This source package does two things.

a)  It contains code to perform the css authentication protocol,
    allowing locked sectors on the DVD disc to be accessed.

    This also allows us to read the disc key and title keys.

b)  It contains an implementation of the css decryption algorithm,
    so that we can watch DVD's.

Also included are some test programs to wrarp around the above code
blocks so that something usefule can be performed.

The programs included are tstdvd,  reset,  dvdinfo and css-cat.

tstdvd can be used to unlock the disc (saving the disk key) and
to extract the title keys.  usage is:

  reset /path/to/dvd/device

    This will reset all AGIDs that the drive has given out.  This
    can sometimes be useful when something goes wrong.

  tstdvd /path/to/dvd/device

    This will authenticate the device and save the disk key into
    a file in the current directory called "disk-key".

  (mount the dvd somewhere)

  tstdvd /path/to/dvd/device /mount/path/video_ts/vts_01_1.vob

    This will reauthenticate and then read the title key for
    the chosen vob file,  saving it in a file in the current
    directoy called "title-key".

  Do the above title key extraction for each title on the disc,
renaming the title-key files to title1-key,  title2-key etc.

  dvdinfo /path/to/dvd/device

    Displays some info from the physical and copyright pages.  This
    includes the region limits on the disc,  its encryption status,
    and the authentication status.

  css-cat [-t title-no] [-m mpeg-audio-no ] [-vPpm12345678] vob_file

    This will decrypt the selected vob file and send to stdout.  It
needs the files "disk-key" and "titleX-key" to be in the current
directory.  The default title-no is one,  so by default it will look
for "title1-key".

    The options select what will be sent to stdout.  By default,  nothing
will.  The m option is not yet coded,  the v option selects video, the
numbers select the appropriate AC3 stream.
    It will normally extract the selected stream from the enclosing
Program stream,  thus giving an elemental stream.  However if the K option
(or more than one stream) is selected then the data will be left inside
the PES packets,  allowing a subsequent demux program to determine the
data type.

    I tend to use:

    cat /dvd/video_ts/vts_01_[1-9].vob|css-cat -v1P -|mpeg2player -vob -f -

NOTE:  To use the above you need to have a kernel which incorporates the
       DVD ioctls.  This can either be the original patch by Andrew Veliath
       or Jens Axboe's patches.  If using Andrews versio of the patches,
       you'll have to change the use of .key in the sources to .key1/.key2
       (the places are quite easy to find).

       Jens site is www.kernel.dk

Changes:
       Patches have been applied to use the OpenBSD headers,  so maybe it'll
       work.

       There a some more keys included.  It should now be able to decrypt
       all titles currently on the market.  I think the last two keys can
       be removed.  Someone with 'The Matrix' please test and get back to
       me.

       Mpeg audio streams should now be extractable when filtering,  this is
       untested.

       It now copes with System headers in the Pack layer (those 0x000001bb
       start codes).

       The command line options have changed between the last version and
       this one - pay attention.

DF     1999/11/05