Cryptography – Video cryptography – Copy protection or prevention
Reexamination Certificate
1998-12-08
2002-11-12
Darrow, Justin T. (Department: 2152)
Cryptography
Video cryptography
Copy protection or prevention
C380S203000, C713S165000, C713S173000, C705S051000, C705S057000
Reexamination Certificate
active
06480607
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a data reproducing method and apparatus, a data transmitting method, a data transmitting system, and a data processing method and apparatus for protecting the copyright of data recorded on a recording medium or transmitted over a transmission medium, and for safeguarding against unauthorized duplication.
2. Description of the Related Art
Recently, with coming into widespread use of digital contents, such as Internet or digital video discs, infringements of the digital contents by unauthorized duplication of the digital contents, frequently give rise to a problem.
For coping with this problem, there has recently been proposed a method of prohibiting unauthorized copying of picture or music data purveyed in a stored state on a recording medium or using a network as a transmission medium by burying the copyright information in the data by watermark processing.
The watermark processing is the processing of burying the information as a noise in a perceptually non-crucial portions present im the picture or music data, that is in the non-redundant portions with respect to the music or the picture. The copyright information, buried in the picture or music data by such watermark processing, can scarcely be removed, while it can be retrieved even after filtering or data compression.
For overcoming the above problem, it has been proposed to bury the watermark processing in picture data etc or to encrypt data being recorded or transmitted to prohibit unauthorised duplication. By encrypting the recorded or transmitted data, unauthorized duplication cannot be made unless the encrypting algorithm is decoded.
FIG. 1
shows a conventional optical disc reproducing device exploiting the above-mentioned watermark processing and encryption.
The conventional optical disc reproducing device
100
, shown in
FIG. 1
, is applied to, for example, a personal computer.
This optical disc reproducing device
100
includes an optical disc drive
101
, a data processing device
102
for doing data processing on picture data etc read out from the optical disc drive
101
, and a transmission line
103
for interconnecting the optical disc drive
101
and the data processing device
102
.
In a data area of an optical disc D is recorded picture data on moving or still pictures or speech data on music or speech. These data are previously compressed in accordance with the MPEG system. On the picture data, the copyright information is superimposed by the above-mentioned watermark processing.
The copyright information, superimposed on the picture data, may be exemplified by the following copyright control information:
That is, there are superimposed on the picture data “copy free”, specifying that picture or music data recorded on the recording medium or transmitted can be copied, “one copy”, specifying that only one copying operation is possible, “no more copy” specifying that data has been copied from the above “one copy” data, or “never copy” specifying that copying cannot be permitted. The reproducing device or the recording device, which has detected this copyright control information, limits reproduction or recording on the picture or music data.
The compressed picture data or compressed speech data, recorded on this optical disc D, is encrypted by a predetermined encrypting key.
On the optical disc D, there is recorded the media type information of this optical disc D, along with the above-mentioned picture data or audio data. This media type information is the information specifying whether the optical disc is the read-only ROM disc or a recordable RAM disc.
From this optical disc D, the above media type information as well as the compressed picture or audio data is read out by the optical disc drive
101
.
The optical disc drive
101
sends the read-out compressed picture data, compressed speech data and the media type information over the transmission line
103
to the data processing device
102
. The data transmitted on the transmission line
103
is transmitted after being encrypted by the so-called contents scramble system (CSS).
If the present optical disc reproducing device
100
is applied to, for example, a personal computer, the transmission line
103
is connected by the bus line.
The data processing device
102
includes a CSS decoder
104
, an MPEG decoder
105
, a media type decoder
106
, watermark (WM) detection/re-encoding unit
107
, an output controller
108
, and switches
111
,
112
.
The data processing device
102
is enclosed in, for example, a data card etc loaded on a personal computer.
The CSS decoder
104
is fed with the compressed picture or audio data and the media type information, transmitted in the encrypted form, and executes decryption using a predetermined encryption key. If decryption is not made using the correct decryption key, the ensuing processing cannot be effectuated. If decryption is done using the correct encryption key, this CSS decoder
104
sends picture data and audio data to the MPEG decoder
105
, while sending the media type information to the media type decoder
106
.
The MPEG decoder
105
expands the compressed picture and speech data. The expanded picture data is sent to the watermark (WM) detection/re-encoding unit
107
, while the expanded speech data is outputted via switch
111
to outside.
The media type decoder
106
decodes the media type information sent from the CSS decoder
104
to detect the information on whether the optical disc D reproduced by the optical disc drive
101
is a ROM disc or a RAM disc, and sends the detected information to the output controller
108
.
The watermark (WM) detection/re-encoding unit
107
detects the copyright control information, superimposed on the picture data by watermark processing. The detected copyright control information is “copy free”, “one copy”, “no more copy” or “never copy”, as described above. The watermark (WM) detection/re-encoding unit
107
sends the detected copyright control information to the output controller
108
. If, as a result of detection of the copyright control information, the watermark (WM) detection/re-encoding unit
107
has detected “one copy”, it re-encodes the copyright control information superimposed on the picture data by watermark processing to change the copyright control information to “no more copy” and outputs the result to outside via switch
112
. If, as a result of detection of the copyright control information, the watermark (WM) detection/re-encoding unit
107
has detected the information other than “one copy”, it outputs the detected result to outside via switch
112
without performing the re-encoding.
The output controller
108
performs on/off control of the switch
111
and the switch
112
, based on the information sent from the media type decoder
106
and the watermark (WM) detection/re-encoding unit
107
. Specifically, if the optical disc D is the ROM disc and the copyright control information is “no more copy”, and if the optical disc D is the RAM disc and the copyright control information is “one copy”, the output controller
108
assumes that data recorded on the optical disc D has been duplicated illicitly, and accordingly controls the switches
111
,
112
to off states.
In the conventional optical disc reproducing device
100
, as described above, it is possible to encrypt data transmitted between the optical disc drive
101
and the data processing device
102
to prevent unauthorized duplication and to manage control for halting the reproduction of the illicitly duplicated optical disc D using the copyright control information.
In the above-described conventional optical disc reproducing device
100
, the processing of superimposing the copyright control information by watermark processing is performed on base-band picture data prior to MPEG encoding. There are occasions, however, wherein the copyright control information is superposed on an elementary stream prior to MPEG encoding. In such case, the data processing device
102
of the optical disc reproducing
Ezaki Tadashi
Kimura Yuji
Kori Teruhiko
Ogino Akira
Darrow Justin T.
Frommer William S.
Frommer & Lawrence & Haug LLP
Kessler Gordon
Sony Corporation
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