WO1998016928A1

WO1998016928A1 - Method and system for managing access to data

Info

Publication number: WO1998016928A1
Application number: PCT/JP1997/002822
Authority: WO
Inventors: Kunihiko Miwa; Hiroya Kobayashi; Norishige Morimoto
Original assignee: International Business Machines Corporation
Priority date: 1996-10-16
Filing date: 1997-08-12
Publication date: 1998-04-23
Also published as: CA2265647A1; CA2265647C

Abstract

A system for managing access to data and effectively preventing illegal access to data is provided with an access management information burying system in which management information for managing access to the data is prepared and the management information is buried in the data by deforming the data without changing the quantity of data. A method for managing access to data in which, the management information buried in the data by deforming the data without changing the quantity of the data is extracted and access to the data is managed in accordance with the extracted information. A method for changing the management of access to data in accordance with the kind of the medium (RAM or ROM) where the data are stored. The management information including the information for controlling the recording, receiving, reproducing, output hindering, copying history of the data, or changing of the management information. By the access management method, the illegal copying, etc., of the data can be prevented and a literary work can be protected effectively.

Description

Description Data access control method and system [Technical field]

The present invention relates to a method and a system for managing access to data by using management information embedded in data. In particular, the present invention embeds management information in data, and based on this management information, Managing access to the data.

[Background technology]

As the multimedia environment becomes more widespread, systems that handle digital information such as DVDs (digital 'video' discs), DVCs (digital video cameras), digital CS satellite broadcasts, and the Internet are becoming more common. It has become. Various devices that can process and transfer high-capacity multi-data at high speed are also being developed. However, the ability of these devices to spread in the future depends on the number of attractive content applications such as theatrical movies. No matter how good the hardware is, it will be difficult to disseminate it unless a large number of contents are distributed to motivate consumers.

The problem here is the protection of copyrighted works. Despite the fact that DVDs, etc., have sufficient hardware specifications for the distribution of theatrical films, etc., content providers are not able to protect these contents, especially when it comes to illegal copying. No satisfactory specifications have been provided. Digital data is extremely easy to copy and modify, but no effective specifications are provided to prevent it. Therefore, many attractive uses of these media At present, it is impossible to expect content distribution. In fact, DVC has not been released as a dedicated camera-capturing device because the problems related to the protection of copyrighted works have not been solved. Thus, effective protection of digitized works is indispensable for the further spread of multimedia, and the development of protection technologies and the establishment of standardized standards are expected.

Conventionally, as one of an attempt to limit the duplication of digital content such as music, CGMS 1 eye ^ "(adopted force ^s Mel Copy Generation Management System I ¾ No. in D AT (digital audio 'tape) The CGMS signal is 2-bit data and represents the following replication conditions.

C GM S signal duplication condition duplication prohibited

0 0 No limit on duplication

1 0 One-time copying is possible. In this method, these two bits of data are directly written in a predetermined place in the format. When data is copied, the CGMS signal is detected on the receiving device side, and if the content is "copy prohibited", the receiving device stops copying the content. However, since this entry location can be easily specified and its content can be easily rewritten, the user can easily rewrite the content of this signal. In other words, in the conventional technology: • The method of adding the management information separately from the data.

• It is easy to identify where management information is located. However, it was difficult to effectively prevent illegal duplication of content. Therefore, there is a demand for the development of technology that can effectively restrict access to digital content and effectively prevent illegal duplication.

[Disclosure of the Invention]

In view of the above problems, an object of the present invention is to provide a system capable of controlling access to data and effectively preventing illegal access to data.

In order to achieve the above object, there is provided an access management information embedding system which prepares management information for performing data access management, and embeds the management information in the data by changing the data amount invariably. At the time of management, a method is adopted in which embedded management information is extracted from the data by changing the data amount invariably, and access to the data is managed according to the extracted management information. In addition, a method of changing access management for the data according to the type of medium R AM (rewritable type R (write-once type) or ROM (read-only type)) on which the data is stored is adopted. The management information includes information for controlling the recording of the data, the reception of the data, the reproduction of the data, the interruption of the output of the data, the duplication history of the data, or the change of the management information.

Controlling the recording of the data means, for example, that when management information is embedded in data included in a medium such as a CD-ROM, the contents of the CD-ROM are recorded or copied on another medium, for example, a DVD or the like. It means that permission or prohibition is allowed.

Controlling the reception of the data means, for example, through a radio network. When management information is embedded in incoming data, it means that the data is received by the receiver and output of the data outside the receiver is permitted or prohibited.

Controlling the reproduction of the data means that, for example, when management information is embedded in data included in a medium whose medium type is RAM (rewritable type) or R (write-once type), this data reproduction is performed. Means permission or prohibition.

Controlling the output disturbance of the data means that, for example, when management information is embedded in data included in a medium whose type is RAM or R, the output of this data to the outside is permitted or prohibited, This means that noise is superimposed on the output signal to control output disturbance.

Controlling the copy history of the data means that, for example, if the management information embedded in the data contains information that can be copied only once, after the copy is performed once, copying is prohibited separately from the management information. Is added to the management information as additional information, and subsequent duplication or reproduction is controlled by the management information and the additional information.

Controlling the change of the management information means that, for example, when the management information embedded in the data includes information that can be copied only once, after performing the copying once, the management information itself is changed. Means that future duplication is prohibited.

The management information relates to data recording, duplication, reception, reproduction, duplication history, output obstruction, and the like.When accessing data, access control is performed based on the embedded management information. The present invention for performing the above can be applied to other management as appropriate without departing from the essence of the invention, such as limitation of access devices, limitation of access and users, data expiration date, authentication information, and the like. In the present invention, “embedding” means that specific information is concealed in the form of data deformation using data hiding technology or the like. Here, data hiding is a general term for the technology for embedding certain information in other media (still images, audio, moving images, etc.). Unlike encryption, this technology aims at information processing. It is not how to keep the information confidential, but how to integrate it with the medium in which the information is embedded.

One of the major features of data hiding is that it is an invisible marking method. When embedding information in media, instead of adding data bits, embedding information by processing (data deformation) the existing data so that it cannot be detected by human vision (data deformation). No increase in total data volume due to For example, by embedding text information and audio information in an image, the storage side can handle only one type of medium. Another major feature is the inseparability of embedded information. Data hiding embeds additional information directly in the data structure of the medium, not in a header or a separate file, so that even if the medium's platform or data format changes, as long as the quality of the original data is preserved The embedded information can be retrieved. The present invention relates to a method and a system for managing access to data by using management information embedded in data by using such a data hiding technique or the like. It should be noted that the access management method of the present invention is not limited to a specific data hiding technology, but can be used as it is as long as it is a technology for embedding information by data transformation in which the data amount does not change. I want to be.

[Brief description of drawings]

FIG. 1 is a diagram showing a procedure for recording data on a medium.

Fig. 2 shows data high-speed data using PBC (Pixel Block Coding). FIG. 9 is a diagram for explaining an example of extraction and extraction.

FIG. 3 is a diagram for explaining data hiding using PCB when one pixel is one pixel.block.

FIG. 4 is a diagram showing a procedure for managing reproduction of data recorded on a medium.

FIG. 5 is a block diagram of a system for managing and outputting data access.

FIG. 6 is a diagram for explaining an arrangement state of pictures in MPEG.

FIG. 7 is a diagram showing a state of a macro block arranged in a B picture.

FIG. 8 is a block diagram of a data access management system according to another embodiment.

The correspondence between the numbers and the names of the main components is as follows.

5 1 D V D-ROM 5 2 Reader

5 3 Demodulator 5 4 喑 decoder

5 5 MPEG decoder 5 6 Management information extractor

5 7 DZA converter 5 8 Management information changer

5 9 switch 6 0 jamming signal generator

6 1 Data supply unit 6 2 Signal processing system

6 3 Output section

[Best Mode for Carrying Out the Invention]

FIG. 1 is a diagram showing a procedure (authoring) for recording data on a recording medium. Data such as images, sounds, and software are recorded on DVD-ROM media according to the following procedure. Data that is analog data is converted to digital data by performing analog / digital conversion processing (Step 11). The converted digital data is compressed using, for example, a Moving Picture Experts Group (MPEG) (step 12). The compressed data is further encoded, encrypted (step 13), modulated (step 14), and recorded on DVD-ROM media.

In this embodiment, the data is stored in the DVD-ROM after the management information is embedded in the data before, during, or after the compression. This management information is for restricting access to the data when the system accesses data stored in the DVD-ROM, and the system is controlled based on the management information. In this embodiment, management information for managing data duplication will be described as an example. For example, in the management information, each status is represented by the following 2-bit data. Status Content of management information Copy prohibited

No limit on duplication 00 (or no data) One-time duplication possible 10 Embedding of management information in data is performed, for example, between analog-to-digital conversion (step 11) and MPEG compression (step 12) (or after compression). ). This embedding can be performed by a technique called data hiding.

Here, as an example, a method of embedding management information to be concealed in certain data and a method of extracting embedded data are described. Cell Block Coding (Pixel Block Coding) (PBC) is explained.

When PBC is used, in data hiding and extraction, data is processed according to a predetermined conversion rule. Generally, in an image, primary characteristics such as pixel values of two adjacent pixels have a high correlation with each other. For example, when a “forest” part exists in a part of the image, adjacent pixels are very similar green and have a high correlation with each other. Therefore, even if these pixels are replaced, it will be almost impossible to visually recognize the replacement. That is, even if a pixel value having a high correlation is operated according to a certain rule, the visual image quality hardly deteriorates.

In view of this property, an image area having at least one pixel is defined as a pixel * block (embedded area), and the characteristics of the adjacent pixel blocks are intentionally manipulated based on a certain conversion rule. Hide bit data. The data is represented by a comparison of the properties of adjacent pixel blocks. When extracting data, data is extracted according to the extraction rules determined based on the conversion rules.

The bit information is expressed by exchanging the characteristic values (eg, luminance values) of two adjacent pixels / blocks according to the following conversion rules.

(Conversion rules)

Bit "1,": When the characteristic value of one pixel block (PB1) is larger than the characteristic value of the other pixel (PB2)

Bit "0": the characteristic value of the other pixel 'block (P B 1) is the other

(PB2) smaller than the characteristic value The bit information is extracted by comparing the characteristic values (eg, brightness values) of two adjacent pixel 'blocks according to the following extraction rule corresponding to the above conversion rule.

(Extraction rules)

When the characteristic value of one pixel block (PB1) is larger than the characteristic value of the other (PB2): bit "1"

When the characteristic value of one pixel block (PB1) is smaller than the characteristic value of the other (PB2): bit "0" Fig. 2 shows the data hiding and extraction using PBC. FIG. Pixel 'blocks PB 1 and PB 2 may be defined as a set of a plurality of pixels, for example, 3 × 3 pixels, or one pixel may be defined as one pixel block. Neighboring pixel blocks have a high degree of correlation, so that even if the positions are interchanged, the image is not perceived to be inferior enough to be visually recognizable. Wax (Fig. 2 (a)). Let us consider the case where the position of the pixel 'block in the original image is as shown in Fig. 3 (b). First, the characteristic values of two pixel blocks are compared, and as a result, it is assumed that the characteristic value of PB1 is larger than the characteristic value of PB2. When data "1" is hidden in the original, the characteristic value of these blocks is not replaced because the characteristic value of pixel.block already satisfies the condition of data "1" in the above conversion rule. . On the other hand, when data is extracted, if the characteristic value of PB1 is large, data "1" is extracted because the extraction rule defines that the data is "1". When hiding the data "0" in the original, the relationship between the pixel block characteristic values in the original and the data in the conversion rule

Since the condition of "0" is not satisfied, the characteristic value of the pixel 'block is replaced. However, this replacement is not visually recognizable. At the time of extraction, data is obtained from the relationship between the characteristic values of these blocks according to the extraction rule. " 0 "is extracted.

As the characteristic value, in addition to the luminance value as described above, a value relating to the primary characteristic and a value relating to the secondary characteristic of the pixel 'block (embedded area) can be used. Primary characteristics are direct parameters of pixel values, such as the luminance and chromaticity of a pixel block. Further, the secondary characteristic is obtained by decomposing the primary characteristic, such as a value indicating a statistical property such as an average value and a variance of the parameter.

Also, note that the pixel blocks targeted for PBC are not necessarily limited to adjacent blocks. Hereinafter, a luminance value as a primary characteristic and a variance value as a secondary characteristic will be described as examples as characteristic values of a pixel block.

First, the case where the characteristic value of the pixel block is a luminance value will be described. In natural images, in most cases, the correlation between adjacent pixels is so high that exchanging their size does not cause a large deterioration in image quality. FIG. 3 is a diagram for explaining embedding of 6-bit data into six pixels / block using PBC when one pixel is a pixel / block.

If a block containing a relatively large number of pixels is used to increase the resistance to image editing and compression, if the average brightness of all pixels in the block is switched between blocks, a stripe pattern will appear on the image. Noise may occur. So the pixel luminance value in the block Is used as a characteristic value.

Pixels.When the property of the luminance value of a block is decomposed into the average value h and the variance value d, the average value is simply replaced if the variance value d is replaced while the average value h is unchanged in the pixel 'block. The impact on the surface quality is smaller than in the case where Therefore, by taking advantage of this property, the characteristic value of the pixel 'block is set as the variance d, and the variance d is replaced according to the conversion rule, so that the information can be hidden by the data deformation in which the data amount is invariable. Japanese Patent Application No. 8—1 5 9 3 3 0 (Refer to in-house reference number JA9-96-044)

As shown in FIG. 2 (c), let us consider a case where the pixel block PB1 has an average value h1 and a variance value d1, and the block PB2 has an average value h2 and a variance value d2. When hiding bit "1", the condition of bit "1" in the conversion rule is not satisfied because d l <d2. Therefore, only the variance d of both pixels is replaced. This is equivalent to exchanging the shape of the distribution between the two pixel blocks without changing the average value h of the characteristic values of the pixels in the block.

As described above, in embedding information using the data hiding technique, first, an embedding area in which management information is embedded is specified in the data. Then, a conversion rule is prepared in which the contents of the information to be embedded correspond to the state (characteristic) of the embedding area, and the state (characteristic) of the embedding area is directly referred to according to the management information by referring to this rule. Manipulate. As a result, management information can be embedded in the data. By directly manipulating the original data, management information integrated with the original data is embedded. Therefore, since it is difficult to separate and modify only the management information, data access management can be performed effectively. Regarding the above-mentioned PBC, a patent application in Japan, Japanese Patent Application No. 8-1593330 (internal reference number JA9-96-044) In detail. Such technologies are collectively referred to as data 'hiding, digital watermarking, etc.'

The management information is embedded using the above-mentioned data hiding technique, and the data stored in the DVD_ROM is accessed by the following procedure. First, data is read from the DVD-ROM. As shown in Fig. 1, this read data is obtained by compressing the data with the management information embedded in it (Step 11), encoding it, encrypting it (Step 12), and modulating it (Step 14). is there.

FIG. 4 is a diagram showing a procedure for managing a data access method. First, data with embedded information is accessed ■ The system is supplied. The data source is, for example, a storage medium (media) such as DVD-ROM or CD-R, communication such as the Internet, or satellite broadcasting. The supplied data is demodulated (step 41) and decoded (step 42). If the data is MPEG compressed, decompress it (Step 43). The management information embedded in the data is extracted, and if necessary, the content of the management information is changed, and the necessary change is embedded again in the data. In order to extract management information from the data input to the recorder, the above-mentioned data.hiding extraction process is used. First, the embedding area where management information is embedded is specified from the read data. Next, the management information is extracted according to the state of the embedding area by referring to the extraction rule corresponding to the content of the data for extracting the state of the embedding area. Here, if the extracted management information is data “00”, data duplication is permitted according to the above rules. If the data is “11”, this means that data duplication is prohibited. In this case, control the access system to prohibit data replication. Data "10" means that data can be duplicated conditionally (once). What this means is A copy based on the data in the original DVD-ROM will be allowed, but further duplication based on this copy is prohibited. In this case, it is necessary to control the access system to allow the data to be copied only once, and to prevent the data from being further copied using the copied data as a source. It is important to prohibit further duplication based on the original copy. (Only once can be duplicated.) Rewrite data to “1 1” (Duplicate prohibited) and output as output signal. Since the management information indicating the condition of “duplication prohibited” is embedded in the data as the output signal, further duplication based on this duplicated data is not possible. In addition, there is an option to add a bit indicating the duplication history once, which will be used in future playback control to distinguish between illegally copied and illegally copied ones. It is essential to

FIG. 5 is a block diagram of a system for reproducing data stored in the DVD-ROM. In the DVD-ROM 51 set in the data supply unit 61, as described above, data in which management information is embedded using the data-hiding technique is stored. The data read from the readout unit 52 in the data supply unit 6 1 is used to form a signal processing system 62,

It is processed by the encryption / decryption unit 54 and the MPEG decoding unit 55. This results in decompressed digital data.

The management information extractor 56 specifies the embedding area where the management information is embedded from the decompressed digital data (or directly from the MPEG data) output from the MPEG decoder 55, and also specifies the embedding area. By referring to the extraction rules corresponding to the contents of the data for extracting the state of Management information is extracted according to the state of the embedding area. (Note that management information can be extracted before and after MPEG decompression.) The DZA converter 57 in the signal processing system 62 converts the digitized data from which management information has been removed into analog data. Convert and output an analog playback signal (for example, NTSC). In addition, the interference signal generated by the interference signal generator 60 (for example, APS: Analogue Protection System such as Macrovision Signal) is selectively converted into an analog reproduction signal by the switch 59 in the output section 63. Superimposed. The switch 59 is controlled by a control signal from the management information extractor 56. The output unit 63 outputs the analog playback signal or the superimposed signal as an analog output signal. In this system, if the management information extracted by the management information extractor 56 permits data duplication, the management information extractor 56 issues a control signal to turn off the switch 59. Output. In this case, the interference signal is not superimposed on the analog reproduction signal, and the analog reproduction signal is output as it is.

On the other hand, if the management information prohibits data duplication, the management information extractor 56 outputs a control signal to turn on the switch 59. In this case, a signal is output in which the interference signal generated by the interference signal generator 60 is superimposed on the analog signal from the DZA converter 57. If you try to display an image on a monitor based on a signal on which a disturbing signal is superimposed, a normal image can be displayed on the monitor without being affected by the disturbing signal due to the characteristics of the monitor. it can. However, if you try to record this video using a digital VTR that has an analog input terminal, you will not be able to record normal video due to the effects of interfering signals. Therefore, even if video can be reproduced from the signal with the interfering signal superimposed, it cannot be digitized and recorded, effectively preventing data duplication. can do.

If the management information on the recorder side is "copy once only", the management information changer 58 changes the management information in the read data to "copy prohibited" when recording it on the recorder. Embed the information when writing it to the next media. As a result, subsequent data duplication based on the duplicated data can be effectively prevented.

Further, apart from the basic management information, additional information for controlling copy (reproduction) and reproduction in more detail may be used. This facilitates flexible control according to the type of recording and playback media (ROM, RAM or R type, etc.). status

Playback media Playback media Recording media management Addition

ROM type RAMZR RAM / R information Information Playback: OK Playback 'NG Copy: NG 11 0

Play: OK Play. NG Duplicate: NG 11 1

Play: OK Play: OK Duplicate: OK 00 0

Play: OK Play: OK Duplicate: OK 00 1

N / A Playback: OK Copy: NG 100

N / A Playback: OK Copy: NG 10 1 "0" in the above additional information indicates that no copy has been performed, and "1" indicates that copy has been performed once. N / A on ROM-type playback media means that this combination does not exist. That is, data 11 (unconditional duplication is not possible), 10 (duplicate only once), 00 (unconditional duplication) In addition to the above information, the basic management information is deleted by using one bit of additional information indicating whether or not the data has been copied once. It can be performed. The additional information may be embedded by the same embedding method as the previously embedded data (management information), or may be embedded by another embedding method to enhance security. As another embodiment, the additional data may be controlled not only by one bit but also by using a large number of bits. In any case, the present invention can be similarly implemented without departing from the essence of the present invention.

Furthermore, the management information is not limited to the information on the restriction on duplication, but can be applied to various management information that controls the system. For example, the management information is combined with the determination result of the media type. The following reproduction permission information may be used.

(When media type = RAM)

Status Contents of management information Reproduction prohibited 1 1

No playback limit 0 0

Reproducible only once 1 0 Control to prevent data from being output from the system if the reproduction permission information permits data reproduction, and if data reproduction is prohibited, data reproduction is prohibited I do. In addition, the management information may be an expiration date that defines a period during which data can be reproduced or recorded, authentication information for reproducing media contents, a disc key, a title key, and the like. Each piece of information is the data needed to access the data. Another data hiding technique will be described as a second embodiment. In this embodiment, it should be noted that the embedding of the management information is performed at the time of MPEG encoding, and that the extraction can be directly performed from the MPEG data, which is different from the above-described embodiment.

The following is a brief description of the actual embedding of management information in MPEG, taking the data 'hiding method of Japanese Patent Application Laid-Open No. 8-27272 (house number JA9-96-074) as an example. Explain to

In M PEG, forward prediction from past reproduced images, backward prediction from future reproduced images, and bidirectional prediction using both forward prediction and backward prediction are used.

FIG. 6 is a diagram for explaining an arrangement state of pictures in MPEG. As shown in this figure, in order to realize bidirectional prediction, MPEG defines three types of frames: I picture, P picture, and B picture.

Here, the I picture is a picture that has been subjected to intra-coding (intra-coding), and all macroblocks in this picture have been subjected to intra-coding (predictive coding within a frame). A P picture is an image that has been subjected to inter-frame forward prediction coding, but some macro blocks in this picture may be intra-coded. A B picture is an image obtained by performing bidirectional predictive coding between frames. A macro block in a B picture is basically encoded by forward prediction, backward prediction, or bidirectional prediction, but may include an intra code. The screen for intra-coding the entire screen is an I picture, and the I picture and P picture are coded in the same order as the moving picture. On the other hand, a B picture encodes a B picture inserted between the I picture and the P picture after processing the I picture and the P picture. The embedding area in which the management information is embedded is a macroblock of a B picture, and one bit of information can be embedded in one macroblock. Therefore, if the message 'data is multi-bit, it is necessary to perform embedding processing for the corresponding number of macro blocks. FIG. 7 is a diagram showing a state of a macro block arranged in a B picture. A macroblock is a unit to be encoded. For each macroblock, motion compensation is performed on a luminance block of 16 pixels XI 6 pixels, and a motion compensation inter-frame prediction method is performed for each macroblock, and information compression based on temporal screen correlation is performed.

Macroblocks in a B picture can be classified into the following four types of prediction.

• Intra macro block (intra-frame prediction macro block)

This is a macroblock that is encoded using only the information of the screen itself without performing inter-frame prediction.

• Forward prediction macroblock

It is a macroblock that is forward predictive coded by referring to a past I picture or P picture (reference frame). Specifically, a 16-pixel X 16-pixel square area that is the most similar in the past reference frame is searched, and the prediction error (ΔΔ), which is the difference from the square area, and the spatial relative It has information about the position (motion vector). Here, the prediction error ΔΡ is expressed as a difference between luminance and chrominance of 16 pixels × 16 pixels. It is up to the encoder to determine the criteria for selecting a similar square area. 'Backward prediction macroblock

This macroblock is subjected to backward prediction coding by referring to a future reference frame in the display order. It searches for the most similar area in the future reference frame, and has information about the prediction error (ΔΝ), which is the difference from that area, and the spatial relative position (motion vector).

• Bidirectional prediction macroblock

This is a macroblock in which bidirectional prediction coding is performed by referring to past and future reference frames. A search is made for the most similar area in the past reference frame and the most similar area in the future reference frame, and the prediction error is the difference between the average of these two areas (averaged for each pixel). ((ΔΝ + ΔΡ) / 2) and information on their spatial relative position (two motion vectors). In order to embed message data, at least one macroblock to be embedded must be specified in the B picture. This may be defined as, for example, each macroblock (embedded region) existing from the first line to the third line of the B picture, or may be the entire macroblock in a certain frame. As described above, in addition to the format being defined in advance, the position sequence can be determined using an algorithm for generating the position sequence. The algorithm for generating the position sequence can use, for example, the algorithm disclosed in Japanese Patent Application No. 8-1559330 (in-house reference number JA9-96-044). Next, 1-bit data is embedded into one macroblock based on the embedding rule in the macroblock specified as the target of the embedding processing. This embedding rule uses bit information for macroblock prediction. It is associated with the type, for example, the following rules.

(Embedding rules)

Bit information to be embedded Type of macroblock inter-frame prediction Bit "1" Bidirectional prediction macroblock (represented by B) Bit "0" Forward prediction (represented by P), or

Backward prediction macroblock (represented by N) For example, consider a case where management information “1 0 1 0” is embedded. This 4-bit data is embedded in order into the four embedded areas (macroblocks) from the first to the fourth left of the first line shown in Fig. 7. First, since the first data is bit "1", the prediction type of the leftmost macroblock (first embedding area) is determined to be bidirectional prediction (B) according to the embedding rules. The prediction error in this case is a prediction error that is a difference between the average of the most similar area in the past reference frame and the average of the most similar area in the future reference frame. The next data is bit "0".

Therefore, according to the embedding rules, the prediction type of the second macroblock (second embedding region) is either forward prediction (P) or backward prediction macroblock (N). In this case, in order to suppress image quality degradation, the prediction error in forward prediction and the prediction error in backward prediction are compared, and a type having a small prediction error is selected. In the example of Fig. 3, forward prediction (P) is selected for the second macroblock because the prediction error in forward prediction is smaller than that in backward prediction. A similar procedure is repeatedly applied to the third and fourth embedding areas.

That is, the prediction type of the third macroblock from the left is bidirectional prediction. (B), and the prediction type of the fourth macroblock is determined as backward prediction (N) because the prediction error in backward prediction is smaller. In this way, by setting the inter-frame prediction type of the first to fourth embedment areas to “BPBN”, respectively, the management information “1 10 1 0” Embedded inside. The above is an example of embedding management information in MPEG using the data hiding method disclosed in Japanese Patent Application Laid-Open No. Hei 8-27272 (house serial number JA9-96-074). Hereinafter, a method of extracting the management information embedded by the above procedure will be described. When extracting management information, first, information for specifying the macro block in which the management information is embedded must be provided. This can be given as information from the outside or embedded in the data itself in advance. In addition, if the position of the embedding area is standardized, or if you know the algorithm to generate the position sequence, you can extract the message data. The method for extracting message data using the position sequence is disclosed in, for example, Japanese Patent Application No. 8-159330 described above.

Next, the embedded information is extracted by referring to the extraction rule from the prediction type in the specified embedding area. This extraction rule associates the type of macroblock prediction with bit information and must be given as information at the time of extraction. The rules include, for example, the following rules. It should be noted that the correspondence between the prediction type and the bit information in this extraction rule corresponds to that of the embedding rule described above.

(Extraction rules) Type of macroblock inter-frame prediction Bit information extracted Bidirectionally predicted macroblock (B) Bit ', 1 "Forward prediction (represented by P) or Bit', 0" Backward prediction macroblock As shown in Fig. 7 The case where management information is embedded will be described. As a premise, it is known that the management information is embedded in the first to fourth macro blocks on the left of the first line in FIG. Since the prediction type of the leftmost macroblock is bidirectional prediction (B), bit "1" is extracted by referring to the extraction rule. Since the prediction type of the second macroblock is forward prediction (P), bit “0” is extracted according to the extraction rule. By repeatedly applying the same procedure to other macroblocks, bits "1" and "0" are sequentially extracted. As a result, management information “1 0 1 0” is extracted from these areas. According to the present embodiment, when encoding a moving image, the prediction type of the macroblock and the bits to be embedded are determined in association with each other. Therefore, management information can be embedded in a moving image with almost no effect on the compression efficiency of the moving image and with almost no deterioration in image quality. Furthermore, it is very difficult to remove the management information embedded in this way from a moving image. Furthermore, since the amount of information to be embedded hardly depends on the content of the image, it is possible to embed the message data efficiently.

As can be seen from the above description, according to the present invention, management information is embedded in data by using a data hiding method or the like, which is embedded by data transformation in which the data amount does not change, and is used when data is accessed (such as when reproducing or recording). In addition, based on this management information, control of the system to manage data access Is characterized by performing Therefore, it should be particularly noted that the present invention is not limited to the data-hiding method disclosed above, but can be applied to various methods.

Finally, the data access system shown in FIG. 8 will be described. The management information described above expresses three statuses with two bits, but the embodiment described here is a one-bit management information, and intends to give substantially three statuses to the system. . For this purpose, the system of this embodiment is characterized in that it has a controller 81 that detects the state of data being supplied to the system and controls the output of the system according to the state. The data supply device 82 is for supplying data in which management information is embedded to the access system. For example, an optical system for reading data from a DVD-ROM or data on the Internet to the system. There is a circuit for taking in. Here, the management information is represented by 1-bit data, each of which indicates the following information.

(Management information)

Status Contents of management information

Reproduction prohibited 1

Replication permission 0 The data supplied from the data supply unit 82 is processed by a signal processing system 83 that performs demodulation, decoding of signals, DZA conversion, and the like. The management information extraction unit 84 identifies the embedding area in which the management information is embedded from the data processed by the signal processing system 83, and associates the state of the embedding area with the content of the data to be extracted. The management information is extracted according to the state of the embedding area by referring to the extraction rule. The management information extractor 84 A control signal is output according to the extracted information. The control signal is for controlling the output device 85, and selectively superimposes the interference signal generated by the interference signal generator 86 on the output signal according to the content thereof and outputs the resultant signal. That is, when the management information is bit “0” (duplication permitted), the switch in the output device 85 is turned off and data is output. On the other hand, when the management information is bit "1" (copy prohibited), the switch is turned on and the interference signal is superimposed on the data and output. Note that this point is almost the same as the operation of the components of the system in FIG. 5, and will not be described in further detail. The controller 81 is connected to the data supplier 82 and monitors how the data is being supplied to the access system. Then, even if the management information is bit "0", that is, the data is permitted to be copied, the switch in the output device 85 is turned on according to the result of the supply state, and the superimposed signal is output. Control output device 85 so that it is output. In other words, even though the management information itself permits data duplication, data duplication is forbidden.

The specific data supply state is, for example, "When data is taken into the access system via a recording medium, the capacity of the set recording medium at the time of duplication is read-only or rewritable \ The type of recording medium is the area on the recording medium that cannot be tampered with.

In the (lead-in area), the system can be recognized as hardware, so it can be easily distinguished. The controller 81 does not forcibly control the switch when data replication is attempted while data is being supplied from a read-only recording medium. Therefore, the access system operates according to the extracted management information, and data can be copied as long as the management information permits copying. Meanwhile, the data If an attempt is made to copy data while the data is supplied from a rewritable recording medium, the controller 81 turns on the switch regardless of the content of the management information. Therefore, data cannot be copied from a rewritable recording medium.

Generally, when trying to prevent the unauthorized duplication or falsification of prominent or important content, the content supplier stores it in the ROM and distributes it. Therefore, the fact that the supply is in ROM format means that the data is the original, not a duplicate. On the other hand, when data is supplied in RAM or R, the data can be regarded as a duplicate of the original data stored in ROM or already in this RAM or R in most cases. . Therefore, as long as the data stored in the ROM is considered to be original and that in RAM or R is considered to be a copy, by providing such a function in the system, further duplication of the copy, That is, illegal duplication can be effectively prevented. As a result, the system determines whether the data is original or not based on its supply status, even if it is a 1-bit management information that can only indicate the two statuses of "permission of duplication". Thus, a third status, "one-time duplication allowed", can be substantially given to the system. Since the embedded management information can be represented by one bit instead of two bits, there is no need to consider the order of bits, other than the size of the management information. When the management information is 2 bits, if the bit arrangement is different between "01" and "10", it is necessary to consider the order in extracting the information. Then you don't need this. Therefore, there is an effect that the extraction accuracy of the management information is significantly improved.

In addition to the above examples, the supply status to be monitored is as follows: "When data is acquired via communication, broadcast, etc., the access system is Connected to the network? " In this case, if the data is connected to the network at the time of duplication, it can be regarded as the original data. However, at the time of duplication, if it is not connected to the network, it can be regarded as a duplicate of a copy stored outside the network (for example, R 例えば M in your own system). Therefore, when duplicating via a network, duplication may be permitted provided that it is connected to the network. In addition, various methods are conceivable, including monitoring when data is available. [Industrial applicability].

In this way, after embedding the receiver's access condition for the content to be supplied in the content itself as management information, the provider distributes the content to the general public. The access system receiving the content has the function of extracting the management information embedded in the content and controlling the access to the content according to the access conditions defined by the system. Therefore, it is possible to effectively prohibit the access of the content by the recipient, especially the illegal duplication of the content by the recipient, in the recipient's system.

Claims

The scope of the claims

1. A method for managing access to data by using management information embedded in the data by a data amount invariable data transformation, comprising the steps of extracting management information embedded in the data; Managing access to the data in accordance with the management information.

Including, data access management methods.

2. The method of claim 1, wherein the step of managing access further comprises: changing a management of access to the data according to a type of a medium on which the data is stored.

3. The method according to claim 2, wherein the type of the medium is ROM, RAM or R.

4. The management information includes information for controlling the recording of the data, the reception of the data, the reproduction of the data, the obstruction of the output of the data, the duplication history of the data, or the change of the management information. The method according to claim 1, wherein the method comprises:

5. The step of managing access includes, after performing access management on the data in accordance with the management information, separately from the management information, additional information for managing access to the data. Embedded in the data, and based on the management information and the additional information, perform access control on the data thereafter;

5. The method according to claim 4, comprising:

6. A system for managing data access,

Means for extracting, from the data, management information embedded by data transformation in which the data amount does not change; Means for managing access to the data according to the extracted management information;

A data access management system comprising:

7. The system according to claim 6, wherein said means for managing access further comprises means for changing management of access to said data according to a type of a medium on which said data is stored.

8. The system according to claim 7, wherein the type of the medium is ROM, RAM or R.

9. The management information includes information for controlling recording of the data, reception of the data, reproduction of the data, obstruction of output of the data, copy history of the data, or change of the management information. The system according to claim 6, further comprising:

10. The means for managing access further comprises:

Means for embedding, in the data, additional information for managing access to the data, separately from the management information, after performing access management for the data in accordance with the management information;

Means for performing subsequent access management to the data according to the management information and the additional information;

The system according to claim 9, comprising:

1 1. A data recording system,

Means for extracting, from the data, management information embedded by data transformation in which the data amount does not change;

Means for controlling recording of the data on a medium in accordance with the extracted management information;

A data recording system comprising:

1 2. Data replication system, Means for extracting, from the data, management information embedded by data transformation in which the data amount does not change;

Means for controlling the duplication of the data on the medium in accordance with the extracted management information;

A data replication system comprising:

1 3. Data receiving system,

Means for receiving data by a receiver;

Means for extracting, from the received data, management information embedded by data transformation in which the data amount is invariable;

Means for controlling output of the data to the outside of the receiver according to the extracted management information;

A data receiving system comprising:

1 4. Data playback system,

Means for controlling the reproduction of the data in accordance with the extracted management information.

1 5. Data output disturbance system,

Means for controlling output interruption of the data according to the extracted management information;

A data output obstruction system comprising:

1 6. A data replication history management system,

Management information and calories embedded by data transformation that does not change data volume Means for extracting information from the data;

Means for controlling duplication of the data according to the extracted management information and additional information;

Means for embedding the additional information in the data according to a result of the copy control of the data when the additional information does not exist in the data;

Means for changing the additional information and embedding it in the data in accordance with the result of the data replication control, when the additional information is present in the data, a data replication history management system.

1 7. Data access management information change system,

Means for extracting, from the data, access management information of the data, which is embedded by the data transformation in which the data amount does not change;

Means for controlling access to the data according to the extracted access management information;

Means for changing the access management information according to a result of the data access control,

A data access management information change system comprising:

18. The system according to claim 11, wherein the control unit further includes a unit configured to change the control according to a type of a medium including the data.

1 9. An access management information embedding system for embedding information for managing data access in the data,

Means for preparing management information to be embedded;

Means for embedding the management information in the data by changing the data amount invariably,

An access management information embedding system comprising:

20. The management information for performing data access control is embedded in the data. A medium including a program for embedding, the program having a function of preparing management information to be embedded;

A function of embedding the management information in the data by changing the data amount invariably,

A medium including a program, characterized by having:

2 1. A medium including a program for performing data access management, the program comprising:

A function to extract management information embedded in data by changing the data amount

A function of managing access to the data in accordance with the extracted management information;

A medium including a program, characterized by having: