4.8 What is DeCSS?
Description
This article is from the DVD Formats FAQ, by jtfrog@usa.net (Jim Taylor) with numerous contributions by others.
4.8 What is DeCSS?
CSS (Content Scrambling System) is an encryption and authentication scheme
intended to prevent DVD movies from being digitally copied. See 1.11 for
details. DeCSS refers to the general process of defeating CSS, as well as
to DeCSS source code and programs.
Computer software to decrypt CSS was released to the Internet in October
1999 (see Dana Parker's article at
http://www.emediapro.net/news99/news111.html), although other "ripping"
methods were available before that (see www.dvdutils.com, go.to/dvdsoft,
and www.neophile.net). The difference between circumventing CSS encryption
with DeCSS and intercepting decrypted, decompressed video with a DVD ripper
is that DeCSS can be considered illegal under the DMCA and the WIPO
treaties. The DeCSS information can be used to "guess" at master keys, such
that a standard PC can generate the entire list of 400 keys, rendering the
key secrecy process useless.
In any case, there's not much appeal to being able to copy a set of movie
files (without menus and other DVD special features) that would take over a
week to download on a 56K modem and would fill up a 6G hard disk or a dozen
CD-Rs. The supporters of DeCSS point out that it was only developed to
allow DVD movies to be played on the Linux operating system, which had been
excluded from CSS licensing because of its open-source nature. This is
specifically allowed by DMCA and WIPO laws. What most DeCSS proponents fail
to acknowledge (or perhaps fail to realize) is that the DeCSS.exe program
being posted on the Internet is a Windows application that is clearly
intended for copying movies. This lack of differentiation between the DeCSS
process in Linux and the DeCSS.exe Windows application is hurting the cause
of DeCSS backers. See OpenDVD.org for more information on DeCSS.
Worthy of note is that DVD piracy was around long before DeCSS. Serious DVD
pirates can copy the disc bit for bit, including the normally unreadable
lead in (possible only with specially modified drives), or copy the video
output from a standard DVD player, or get a copy of the video from another
source such as laserdisc, VHS, or a camcorder smuggled into a theater. It's
certainly true that DVD piracy is problem, but DeCSS has little to do with
it.
Shortly after the appearance of DeCSS, the DVD CCA filed a lawsuit and
requested a temporary injunction in an attempt to prevent Web sites from
posting (or even linking to!) DeCSS information. The request was denied by
a California court on December 29, 1999. On January 14, 2000, the seven top
U.S. movie studios (Disney, MGM, Paramount, Sony [Columbia/TriStar], Time
Warner, Twentieth Century Fox, and Universal), backed by the MPAA, filed
lawsuits in Connecticut and New York in a further attempt to stop the
distribution of DeCSS on Web sites in those states. On January 21, the
judge for the New York suit granted a preliminary injunction, and on
January 24, the judge for the CCA suit in California reversed his earlier
decision and likewise granted a preliminary injunction. In both cases, the
judges ruled that the injunction applied only to sites with DeCSS
information, not to linking sites. (Good thing, since this FAQ links to
DeCSS sites!) The CCA suit is based on misappropriation of trade secrets
(somewhat shaky ground), while the MPAA suits are based on copyright
circumvention. On January 24, 16-year old Jon Johansen, the Norwegian
programmer who first distributed DeCSS, was questioned by local police who
raided his house and confiscated his computer equipment and cell phone.
Johansen says the actual cracking work was done by two anonymous
programmers, one German and one Dutch, who call themselves Masters of
Reverse Engineering (MoRE).
This all seems to be a losing battle, since the DeCSS source code is
available on a T-shirt and was made publicly available by the DVD CCA
itself in court records--oops! See Fire, Work With Me for a facetious look
at the broad issue.
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