Contents copying system, copying method, computer-readable...

Details Contents copying system, copying method, computer-readable... Contents copying system, copying method, computer-readable...

2000-03-10

2003-09-02

Trammell, James P. (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

06615192

ABSTRACT:

This application is based on applications No. 11-066404 and 11-106773 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a contents copying system, copying method, computer-readable recording medium and disc drive copying contents recorded on one recording medium onto a different recording medium.
2. Description of the Background Art
DVD-ROMs (Digital Versatile Disc Read-Only Memory) and DVD-RAMs (Digital Versatile Disc Random Access Memory) are portable optical discs which can store 4.7 gigabytes of data on a single side, despite having a diameter of only 120 mm. Such discs are soon expected to come into widespread use. Since both have a logical format ideally suited for recording computer data, movies and music, it is likely that disc drives capable of accessing both DVD-ROMs and DVD-RAMs will be provided as standard equipment in most personal computers in the near future.
When the DVD-ROM format used is DVD-Audio, the copyright owner requires that copying of data stored on a disc be strictly limited using a standard DVD copyright protection method and CCI (Copy Control Information). The following is a brief outline of such a method. First, a content is recorded on a recording medium such as a DVD-Audio disc after being encrypted using a cipher key (generally known as the title key) determined by the content owner. One title key is generally provided for each group of contents, or title, and one or more titles may be recorded on a single disc. The title key is encrypted using a cipher key unique to that particular DVD-Audio disc (generally known as the disc key) and recorded in a sector header area on the DVD-Audio disc. The disc key itself is encrypted using another cipher key (generally known as the master key) determined by the manufacturers of contents decoders, and recorded in a lead-in area of the DVD-Audio disc. The sector header area and the lead-in area cannot be accessed by ordinary users, making it extremely difficult to obtain title keys recorded on the DVD-Audio disc.
The following is an explanation of how the contents are used by devices.
The above described DVD copyright protection method does not restrict the transmission of encrypted contents between devices, but rather completely prohibits the output of unencrypted contents between devices. Furthermore, the method imposes strict limitations on the transfer of title keys between devices. This applies both to when two devices such as a DVD-Audio drive and a contents decoder are connected and contents reproduced, and to when two devices such as a DVD-Audio drive and a DVD-RAM drive are connected and contents are copied from DVD-Audio onto DVD-RAM. Basically, a title key can only be transmitted if two devices have successfully performed mutual authentication, thereby confirming whether they are legitimate devices compliant with the DVD copyright protection standard. Here, a title key is not transmitted between the devices after being encrypted by the disc key, but is transmitted after being encrypted by another cipher key (the session key) which was shared by the devices when mutual authentication was performed.
FIG. 1A
shows a contents reproduction system formed from a connected DVD-Audio disc drive and contents decoder. The disc drive in the drawing has a disc access unit
101
for reading contents from a DVD-Audio disc, and a bus authentication unit
102
for performing mutual authentication with a connected device-via a bus, and the decoder has a bus authentication unit
103
for performing mutual authentication with a connected device via a bus, a descrambler
104
for descrambling encrypted contents using a title key, and an audio decoder
105
for reproducing contents that have been descrambled. In the drawing, the title key is transferred after the bus authentication units
102
and
103
have authenticated each other, thereby enabling the reproduction of contents to be prohibited if a bogus device has been connected.
Finally, the copying of contents between two connected disc drives is explained. Copying performed by a standard computer system, or so-called file copying, is performed by reading contents recorded on an original recording medium and recording it unchanged onto a target recording medium. Legitimate contents copying, however, cannot take place simply by reading encrypted contents recorded on an original recording medium and recording it onto a copy target. Additional processing needs to be performed before this procedure can truly be referred to as contents copying. In this processing, a title key recorded on the original recording medium is read and decrypted using the disc and master keys, then information unique to the target recording medium is read from the target recording medium and used to reencrypt the title key before it is recorded on the target recording medium. The processing for decrypting and then reencrypting a title key is necessary in contents copying because the decoder in the contents reproduction system of
FIG. 1A
requires the connected disc drive to transfer a legitimate title key.
Contents copying is performed as in the above description. Under the DVD-Video standard, such contents copying has been completely prohibited at the request of the video contents providers. In the case of audio contents, however, making copies for personal use, such as from CD to MD (Mini Disc™), is widely accepted, and so there was a need to accommodate such copying under the DVD-Audio standard. CCI (Copy Control Information) is specified by the DVD-Audio standard to enable contents copying to be performed under certain conditions. CCI corresponding to each content is set in a DVD-Audio disc. CCI may be set at any one of four.levels for each content. These levels are ‘copy free’ allowing copies to be made freely, ‘copy once’ allowing a first-generation copy to be made, ‘no more copies’ prohibiting additional copies being made, and ‘never copy’ prohibiting copying altogether. When CCI for a content is ‘copy once’, the number of copies may be set at between one and ten.
A DVD-Audio disc drive is equipped with a copy authorization control unit that determines whether copies are authorized by referring to CCI. This means that the copy authorization control unit holds copy management information, consisting of ID information for the contents which have already been recorded on the DVD-RAM, and a number of copies showing the number of times that each content has been recorded. When a content is recorded on DVD-RAM, the copy authorization control unit is responsible for increasing the number of copies, and prohibiting copying after the number of copies reaches the number shown in the CCI. If the CCI shows that contents copying is authorized by the copy authorization control unit, the title key is transmitted between the devices via mutual authentication, as explained above, and recorded on DVD-RAM.
FIG. 1B
shows a contents copying system formed from two connected disc drives: a playback drive (player) for reading contents from a DVD-Audio disc, and a recorder drive (recorder) for recording contents on DVD-RAM. The player and recorder in the contents copying system shown in the drawing respectively include disc access units
111
and
112
accessing DVD-Audio and DVD-RAM, bus authentication units
113
and
114
performing mutual authentication via a bus, and copy authorization control units
115
and
116
determining what restrictions have been placed on copying the contents of the DVD-Audio disc. Only if the copy authorization control units
115
and
116
determine that copying is authorized, and bus authentication units
113
and
114
confirm the authenticity of the opposing device in each case, is encrypted contents copied from DVD-Audio onto DVD-RAM, along with the encrypted title key.
However, an individual user must acquire both the player for reading contents from DVD-Audio and the recorder for recording contents onto DVD-RAM if they wish to copy audio contents, so that t

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