EFF Question "Tech" 5. "Top five myths about DeCSS.  What are the top five greatest
misunderstandings about the DeCSS technology and why are they wrong?"

maintained by Rob Warren
last updated 3/22/2000



1. DeCSS is a component in a Linux video player.

    DeCSS is a standalone utility that descrambles a DVD video datastream; 
    it is neither a playback mechanism nor a copying mechanism.  It is 
    also not a component in any other piece of software.  DeCSS does one
    thing and one thing only - descrambles .VOB data files and produces
    unscrambled MPEG-2 video files.

    DeCSS is in no way required for the LiViD DVD player to function; the
    CSS descrambling features of LiViD are provided by the Fawcus css-auth
    descrambling code which was developed from the DeCSS source code.  
    This descrambling code was incorporated into the next version of DeCSS,
    DeCSS 1.1, in October 1999.

    It is important to realize that while DeCSS is making all the press,
    there are a number of "unCSSing" programs available now in source code
    form.  Most of these were based on the Fawcus code and the cryptographic
    analysis of CSS written by Frank Stevenson.

		
2.  DeCSS allows anyone to make a fully functional, complete copy of a DVD
    movie and transfer it electronically, over the Internet, or make a
    functioning copy on a recordable DVD.

    DeCSS allows you to decrypt the .vob files that hold the DVD video.  Once
    decrypted they can be played as MPEG-2 movies on various decoder software.  They
    cannot however make a functional DVD disk image without DVD authoring tools, or
    some other software to make the UDF image.  No freely available software dose
    this at this time.

    Instructions are available on the Internet, however, for converting the
    resulting MPEG-2 video files into MPEG-1 files and writing them to Video-CD.
    This method, however, does not produce a perfect copy of a DVD - there is
    a corresponding loss of quality that comes with reencoding the video data
    in a more primitive format.

    

3.  DeCSS has nothing to do with playing DVD's on Linux, because it 
    is a Windows application.

    The fact that DeCSS is a Microsoft Windows application has nothing
    to do with it.  Several people have suggested that DeCSS was written
    for Windows because Windows had support for reading the Micro-UDF
    filesystems in which DVD data is stored.  Linux and FreeBSD (which seems
    to have been the M.O.R.E. development platform of choice) did not.

    According to most sources, DeCSS was written as a "proof of
    concept" program in order to test the algorithm and to demonstrate
    that it worked.  It was a necessary step towards building an independent
    software DVD player; architecture existed under Windows that made
    this test easier than the architecture under free Unixes at the time.


4.  DeCSS was written by a 15-year-old, Jon Lech Johansen, in Norway.

    DeCSS appears to have been a collaboration between Johansen and two
    German computer programmers that have not as of yet been identified.
    Johansen suggests in interviews that the programmer most responsible
    for the creation of DeCSS is in fact one of these two German programmers,
    who does not wish to be publicly identified for obvious reasons.  The
    three together made up the group known as Masters of Reverse Engineering
    (M.O.R.E.).

    Only the very first versions of DeCSS relied on CSS decryption code
    written by members of this group; the initial DeCSS decryption was done
    using a decryption key found in a Windows software DVD player.  The
    CSS system itself was found to be weak by the LiViD group, who themselves
    produced source code to decrypt CSS without the need for a key. The 
    code of "css-auth" which still uses the Xing key, however, is at the 
    core of the LiViD DVD player and current releases of DeCSS. 

    Johansen distributed DeCSS from his webpage, hosted on his father's
    servers.


5.  DeCSS is a tool for piracy, and that's all it is.  The people who created
    it and disseminated it on the Internet are only trying to steal the MPAA
    member' intellectual property.



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