KR100279523B1 - Copy protection device and information recording medium used in such a copy protection device - Google Patents

Abstract

The present invention prevents unauthorized copying of multimedia data recorded on an information recording medium by using electronic perspective information and key information. The electronic perspective information embedded in the multimedia data is extracted by the electronic perspective extraction circuit 11 on the decoding unit side. Then, the disc key is obtained using this electronic perspective information and the partial master key. Then, the multimedia data is decrypted using the disk key thus obtained.

Description

Copy protection device and information recording medium used in such a copy protection device

The present invention relates to a copy protection device for preventing illegal copying from a recording medium for digitally recorded data. Moreover, this invention relates to the information recording medium used for such a copy protection apparatus.

Background Art Floppy disks, compact disks, DVDs (digital video disks), and the like have been developed as recording media for digitalized multimedia information (images, audio, etc.).

In various digital recording media as described above, since digital data is usually recorded as it is (including compressed or decoded data), the recorded data can be easily copied to other media without loss, thereby preventing problems such as copyright infringement. It is happening.

In order to solve this problem, there is also a method of encrypting digital data and recording it on a recording medium. In this case, copying becomes possible if the management of the encryption key used for encrypting the recorded data is insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a copy preventing apparatus for preventing an illegal copy from a digitally recorded recording medium.

Moreover, an object of this invention is to provide the information recording medium used for such a copy protection apparatus.

1 is a block diagram showing a copy preventing apparatus according to a first embodiment of the present invention.

Fig. 2 is a flowchart for explaining the operation of the copy preventing device according to the first embodiment of the present invention.

Fig. 3 is a flowchart showing the operation of the decryption / decision circuit of the master key of the copy protection device according to the first embodiment of the present invention.

Fig. 4 is a block diagram showing a method of recording data on an information recording medium used in the copy protection device according to the first embodiment of the present invention.

5 is a block diagram showing a copy preventing apparatus according to a second embodiment of the present invention.

Fig. 6 is a flowchart showing the operation of the copy protection device of the second embodiment of the present invention.

Fig. 7 is a block diagram showing a method of recording data on an information recording medium used in a copy protection device according to a second embodiment of the present invention.

8 is a block diagram showing a copy preventing apparatus according to a third embodiment of the present invention.

Fig. 9 is a flowchart showing the operation of the copy protection device of the third embodiment of the present invention.

Fig. 10 is a block diagram showing a method of recording data on an information recording medium used in the copy protection device according to the third embodiment of the present invention.

According to claim 1 of the present invention for achieving this object,

An encryption unit,

A copy protection device comprising a decryption unit connected to the encryption unit via a CPU bus,

The encryption unit

First encryption means for encrypting an encrypted disk key encrypted using the disk key itself using a shared encryption key shared between the encryption unit and the decryption unit;

First transmitting means for transmitting the disk key encrypted by the first encrypting means via the CPU bus;

Second encryption means for encrypting a disk key encrypted using a master key using the shared encryption key;

Second transmission means for transmitting the disk key encrypted by the second encryption means via the CPU bus;

Third encryption means for encrypting the multimedia data embedded with the electronic perspective information which is a part of the master key by using the shared encryption key;

Third transmission means for transmitting the multimedia data encrypted by the third encryption means via the CPU bus;

Fourth transmitting means for transmitting the encrypted multimedia data using the disc key,

The decoding unit

First decrypting means for decrypting the disk key transmitted from said first transmitting means using said shared encryption key,

Second decrypting means for decrypting the disk key transmitted from said second transmitting means using said shared encryption key,

Third decrypting means for decrypting the multimedia data transmitted from the third transmitting means using the shared encryption key;

Extraction means for extracting the perspective information from the multimedia data decoded by the third decoding means;

Based on the disc key decoded by the first decoding means, the disc key decoded by the second decoding means, perspective information extracted by the extracting means, and a partial master key corresponding to a part of the master key. Disk key obtaining means for obtaining a disk key by

And a fourth decoding means for decoding the multimedia data transmitted by the fourth transmitting means using the disk key acquired by the disk key obtaining means.

Moreover, according to claim 2 of the present invention,

In the copy preventing device according to claim 1,

The disk key obtaining means

First acquiring means for acquiring a master key candidate based on the partial master key and the perspective information;

Second acquiring means for acquiring the first disc key candidate by decoding the disc key decoded by the second decoding means using the master key candidate acquired by the first acquiring means;

Third acquiring means for acquiring the second disc key candidate by decoding the disc key decoded by the first decoding means by using the first disc key candidate acquired by the second acquiring means;

Determination means for determining whether or not the first disk key candidate acquired by the second obtaining means and the second disk key candidate acquired by the third obtaining means are identical;

And a determining means for determining the first disk key candidate as a disk key when the determining means determines that the first disk key candidate and the second disk key candidate match. Is provided.

According to claim 5 of the present invention,

An encryption unit,

A copy protection device comprising a decryption unit connected to the encryption unit via a CPU bus,

The encryption unit

First encryption means for encrypting an encrypted disk key encrypted using the disk key itself using a shared encryption key shared between the encryption unit and the decryption unit;

First transmitting means for transmitting the disk key encrypted by the first encrypting means via the CPU bus;

Second encryption means for encrypting a disk key encrypted using a master key using the shared encryption key;

Second transmission means for transmitting the disk key encrypted by the second encryption means via the CPU bus;

Third transmitting means for transmitting the multimedia data, encrypted with the disk key and embedded with the electronic perspective information which is part of the master key, through the CPU bus;

Fourth transmitting means for transmitting encrypted multimedia data using the disc key and the perspective information,

The decoding unit

First decrypting means for decrypting the disk key transmitted from said first transmitting means using said shared encryption key,

Second decrypting means for decrypting the disk key transmitted from said second transmitting means using said shared encryption key,

Disk key acquisition means for acquiring a disk key based on the disk key decoded by the first decoding means, the disk key decoded by the second decoding means, and a partial master key corresponding to a part of the master key; ,

Third decoding means for decoding the multimedia data transmitted by the third transmission means by using the disk key acquired by the disk key obtaining means;

Extraction means for extracting electronic perspective information from the multimedia data decoded by the third decoding means;

And fourth decoding means for decoding the multimedia data transmitted by the fourth transmitting means based on the electronic perspective information extracted by the extracting means and the disk key obtained by the disk key obtaining means. A copy preventing device is provided.

According to claim 8 of the present invention,

An encryption unit,

A copy protection device comprising a decryption unit connected to the encryption unit via a CPU bus,

The encryption unit

First encryption means for encrypting an encrypted disk key encrypted using the disk key itself using a shared encryption key shared between the encryption unit and the decryption unit;

First transmitting means for transmitting the disk key encrypted by the first encrypting means via the CPU bus;

Second encryption means for encrypting a disk key encrypted using a master key using the shared encryption key;

Second transmission means for transmitting the disk key encrypted by the second encryption means via the CPU bus;

Third transmitting means for transmitting the multimedia data, encrypted with the disk key and embedded with the electronic perspective information which is part of the master key, through the CPU bus;

A fourth transmission means for transmitting the multimedia data encrypted with the disk key and superimposed with the electronic perspective information through the CPU bus,

The decoding unit

First decrypting means for decrypting the disk key transmitted from said first transmitting means using said shared encryption key,

Second decrypting means for decrypting the disk key transmitted from said second transmitting means using said shared encryption key,

Disk key acquisition means for acquiring a disk key based on the disk key decoded by the first decoding means, the disk key decoded by the second decoding means, and a partial master key corresponding to a part of the master key; ,

Third decoding means for decoding the multimedia data transmitted by the third transmission means by using the disk key acquired by the disk key obtaining means;

Extraction means for extracting electronic perspective information from the multimedia data decoded by the third decoding means;

Fourth decoding means for decoding the multimedia data transmitted by the fourth transmitting means by using the disk key acquired by the disk key obtaining means;

And a fifth decoding means for decoding the multimedia data decoded by the fourth decoding means by using the electronic perspective information extracted by the extracting means.

In the present embodiment, an operation of encrypting certain data a using a key K is represented by Ek (a), and an operation of decrypting certain data a using a key K is represented by Dk (a). By using this expression, for example, an operation of encrypting a data a using a key K and decrypting it is represented by Dk (Ek (a)).

In this embodiment, a system for reproducing audio data compressed and encrypted according to a data compression standard called MPEG-Audio recorded on a DVD will be described as an example.

In the present embodiment, for example, it is assumed that a plurality of predetermined master keys are prepared, and one or a plurality of master keys are assigned to a decoding unit maker (or a DVD production / sale company) for each predetermined unit.

<1st embodiment>

EMBODIMENT OF THE INVENTION Hereinafter, 1st Embodiment of this invention is described.

1 is a block diagram showing a copy preventing apparatus according to a first embodiment of the present invention.

The system according to the present embodiment is provided in a calculator such as a personal computer (hereinafter referred to as a PC) and connected to a so-called CPU bus of a CPU used for reproduction, and has a configuration in which encrypted data flows on the CPU bus. In addition, in FIG. 1, only the part regarding CPU used for reproduction is shown.

As shown in FIG. 1, the copy protection device of this embodiment is provided with the encryption unit A and the decryption unit C. As shown in FIG. This encryption unit A and the decryption unit C may be provided in the DVD drive which reads data from DVD1. The DVD drive device may also be connected without passing through the CPU bus.

The encryption unit A and the decryption unit C are connected to the CPU bus B. The output of data from the decoding unit C is performed via, for example, an I / O port other than the CPU bus B. As a result, in the present embodiment, input and output of data is performed without passing through the CPU bus B, but the CPU bus B is used for data transfer between the encryption unit A and the decoding unit C.

The encryption unit A includes demodulation / error correction circuits 2 and 7, encryption circuits 4 and 9, and control switch 8. When the first processing unit of the data string is input to the control switch 8, the control signal CS1 is input to apply data to the encryption circuit 9 and to output it to the CPU bus B as it is otherwise.

In FIG. 1, although two encryption circuits 4 and 9 are shown in the encryption unit A, it can actually implement | achieve one encryption circuit.

Here, the encryption unit A is formed as one independent IC chip.

On the other hand, the decoding unit C is provided with the decoding circuits 5, 10, 12, the master key decoding / decision circuit 6, the electronic perspective extraction circuit 11, and the control switch 13. As shown in FIG.

When the first processing unit of the data string is input to the control switch 13, a signal from the electronic perspective extraction circuit 11 is used as an input signal, and otherwise, the signal from the decoding circuit 12 is input signal. The control signal CS2 is inputted so as to be.

In the decoding unit C, an MPEG decoder 14 and a D / A converter 15 for converting decoded voice data from digital data to analog are provided.

In Fig. 1, four decoding circuits 5, 10, 12, and 14 are shown in the decoding unit C, but in practice, one decoding circuit can be realized. It is assumed that the decoding unit C is formed as one independent IC chip.

In the decoding unit C, a part of the master key described later is registered (created and input). It is assumed that the master key is recorded in a hidden area inside the chip so that the user cannot intentionally take it out of the chip of the decoding unit C so that the user cannot obtain it from the outside.

Here, setting of the number of types of EMki (Dk) generated by encrypting the disk key recorded on DVD 1 using the master key Mki and the number of types of Mkj 'of the partial master key included in the decryption unit C will be described later, for example. Several methods are contemplated as follows.

(Method 1) In DVD 1, a disk key EMki (Dk) encrypted by one master key having i of 1 to n is recorded, and n corresponding to all of j = 1 to n in the decryption unit C. Part master keys Mkj '.

(Method 2) On DVD 1, disc keys EMki (Dk) encrypted according to n master keys corresponding to all i = 1 to n are recorded, and in decryption unit C, j is any one portion of 1-n. The master key Mkj '.

(Method 3) The above-described (Method 2) is expanded, and on DVD 1, disc keys EMki (Dk) encrypted by n master keys corresponding to all i = 1 to n are recorded, and in decryption unit C j is provided with m (2 <m <n) partial master keys Mkj 'previously selected from 1 to n.

(Method 4) m masters having i of m (2 <m <n) type selected from 1 to n in DVD 1 in the column in which DVD 1 and decoding unit C are reversed in the above (Method 3). The disk key EMki (Dk) encrypted with the key is recorded, and the decryption unit C is provided with n partial master keys Mkj 'corresponding to all of j = 1 to n.

(Method 5) On DVD 1, disc keys EMki (Dk) encrypted with n master keys corresponding to all i = 1 to n are recorded, and n corresponding to all j = 1 to n in the decryption unit C as well. The partial master key Mkj 'is provided.

In addition, some of the key information WM and the calculation in the decryption / decision circuit 6 embedded as the electronic perspective are also changed by the above method.

In addition, the encryption key / decryption key used for encryption communication performed via the CPU bus B is referred to as common key encryption Bk. The method of sharing the encryption key between the encryption unit A and the decryption unit C is the same as the conventional method.

In addition, the whole control shall be in charge of the control part which is not shown in figure. The control unit can be realized by, for example, executing the program with the CPU of the calculator. Specific examples of the control by this control unit are instructions for reading data from DVD 1, designation of a data transfer target, instructions for outputting data from a decoding unit, and the like.

In addition, the trigger of the controller is considered to be performed by the user through, for example, a user interface or a process in a certain application program.

In the present embodiment, the digital source audio data string is D-Audio, and the audio data string (compressed data string) is AD = {AD1, AD2,. , ADi,… }, Voice data in which data of a part of the master key is embedded as electronic perspective is represented by WM (ADi).

In some cases, copy control electronic perspective information is embedded in the audio data string AD separately from the electronic perspective information embedded here. In addition, the encryption key (hereinafter referred to as shared encryption key) shared between the encryption unit and the decryption unit is Bk, the encryption key (disk key) for encrypting the voice data string, Dk, and the n encryption keys (master key) for encrypting the disk key. Key bundles {Mk1, Kk2,… , Mki,… , Mkn}, and key bundles of the partial master keys registered in the decoding unit, {Mk1 ', Mk2',... , Mkj ',… , Mkm '}.

The partial master key is a key corresponding to m keys of the n master keys, and the individual partial master keys are data prepared in advance so that the master key can be obtained by performing some kind of operation on the data extracted from WM (ADi).

EDk (Dk) represents a disk key generated by encrypting using the disk key itself, and {EMki (Dk) (i = 1,…, n)} represents a disk key generated by encrypting using each of n master keys. WM (ADi) represents voice data ADi generated by embedding some data of the master key using an electronic perspective technique, EDk (ADi) represents voice data generated by encrypting using the disk key Dk, EBk (EDk (Dk)) represents the disk key itself encrypted using the shared encryption key Bk, and EBk (EMki (Dk)) generates the encryption using the shared encryption key Bk. And a disk key encrypted using the master key bundle, and EBk (EDk (ADi)) represents voice data encrypted using the disk key generated by encrypting using the shared encryption key Bk.

On DVD 1, EDk (Dk) generated by encrypting the disk key with the disk key itself and {EMki (Dk), generated by encrypting the disk key with the master key bundle, are the key recording area (lead-in area) of the innermost circumference. Recorded in the audio data string AD = {AD1, AD2,... , ADi,… } It is assumed that the EMki (ADi) generated by encrypting using a WM (ADi) and a disk key embedded with a part of the master key information as electronic perspective is recorded in the data recording area (data area).

The operation of this embodiment will be described below with reference to the flowchart of FIG. 2.

In step S11, the encryption key Bk used for the communication between the encryption unit A and the decryption unit C is shared by both units using the existing encryption key sharing protocol 3.

In step S12, a disc key {EMki (Dk) encrypted using a disc key EDk (Dk) and a master key bundle encrypted using the disc key Dk itself, recorded on DVD 1 by a DVD drive device (not shown). }, And encrypting using the encryption shared key Bk in the encryption circuit 4 to generate EBk (EDk (Dk)) and {EBk (EMki (Dk))}, and through the CPU interface B to the decryption unit C. send. In addition, the data read out from the DVD 1 is demodulated / error corrected by the demodulation / error correction circuit 2 before being input to the encryption circuit 4.

In step S13, the decryption unit C decrypts the EBk (EDk (Dk)) and {EBk (EMki (Dk))} received by the decryption circuit 5 via the CPU interface B by using the encryption shared key Bk. (Dk) and {EMki (Dk)}.

In step S14, the encryption unit A reads the audio data WM (MDi) embedded in a part of the master key Mki, which is recorded on the DVD 1 by an electronic drive, not shown in the figure. In Ebk (WM (ADi)) is generated by encrypting using the encryption shared key Bk, and sent to the decryption unit C via the CPU interface B. Before the data read from the DVD 1 is input to the encryption circuit 9, the demodulation / error correction circuit 7 performs demodulation and error correction in the data.

In step S15, the decryption unit C decrypts the EBk (WM (ADi)) received by the decryption circuit 10 via the CPU interface B using the encryption shared key Bk, and takes out WM (ADi). Thereafter, the electronic perspective extraction circuit 11 extracts some information WM of the master key Mki embedded in the data ADi. After extracting the information WM, the WM (ADi) is sent to the MPEG decoder 14 as it is through the control switch 13.

In step S16, the disk key EDk (Dk) encrypted using the disk key Dk itself obtained in steps S13 and S15, respectively, the disk key {EMki (Dk)} encrypted using the master key bundle, and some information of the master key The disc key Dk is taken out from the decoding / decision circuit 6 by using the WM and the partial master key bundle previously registered in the decoding unit.

The operation in the decoding / decision circuit 6 will be described below with reference to FIG. 3.

In the decoding unit C, a partial master key Mkj 'is taken out from the memory J0 in which a partial master key bundle {Mkj'} is registered, and operation J1 for generating a predetermined master key using the partial information WM of the master key is performed. To obtain the master key candidate Mkj.

In the decryption circuit J2, the decryption process is performed using the master key candidate Mkj on the disk key EMki (Dk) encrypted using the master key bundle {Mki} to obtain the disk key candidate Dk '.

In the decryption circuit J3, the decryption process is performed using the disk key candidate Dk 'to EDk (Dk) in which the disk key is encrypted using the disk key itself to obtain the disk key candidate Dk ".

In J4, if the disk key candidate Dk "is compared with the disk key candidate Dk 'and is the same, the disk key candidate Dk' is sent as the correct disk key Dk by the decoding / decision circuit 6. In the case where the comparison results in both of them, The above operation is repeated until the correct disk key Dk is obtained.

In step S17, the audio data EDk (ADi) encrypted by the disk key Dk, which is recorded on the DVD 1 by the DVD drive device (not shown), is read out and sent to the decryption unit C via the CPU interface B. In addition, the demodulation / error correction circuit 7 performs demodulation and error correction in the data before the data read from the DVD 1 is sent to the CPU interface B.

In step S18, the EDk (ADi) received via the CPU bus B in the decoding circuit 12 in the decoding unit C can be decoded using the disk key Dk to obtain compressed speech data ADi that is plaintext.

In step S19, it is further determined whether or not the decoding process is to be continued. When continuing, the processes of step S17 and step S18 are repeatedly performed.

When the audio data ADi obtained as described above is compressed according to a data compression standard called, for example, MPEG audio, it is decoded (extended) by the MPEG decoder 14 and converted into an analog signal by the D / A converter 15. Then, it is sent to a speech amplification / output device such as a speaker amplifier (not shown) and reproduced.

In addition, you may execute the said step S12 and step S14 first.

Also, the voice data for embedding some information of the master key as electronic perspective information has a length sufficient to embed some key information of the master key, and if the length is insufficient, the electronic perspective information is delivered in a plurality of voice data units. It is purchased.

When the audio data ADi is delivered from the decoding circuit 12 to the MPEG decoder 14, the audio data ADi may be delivered not only in one audio data ADi unit but also in a predetermined number of units.

Therefore, according to the copy preventing device of the present embodiment, since the electronic perspective information must be used to decrypt the disk key, illegal acts of selling illegally copied media can be prevented and copyright infringement can be prevented.

According to the copy protection device of the present embodiment, as shown in Fig. 1, the circuit used for encryption and decryption can be designed separately as the core of the reproduction portion of a digital recording / reproducing apparatus such as DVD 1 or the like. Therefore, even if the encryption or the electronic perspective is broken, it is only necessary to exchange the decryption unit C (or the encryption unit A and the decryption unit C).

According to the copy preventing device of the present invention, even if data stored on the CPU bus B is stored, it cannot be reproduced or used.

In addition, since the master key information registered in advance on the decoding unit C side is not the complete key information, the complete key information cannot be obtained unless the key information included in the contents is used every time the DVD 1 is played. If the master key information registered in the decryption unit is completely revealed and attempts to use it illegally for the first time, DVD 1 cannot be played back normally.

Finally, a recording method of audio data and key information on DVD 1 in the present embodiment will be described with reference to FIG.

In this system, when the input voice is analog data A-Audio, first, the A / D converter 21 converts the digital data into D-Audio, and the converted digital data is used by the electronic perspective embedding circuit 22 as necessary. Therefore, information such as copy control (CCI) is purchased. In addition, the electronic see-through embedding circuit 22 may be omitted in some cases. The data is then compressed by the MPEG audio coding circuit 23.

The output audio data ADi of the MPEG audio coding circuit 23 is output to the electronic see-through embedding circuit 25 when the switching switch 24 embeds some information WM of the master key.

In the electronic see-through embedding circuit 25, when data is input, after the partial information of the master key is embedded in the voice data ADi as electronic see-through, the data WM (ADi) is output.

The audio data ADi is input into this electronic see-through embedding circuit 25 until all of the partial information WM of the master key prepared in advance is embedded. The audio data WM (ADi) into which the partial information WM of the master key is embedded is recorded on the DVD 27 as it is.

The voice data ADi, which does not need to embed some information WM of the master key, is outputted to the encryption circuit 26 by the switching switch 24. The encryption circuit 26 encrypts the input voice data ADi using the disk key Dk. The encrypted voice data Dk (ADi) is recorded on the DVD 27.

The DVD 27 also records {EMki (Dk)} in which the disk key Dk used for encrypting the voice data ADi is encrypted with the master key bundle, and Dk (Dk) encrypted with the disk key itself using the disk key.

In addition, in the example of FIG. 4, although some information of the master key is embedded in the audio data ADi compressed by the MPEG audio encoding circuit 23 as electronic perspective, the electronic perspective embedding circuit 25 is embedded in digital audio data before compression. It is also possible. In this case, the electronic see-through embedding circuit 25 can be omitted.

<2nd embodiment>

Next, the copy prevention apparatus which concerns on 2nd Embodiment of this invention is demonstrated.

It is a figure which shows the copy prevention apparatus which concerns on 2nd Embodiment of this invention. In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, and the description is abbreviate | omitted.

The copy protection device according to the present embodiment is connected to a so-called CPU bus of a CPU used for reproduction provided in a calculator such as a personal computer, and has a configuration in which encrypted data flows on the CPU bus. In addition, in FIG. 5, only the part regarding CPU used for reproduction is shown.

The encryption unit A and the decryption unit C are connected to the CPU bus B. Output of data from the decoding unit is performed via, for example, an I / O port or the like other than the CPU bus. As a result, in the present embodiment, similarly to the first embodiment, data input and output is performed without passing through the CPU bus B, but the CPU bus B is used for data transfer between the encryption unit A and the decoding unit C.

The encryption unit A includes the demodulation / error correction circuits 2 and 7 and the encryption circuit 4. The encryption unit A shall be formed as one independent IC chip.

On the other hand, the decoding unit C is provided with the decoding circuits 5 and 34, the master key decoding / decision circuit 31, the electronic perspective extraction circuit 35, the control switch 33, and the key generation circuit 32. As shown in FIG.

When the first processing unit of the data string is input to the control switch 33, the control signal CS is separately used so that the disk key Dk is used as the input signal, and otherwise, the signal from the key generation circuit 32 is used as the input signal. Is entered.

In the present embodiment, it is assumed that the decoding unit C includes the MPEG decoder 14 and the D / A converter 15 for converting the decoded audio data from digital data to analog data.

In FIG. 5, two decoding circuits 5 and 34 are shown in the decoding unit C, but in practice, one decoding circuit can be realized. It is assumed that the decoding unit C is formed as one independent IC chip.

In the decoding unit, a part of the master key described later is registered (created and input). It is assumed that the master key is recorded in a hidden area inside the chip so that the user cannot intentionally take it out of the chip of the decoding unit C so that the user cannot obtain it from the outside.

Here, the first embodiment is carried out for setting the number of types of EMki (Dk) generated by encrypting the disk key recorded on DVD 1 using the master key Mki and the number of types of Mki of the partial master key included in the decryption unit C. The same considerations apply to forms.

In addition, the encryption key / decryption key (all of which are Bk since the common key encryption is used) used for encryption communication performed via the CPU bus B is assumed to be shared between the encryption unit A and the decryption unit C.

In addition, the whole control shall be in charge of the control part which is not shown in figure. The control unit can be realized by, for example, executing the program with the CPU of the calculator. Specific examples of the control by the control unit are instructions for reading data from a DVD, designation of a data transfer target, instructions for outputting data from a decoding unit, and the like.

In addition, the trigger of the controller is considered to be performed by the user through a user interface, for example, from a process in an application program, or the like.

In the present embodiment, the digital source audio data string is D-Audio, and the audio data string (compressed data string) is AD = {AD1, AD2,. , ADi,… }, Voice data in which data of a part of the master key is embedded as electronic perspective is represented by WM (ADi).

In some cases, copy control electronic perspective information is embedded in the audio data string AD separately from the electronic perspective information embedded here. In addition, Bk the encryption key (hereinafter referred to as shared encryption key) shared between the encryption unit A and the decryption unit C, Dk the encryption key (disk key) for encrypting the voice data string, and n encryption keys (master key for encrypting the disk key). ) Key bundles of {Mk1, Kk2,... , Mki,… , Mkn}, key bundles of the master keys registered in the decoding unit are set to {Mk1 ', Mk2',... , Mkj ',… , Mkm '}.

In FIG. 5, EDk (Dk) represents a disk key generated by encrypting using the disk key itself, and {EMki (Dk) (i = 0, 1,..., N-1)} represents n master keys. Each represents a disk key generated by encryption using WM (ADi) represents voice data generated by embedding information necessary for generating an encryption key of subsequent speech data using an electronic perspective technology, and E _{Dk + WM} (ADi) indicates voice data generated by encrypting using the information WM and disk key Dk previously sent to the decryption unit by electronic fluoroscopy, and EBk (EDk (Dk)) is generated by encrypting using the shared encryption key Bk. The encrypted disk key is used to represent the encrypted disk key itself, and EBk (EMki (Dk)) represents the disk key encrypted using the master key bundle generated by encrypting using the shared encryption key Bk, respectively.

On DVD 1, EDk (Dk) generated by encrypting the disk key with the disk key itself and {EMki (Dk), generated by encrypting the disk key with the master key bundle, are the key recording area (lead-in area) of the innermost circumference. Recorded in the audio data string AD = {AD1, AD2,... , ADi,… } EDk (WM (ADi)) and a data key (a key generated from information WM sent to a decryption unit as a disk key and electronic perspective) in which part of the information for generating a decryption key of subsequent speech data is embedded as electronic perspective. It is assumed that E _{Dk + WM} (ADi) generated by encrypting using the data is recorded in the data recording area (data area).

Hereinafter, the operation of the present embodiment will be described with reference to the flowchart of FIG. 6.

In step S21, the encryption key Bk used for the communication between the encryption unit A and the decryption unit C is shared to both units using the existing encryption key sharing protocol.

In step S22, a disc key {EMki (Dk) encrypted using a disc key EDk (Dk) and a master key bundle encrypted using the disc key Dk itself, recorded on DVD 1 by a DVD drive device (not shown). }, And encrypting using the encryption shared key Bk in the encryption circuit 4 to generate EBk (EDk (Dk)) and {EBk (EMki (Dk))}, and through the CPU interface B to the decryption unit C. send.

In addition, the data read out from the DVD 1 is demodulated / error corrected by the demodulation / error correction circuit 2 before being input to the encryption circuit A.

In step S23, the decryption unit C decrypts the EBk (EDk (Dk)) and {EBk (EMki (Dk))} received by the decryption circuit 5 via the CPU interface B using the encryption shared key Bk to obtain the EDk. (Dk) and {EMki (Dk)}.

In step S24, the disk key EDk (Dk) encrypted using the disk key Dk itself, the master key bundle Mkj previously registered in the decryption unit and the disk key {EMki (Dk)} encrypted using the master key bundle Mki are selected. The disk key Dk is taken out from the decoding / decision circuit 31 for use.

Next, the operation in the decoding / decision circuit 31 will be described.

A master key bundle {Mkj} is retrieved from a memory in which a master key bundle {Mkj} is registered in the decryption unit, and the decryption process is performed using the master key candidate Mkj for the disk key EMki (Dk) encrypted using the master key bundle {Mki}. Is performed to obtain the disc key candidate Dk '.

The decryption process is performed using the disk key candidate Dk 'to EDk (Dk) in which the disk key is encrypted using the disk key itself to obtain the disk key candidate Dk ".

If the disc key candidate Dk "and the disc key candidate Dk 'are the same, the disc key candidate Dk' is sent as the correct disc key Dk by the decoding / decision circuit 31. If the comparison results in both of them, the right disc is correct. The above operation is repeated until a key is obtained.

In step S25, in the encryption unit A, the information necessary for generating the decryption key of the audio data after being encrypted with the disk key Dk recorded on the DVD 1 by a DVD drive device (not shown) is embedded as electronic perspective. EDk (WM (ADi)) is read and sent to the decoding unit C via the CPU interface B. In addition, before the data read from the DVD 1 is input to the encryption circuit A, the demodulation / error correction circuit 7 performs demodulation and error correction in the data.

In step S26, the decoding unit C decodes EDk (WM (ADi)) received by the decoding circuit 34 via the CPU interface B using the disk key Dk, and takes out WM (ADi), followed by electronic perspective. The extraction circuit 35 extracts the information WM necessary for generating the decoding key of the voice data after being embedded in the data ADi. After extracting the information WM, the WM (ADi) is sent to the MPEG decoder 14 as it is. In addition, the key generation circuit 32 generates the decoding key Dk + WM for voice data using the disk key Dk and the key generation information WM.

At this time, the decryption key (which is the same key in the case of the common key cryptography) corresponding to the encryption key used when recording the audio data on the DVD disk 1 is generated in advance, but the disk used for encrypting / decrypting the first audio data. Various relationships described below can be set between the key, the key generation information WM, and the key used for encrypting / decrypting subsequent voice data. In the present description, subsequent voice data (encryption / decoding) keys are represented by Dk + WM.

(Relationship 1) An exclusive logical sum obtained by adjusting the disk key Dk and the key generation information WM to the same data length as the disk key by some means is used as the encryption key for the subsequent voice data.

(Relationship 2) The encryption of the disk key Dk with the key generation information WM as the encryption key is the encryption key for the subsequent voice data.

In step S27, the audio data E _{Dk + WM} (ADi) encrypted by the audio data key Dk + WM recorded on the DVD 1 by a DVD drive device (not shown) is read out and decoded into the decoding unit C through the CPU interface B. send. In addition, the demodulation / error correction circuit 7 performs demodulation and error correction in the data before the data read from the DVD 1 is sent to the CPU interface B.

In step S28, the decoding unit C decodes E _{Dk + WM} (ADi) received via the CPU bus B in the decoding circuit 34 by using the voice data key Dk + WM to obtain compressed speech data ADi that is plain text. Can be.

In step S29, it is further determined whether or not the decoding process is to be continued. When continuing, the processes of step S27 and step S28 are repeatedly performed.

When the audio data ADi obtained as described above is compressed according to a data compression standard called, for example, MPEG audio, it is decoded (extended) by the MPEG decoder 14 and converted into an analog signal by the D / A converter 15. Then, it is sent to a speech amplification / output device such as a speaker amplifier (not shown) and reproduced.

The voice data embedded in the key generation information of the voice data key as electronic perspective information has a length sufficient to embed the key generation information of the voice data key. If the length is insufficient, the electronic perspective information is a plurality of voice data units. Purchased by delivery to.

When the audio data ADi is delivered from the decoding circuit 34 to the MPEG decoder 14, the audio data ADi may be delivered not only in one audio data ADi unit but also in a predetermined number of units.

Therefore, according to the copy preventing apparatus of the present embodiment, the perspective data is embedded in the multimedia data and the multimedia data is decoded using the embedded perspective information, thereby preventing illegal acts from selling illegal copies of media. Can prevent copyright infringement.

In the present embodiment, as in the first embodiment, the circuit used for encryption and decryption can be designed separately from the place where the core of the reproduction portion of a digital recording / reproducing apparatus such as a DVD becomes as shown in FIG. Even if the encryption or electronic perspective is broken, the decryption unit C (or the encryption unit A and the decryption unit C) need only be exchanged.

Finally, a recording method of audio data and key information on DVD 1 in the present embodiment will be described with reference to FIG.

In this system, when the input voice is analog data A-Audio, it is assumed that the input voice is input after converting the digital voice data D-Audio to the A / D converter 21 first.

In the electronic see-through embedding circuit 42, data obtained by embedding the information WM necessary as an electronic see-through information necessary for generating an encryption key for use in encrypting and recording audio data on the DVD 47 to digital data D-Audio which is first inputted is generated. The data is compressed by the MPEG audio coder 43 to output audio data WM (ADi).

At this time, the key generation circuit 46 generates the encryption key Dk + WM from the information WM and the disk key Dk necessary for generating the encryption key for recording on the DVD 47.

The key generation circuit 46 is limited to the configuration in which the encryption key Dk + WM cannot be created on either the disk key Dk or the key information WM, and various things are considered.

The output audio data ADi of this MPEG audio encoding circuit 43 is encrypted using the disk key Dk in the encryption circuit 44, and the encrypted audio data EDk (WM (ADi)) is recorded on the DVD 47.

In the electronic see-through embedding circuit 42, when all the information WM necessary for generating the encryption key Dk + WM for recording to the DVD 47 is embedded, the switching switch 41 is switched by the control signal CS, and the digital thereafter. The data D-Audio is input directly to the MPEG audio coding circuit 43, and the compressed audio data ADi is output.

The encryption circuit 44 outputs E _{Dk + WM} (ADi) by encrypting the input voice data ADi using the encryption key Dk + WM. The output encrypted data E _{Dk + WM} (ADi) is recorded on the DVD 47.

The DVD 47 records {EMki (Dk)} in which the disk key Dk used for encrypting the voice data ADi is encrypted with the master key bundle, and Dk (Dk) encrypted by the disk key itself using the disk key.

In the present embodiment, for the sake of simplicity, the voice data ADi compressed by the MPEG audio coder is directly encrypted with the encryption key Dk + WM. For example, the data can be more firmly secured by improving to the following form.

(Improvement method) After the key generation information WM is changed into time-series information MWi and all the audio data is embedded as electronic perspective information, the encryption key at the time of recording on the DVD 47 is also changed every time based on the purchase information WMi, and the encryption key. Is Dk + WMi-1, and the encrypted voice data EDk + WMi-1 (WM (ADi)) is recorded on the DVD 47.

<Third embodiment>

8 is a block diagram showing a copy preventing apparatus according to a third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, and the description is abbreviate | omitted. 8, only the parts related to the CPU used for reproduction are shown.

The copy protection device according to the present embodiment includes a DVD drive device (not shown) that reads data from DVD 1, an encryption unit A and a decryption unit connected to the DVD drive device without going through a CPU bus or embedded in the DVD drive device. C is provided.

The encryption unit A and the decryption unit C are connected to the CPU bus B. The output of data from the decoding unit C is performed via the I / O port or the like other than the CPU bus B, for example. As a result, in the present embodiment, input and output of data is performed without passing through the CPU bus B, but the CPU bus B is used for data transfer between the encryption unit A and the decoding unit C.

The encryption unit A includes the demodulation / error correction circuits 2 and 7 and the encryption circuit 4. The encryption unit A shall be formed as one independent IC chip.

On the other hand, the decoding unit C is provided with the decoding circuits 5 and 50, the master key decoding / decision circuit 31, the electronic perspective extraction circuit 51, the superposition information removal circuit 53, and the delay circuit 52. As shown in FIG. In the present embodiment, it is assumed that the decoding unit C includes the MPEG decoder 14 and the A / D converter 15 for converting the decoded audio data from digital data to analog data.

Although two decoding circuits 5 and 50 are shown in the decoding unit C, it is actually possible to realize one decoding circuit. It is assumed that the decoding unit C is formed as one independent IC chip.

In the decoding unit, a master key is registered (created and input) in the same manner as in the second embodiment. It is assumed that the master key is recorded in a hidden area inside the chip so that the user cannot intentionally take it out of the chip of the decoding unit so that the user cannot obtain it from the outside.

Here, the first embodiment is carried out for setting the number of types of EMki (Dk) generated by encrypting the disk key recorded on DVD 1 using the master key Mki and the number of types of Mki of the partial master key included in the decryption unit C. The same considerations apply to forms.

In addition, the encryption key / decryption key (all of which are Bk since the common key encryption is used) used for encryption communication performed via the CPU bus B is assumed to be shared between the encryption unit A and the decryption unit C.

In addition, the whole control shall be in charge of the control part which is not shown in figure. The control unit can be realized by, for example, executing the program with the CPU of the calculator. Specific examples of the control by the control unit are instructions for reading data from a DVD, designation of a data transfer target, instructions for outputting data from a decoding unit, and the like.

In addition, the trigger of the controller is considered to be performed by the user through a user interface, for example, from a process in an application program, or the like.

In the present embodiment, the digital source audio data string is D-Audio, and the audio data string (compressed data string) is AD = {AD1, AD2,. , ADi,… }, A piece of information is represented by WM (ADi) of audio data embedded as electronic perspective.

In some cases, copy control electronic perspective information is embedded in the audio data string AD separately from the electronic perspective information embedded here. In addition, Bk the encryption key (hereinafter referred to as shared encryption key) shared between the encryption unit A and the decryption unit C, Dk the encryption key (disk key) for encrypting the voice data string, and n encryption keys (master key for encrypting the disk key). ) Key bundles of {Mk1, Kk2,... , Mki,… , Mkn}, the key bundle of the master key registered in the decoding unit C is {Mk1 ', Mk2',... , Mkj ',… , Mkm '}.

In FIG. 8, EDk (Dk) represents a disk key generated by encrypting using the disk key itself, and {EMki (Dk) (i = 0, 1,..., N-1)} represents n master keys. Each represents a disk key generated by using encryption, and WM (ADi) represents voice data generated by embedding information necessary for generating an encryption key of subsequent voice data into voice data ADi using electronic perspective technology.

EDk (WM (ADi)) represents WM (ADi) generated by encrypting using the disk key Dk, and ADi x WM represents voice data ADi superimposed information WM previously sent to the decryption unit by electronic fluoroscopy. , EDk (ADi × WM) represents (ADi × WM) generated by encrypting using disk key Dk, and EBk (EDk (Dk)) represents EDk (Dk) generated by encrypting using shared encryption key Bk. EBk (EMki (Dk)) represents EMki (Dk) generated by encrypting using the shared encryption key Bk, respectively. However, "x" represents a superposition operation, and represents the operation aimed at disturbing data. For example, '×' indicates to perform proper scramble, and 'ADi × WM' indicates to scramble ADi using a suitable WM.

On DVD 1, EDk (Dk) generated by encrypting the disk key with the disk key itself and {EMki (Dk), generated by encrypting the disk key with the master key bundle, are the key recording area (lead-in area) of the innermost circumference. Recorded in the audio data string AD = {AD1, AD2,... , ADi,… } Discard the EDK (WM (ADi)) generated by encrypting the voice data embedded as WM by electronic perspective information superimposed on the subsequent voice data using a disk key and the superimposed voice data of electronic perspective information WM. It is assumed that EDk (ADi x WM) generated by encrypting using a key is recorded in the data recording area (data area).

Hereinafter, the operation of the present embodiment will be described with reference to the flowchart of FIG. 9.

Step S31 to step S35 are the same as step S21 to step S25 of the flowchart shown in FIG. 6 demonstrated in 2nd Embodiment.

In step S36, the decoding unit C decodes EDk (WM (ADi)) received by the decoding circuit 50 via the CPU interface B using the disk key Dk, and takes out WM (ADi), followed by electronic perspective. The extraction circuit 51 extracts the information WM superimposed on the audio data after being embedded in the data ADi.

After extracting the information WM, the WM (ADi) is sent to the MPEG decoder 14 as it is. At this time, in the method of superimposing the information WM superimposed on the DVD disc 1 and the information WM superimposed on the audio data, various relationships can be set as follows, for example. In this description, the operation used for this superimposition is represented by the symbol 'x'.

(Relationship 1) An exclusive logical OR of superimposition information WM adjusted to the same data length as voice data ADi by some means is performed.

(Relationship 2) The voice data ADi is encrypted using the superimposition information WM as an encryption key.

In step S37, the EDk (ADi x WM) generated by encrypting the superimposed audio data of the perspective information WM using the disk key Dk recorded on DVD 1 by a DVD drive device (not shown) is read out, and the CPU interface. Send to decoding unit C through B.

In addition, the demodulation / error correction circuit 7 performs demodulation and error correction in the data before the data read from the DVD 1 is sent to the CPU interface B.

In step S38, the decoding unit C decodes EDk (ADi x WM) received via the CPU bus B in the decoding circuit 50 using the voice data key Dk, and the superimposition information WM in the superposition information removal circuit 53. To get the compressed speech data ADi, which is plain text.

In step S39, a determination is made as to whether to continue the decoding process, and in the case of continuing, the processes of step S37 and step S38 are repeatedly performed.

When the audio data ADi obtained as described above is compressed according to a data compression standard called, for example, MPEG audio, it is decoded (extended) by the MPEG decoder 14 and converted into an analog signal by the D / A converter 15. Then, it is sent to a speech amplification / output device such as a speaker amplifier (not shown) and reproduced.

The superimposed information embedded in the audio data can also be delivered in a plurality of audio data units and embedded as necessary.

When the audio data ADi is delivered from the decoding circuit C to the MPEG decoder 14, the audio data ADi may be delivered not only in one audio data ADi unit but also in a predetermined number of units.

Therefore, according to the copy preventing device of the present embodiment, since the electronic perspective information is embedded in the multimedia data and the embedded multimedia information is decoded, the illegal copy can be prevented.

In the present embodiment, as in the above-described embodiment, the circuit used for encryption and decryption can be designed separately from the place where the core of the reproduction portion of a digital recording / reproducing apparatus such as a DVD becomes as shown in FIG. Even if the encryption or the electronic perspective is broken, the decryption unit C (or the encryption unit A and the decryption unit C) need only be replaced.

In any of the above-described embodiments, the CPU bus communication unit using the shared encryption key can be omitted, and the preferred embodiment can be corrected to a single DVD player.

Finally, a recording method of audio data and key information on the DVD will be described with reference to FIG.

In this system, when the input voice is analog data A-Audio, it is assumed that the input voice is input after converting the digital voice data D-Audio with an A / D converter first.

The electronic perspective embedding circuit 64 embeds the information WM superimposed on the subsequent audio data into the digital data D-Audio inputted as the first, as electronic perspective information, and is further compressed after being compressed by the MPEG audio encoder 63. Voice information WM (ADi) is output.

In the encryption circuit 62, voice data EDk (WM (ADi)) obtained by encrypting the voice information WM (ADi) embedded in the electronic perspective using the disk key Dk is generated. The encrypted voice data EDk (WM (ADi)) is recorded on the DVD 61.

In the electronic see-through embedding circuit 64, when all the information WM superimposed on the voice data is embedded, the switching switch 65 is switched by the control signal CS, and the digital data D-Audio thereafter is MPEG audio encoding. After being compressed to the circuit 66, the electronic perspective information superimposition circuit 67 superimposes (indicated by the 'x' symbol) in the electronic perspective information superimposition circuit 67, and superimposed speech data ADi x WM is output.

The superimposed voice data ADi x WM is encrypted using the disk key Dk in the encryption circuit 62 in the same manner as the voice information WM (ADi) embedded in electronic perspective and recorded on the DVD 61 as encrypted voice data EDk (ADi x WM). .

In addition, the DVD 61 includes {EMki (Dk)} which encrypts the disk key Dk used for encrypting the voice data ADi and the superimposed voice data ADi × WM, and the disk key itself using the disk key itself. Dk) is recorded.

In the present embodiment, for the sake of simplicity, the information WM superimposed on the speech data compressed by the MPEG audio coder is the same throughout the entire data, but the data can be more firmly protected by, for example, improving the following form.

(Improvement method 1) With the key generation information WM as information MWi changing over time series, information necessary for reproduction of all voice data is embedded as electronic perspective information, and information WMi embedded therein is used as information to disturb the next voice data. do. As a result, the above-mentioned superimposed audio data ADi x WM is recorded on DVD 1 in the state of EDk (WMi (ADi) x WMi-1).

(Improvement Method 2) The key generation information WM is information MWi that changes over time series, and information necessary for reproduction of all voice data is embedded as electronic perspective information, and the information WMi embedded there is disturbed in the voice data of the data itself. It is information. Therefore, after disturbing ADi with WMi, WMI is also embedded in the data. As a result, the above-mentioned superimposed audio data ADi x WM is recorded on DVD 1 in the state of EDk (WMi (ADi x WMi)).

(Improvement method 3) According to the general description of the above-described improvement methods 1 and 2, information necessary for reproduction of audio data at a certain point in time is embedded as electronic perspective information, and information WMi embedded there is disturbed at any point in time. We do with information to say. Therefore, after disturbing ADi to WMj, the WMj is also embedded as audio visual ADj as voice data ADj at another point in time. As a result, the above-described superimposed audio data ADi x WMj is recorded on DVD 1 in the state of EDk (WMi (ADi x WMj)).

As mentioned above, although 1st Embodiment, 2nd Embodiment, and 3rd Embodiment were each demonstrated, this embodiment is not limited to these, etc. It is not limited to these, and it implements in various ways. Can be.

In each embodiment, the information recording medium has been described as a DVD, but the present invention can also be applied to other recording media such as a CD-ROM.

In each of the embodiments, the audio data string has been described as an example of the information to be decoded, but the present invention can also be applied to a reproducing apparatus for other forms of information such as image data.

In each embodiment, the case where the information to be decoded is compressed according to the standard of MPEG audio has been described as an example. However, the present invention is not limited to this, and data compression or encoding may be performed according to other standards. In this case, another corresponding decoding circuit is provided instead of the MPEG audio decoding circuit. Moreover, it may be encoding or the like. In this case, the MPEG audio decoding circuit is removed.

In addition, a plurality of types of decoding circuits and the like may be provided so that any of the data (or data requiring decoding) that has been compressed or decompressed in various manners may be provided, and may be configured by switching them appropriately (or not using them). It may be. In this case, a method of reading an identifier indicating a decoding circuit or the like to be used from a recording medium such as a DVD, for example, and selecting an appropriate decoding circuit or the like in accordance with the identifier is considered.

In addition, the structure of the decoding / decision circuit shown in 1st Embodiment is an example, and various structures are considered otherwise.

According to the present invention, since a part of the information necessary for accurately decoding or reproducing the recorded data is embedded in the data recorded on a recording medium such as a DVD, information necessary for reproduction by electronic perspective technology or the like is transmitted. Only the right one that can correctly decode (restore) each of the data can completely decode (restore) the data.

As a result, it is possible to protect copyrights more firmly by preventing illegal acts of selling illegally copied media.

Claims (13)

An encryption unit, A copy protection device comprising a decryption unit connected to the encryption unit via a CPU bus, The encryption unit First encryption means for encrypting an encrypted disk key encrypted using the disk key itself using a shared encryption key shared between the encryption unit and the decryption unit; First transmitting means for transmitting the disk key encrypted by the first encrypting means via the CPU bus; Second encryption means for encrypting a disk key encrypted using a master key using the shared encryption key; Second transmission means for transmitting the disk key encrypted by the second encryption means via the CPU bus; Third encryption means for encrypting the multimedia data embedded with the clairvoyant information, which is part of the master key, using the shared encryption key; Third transmission means for transmitting the multimedia data encrypted by the third encryption means via the CPU bus; Fourth transmitting means for transmitting the encrypted multimedia data using the disc key, The decoding unit First decrypting means for decrypting the disk key transmitted from said first transmitting means using said shared encryption key, Second decrypting means for decrypting the disk key transmitted from said second transmitting means using said shared encryption key, Third decrypting means for decrypting the multimedia data transmitted from the third transmitting means using the shared encryption key; Extraction means for extracting the perspective information from the multimedia data decoded by the third decoding means; Based on the disc key decoded by the first decoding means, the disc key decoded by the second decoding means, perspective information extracted by the extracting means, and a partial master key corresponding to a part of the master key. Disk key obtaining means for obtaining a disk key by And a fourth decoding means for decoding the multimedia data transmitted by the fourth transmitting means by using the disk key acquired by the disk key obtaining means. The method of claim 1, The disk key obtaining means First acquiring means for acquiring a master key candidate based on the partial master key and the perspective information; Second acquiring means for acquiring the first disc key candidate by decoding the disc key decoded by the second decoding means using the master key candidate acquired by the first acquiring means; Third acquiring means for acquiring the second disc key candidate by decoding the disc key decoded by the first decoding means by using the first disc key candidate acquired by the second acquiring means; Determination means for determining whether or not the first disk key candidate acquired by the second obtaining means and the second disk key candidate acquired by the third obtaining means are identical; And determining means for determining the first disk key candidate as a disk key when the determining means determines that the first disk key candidate matches the second disk key candidate. The method of claim 1, And the multimedia data is voice data compressed according to the MPEG standard. The method of claim 1, And a fifth decoding means for decoding the multimedia data decoded by the fourth decoding means according to the MPEG standard. An encryption unit, A copy protection device comprising a decryption unit connected to the encryption unit via a CPU bus, The encryption unit First encryption means for encrypting an encrypted disk key encrypted using the disk key itself using a shared encryption key shared between the encryption unit and the decryption unit; First transmitting means for transmitting the disk key encrypted by the first encrypting means via the CPU bus; Second encryption means for encrypting a disk key encrypted using a master key using the shared encryption key; Second transmission means for transmitting the disk key encrypted by the second encryption means via the CPU bus; Third transmitting means for transmitting the multimedia data, encrypted with the disk key and embedded with the electronic perspective information which is part of the master key, through the CPU bus; Fourth transmitting means for transmitting encrypted multimedia data using the disc key and the perspective information, The decoding unit First decrypting means for decrypting the disk key transmitted from said first transmitting means using said shared encryption key, Second decrypting means for decrypting the disk key transmitted from said second transmitting means using said shared encryption key, Disk key acquisition means for acquiring a disk key based on the disk key decoded by the first decoding means, the disk key decoded by the second decoding means, and a partial master key corresponding to a part of the master key; , Third decoding means for decoding the multimedia data transmitted by the third transmission means by using the disk key acquired by the disk key obtaining means; Extraction means for extracting electronic perspective information from the multimedia data decoded by the third decoding means; And fourth decoding means for decoding the multimedia data transmitted by the fourth transmitting means based on the electronic perspective information extracted by the extracting means and the disk key obtained by the disk key obtaining means. Copy protection device. The method of claim 5, And the multimedia data is voice data compressed according to the MPEG standard. The method of claim 5, And a fifth decoding means for decoding the multimedia data decoded by the fourth decoding means according to the MPEG standard. An encryption unit, A copy protection device comprising a decryption unit connected to the encryption unit via a CPU bus, The encryption unit First encryption means for encrypting an encrypted disk key encrypted using the disk key itself using a shared encryption key shared between the encryption unit and the decryption unit; First transmitting means for transmitting the disk key encrypted by the first encrypting means via the CPU bus; Second encryption means for encrypting a disk key encrypted using a master key using the shared encryption key; Second transmission means for transmitting the disk key encrypted by the second encryption means via the CPU bus; Third transmitting means for transmitting the multimedia data, encrypted with the disk key and embedded with the electronic perspective information which is part of the master key, through the CPU bus; A fourth transmission means for transmitting the multimedia data encrypted with the disk key and superimposed with the electronic perspective information through the CPU bus, The decoding unit First decrypting means for decrypting the disk key transmitted from said first transmitting means using said shared encryption key, Second decrypting means for decrypting the disk key transmitted from said second transmitting means using said shared encryption key, Disk key acquisition means for acquiring a disk key based on the disk key decoded by the first decoding means, the disk key decoded by the second decoding means, and a partial master key corresponding to a part of the master key; , Third decoding means for decoding the multimedia data transmitted by the third transmission means by using the disk key acquired by the disk key obtaining means; Extraction means for extracting electronic perspective information from the multimedia data decoded by the third decoding means; Fourth decoding means for decoding the multimedia data transmitted by the fourth transmitting means by using the disk key acquired by the disk key obtaining means; And a fifth decoding means for decoding the multimedia data decoded by the fourth decoding means by using the electronic perspective information extracted by the extracting means. The method of claim 8, And the multimedia data is voice data compressed according to the MPEG standard. The method of claim 8, And a fifth decoding means for decoding the multimedia data decoded by the fourth decoding means according to the MPEG standard. Computer-readable media, Encrypted disk key data encrypted using the disk key itself, Disk key data encrypted using the master key, Multimedia data embedded with electronic perspective information which is a part of the master key; A computer program product having multimedia data encrypted using the disc key, And wherein each of the data is recorded in an executable form on the medium, can be mounted on a computer, and executed by a processor. Computer-readable media, Encrypted disk key data encrypted using the disk key itself, Disk key data encrypted using the master key, Multimedia data encrypted with the disk key and embedded with electronic perspective information that is part of the master key; A computer program product having multimedia data encrypted using the disc key and the perspective information, And wherein each of the data is recorded in an executable form on the medium, can be mounted on a computer, and executed by a processor. Computer-readable media, Encrypted disk key data encrypted using the disk key itself, Disk key data encrypted using the master key, Multimedia data encrypted with the disk key and embedded with electronic perspective information that is part of the master key; A computer program product having multimedia data encrypted with the disk key and having the electronic perspective information superimposed thereon, And wherein each of the data is recorded in an executable form on the medium, can be mounted on a computer, and executed by a processor.