Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Particular communication authentication technique
Reexamination Certificate
1998-12-08
2003-02-25
Barron, Gilberto (Department: 2132)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Particular communication authentication technique
C380S202000, C380S203000, C380S242000, C380S226000
Reexamination Certificate
active
06526510
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a signal reproducing method and apparatus, a signal recording method and apparatus and a signal recording system in which the copyright information is superimposed on picture or music data and control is performed on the basis of the copyright information.
2. Description of the Related Art
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 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 this watermark processing, can scarcely be removed, and can be retrieved even on filtering or data compression.
Among different items of the copyright information, thus buried by watermark processing in the picture or music data, there is the copyright control information.
This copyright control information is the information specifying whether the picture or music data recorded on a recording medium or transmitted over a transmission medium is “copy free” (copying possible), “one copy” (only one copying possible), “no more copy” (copying cannot be continued further) or “never copy” (copying is not permitted). The reproducing device or the recording device, which has detected this copyright control information, limits reproduction or recording for the picture or music data.
Among the items of the copyright control information, there is the information indicating “one copy”, as described above. If the information indicating “one copy” is buried in the picture data etc, the user can copy from the source medium to another medium he or she owns. However, the information specifying “no more copy” is buried in the picture data etc recorded on the latter medium so that the user is prohibited from copying from this latter medium. Thus, the copyright control information is able to realize copying control to only one generation.
FIG. 1
shows a conventional optical disc system made up of an optical disc reproducing device
110
and an optical disc recording device
120
. Referring to
FIG. 1
, the operation of rewriting the copyright control information from “one copy” to “no more copy” in case of copying picture data etc recorded on a source disc S to a rewritable disc RW is explained in detail.
The optical disc reproducing device
110
reproduces picture data and speech data recorded on the source disc S. In the picture data etc is buried the copyright control information reading “one copy” by watermark processing. The optical disc reproducing device
110
outputs; reproduced picture data etc at an output terminal
111
to send the data over a transmission medium
130
to the optical disc recording device
120
.
The transmission medium
130
may be any suitable medium, such as communication cable, e.g., telephone line, bus line in a computer or a cable for AV. The picture data transmitted over the transmission medium
130
may be analog signals.
The optical disc recording device
120
receives the picture data etc transmitted over the transmission medium
130
at an input terminal
121
. By a watermark (WM) detection unit
122
, the optical disc recording device
120
detects the copyright control information superimposed on the picture data. Then, a watermark (WM) verification unit
123
verifies whether or not the copyright control information detected by the watermark (WM) detection unit
122
is “one copy”. If the optical disc recording device
120
verifies that the copyright control information reading “one copy” is superimposed on the input picture data, a watermark (WM) rewriting unit
124
rewrites the copyright control information superimposed on the picture data to “no more copy”.
The optical disc recording device
120
records the picture data, whose copyright control information has now been rewritten to “no more copy”, on the rewritable disc RW by a recording unit
125
.
If the optical disc recording device
120
detects “copy free” as the copyright control information, it allows the recording unit
125
to record directly the picture data on the rewritable disc RW, without rewriting the copyright control information. If the optical disc recording device
120
detects “never copy” as the copyright control information, it terminates the recording operation.
In the conventional optical disc system
100
, as described above, change of the copyright control information from “one copy” to “no more copy” is done by the RW rewriting unit
124
of the optical disc recording device
120
by way of limiting the copying to only one generation.
Meanwhile, the rewriting of the copyright control information from “one copy” to “no more copy” needs to be performed by a recording device owned by the user. However, in watermark processing, it is usually difficult to remove or rewrite the copyright control information buried in picture data etc. Although it is retained to be feasible to bury the new information by, as it were, multiple writing, on the copyright control information already buried by watermark processing in the picture data etc. This, however, leads to obstruction to the visual or auditory system, while producing undesirable interference between the new information and the old information.
For reinforcing the above-described method of burying the copyright control information in the picture data by such watermark processing, there has recently been proposed a method of writing the information termed a token or a ticket, specifying the generation limiting information indicating the number of times of possible copying or reproduction, on the so-called user area of digital data, by way of generation limitation.
If a datastream, containing digital picture data etc, is a main stream, the token or ticket is written in a sub-stream containing the control information etc of data contained in this main stream. If the picture data etc is compressed in accordance with the MPEG system and recorded on a recording medium or transmitted in this compressed form, the token or ticket is written in a header part or in the user area of this MPEG stream. In addition, the token or the ticket is written in an encrypted form for prevention of unauthorized duplication.
The token is the information specifying that one-generation copying is possible and is made up at least of one bit. If this token is written in the user area etc of the picture data etc, the user is able to copy from the source medium to an other medium in his or her possession. However, on this other recording medium, on which copying has now been made, data is recorded subject to erasure or destruction of the token. This prohibits the user from copying from this other recording medium. Therefore, this token renders it possible to control the copying to only one generation.
The ticket is digital data specifying the number of copying generations. Each time picture data etc is copied for a recording medium to another, the ticket has its value decremented to supervise the number of copying generations. Of course, this ticket is not incremented in its value. If this ticket is already written in the user area etc of the picture data etc, the user is able to copy from the recording medium carrying the recorded picture data to another recording medium in his or her possession. On the latter recording medium, on which the picture data has now been recorded, the ticket is decremented in its value by one, so that the number of possible copying generations in case of copying from this other recording medium is decremented by one. Thus, the ticket renders it possible to limit the number of generations of possible duplication.
This ticket may also be set to indicate not only the number of possible copying generations b
Ezaki Tadashi
Kimura Yuji
Kori Teruhiko
Ogino Akira
Barron Gilberto
Frommer William S.
Smid Dennis M.
Sony Corporation
Zand Kambiz
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