Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Particular communication authentication technique
Reexamination Certificate
1998-07-31
2001-05-08
Peeso, Thomas R. (Department: 2132)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Particular communication authentication technique
C713S164000, C713S165000, C713S182000
Reexamination Certificate
active
06230268
ABSTRACT:
TECHNOLOGY AREA OF THE INVENTION
This invention relates to a data control system using an electronic watermarking technique (data-hiding). More particularly, this invention relates to a technique of allowing data to be handled by a desired data control (copying control, play-back control and receiving control, etc., for example) in a place where the data is delivered using a token which has a control flag indicating to effect a data control and information of a manner of controlling the data.
PRIOR ART
As a multimedia environment is widely spread out, a problem is the protection of a copyrighted material. Despite a digital video disk (DVD), a set top box (STB), a cable television system and a network distribution, etc., have a sufficient specification in hardware aspect for distribution of theater movies, no specification sufficiently satisfying suppliers of the contents has been provided as to the protection of the contents, particularly, the problem of illegal reproduction (copy). This is because an effective specification has not been provided to prevent such problem despite it is very easy to copy and modify data contents of digital data. This invention provides a mechanism of safely distributing many attractive contents which use such media with a method for embedding a control mechanism in the content itself so as to allow the content to be distributed with a condition to permit copying only once (one time copy).
Some methods of data control have so far existed to protect contents and prohibit the contents from being copied and played back. PUPA6-4026, for example, discloses a technique of generating a code
2
which is converted from a suitably generated code
1
by a one-way conversion f as a code indicating permission information of each category and the code
1
and the code
2
are both described when a permission is indicated while only the code
2
is described when prohibition is indicated to make generation of permission state difficult. However, this method allows multiple copying by saving the code
1
and thereafter describing it together with the code
2
.
For example, PUPA 6-309239 discloses a method of permitting one time only copying in which, using a flag file indicating that a data file has not been copied, an encrypted data file is converted to an original data file if the flag file exists and then the flag file is erased after the data file is copied. However, because the flag file is a file separate from the data file, multiple copying is easily done simply by saving the flag file and reproducing it in this method. In addition, because it is determined that play-back is prohibited if the flag does not match or exist, even a content which is photographed or produced by an author falls in the category of prohibition.
The prior art methods basically use a code or a flag which is separate from the data in applying a data control. Once such separate code or flag is identified in such methods, manipulation of such code or flag is possible so that these methods have a weak point against a willful attack by a third party. A technique usable for data control which is free from such disadvantages is desired. Further, it is desired to obtain a novel data control method which is totally independent of conventional data control methods and is upper or downward compatible without affecting existing video distributing system or the mechanism of devices.
The electronic watermarking technique exists for the copyright protection of a still image, motion picture and a voice. The electronic watermarking technique is a technique which is also called data hiding (TM). Simply stating, this is a collective name of a technique for embedding certain information in other media (still image, voice and motion picture, etc.) and aims at the way of integrating the information in a medium in which the information is embedded rather than the way of hiding information as used in encryption. In other words, a method is employed for embedding information which is desired to be hidden in the data of a medium by manipulating the data of the medium. This means, in image data for example, information other than the essential data is carried by modifying a pixel value such as the brightness. Incidentally, the term “embed” as used in this invention means that extra information is hidden in the form of modification of the data itself.
One of major characteristics of the electronic watermarking is that it is an invisible or inaudible marking technique. In embedding information in media, the existing data is so modified (data modification) that the data is not detected by a human eyesight rather than appending data bits so that total data size is not increased by embedding the appended information. For example, embedding data in an image consisting of 640×480 pixels does not increase the number of pixels. Also, by embedding text information or voice information in an image, it is enough for the storage side to handle a single kind of medium. One of the most remarkable characteristics is the inseparability of embedded information. Because the electronic watermarking embeds the appended information directly in the data structure of the medium rather than a header or a file, the embedded information can be detected even if the platform or the data format changes so long as the quality of the original data is preserved.
An example of a data control method using the electronic watermarking technique is given below. Not only in recording, copy and play-back in a place where data is delivered, but also in the broadcasting of data by a radio wave, whether to permit receiving of data or not (receiving control) can be controlled entirely in a similar manner.
(1) a step of embedding a control flag (CF) indicating a protection level of the contents in video data using a electronic watermarking technique,
(2) a step of detecting the CF embedded in said contents to determine whether or not recording or play-back of the video is permitted for suitably controlling recording or play-back (video recording is stopped when a CF indicating prohibition of recording is detected in recording while it is determined that the video is an illegal copy and play-back is stopped when a medium played back is for recording and a CF indicating prohibition of recording is detected in play-back.), and
(3) a step of permitting recording and leaving a record indicating that the video has been recorded when a CF indicating permission of one time only recording is detected, and prohibiting another recording by the CF and the recorded mark when the recorded contents are played back and another recording is attempted.
The steps (1) and (2) can be implemented by embedding a CF in the contents in advance by the electronic watermarking technique in preparing the contents. The step (3) can be also implemented to prohibit another recording using the electronic watermarking in the manner similar to the steps (1) and (2). However, a problem exists in this case. A video recording apparatus is mostly possessed by an end user in general and it has to be made compactly and in a low price. It is practically difficult to implement the electronic watermarking embedding for appending a mark of recording done by taking image quality and residual signal intensity into consideration in preparing contents in such apparatus of a limited processing capability.
When the subject video data is image data which is MPEG compressed, for example, it is necessary to restore the image data which has embedded therein a mark of recording done by re-composing it with the rest of data (voice data and sub-picture, etc.) in addition to separation of video data for detecting the CF. The sum of buffers and circuits required therefor would amount to more than twice as large as the CF detection circuit and this does not give a practical solution. Further, because video data which subjects to embedding consists of I-frame, a disadvantage exists in which the embedded information does not remain in other frames (B and P) when the data is decompressed.
SUMMARY OF THE INVE
Miwa Kunihiko
Morimoto Norishige
Shimizu Shuichi
Herzberg Louis P.
International Business Machines - Corporation
Peeso Thomas R.
Scully Scott Murphy & Presser
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