSS make copyright
infringement easier, this system has never been effective
in preventing illegal mass copying of DVDs by criminal
gangs, even before the system was found to be flawed.
CSS is an example of certificate-based encryption.
Product activation: Invalidates or severely restricts
a product's functionality until the product is registered
with a publisher by means of a special identification
(activation) code. The process often uses information
about the specific configuration of the hardware on
which the software runs, hashing it with the identification
number specific to the product's license. Microsoft
was the first company to utilize this method in its
Microsoft Reader product. Activation was later used
with Windows XP and then with Office XP. Ultimately,
workarounds which bypassed the product activation system
have been developed. In 2003, Intuit's use of a flawed
product activation scheme angered thousands of customers
who were denied legitimate use of the product, resulting
in a formal apology by Intuit and discontinuation of
the use of the mechanism.
Digital watermarking: Allows hidden data, such as a
unique disc ID, to be placed on the media. Then, the
name and address of the purchaser would be taken at
the location of sale, and entered into a database along
with the unique media ID. This does not prevent copying,
but it ensures that any copies made of the media will
bear the same hidden information—so if the content
appeared on (for example) P2P networks, the ID number
could be easily extracted and the purchaser prosecuted.
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Legalities
of DVD Copying - Intro to DRM 