Optical disc copy management system

Details Optical disc copy management system Optical disc copy management system

1998-08-26

2003-03-18

Sough, Hyung-Sub (Department: 3621)

Data processing: financial, business practice, management, or co

Business processing using cryptography

Usage protection of distributed data files

C705S001100, C705S050000, C705S051000

Reexamination Certificate

active

06535858

ABSTRACT:

The invention relates to the area of Compact Disc (CD) including all existing or future formats of CD Audio and CD-ROM and any existing or future combinations of compact discs or other optical storage media. In particular the present invention relates to a copy protection and to a copy control mechanism by authentication of optical record carriers, here to a method of obtaining a copy protected optical record carrier, a method of accessing a copy protected optical record carrier and such an optical record carrier itself.
Optical storage discs with information stored on one or both sides have come to be used for a variety of purposes, most notably in the music, games, video and computer industry. Digital information is stored on the optical storage media in the form of pits arranged along circular, concentric tracks on one or on both sides of the disc. The track is typically read from the inside out, but may also be read form outside in, as it is already used for some optical storage media. The data itself on the track is divided into sectors, each equal in length, containing equal amounts of information.
To manufacture an optical storage device, a CD glass master is made by exposing photoresist which is on a glass plate by a modulated laser. The modulation of the laser corresponds to the digital information that is stored on the final disc. Thereafter, exposure, developing and removing those exposed spots form tiny indentations in a single spiral on the glass master are conducted. The pattern and the length of the indentations along this track represent the recorded information digitally. Usually, in a following galvanic process nickel is applied to this glass master to get the nickel master which is the tool for moulding replicas in an injection moulding process. The pattern of the nickel master referred to as pits and land as illustrated in
FIGS. 1
a
and
1
b
is then embossed on the surface of a polycarbonate or PMMA substrate, which results in a copy of the nickel master that forms the basis of the optical storage disc. The stamped replicas are then coated with a reflective (aluminium or gold) layer and in order to prevent this reflective layer from oxidation a protective layer is applied to the discs.
FIGS. 2
a
and
2
b
illustrates the readout of a Compact Disc. A laser beam is focusing onto the surface of the disc. If the laser light falls on the land area most of it will be reflected. If the laser falls on a pit area the light will be refracted and scattered and only a small portion will return in the original direction. This means that the readout electronics can differ between a “0” or “NO” and a “1” or “YES” information and furthermore the electronics of a CD reader can reconstruct the digital information which was recorded onto the disc originally.
Although audio reproduction was the primary motivation for development of the CD, and because of cost reductions resulting from the popularity of audio CDs, the CD has recently become a preferred form for storing data for a computer in the form of read only memory, i.e. CD-ROM.
The format in which audio information is stored on a CD is known as the “Red Book” standard. Under Red Book digital data on a CD is organized into indexed tracks. As illustrated in
FIG. 4
, the digital samples for left and right audio channels are interleaved with error correcting codes, so called C
1
. C
2
error corrections, and SUBCODE data into organized CD blocks. Throughout the disc, the interleaved SUBCODE information defines the current position in minutes, seconds, frames, both with respect to the current track and with respect to the entire disc.
The so called “Yellow Book” standard is typically as a format for a CD-ROM. The Yellow Book format is similar to the Red Book format in many respects, including the use of data organized into tracks, interleaved with error correction code and SUBCODE information but replacing the Audio information by computer data. Besides the Red Book and Yellow Book standard there exist many more standards developed for optical storage media covering audio data, computer data, video data and combinations of these information.
According to these standards every block of a CD has to be accessible.
FIG. 3
illustrates a standard CD-ROM mode 1 data sector which consists of 12 bytes MAINCODE SYNCHRONIZATION FIELD, 3 bytes ADDRESS, 1 byte MODE, 2048 byte of USER DATA, 4 bytes ERROR DETECTION CODE, 8 bytes of ZEROS and 276 bytes of ERROR CORRECTION CODE. Such a CD-ROM data sector, i.e. CD block or block, comprises 2352 bytes and is {fraction (1/75)} (one seventy-fifth) of a second.
The 2352 bytes of 1 data sector are carried in 98 Frames depicted in
FIG. 4
, wherein each Frame includes 24 bytes of said data sector. Additionally to this data, each Frame comprises 4 bytes C
2
error correction, 4 bytes C
1
error correction and 1 byte SUBCODE data. The 1 byte SUBCODE data is divided into 8 SUBCODE channels called SUBCODE P, Q, R, S, T, U, V. W field, which are also shown in FIG.
4
. Each SUBCODE channel consists of 98 bits that are build by 2 synchronization bits and 96 data bits.
As is illustrated in
FIG. 5
, a SUBCODE Q channel consists of 98 bits, which is referred to as SUBCODE Q field in this invention. All other SUBCODE channels (P, R, S, T, U, V, W) are similar to the Q channel, but carry different information. The first 2 bits of each SUBCODE channel represent the SUBCODE SYNC patterns S
0
and S
1
. These patterns are necessary to synchronize a CD reader to spin the CD at a constant linear velocity.
Each SUBCODE channel has a different function and content, the following description refers to the SUBCODE Q channel only.
The next 4 bits after the SUBCODE SYNC patterns represent the CONTROL FIELD which describes the kind of information of a track as shown in table 1.
TABLE 1
SUBCODE Q CONTROL FIELD
MSB LSB
00x0
2 audio channels without pre-emphasis
00x1
2 audio channels with pre-emphasis of 50/15 &mgr;seconds
10x0
4 audio channels without pre-emphasis
00x1
4 audio channels with pre-emphasis of 60/15 &mgr;seconds
01x0
data track (CD-ROM)
01x1
reserved
11xx
reserved
xx0x
digital copy prohibited
xx1x
digital copy permitted
The next four bits represent the ADDRESS FIELD and specify the mode. There are several modes (e.g. mode 1, mode 2, mode 3) but for the background of this invention the address mode 1 is explained in detail only.
For mode 1 there are two different data formats possible. For the background of this invention an explanation of the program and lead-out area only of the SUBCODE Q channel is given, as it is illustrated in FIG.
5
.
TNO, 8 bits, represents the track number running from 0 to 99. A track numbered with AA represents the lead-out track.
X, 8 bits, represents the index number within a track which can range between 0 to 99.
MIN, SEC, FRAME, 8 bits each, is the running time within a track expressed in 6 digits BCD, The minutes of a track are stored in MIN, the seconds are stored in 10 SEC and the frames are stored in FRAME. One second is subdivided into 75 frames (from 0 to 74).
ZERO, all 8 bits are set to zero (0x00).
AMIN, ASEC, AFRAME, 8 bits each, is the running time on the disc expressed in 6 digits BCD. The minutes of a track are stored in AMIN, the seconds are stored in ASEC and the frames are stored in AFRAME. One second is subdivided into 75 frames (from 0 to 74).
CRC is a 16 bit cyclic redundancy check on CONTROL, ADDRESS, TNO, X, MIN, SEC, FRAME, ZERO, AMIN, ASEC, and AFRAME. On the disc the parity bits are inverted. The remainder has to be checked at zero. The CRC is calculated according to following polynomial:
P
(
x
)=
x
16
+x
12
+x
5
+1
The 16 bit CRC field is a parity information that checks the correctness of the CONTROL, ADDRESS, TNO, X, MIN, SEC, FRAME, ZERO, AMIN, ASEC, and AFRAME fields.
Despite apparent advantages of CD-ROM there remain some drawbacks to use a compact disc for marketing and selling large and expensive software packages. A serious drawback is that there is currently no reliable method of protecting a CD-ROM from being c

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