Chapter 1

hardware and software must include a CSS decryption module. All
DVD-ROM drives have extra firmware to exchange authentication and
decryption keys with the CSS module in the computer.
Since 2000, new DVD-ROM drives are required to support regional management
in conjunction with CSS (refer to “What Are Regional Codes,
Country Codes, and Zone Locks?” and see Chapter 4’s “Can I Play DVDs
on My Computer?”). DVD-Video equipment manufacturers of drives,
decoder chips, decoder software, and display adapters must license CSS.
CSS licenses are free, but obtaining one is a lengthy process, so it’s recommended
that interested parties apply early. CSS is administered by the
DVD Copy Control Association (DVD CCA). Near the end of May 1997, CSS
licenses were finally granted for software decoding. The license is
extremely restrictive in an attempt to keep the CSS algorithm and keys
secret. Of course, nothing that’s used on millions of players and drives
worldwide could be kept secret for long. In October of 1999, the CSS algorithm
was cracked and posted on the Internet, triggering endless controversies
and legal battles (see “What Is DeCSS? in Chapter 4).
Content Protection for Prerecorded Media (CPPM)
Content Protection for Prerecorded Media (CPPM) is used only for DVD-
Audio. It was developed to be an improvement of CSS. Keys are stored in
the lead-in area, but unlike CSS no title keys are placed in the sector headers.
Each volume has a 56-bit album identifier, similar to a CSS disc key,
stored in the control area. Each disc contains a media key block, stored in
a file on the disc. The media key block data is logically ordered in rows and
columns used during the authentication process to generate a decryption
key from a specific set of player keys (device keys). If the device key is
revoked, the media-key-block-processing step results in an invalid key
value. As with CSS, the media key block can be updated to revoke the use
of compromised player keys. The authentication mechanism is the same
as CSS, so no changes are required for the existing drives. A disc may
contain both CSS and CPPM content if it is a hybrid DVD-Video/DVD-
Audio disc.
Content Protection for Recordable Media (CPRM)
General DVD 23
Content Protection for Recordable Media (CPRM) is a mechanism that ties
a recording to the media on which it is recorded. CPRM is supported by
some DVD recorders, but not by many DVD players. Each blank, recordable
DVD has a unique 64-bit media ID etched in the BCA (see “What Is BCA?”
in Chapter 3). When protected content is recorded on the disc, it can be