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