Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – For copying
Reexamination Certificate
1999-05-25
2001-11-20
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
For copying
C369S053210, C369S275300
Reexamination Certificate
active
06320829
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital copy control technique employed in a system in which digital apparatuses, such as DVD (digital video disc) recording/reproduction apparatuses, digital VCR, and digital TV, are connected to each other via interfaces having the function of mutual authentication. In particular, this invention is concerned with such a digital copy control technique that effectively prevents unauthorized copying that is not intended by a creator or producer of data, while limitedly permitting digital copying of the data.
2. Prior Art
In a conventional digital data transmission system, digital recording/reproduction apparatuses, such as optical disc (e.g., DVD) reproduction apparatus, digital TV, digital VCR, and others, are connected to each other via an IEEE-1394 bus that serves as an intelligent interface, so that data contents, such as pictures and music, are transmitted and received between these digital apparatuses. When digital data is transmitted and received between these apparatuses, the system checks if each of the apparatuses operates in a manner as intended by the creator or producer who created the contents of the data, and, if any apparatus does not operate as intended by the creator, data transfer is prohibited, to thereby prevent the user from illegally copying the picture and./or music contents against the intention of the creator.
Digital main data to be transmitted contains copy control information called “CCI”. The CCI consists of two bits, namely, “00”, “10” or “11”, where “00” indicates permission of free copying, “10” indicates permission of one-time copying, and “11” indicates prohibition of copying.
Upon transmission of digital data, the transmitter-side apparatus initially checks the CCI to determine its copy restriction level for the contents of the digital data, and also checks, on the IEEE-1394 bus, whether the receiver-side apparatus operates in a manner as intended by the content creator. If complete authentication is established between the receiver-side apparatus and the transmitter-side apparatus, the contents is encrypted and transmitted from the transmitter-side apparatus. In this case, where the CCI information of the digital data transmitted from the transmitter-side apparatus is, for example, “10”, and the receiver-side apparatus is a sound recording apparatus, the CCI is rewritten into “11” and thus recorded during copying of the digital data. As a result, second and subsequent copying actions are prohibited, and thus only one-generation copying is realized.
As another method for preventing unauthorized copying by digital picture apparatuses, it has been proposed to use electronic watermark information (generally called “watermark”). In this method, watermark information may be directly added to a non-obvious or low-intensity portion of the waveform of a picture signal, or may be embedded into a particular frequency component of frequency conversion information of the original signal. By providing the watermark with information on permission/prohibition of copying, the watermark is able to indicate whether free copying is permitted, or only reproduction of the data is permitted, for example.
In the conventional copy control method using CCI as described above, however, when the receiver-side apparatus rewrites the CCI from “10” (indicating permission of one-time copying) into “11” (indicating prohibition of copying), for example, it is relatively easy to rewrite “10” into “00” (indicating permission of free copying) through two-bit manipulation, thus causing a problem that unauthorized copying may be done without difficulty.
In the method using watermarks, on the other hand, watermark information is distributed over a relatively wide range of main data containing picture and/or voice information, and it is therefore difficult for the receiver-side apparatus to rewrite this information. If the watermark information is to be rewritten on the user level, the receiver-side apparatus must be equipped with a considerably large circuit. This is advantageous over the use of CCI in terms of prevention of unauthorized or illegal copying. However, since the watermark cannot be easily rewritten as described above, it is rather difficult to permit only one-time copying by rewriting or changing the flag (i.e., watermark) as in the case where CCI is used.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to prevent unauthorized digital copying more effectively, while allowing the use of different forms or levels of copy restriction.
To attain the above object, the present invention provides a digital copy control method of controlling copying of digital data from a digital recording medium, which digital data is transmitted from a transmitter-side apparatus to a receiver-side apparatus through interfaces thereof in a system of a plurality of digital apparatuses that are connected to each other through a bus and mutually authenticated, the interfaces permitting transmission and receiving of the digital data only between the authenticated apparatuses, the digital copying control method restricting reproducing and recording operations of the transmitter-side apparatus and the receiver-side apparatus based on copy control information contained in the digital data for restricting copying of the data so as to prevent unauthorized copying, comprising the steps of adding the copy control information indicating a copy restriction level, to main of data of the digital data recorded on the digital recording medium such that the main data contains a first portion containing at least one of picture information and voice information, and a second portion containing the copy control information, adding electronic watermark information to the second portion of the main data containing the at least one of picture information and voice information, adding an error correction code to the main data, and then adding intentional error information having a particular pattern to the digital data, determining whether the digital recording medium from which the digital data is to be reproduced and transmitted from the transmitter-side apparatus is authorized one or not, based on the copy control information, the electronic watermark, and the error information having the particular pattern, and restricting the reproducing and recording operations of the transmitter-side apparatus and the receiver-side apparatus with respect to the digital data in the digital recording medium, depending upon whether the digital recording medium is authorized one or not.
To attain the above object, the present invention provides a digital recording medium in which digital data including main data is recorded for reproduction or recording on another recording medium, wherein the main data includes a first portion comprising at least one of picture and voice information, and a second portion comprising copy control information indicating a copy restriction level, the copy control information being rewritten upon digital copying of the main data so that the copy restriction level is raised to a higher level, the main data further including electronic watermark information that is added to the first portion of the main data comprising the at least one of picture and voice information, the electronic watermark information being unable to be rewritten upon digital copying of the main data, wherein a medium mark is added to a portion of the digital data in which the main data is not recorded, such that the medium mark is not read by an external device, and wherein reproduction and digital copying of the main data are controlled in accordance with an intention of a producer of the main data, based on a combination of contents of the copy control information, electronic watermark information, and the medium mark.
To attain the above object, the present invention provides an apparatus for producing a digital recording medium, comprising a watermark information adding device that adds electronic watermark informatio
Furukawa Masamichi
Matsumoto Seiji
Huber Paul W.
Pillsbury & Winthrop LLP
Yamaha Corporation
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