KR20000036131A - Method and system for managing access to data - Google Patents

Abstract

The present invention provides a system capable of managing access to data and effectively preventing illegal access of data, and preparing management information for access management of data, and storing the management information in the data, Provided is an access management information embedding system that is embedded through data quantity invariant data transformation. In access management of data, there is provided a method of extracting management information embedded in data through data amount invariant data transformation, and managing access to the data according to the extracted management information. Further, a method of changing the management of access to the data is provided in accordance with the type of the medium (RAM or ROM) in which the data is stored. The management information also 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 copy history of the data, or the change of the management information. By this access management method, illegal copying of data and the like can be prevented, and the copyrighted work can be efficiently protected.

Description

METHOD AND SYSTEM FOR MANAGING ACCESS TO DATA

As the multimedia environment spreads, digital information processing systems such as DVD (Digital Video Disc), DVC (Digital Video Camera), Digital CS Satellite Broadcasting, and the Internet are becoming more and more common. In addition, various devices capable of processing / transmitting a large amount of multiple data at high speed have also been developed. However, whether or not these devices will become popular will depend on the number of applications that handle attractive content, such as theater movies. No matter how good hardware exists, it will be difficult to disseminate such a device unless a large amount of content is distributed that stimulates a consumer's desire to purchase.

The problem at this time is the protection of the work. For example, although DVD has a hardware specification sufficient for distribution of movie theaters, etc., a specification that the content provider can fully understand when it comes to the protection of these contents, especially illegal copying (copy). This is not being provided. Although digital data is extremely simple to copy and change its contents, no valid specification is provided to prevent such duplication. Therefore, the reality is that distribution of a large number of attractive contents using these media (media) cannot be expected. In fact, DVC is the only commercially available camera-only machine because the issue of protection of such works is not solved. As such, the efficient protection of digitized copyrighted works is essential to further spread of multimedia, and the development of protection technology and the establishment of standardized standards are expected.

Conventionally, one attempt to limit the duplication of digital content such as music is to use a CGMS signal (Copy Generation Management System signal) in DAT (Digital Audio Tape). The CGMS signal is 2 bits of data and represents the following replication condition.

CGMS Signal Replication Conditions

11 No duplication

00 No limit of replication

10 can be replicated only once

This method writes these two bits of data as they are to a predetermined place in the format. When copying data, this CGMS signal is detected on the receiving device side, and if the content is " copying prohibited ", the receiving device stops copying the content. However, since this writing place can be easily specified and the contents can be simply rewritten, the user can easily rewrite the contents of this signal. That is, in the method according to the prior art,

A method of adding the management information separately from the data,

· It is easy to specify where management information is located

Because of such drawbacks, it is difficult to effectively prevent illegal copying of contents. Therefore, there is a demand for the development of a technology that can effectively restrict access to digital content and effectively prevent illegal copying and the like.

Disclosure of the Invention

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

In order to achieve this object, there is provided an access management information embedding system which prepares management information for performing access management of data, embeds the management information into the data through data transformation in which the amount of data does not change, and In access management, a method of extracting management information embedded in data through data transformation in which the amount of data does not change, and managing access to the data according to the extracted management information. Further, a method of changing the management of access to the data is used in accordance with the type of the medium such as RAM (rewritable type) / R (write once type) or ROM (read only type) in which the data is stored. The management information may include 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 copy history of the data, or the change of the management information.

Controlling the recording of the data allows, for example, when management information is embedded in data included in a medium such as a CD-ROM, allowing the contents of the CD-ROM to be recorded or copied to another medium, such as a DVD, or the like. It means to ban.

Controlling the reception of the data means that when management information is embedded in data input through radio waves or a network, for example, receiving the data through a receiver and allowing or prohibiting the data from being output from the receiver. it means.

Controlling the reproduction of the data permits or prohibits the reproduction of the data when, for example, management information is embedded in data contained in a medium whose type is RAM (rewritable type) or R (once write type). I mean.

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 data is allowed to be output to the outside or prohibited or output signal is output. Superimposed noise to control output disturbance.

Controlling the copy history of the data means that, for example, when there is information that can be copied only once in the management information embedded in the data, after the copy is made once, the copy prohibition information is added to the management information separately from the management information. In addition to the additional information, it means to control the duplication or reproduction later using the management information and the additional information.

Controlling the change of the management information means that, for example, when there is information that can be copied only once in the management information embedded in the data, after the copy is made once, the management information is changed by itself to prevent subsequent copying. And the like.

Although the management information relates to recording, duplication, reception, reproduction, duplication history, output interruption, etc. of data, the present invention performs access control on the basis of the contents of the embedded management information when accessing data. As long as it does not depart from the essence of the invention, such as a limitation of a device, a limitation of an access user, a data expiration date, authentication information, etc., it can be suitably applied to other management.

In addition, in the present invention, "embedding" means concealing specific information by modifying the data itself, using a data hiding technique or the like. Here, the term "data concealment" is a general term for a technology for embedding certain information into another medium (still image, voice, moving picture, etc.), and unlike encryption, how to conceal information is not a medium of embedding information. It is aimed at integrating with.

One of the main features of data concealment is the invisible marking technique. When embedding the information in the media, instead of adding data bits, the data is embedded by processing (data transformation) so that existing data cannot be detected by human vision, so that the total amount of data by embedding the additional information. Does not increase. For example, by embedding text information or audio information into an image, only one type of medium can be processed on the storage side. In addition, one of the main features is the inseparability of embedded information. Since data concealment embeds additional information directly into the data structure of the medium, rather than in headers or separate files, even if the platform or data format of the medium changes, the embedded information can be extracted as long as the quality of the original data is preserved. Can be.

The present invention relates to a method and system for managing access to data using management information embedded in data using such data hiding technology. Note that the access management method of the present invention is not limited to a specific data concealment technique, and any technique may be used as long as the technique embeds information through data transformation in which the data amount does not change.

The present invention relates to a method and system for managing access to data using management information embedded in data, and in particular, embedding management information in data, and accessing the data based on the management information. Relates to managing access to data.

1 is a diagram showing a procedure of recording data on a media;

2 is a view for explaining an example of data concealment and extraction using PBC (Pixel Block Coding),

3 is a view for explaining data concealment using a PCB in the case where one pixel is one pixel block;

4 is a diagram showing a procedure for managing reproduction of data recorded on media;

5 is a block diagram of a system for managing and outputting access to data;

6 is a view for explaining an arrangement state of pictures in MPEG;

7 is a diagram showing a state of a macro block disposed in a B picture;

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

Explanation of symbols for the main parts of the drawings

51: DVD-ROM 52: Reader

53: Demodulator 54: Crypto Decryptor

55: MPEG Decoder 56: Management Information Extractor

57: D / A converter 58: management information changer

59: switch 60: jammer generator

61 Data Supply 62: Signal Processing System

63: output unit

Best Mode for Carrying Out the Invention

1 is a diagram illustrating an authoring process of recording data on a recording medium. Data such as images, audio, software and the like are recorded in the DVD-ROM media in the following order. The data in analog form is converted into digital data through an analog / digital conversion process (step 11).

This converted digital data is compressed using, for example, Moving Picture Experts Group (MPEG) (step 12). This compressed data is again encoded, encrypted (step 13), and modulated (step 14) to be recorded on the DVD-ROM media.

In the present embodiment, the data is embedded in the data before compression or during compression, after compression, and then stored in the DVD-ROM. This management information is for restricting access to this data when the system accesses data stored in the DVD-ROM, and the system is controlled based on this management information. In this embodiment, management information for managing duplication of data will be described as an example. For example, the management information expresses each state as two bits of data as follows.

Content of State Management Information

Do not copy 11

No replication limit 00 (or no data)

Can be duplicated only once 10

The embedding of management information for the data is performed, for example, between (or after) the analog-to-digital conversion (step 11) and MPEG compression (step 12). This landfill can be accomplished through a technique called data hiding.

Here, as an example, pixel block coding (hereinafter referred to as PBC), which is a method of embedding management information to be concealed in certain data and a method of extracting embedded data, will be described.

In the case of using the PBC, in concealment and extraction of the data, the data is processed according to a predetermined conversion rule. In general, in an image, primary characteristics such as pixel values of two adjacent pixels have a high correlation with each other. For example, when a part of "forest" exists in a part of an image, adjacent pixels are extremely similar green and have high correlation with each other. Therefore, even if these pixels were replaced, it would be almost impossible to visually recognize this replacement. In other words, even if the pixel values having a high correlation are manipulated according to any rule, the visual quality deterioration hardly occurs.

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

The bit information is expressed by replacing and operating characteristic values (e.g., luminance values) of two adjacent pixel blocks according to the following conversion rules.

(Conversion rule)

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

Bit "0": When the characteristic value of one pixel block PB1 is smaller than the characteristic value of the other PB2

Further, the bit information is extracted by comparing the characteristic values (for example, luminance values) of two adjacent pixel blocks according to the following extraction rule corresponding to the above conversion rule.

(Extraction rule)

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 "O"

2 is a diagram for explaining concealment and extraction of data using PBC. The pixel blocks PB1 and PB2 may be defined as a set consisting of a plurality of pixels, for example, 3x3 pixels, or one pixel may be defined as one pixel block. Since adjacent pixel blocks have a high correlation, even if the replacement operation of those positions is not performed, it will not feel that the image has deteriorated visually recognizable (Fig. 2 (a)). Consider the case where the position of the pixel block in the original image is the same drawing (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 that of PB2. When the data "1" is concealed in the original image, since the characteristic values of the pixel blocks already satisfy the condition of the data "1" in the conversion rule, the replacement of the characteristic values of these blocks is not executed. On the other hand, when extracting data, when the characteristic value of PB1 is large, since the extraction rule is defined as data "1", data "1" is extracted.

In addition, when the data "0" is concealed in the original image, the relationship of the characteristic value of the pixel block in the original image does not satisfy the condition of the data "0" in the conversion rule, so that the characteristic value of the pixel block is replaced. do. However, this replacement is visually unrecognizable. At the time of extraction, data "0" is extracted from the relationship between the characteristic values of these blocks in accordance with the extraction rule.

As the characteristic value, in addition to the above-described luminance value, a value relating to the primary characteristic and the second characteristic of the pixel block (buried region) can be used. The primary characteristic is a direct parameter of the pixel value, such as the luminance or chromaticity of the pixel block. In addition, the secondary characteristic is obtained by decomposing a primary characteristic like the value which shows statistical property, such as an average value or a variance value of the said parameter.

Note that the pixel blocks that are the target of the PBC are not necessarily limited to adjacent blocks. Hereinafter, as a characteristic value of a pixel block, the luminance value which is a primary characteristic and the dispersion value which is a secondary characteristic are demonstrated to an example.

First, the case where the characteristic value of the pixel block is a luminance value will be described. In a natural image, in most cases, the correlation between adjacent pixels is very high, so that even if they are replaced with each other, the deterioration in image quality is not significant. FIG. 3 is a diagram for explaining that 6-bit data is embedded in six pixel blocks using PBC when one pixel is a pixel block.

In the case of using a block containing a relatively large number of pixels in order to increase the resistance to editing or compression of the image, if the magnitudes of the luminance average values of all the pixels in the block are interchanged between blocks, the stripes on the image may appear. Noise, such as noise, may occur. Thus, a method of using the dispersion value of the pixel luminance value in the block as the characteristic value is considered.

When the property of the luminance value of a pixel block is decomposed into an average value h and a variance value d, the effect of replacing only the variance value d as it is on the pixel block as compared to the case where the average value is simply replaced is an effect on the image quality. This is small. Therefore, in consideration of this property, the characteristic value of the pixel block is set to this variance value d and replaced according to the conversion rule, whereby the information can be concealed through data transformation in which the data amount does not change. See Japanese Patent Application No. 96-159330 (Docket No. JA9-96-044).

As shown in Fig. 2C, the case where the pixel block PB1 has an average value h1 and a dispersion value d1, and the block PB2 has an average value h2 and a dispersion value d2 is considered. When concealing bit "1", since d1 <d2, the condition of bit "1" in the conversion rule is not satisfied. Thus, only the variance value d of these pixel blocks is replaced. This is equivalent to exchanging the size of the distribution shape without changing the average value h of the characteristic values of the pixels in the block between two pixel blocks.

In this way, in the embedding of information using the data concealment technique, the embedding area for embedding management information is first specified in the data. Then, a conversion rule is prepared in which the content of the information to be embedded corresponds to the state (characteristic) of the embedding area. With reference to this rule, the state (characteristic) of the embedding area is directly manipulated according to the management information. Thus, management information can be embedded in the data. By directly operating the original data, management information integrated with the original data is embedded. Therefore, since it is difficult to separate or change only management information, it is possible to efficiently perform data access management. The PBC is described in detail in Japanese Patent Application No. 96-159330 (Docket No. JA9-96-044). It is also referred to as data concealment, electronic watermark, and the like throughout the technology.

Management information is embedded using the data concealment technique, and the data stored in the DVD-ROM is accessed in the following order. First, data is read from the DVD-ROM. This read data is a signal that has been modulated (step (14)) after MPEG compression (step 11), encoding, and encryption (step 12) after embedding the management information embedded therein as described in FIG. .

4 is a diagram illustrating a procedure for managing a data access method. First, data in which information is embedded is supplied to an access system. The source of data is, for example, a storage medium (media) such as a DVD-ROM or a 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, the compressed data is decompressed (step 43). The management information embedded in the data is extracted, and if necessary, the contents of the management information are changed and embedded in the data as much as necessary.

In order to extract management information from data input to the recorder, the above-described data concealment extraction process is used. First, the embedding area in which management information is embedded is read from the read data. Next, by referring to the extraction rule corresponding to the content of data for extracting the state of the embedded area, management information is extracted in accordance with the state of the embedded area. Here, if the extracted management information is data "00", duplication of data is recognized in accordance with the above-described rule. If data &quot; 11 &quot;, this means that data is not copied. In this case, the access system is controlled to prohibit copying of data. The data &quot; 10 &quot; means that data can be copied conditionally (only once). This means that the creation of a copy based on the data in the original DVD-ROM is accepted, but no further copy based on this copy is prohibited.

In this case, it is necessary to control the access system so that the data is replicated only once, and use the copied data as a source to prevent the data from being copied anymore. Since it is important to prohibit further copying based on the copy from the original, copying condition indicated by the management information embedded in the original data at the time of the original copy is set from the data "10" (can be copied only once) from the data "11" ( After the data is rewritten, the data is output as an output signal. In the data as this output signal, since management information indicating a condition of "copying prohibited" is embedded, no further copying based on this copying data is possible. In addition, there is an option of adding a bit indicating a one-time copy history, which is indispensable for distinguishing whether it is legally copied or illegally copied in future playback control.

5 is a block diagram of a system for reproducing data stored in a 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 a data concealment technique is stored. The data read out from the reader 52 in the data supply unit 61 is processed by the demodulator 53, the cryptographic decoder 54, and the MPEG decoder 55 constituting the signal processing system 62. In this way, decompressed digital data can be obtained.

The management information extractor 56 specifies a buried area in which management information is embedded from decompressed digital data (or directly from MPEG data) which is the output of the MPEG decoder 55, and extracts the state of the buried area. By referring to the extraction rule corresponding to the content of the data to be described, management information is extracted in accordance with the state of the buried area. (Note also that management information can be extracted before or after decompressing MPEG.)

The D / A converter 57 in the signal processing system 62 analog-converts digital data from which management information has been removed and outputs an analog reproduction signal (for example, NTSC). In addition, an interference signal generated by the interference signal generator 60 (for example, an APS: Analogue Protection System such as Macrovision Signal) is selectively superimposed on the analog reproduction signal via the switch 59 in the output unit 63. This switch 59 is controlled by a control signal from the management information extractor 56. The output unit 63 outputs an analog reproduction signal or a superimposed signal as an analog output signal.

In this system, when the management information extracted by the management information extractor 56 allows duplication of data, the management information extractor 56 outputs a signal for controlling the switch 59 to the off state. In this case, the disturbance signal does not overlap the analog reproduction signal, and the analog reproduction signal is output as it is.

On the other hand, when the management information prohibits duplication of data, the management information extractor 56 outputs a signal for controlling the switch 59 to the on state. In this case, a signal in which an interference signal generated by the interference signal generator 60 is superimposed on the analog signal from the D / A converter 57 is output. When an image is to be displayed on a monitor based on a signal in which an interference signal overlaps, a normal image may be displayed on the monitor without being affected by the interference signal due to the characteristics of the monitor. However, if a digital VTR having an analog input terminal is used to record this video, normal video cannot be recorded under the influence of the disturbance signal. Therefore, although an image can be reproduced from a signal in which the disturbance signal is superimposed, it cannot be digitized and recorded, so that duplication of data can be effectively prevented.

On the recorder side, when the management information indicates "permit copying only once", the management information changer 58 changes the "copying prohibition" when recording the management information in the read data with the recorder, and changes the information. It is embedded when recording on the next media. Therefore, data duplication based on the duplicated data can be prevented efficiently.

In addition to the basic management information, additional information for controlling copying and reproduction in more detail may be used. Accordingly, it is possible to flexibly control according to the type of the recording / reproducing medium (ROM, RAM, R type, etc.).

condition

Play media play media record media management add

ROM Type RAM / R RAM / R Information Information

Play: OK Play: NG Duplicate: NG 11 0

Play: OK Play: NG Duplicate: NG 11 1

Play: OK Play: OK Duplicate: OK

Play: OK Play: OK Duplicate: OK 00 1

N / A Play: OK Duplicate: NG 10 0

N / A Play: OK Duplicate: NG 10 1

The additional information " 0 " indicates that no copy has ever been made, and " 1 " indicates one copy has been made. In addition, N / A in ROM type playback media means there is no such combination. That is, in addition to the information of data 11 (unconditionally replicable), 10 (can be replicated only once), and 00 (unconditionally replicable), by using additional information 1 bit indicating whether it has been replicated once, basic management information is erased. You can make replication / playback control more detailed and flexible, without changing. The additional information may be embedded in the same embedding method as the previously embedded data (management information), or may be embedded in a separate embedding method in order to increase security. As another embodiment, the additional data may be further controlled by using a plurality of bits without limiting to one bit. Either way, it can implement similarly, without deviating from the essence of this invention.

In addition, the management information is not limited to the information on the restriction of duplication, but can be applied also to various management information for controlling the system. For example, in combination with the determination result of the media type, the following reproduction permission is allowed. Information may be sufficient.

(For media type = RAM)

Content of State Management Information

No playback 11

No limit of playback 00

Can be played only once 10

When the reproduction permission information allows the reproduction of the data, the reproduction of the data is acknowledged, and when the reproduction of the data is prohibited, the control is performed so that the data is not output from the system. In addition, the management information may be an expiration date in which a period in which data can be reproduced or recorded, authentication information for reproducing media content, a disc key, a title key, or the like. Any information is data required for accessing the data.

Another data concealment technique is described as the second embodiment. Note that in this embodiment, embedding of management information is performed at the time of MPEG encoding, and the extraction thereof can be executed directly from the data of MPEG, which is different from the above-described embodiment.

In the following, the data concealment method of Japanese Patent Application No. 96-272721 (Dokect No. JA9-96-074) will be briefly described how embedding of management information in MPEG is actually performed.

In MPEG, bidirectional prediction using both forward prediction from past playback pictures, backward prediction from future playback pictures, and forward prediction and backward prediction are used.

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 an intra-frame coded (intra-encoded) image, and all macro blocks in this picture are intra-coded (intra-frame predictive coding). The P picture is an inter-frame forward predictive coded picture, and some macro blocks in the picture may be intra coded. The B picture is an inter-frame bidirectional predictive coded picture. The macroblocks in the B picture are basically encoded by forward prediction, backward prediction, or bidirectional prediction, but may include intra coding. The picture which intra-codes all pictures is an I picture, and the I picture and the P picture are encoded in the same order as the original moving picture. In contrast, a B picture processes an I picture and a P picture, and then encodes a B picture inserted between them.

The embedding area for embedding management information is a macro block of a B picture, and one bit of information can be embedded in one macro block. Therefore, when the message data has multiple bits, it is necessary to embed the macroblock of the corresponding number. 7 is a diagram illustrating a state of macro blocks arranged in a B picture. Macro blocks are units to be encoded. For each macro block, motion compensation is performed for a luminance block of 16 pixels x 16 pixels, and information compression based on temporal picture correlation is performed in a motion compensation inter-frame prediction method in units of macro blocks.

Macro blocks in a B picture can be classified into the following four types as prediction types.

Intra macroblock (in-frame predictive macroblock)

It is a macroblock encoded only by information of the screen itself without performing inter-frame prediction.

Forward prediction macro block

By referring to a past I picture or P picture (reference frame), this is a macro block to be subjected to forward prediction coding. Specifically, a square region of 16 pixels x 16 pixels, which is the most similar among the past reference frames, is searched for and has information on a prediction error ΔP and a spatial relative position (motion vector), which is a difference from the square region. have. The prediction error ΔP is expressed here as a difference between luminance and color difference of 16 pixels x 16 pixels. Also, the criterion for selecting similar square regions differs depending on the encoder.

Backward prediction macro block

A macroblock that is backward predictively coded by referring to future reference frames in display order. The most similar region of the future reference frames is searched for and contains information on the prediction error ΔN and the spatial relative position (motion vector), which is a difference from the region.

Bidirectional predictive macroblock

By referring to past and future reference frames, it is a macroblock that is bi-predictively coded. Search for the most similar areas of past reference frames and the most similar areas of future reference frames, and predict the error ((ΔN + ΔP) / 2) that is the difference from the average (averaged per pixel) with these areas and It contains information about the spatial relative position of the two motion vectors.

In order to embed the message data, first, at least one macro block to perform embedding processing must be specified among B pictures. This may be defined, for example, as each macro block (embedded area) existing from the first line to the third line of the B picture, or may be the entire macroblock in any frame. In addition to being defined in advance as a format in this manner, it can also be determined using an algorithm for generating a position sequence. As the generation algorithm of the position series, for example, an algorithm disclosed in Japanese Patent Application No. 96-159330 (Docket No. JA9-96-044) can be used. Next, for the macroblock specified as the embedding process, one bit of data is embedded in one macroblock based on the embedding rule. This embedding rule corresponds bit information to the prediction type of the macroblock. For example, the following rule can be given.

(Landfill rules)

Interframe prediction type of bit information macroblock to embed

Bit "1" bidirectional predictive macroblock (indicated by B)

Bit "O" forward prediction (denoted by P), or

Backward prediction macro block (denoted by N)

For example, consider a case where the management information "l010" is embedded. This 4-bit data is embedded in four embedding areas (macroblocks) from the first to the fourth left of the first line shown in FIG. 7 in order. First, since the first data is bit " 1 ", the prediction type of the leftmost macroblock (first buried region) is determined as bidirectional prediction (B) according to the embedding rule. The prediction error in this case is a prediction error that is the difference between the average of the most similar region among the past reference frames and the most similar region among the future reference frames. The next data is bit "0".

Therefore, according to the embedding rule, the prediction type of the second macro block (second buried region) is either forward prediction P or backward prediction macro block N. In this case, in order to suppress deterioration of the image quality, the prediction error in the forward prediction is compared with the prediction error in the backward prediction, and a type having a small prediction error is selected. In the example of FIG. 3, in the second macro block, the forward prediction P is selected because the prediction error in the forward prediction is smaller than the prediction error in the backward prediction. In this order, it is applied repeatedly to the third and fourth buried regions.

That is, the prediction type of the third macroblock from the left becomes bidirectional prediction (B), and the prediction type of the fourth macroblock is determined as backward prediction (N) because the prediction error in the backward prediction is small. In this way, by setting the interframe prediction type of the fourth embedding region to "BPBN" in the first embedding region, management information "1010" was embedded in these regions through data amount invariant data transformation. The above is an example of a method of embedding management information in MPEG using the data concealment method of Japanese Patent Application No. 96-272721 (Docket No. JA9-96-074).

Hereinafter, a method of extracting management information embedded in the above-described order will be described. When extracting management information, first, information for specifying a macroblock in which the management information is embedded should be given. This may be provided from the outside as information or may be embedded in the data itself in advance. In addition, message data can be extracted if the location of the buried region is standardized or if the algorithm for generating the position sequence is known. Moreover, about the extraction method of the message data using a positional sequence, it is disclosed by the said Japanese patent application No. 96-159330, for example.

Next, the information embedded in the buried area is extracted by referring to the extraction rule from the prediction type in the specified embedded area. This extraction rule corresponds to bit information with the prediction type of the macro block, and should be given as information at the time of extraction. Examples of this rule include the following rules. Note 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 rule)

Type of interframe prediction of macroblocks Bit information to be extracted

Bidirectional Prediction Macro Block (B) bit "1"

Forward prediction (denoted by P), or bit "0"

Backward prediction macroblock

The case where management information is embedded like FIG. 7 is demonstrated. As a premise, it is already known that the management information is embedded in the first to fourth macro blocks from the left in the first line of the same drawing. Since the prediction type of the leftmost macroblock is bidirectional prediction (B), with reference to the extraction rule, bit "1" is extracted. Since the prediction type of the second macroblock is forward prediction (P), according to the extraction rule, bit "O" is extracted. By repeatedly applying to other macroblocks in the same order, bits "1" and "0" are sequentially extracted. As a result, management information "1010" is extracted in 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 to be related. Therefore, it is possible to embed management information in the moving image with little effect on the compression efficiency of the moving image and almost no deterioration in image quality. In addition, it is very difficult to remove management information embedded in this way from a moving picture. In addition, since the amount of information to be embedded is almost independent of the content of the image, the message data can be embedded efficiently.

As can be seen from the above description, the present invention utilizes a data concealment method for embedding data through invariant data amount data, and embeds management information in data, and at the time of data access (playback, proxying, etc.). On the basis of this management information, there is a feature in that the system is controlled to manage access to data. Therefore, it is to be noted that the present invention is not limited to the data concealment method as described above, but can also be applied to various methods.

Finally, the data access system shown in FIG. 8 will be described. Although the above-mentioned management information expresses three states by two bits, the embodiment described here is one bit of management information, and intends to give three states substantially to a system. To this end, the system of this embodiment is characterized in that it has a controller 81 which detects in what state data is supplied to the system and controls the output of the system according to the state. The data supplier 82 is for supplying data embedded with management information to an access system. Examples thereof include an optical system for reading data from a DVD-ROM, a circuit for inputting data on the Internet into the system, and the like. Here, the management information is represented by one bit of data representing the following information, respectively.

(Management information)

Content of State Management Information

Do not copy 1

Replication permission 0

The data supplied from the data supplier 82 is processed by the signal processing system 83 which performs demodulation, encryption compounding, D / A conversion, and the like. The management information extracting unit 84 specifies, from the data obtained by being processed by the signal processing system 83, the embedding area in which the management information is embedded, and at the same time, corresponds to the contents of the data extracting the state of the embedding area. By referring to the rule, the management information is extracted according to the state of the buried area. The management information extractor 84 outputs a control signal in accordance with the extracted information. This control signal is for controlling the output unit 85, and depending on the content, it selectively outputs the interference signal generated by the interference signal generator 86 superimposed on the output signal. In other words, when the management information is bit "0" (copy allowance), the switch in the output unit 85 is turned off to output data. On the other hand, when the management information is bit " l " (repeat prohibition), the switch is turned on to output the interference signal superimposed on the data. In addition, since this point is substantially the same as the operation | movement of the component of the system of FIG. 5, it is not demonstrated in detail anymore.

The controller 81 is connected to the data supplier 82 and monitors in what state the data is supplied to the access system. Then, even when the management information indicates bit "0", that is, permission to copy data, the output unit 85 is output so that a superimposed signal is output by turning on the switch in the output unit 85 according to the result of this supply state. ). In other words, despite the fact that the management information itself permits the duplication of data, the duplication of data is forbidden.

The specific data supply state monitors, for example, "when data is recorded in the access system via the recording medium, at the time of duplication, the set recording medium is a read-only type or a rewritable type." The type of recording medium can be easily distinguished because the system can be recognized in hardware in an unalterable area (lead-in area) of the recording medium. When data copying is to be executed while data is supplied from a read-only type recording medium, the controller 81 does not forcibly control the switch. Therefore, according to the extracted management information, the access system operates and can copy data as long as the management information permits duplication. On the other hand, when data is to be copied in a state where data is supplied from a rewritable recording medium, the controller 81 turns on the switch regardless of the contents of the management information. Therefore, data cannot be copied from a rewritable recording medium.

In general, when prominent or important content is intended to prevent unauthorized duplication or unauthorized modification, the source of content is stored in a ROM and distributed. Therefore, the fact that the supply state is in the R0M format can be considered that the data is original, not duplicate. On the other hand, when data is supplied from RAM or R, in most cases, the data can be regarded as a duplicate of the original data stored in the ROM already copied into this RAM or R. Thus, as long as the data stored in the ROM is regarded as the original and also in the RAM or R as it is regarded as a copy, by providing such a function in the system, the copy can be effectively prevented from further copying, that is, illegal copying. have. As a result, even if it is 1-bit management information that can indicate only two states of "replication permission" or not, since the system judges whether or not the data is original, depending on the supply state, the term "copy only once" is defined. Three states can be given to the system substantially.

Since embedded management information can be represented by one bit instead of two bits, it is not necessary to consider the order of bit ordering rather than the problem of the size of the management information. When the management information is 2 bits, the order of the bits is " 1 " Therefore, there is an effect that the extraction accuracy of management information is considerably improved.

In addition to the above example, the supply state to be monitored is considered "when data is input via communication, broadcast, etc., whether or not the access system is connected to the network at the time of duplication". In this case, if data is connected to the network at the time of duplication, it can be regarded as original data. However, at the time of duplication, if it is not connected to a network, it can be regarded as duplication of a duplication stored in a place other than the network (for example, ROM in a magnetic system). Therefore, in the duplication via a network, duplication should be acknowledged provided that it is connected to the network. In addition, various methods are contemplated, including monitoring the time the data is being supplied.

In this way, the access condition of the acquirer to the content to be supplied is embedded in the content itself as management information, and then the supplier distributes the content to the general public. The access system that has received the content extracts management information embedded in the content, and has the function of controlling the access of the content according to the access condition determined by the system itself. Thus, access to the content by the acquirer, in particular illegal copying of the content by the acquirer, can be effectively prohibited by the acquirer's system.

Claims (21)

A method of managing access to data by using management information embedded in the data through data modifications invariant in data amount, Extracting management information embedded in the data; And managing access to the data according to the extracted management information. The method of claim 1, The managing the access further includes changing the management of access to the data according to the type of the medium on which the data is stored. The method of claim 2, And the type of the medium is ROM, RAM or R. The method of claim 1, wherein 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 copy history of the data, or the change of the management information. How to manage data access. The method of claim 4, wherein In the managing of the access, after performing access management on the data according to the management information, additional information for managing access to the data is embedded in the data, separately from the management information. Managing access to the data thereafter by management information and corresponding additional information. In a system for managing access to data, Means for extracting management information embedded from the data amount invariant data transformation from the data; Means for managing access to the data in accordance with the extracted management information. The method of claim 6, The means for managing access further comprises means for changing the management of access to the data in accordance with the type of medium on which the data is stored. The method of claim 7, wherein And the type of the medium is ROM, RAM, or R. The data access management system. The method according to claim 6 to 8, The management information has 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 copy history of the data, or the change of the management information. Access management system. The method of claim 9, Means for managing the access, Means for embedding in said data additional information for managing access to said data separately from said management information after performing access management on said data in accordance with said management information; And means for managing access to subsequent data according to the management information and corresponding additional information. In the data recording system, Means for extracting embedded management information from the data through data modifications invariant in data amount; Means for controlling the recording of the media of the data in accordance with the extracted management information. In the data replication system, Means for extracting embedded management information from the data through data modifications invariant in data amount; Means for controlling copying of the data to media in accordance with the extracted management information. In a system for receiving data, Means for receiving data through a receiver, Means for extracting, from the received data, management information embedded through data transformation invariant in data amount; Means for controlling the output of the data to the outside of the receiver in accordance with the extracted management information. In the data reproduction system, Means for extracting embedded management information from the data through data modifications invariant in data amount; And a means for controlling reproduction of the data in accordance with the extracted management information. In the system of interrupting the output of data, Means for extracting embedded management information from the data through data modifications invariant in data amount; And a means for controlling output disturbance of the data in accordance with the extracted management information. In the data replication history management system, Means for extracting management information and additional information from said data, which are embedded through data amount invariant data modification; Means for controlling the duplication of the data according to the extracted management information and additional information; Means for embedding additional information in the data in accordance with a result of duplication control of the data when no additional information exists in the data; And additional means for changing the additional information and embedding the additional information in accordance with the result of copy control of the data. In the system for changing access management information of data, Means for extracting access management information of the data embedded in the data amount invariant from the data; Means for controlling access to the data in accordance with the extracted access management information; And a means for changing the access management information in accordance with a result of the access control of the data. The method according to claim 11 to 17, And the means for controlling further comprises means for changing the control in accordance with the type of media in which the data is contained. In the access management information embedding system that embeds information for managing access to data in the data, Means for preparing management information for landfill; And a means for embedding said management information in said data through data amount invariant data modification. A medium in which management information for access management of data is embedded in the data, The program, The ability to prepare management information for landfill; And a function of embedding said management information in said data through data modifications invariant in data amount. A medium in which a program for performing data access management is embedded, The program, A function of extracting management information embedded in the data by changing the data amount invariably; And a function of managing access to the data according to the extracted management information.