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About Prevention The Dvd-Rom From To Be Copy - LG GWA-4164B Service Manual

Dvd/cd rewritable drive
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3. About Prevention the DVD-ROM from to be copy

A data is able to encode and record in the disc, if a copyright holder wants to prevent the disc from copying.
If you want to play the disc prevented from the copy......
First of all, ROM-DRIVE and MPEG-2 board identify with each other through the procedure as described
below.
ROM-DRIVE
1. Drive and host gives and takes the ID of 2bit. This ID is AGID (Authentication Grant ID).
The various decoder boards are attached to the host, in these, AGID sets the MPEG-2 board and drive.
2. After the AGID is set, MPEG-2 board generates the challenge key (10 Byte) and transfers to drive. The
board and drive generate key 1 (5Byte) with the challenge key respectively. (Of course, the Algorithm
generating the key 1 is not known.)
3. Compare with the generated key 1, if it corresponds each other, the first step of authentication is
completed. This is a course to identify the MPEG-2 board with a drive.
4. The second step of authentication is a course to identify a drive with the MPEG-2 board.
The dirve generates a challenge key and transfers it to the MPEG-2 board. The dirve and MPEG-2 board
generate the key 2 (5Byte) with the challenge key, compare with each other, and if it corresponds and the
secondary step of authentication is completed.
5. As above, the identification is completed.
6. The dirve and MPEG-2 board generate the Bus key with the key 1 and key 2 and own it.
7. Dirve encodes the disc key and title key with this Bus key and transfers to the MPEG-2 board.
8. The MPEG-2 board reads the encoded disc key and title key with the Bus key only.
9. MPEG-2 board lets data read from the drive to decode with the read disc key and title key and makes into
the video signal by decoding.
In case of a disc enhanced movie of 3 titles......
DISC KEY (2048 Bytes) is used to encode the whole contents in the disc and TITLE
KEY (5 Bytes) is used to encode the title respectively.
So, the data is encoded and stored in a disc through the unknown algorithms
with a disc key and title key. (At this time, the disc key and title key are stored
in a disc.)
...As above, the disc is able to copy when the disc key and title key are
opened.
Then, ROM-DRIVE encodes the disc key and title key and transfers to MPEG-
2 board.
encoded disc key, title key
AGID
Challenge key
HOST
MPEG-2
BOARD
47

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