JP2002124942A - Variable quality data supply system, variable quality data reproducer, data protecting device, method for supplying variable quality data, method for reproducing variable quality data, method for protecting data and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable quality data supply system or the like for supplying contents of less complexity while by the quality of the contents. SOLUTION: A data output unit 1 generates a signal for representing the spectrum of a PCM signal to be encrypted, encodes the signal for representing the spectrum component in a band obtained by dividing the spectrum by using an encryption key prepared according to the band, and serially outputs the data obtained by the encoding. A data reproducer 2 distributes the data output from the unit 1 to the respective bands belonging to the spectrum components represented by the data, and decodes the data by using the decoding key prepared according to the band. A PCM signal having the spectrum represented by the signal obtained by the decoding is generated. The spectrum component of the band not prepared for the decoding key is handled as not existing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data supply system and a data supply method for supplying contents, and more particularly, to a data supply system and a data supply method for supplying contents having variable quality.

[0002]

2. Description of the Related Art In order to sell music and other contents,
A method of distributing data representing content free of charge has been used. The data to be distributed free of charge may represent content of lower quality than the content represented by the paid data sold as a product (for example, if the content is audio, the voice has a limited frequency band compared to the voice represented by the paid data). Is created. When the user who has reproduced the content from the free data desires to purchase the paid data, the user pays the price and purchases the paid data again.

[0003] Also, in order to distribute paid data that has been encrypted in advance together with free data, and to pay for the data and decrypt the charged data when a user who has reproduced the content from the free data desires to purchase the paid data. There is also a method of purchasing a decryption key for the.

[0004]

However, it is troublesome to purchase paid data again. Further, in the method of decrypting the encrypted paid data, the user can only select whether to obtain the decrypted paid data or only the free data. Therefore, it is difficult for a content seller to make an appropriate charge according to the quality of the content, and also for a user to obtain a content of a desired quality at an appropriate price.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and provides a variable quality data supply system and a variable quality data supply method for supplying content with low complexity while making the quality of the content variable. It is an object of the present invention to provide a variable quality data reproduction device, a data protection device, a variable quality data reproduction method, and a data protection method for realizing such a variable quality data supply system and a variable quality data supply method.

[0006]

In order to achieve the above object,
A variable quality data supply system according to a first aspect of the present invention acquires data representing a content, and converts the data into a plurality of parts that represent a plurality of constituent parts of the data and at least one of which can be independently reproduced. Partial data generating means for converting the data into data; encrypting means for encrypting each of the partial data by using an encryption key associated with the partial data; and outputting the encrypted partial data. Is obtained, and when a decryption key associated with at least one of the partial data is supplied, the decryption key is acquired, and the acquired partial data is associated with the acquired decryption key. Decrypting means for decrypting the content using the decryption key, and displaying the decrypted partial data of the content based on the decrypted partial data. Comprising a data restoring means for generating data representative of the portion, and wherein the.

[0007] According to such a variable quality data supply system, since data representing a content is divided into partial data and encrypted for each partial data, an arbitrary number of partial data including partial data that can be reproduced independently. By decoding the data, a content having a quality corresponding to the number of the decoded partial data is obtained. In addition, since it is not necessary to supply unencrypted data again, the complexity of supplying the content is small.

[0008] The partial data generating means may convert the data representing the content into each of the partial data representing a spectrum of the content for each band. In this case, the data restoration means generates data representing the content having a spectrum represented by the decoded partial data and substantially lacking a spectrum represented by the undecoded partial data. Thus, it is sufficient to obtain a content having a quality corresponding to the number of decrypted partial data.

[0009] The variable quality data supply system obtains, from outside, charging amount data indicating a charging amount for the user of the content, and based on the charging amount indicated by the obtained charging amount data, partial data to be decoded. And a decryption key supply unit that supplies the decryption key associated with the determined partial data to the decryption unit. In this case, the decryption unit includes the decryption unit. What is necessary is just to acquire the decryption key supplied by the key supply means. Since the variable quality data supply system has such a configuration, a content having a quality corresponding to the charge amount is supplied to the user.

Further, a variable quality data reproducing apparatus according to a second aspect of the present invention represents a plurality of components of data representing a content, at least one of which can be reproduced independently, and each of which is encrypted. And obtaining a decryption key when a decryption key associated with at least one of the partial data is supplied, and obtaining the decryption key among the acquired partial data. A decryption means for decrypting the content associated with the decryption key using the decryption key, and representing a portion represented by the decrypted partial data in the content based on the decrypted partial data. Data recovery means for generating data.

[0011] According to such a variable quality data reproducing apparatus, an arbitrary number of partial data including partially reproducible partial data out of individually encrypted partial data representing a content can be decrypted. As a result, content having a quality corresponding to the number of decrypted partial data can be obtained.
In addition, since it is not necessary to obtain unencrypted data again, the complexity in reproducing the content is small.

[0012] Each of the partial data may represent, for example, a spectrum of the content for each band.
In this case, the data restoration means generates data representing the content having a spectrum represented by the decoded partial data and substantially lacking a spectrum represented by the undecoded partial data. By
What is necessary is just to be able to obtain the content of the quality according to the number of decrypted partial data.

[0013] Each of the encrypted partial data may include, for example, a bit string representing the intensity of the spectrum of the content, and at least a part of the bit string may be encrypted. In this case, when the decryption means obtains a decryption key associated with the encrypted part of the bit string, the decryption means includes means for decrypting the part using the decryption key, The restoration unit generates data representing the content, assuming that the value of the bit string is the intensity of the spectrum when the undecoded part of the bit string has a predetermined value. What is necessary is just to be able to obtain a content having a quality corresponding to the length and number of a part of the decoded bit string.

The data representing the content is, for example,
PCM (Pulse Code Modulatio)
n) It is composed of a PCM signal obtained by performing modulation.

The method by which the decryption means acquires the encrypted partial data may be, for example, a method of receiving the partial data via a communication line or the like. However, the method is not limited to this. Therefore, the decoding means may include means for obtaining the partial data by reading the partial data from an external recording medium on which the respective partial data is recorded.

A data protection device according to a third aspect of the present invention acquires data representing a content, and at least one of the data represents a plurality of constituent parts of the data and can be independently reproduced. A partial data generating unit that converts the partial data into a plurality of partial data, and an encrypting unit that encrypts and outputs each of the partial data using an encryption key associated with the partial data. Features.

According to such a data protection device, the data representing the content is divided into partial data and encrypted for each partial data. For this reason, an external device decodes an arbitrary number of partial data including partial data that can be played back alone, so that content having a quality corresponding to the number of decoded partial data can be obtained. In addition, since it is not necessary to supply unencrypted data to the outside again, the complexity in supplying the content is small.

The partial data generating means may convert, for example, the data representing the content into each of the partial data representing the spectrum of the content for each band. In this case, the external device generates data representing content having a spectrum represented by the decoded partial data and substantially lacking the spectrum represented by the undecoded partial data, thereby performing decoding. What is necessary is just to be able to obtain the content of the quality according to the number of the divided partial data.

[0019] The partial data generating means may convert, for example, the data representing the content into each of the partial data including a bit string representing the intensity of the spectrum of the content. In this case, the encryption unit may include a unit that encrypts at least a part of the bit string using an encryption key associated with the bit string. In this case, when the external device obtains the decryption key associated with the encrypted part of the bit string, the part is decrypted, and the undecrypted part of the bit string has a predetermined value. Then, by generating data representing the content assuming that the value of the bit string is the intensity of the spectrum, the content having a quality corresponding to the length or number of a part of the decoded bit string may be obtained. .

The method by which the encrypting means outputs the encrypted partial data may be, for example, a method of transmitting the partial data via a communication line or the like. However, the method is not limited to this. Therefore, the encrypting means may include means for recording the encrypted partial data on an external recording medium.

Further, in the variable quality data supply method according to a fourth aspect of the present invention, data representing a content is obtained, and the data represents a plurality of constituent parts of the data, and at least one of the data can be independently reproduced. Is converted into a plurality of partial data, each of the partial data is output by encrypting using an encryption key associated with the partial data, to obtain each of the encrypted partial data, When a decryption key associated with at least one of the partial data is supplied, the decryption key is acquired, and among the acquired partial data, the one associated with the acquired decryption key is obtained. Decrypting using the decryption key, and generating data representing a portion represented by the decrypted partial data in the content based on the decrypted partial data. And butterflies.

According to such a variable quality data supply method, data representing a content is divided into partial data,
Since encryption is performed for each partial data, an arbitrary number of partial data including partial data that can be reproduced independently can be decrypted to obtain a content having a quality corresponding to the number of decrypted partial data. In addition, since it is not necessary to supply unencrypted data again, the complexity of supplying the content is small.

If the partial data to be decrypted is determined based on the amount charged to the user of the content, and the decryption key associated with the determined partial data is supplied, Content having quality according to the amount of money is supplied to the user.

A variable quality data reproducing method according to a fifth aspect of the present invention represents a plurality of constituent parts of data representing a content, at least one of which can be reproduced independently, and each of which is encrypted. Obtaining a plurality of partial data, obtaining a decryption key associated with at least one of the respective partial data, and obtaining the partial data associated with the obtained decryption key among the obtained partial data. And decrypting the content using the decryption key, and generating data representing a portion represented by the decrypted partial data in the content based on the decrypted partial data.

According to such a variable quality data reproducing method, an arbitrary number of partial data, including partially reproducible partial data, of the individually encrypted partial data representing the content is decrypted. As a result, content having a quality corresponding to the number of decrypted partial data can be obtained.
In addition, since it is not necessary to obtain unencrypted data again, the complexity in reproducing the content is small.

[0026] In a data protection method according to a sixth aspect of the present invention, data representing a content is obtained, and at least one of the data represents a plurality of constituent parts of the data and can be independently reproduced. The data is converted into a plurality of partial data, and each of the partial data is encrypted using an encryption key associated with the partial data and output.

According to such a data protection method, data representing a content is divided into partial data and encrypted for each partial data. For this reason, an external device decodes an arbitrary number of partial data including partial data that can be played back alone, so that content having a quality corresponding to the number of decoded partial data can be obtained. In addition, since it is not necessary to supply unencrypted data to the outside again, the complexity in supplying the content is small.

Further, a computer-readable recording medium according to a seventh aspect of the present invention includes:
Represents a plurality of constituent parts of data representing content, at least one of which is independently playable, and obtains a plurality of encrypted partial data, and associates the acquired partial data with at least one of the partial data. A decryption unit that acquires the obtained decryption key, and among the acquired partial data, one that is associated with the obtained decryption key, using the decryption key, Data restoring means for generating data representing a portion represented by the decrypted partial data in the content based on the partial data,
And a program for causing the computer to function.

A computer that executes a program recorded on such a recording medium stores an arbitrary number of partial data including individually reproducible partial data out of individually encrypted partial data representing contents. Decrypt.
For this reason, content having a quality corresponding to the number of decrypted partial data can be obtained. In addition, since it is not necessary to obtain unencrypted data again, the complexity in reproducing the content is small.

A computer-readable recording medium according to an eighth aspect of the present invention includes a computer
Partial data generating means for acquiring data representing content, converting the data into a plurality of partial data representing a plurality of constituent parts of the data and at least one of which can be independently reproduced, and each of the partial data And an encryption unit for encrypting and outputting the encrypted data using an encryption key associated with the partial data, and recording a program for causing the encryption unit to function.

A computer executing a program recorded on such a recording medium divides data representing a content into partial data and individually encrypts the partial data. For this reason, an external device decodes an arbitrary number of partial data including partial data that can be played back alone, so that content having a quality corresponding to the number of decoded partial data can be obtained. In addition, since it is not necessary to supply unencrypted data to the outside again, the complexity in supplying the content is small.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a variable quality data supply system, a variable quality data reproduction device, a data protection device, a variable quality data supply method, a variable quality data reproduction method and a data protection method according to the present invention will be described below. Will be described using a content supply system as an example. FIG. 1 is a diagram showing a configuration of a content supply system according to an embodiment of the present invention. As shown, the content supply system includes a data output unit 1 and a data reproduction unit 2.

As shown in FIG. 1, the data output unit 1 includes an analyzer 11, encryption units 12-0 to 12-n (where n is an integer of 1 or more), and a multiplexer 13
It is composed of

The analyzer 11, as shown in FIG.
Delay units 111-0 to 111- (n-1) and (n +
1) It is composed of samplers 112-0 to 112-n and a filter bank 113.

The delay units 111-0 to 111- (n-1)
Outputs a signal supplied to each of them with a delay of one cycle of this signal. Delay unit 111-k (k is 0 or more (n
-1) The signal output by any integer below is supplied to the sampler 112-k. Also, the delay units 111-j (j
Is an arbitrary integer not less than 0 and not more than (n−2)).
1- (j + 1) is supplied. Delay unit 1
11- (n-1) is supplied with a PCM (Pulse Code Modulation) signal to be encrypted by the data output unit 1.

Therefore, the delay unit 111-k is
1- (n-1) is converted to the PCM signal
A signal delayed by (n−k) cycles of the signal is output. The above-described PCM signal is a signal obtained by performing PCM modulation using an audio signal representing a sound or the like as a change in voltage or current.

The samplers 112-0 to 112-n sample the supplied signals at a frequency (n + 1) of the frequency of the PCM signal to be encrypted, and generate a signal representing the sampling result. , Filter bank 1
13.

As described above, the sampler 112-k includes
The signal output from the delay unit 111-k is supplied. The PCM signal to be encrypted by the data output unit 1 is supplied to the sampler 112-n substantially simultaneously with the supply of the PCM signal to the delay unit 111- (n-1).

The filter bank 113 includes a DSP (Digita
l Signal Processor) and CPU (Central Processing U)
nit) etc. Filter bank 113
Receives the signals output from the samplers 112-0 to 112-n as described above.

The filter bank 113 includes a polyphase filter and a DCT (Discrete Cosine Transform).
m), LOT (Lapped Orthogonal Transform), MLT
(Modulated Lapped Transform) or ELT (Exte
nded Lapped Transform), the first to (n +) representing the spectral distribution of this signal supplied to itself.
(1) Generate up to (n + 1) signals. Then, the p-th (p is an integer from 1 to (n + 1)) signal of the generated (n + 1) signals is supplied to the encryption unit 12- (p-1).

However, among the (n + 1) signals supplied to the encryption units 12-0 to 12-n, the p-th signal represents the spectrum distribution of the signals output from the samplers 112-0 to 112-n. It is assumed that the signal represents a spectrum distribution in a band having a p-th lowest frequency among bands having the same bandwidth obtained by (n + 1) equal division. Specifically, it is assumed that the signal is a digital signal representing the spectrum intensity of each frequency component in a band having the p-th lowest frequency as a bit string having a predetermined number of bits.

The encryption units 12-0 to 12-n have substantially the same configuration as each other, and are composed of a DSP, a CPU, and the like. The encryption unit 12- (p-1) obtains the p-th signal from the signals supplied by the filter bank 113, obtains an encryption key from the outside, and uses the obtained encryption key to generate the p-th signal. And the data (encrypted spectrum component) obtained by the encryption is supplied to the multiplexer 13.

The encryption method performed by the encryption units 12-0 to 12-n is arbitrary, and is, for example, DES (Data Encryption).
ption Standard) or a public key cryptosystem. Also, the encryption units 12-0 to 12-12
The method by which −n obtains the encryption key is arbitrary. For example, the encryption units 12-0 to 12-n may read the encryption key from an external storage device or recording medium.
Further, the encryption unit 12- through an external device via a communication line.
The encryption key is transmitted to the encryption unit 12-0.
~ 12-n may receive this encryption key. Also,
Each of the encryption units 12-0 to 12-n may include a storage device, store an encryption key in advance, and use the encryption key stored therein for encryption.

The multiplexer 13 is composed of a digital logic circuit or the like. The multiplexer 13 serially outputs the (n + 1) encrypted spectral components supplied from the encrypting units 12-0 to 12-n to the data reproducing unit 2 in a predetermined order. Specifically, for example, the encrypted spectrum supplied from the encryption unit 12- (p-1) is sequentially output in ascending order of the value of p.

As shown in FIG. 1, the data reproducing section 2 includes a demultiplexer 21 and decoding sections 22-0 to 22-n.
And a synthesizer 23.

The demultiplexer 21 is constituted by a digital logic circuit or the like. The demultiplexer 21 acquires (n + 1) encrypted spectra that are serially output from the data output unit 1, and converts the acquired encrypted spectra into
According to a predetermined rule, 1 is assigned to the decoding units 22-0 to 22-n.
Supply one to one. In the following, to facilitate understanding, the demultiplexer 21 converts the encrypted spectrum generated by the encryption unit 12- (p-1) from the encrypted spectrum supplied by the data output unit 1 to the data reproduction unit 2 Decryption unit 2
2- (p-1).

The decoding units 22-0 to 22-n have substantially the same configuration as each other, and are constituted by a DSP, a CPU, and the like. The decryption unit 22- (p-1) acquires the encrypted spectrum component supplied from the demultiplexer 21 (that is, the encrypted spectrum component generated by the encryption unit 12- (p-1)), Get the decryption key. Then, the encrypted spectrum component is decrypted using the obtained decryption key, and a signal obtained by the decryption is supplied to the synthesizer 23. The encryption unit 12
In the case where −0 to 12-n perform encryption using the symmetric key encryption method, the decryption key obtained by the decryption unit 22-(p−1) is the encryption key of the encryption unit 12-(p−1). May be the encryption key itself used for encryption. Further, when the encryption units 12-0 to 12-n perform encryption by a public key encryption method, a relationship that "data encrypted using one can be decrypted using the other". Out of the pair of private key and public key in (1), the encryption unit 12- (p-1) uses the public key as the encryption key, and the decryption unit 22- (p-1) uses the secret key. It may be used as a decryption key.

The decryption key supplied to the decryption unit 22- (p-1) is used for correctly decrypting the decrypted spectrum component generated by the encryption unit 12- (p-1). If it is a key, the signal generated by decoding by the decoding unit 22- (p-1) is substantially the same as the p-th signal among the signals generated by the filter bank 113.

On the other hand, when the correct decryption key is not supplied to the decryption unit 22- (p-1), the decryption unit 22- (p-1) performs the encryption regardless of the content of the encrypted spectral component supplied thereto. The spectrum component indicated by the spectrum component is treated as substantially non-existent. (For example, it is assumed that a signal representing a spectrum distribution is not supplied to the synthesizer 23.) The method of determining whether the decryption key is correct or not is arbitrary. For example, the decryption key has a predetermined data format. It may be performed based on whether or not there is.

The method by which the decryption units 22-0 to 22-n obtain the decryption key is arbitrary. For example, the decryption units 22-0 to 22-n may use an external storage device or recording medium. The decryption key may be read. Also, decoding units 22-0 to 22- through an external device via a communication line.
n to the decryption units 22-0 to 22-n
May receive this decryption key. Also, the decoding unit 2
2-0 to 22-n store the decryption key in a rewritable manner (for example, a random access memory (RAM)).
ry)), and the respective decryption keys stored before each decryption may be used for decryption.

As shown in FIG. 3, the synthesizer 23
Filter bank 231 and (n + 1) samplers 2
32-0 to 232-n and n delay units 233-0 to 2
33- (n-1) and adders 234-0 to 234- (n
-1).

The filter bank 231 includes a DSP and a CPU.
And the like, and as described above, the decoding unit 22-0
~ 22-n provide a signal representing the spectral distribution,
Acquire a total of (n + 1) of these signals. And
The filter bank 231 includes a polyphase filter, a DC
Using a method such as T, LOT, MLT, or ELT, a signal having a spectrum distribution represented by a signal acquired by the self is sampled at (n + 1) points at equal intervals (n
+1) signals are generated. Then, of these (n + 1) generated signals, the p-th signal (p is 1 to (n +
1) is converted to a sampler 232- (p−
Supply to 1).

The sampling interval of the value represented by this signal generated by the filter bank 231 depends on the data output unit 1
Samplers 112-1 to 112-n of the analyzer 11
Is substantially equal to the sampling interval. The p-th signal generated by the filter bank 231 is
Of the values obtained by sampling the signal having the spectral distribution represented by the signal supplied to the filter bank 231 at equal intervals at (n + 1) points, the sampling time represents the p-th earliest value.

Each of the samplers 232-1 to 232-n converts a signal supplied thereto to a signal having a frequency (n + 1) times that of the signal, and outputs a PCM signal representing the result of the conversion. Sampler 232- (p-1)
As described above, the p-th signal output from the filter bank 231 is supplied. Then, the sampler 232- (s-
1) converts the signal output by itself into an adder 234- (s-
1) (s is an integer from 1 to n). The sampler 232-n outputs the signal output by itself to the delay unit 233.
To (n-1).

The delay units 233-0 to 233- (n-1)
Outputs a signal supplied to each of them with a delay of one cycle of this signal. The delay unit 233-k (k is 0 or more (n
-1) The signal output by the following arbitrary integer) is an adder 23
4-k. Further, the delay units 233-j (j is 0
The above (any integer less than or equal to (n-2)) is calculated by the adder 234-
The signal output from (j + 1) is supplied. Delay unit 233
− (N−1) is supplied with the signal output from the sampler 232-n as described above.

Adders 234-0 to 234- (n-1)
Outputs a signal representing the sum of the two signals supplied to them. The adder 234-k includes a sampler 232-k.
And a signal is supplied from the delay unit 233-k. The signal output from the adder 234-m (m is an integer of 1 or more and (n-1) or less) is supplied to the delay unit 233- (m-1). The signal output from the adder 234-0 is output to the outside as an output signal of the data reproducing unit 2.

This output signal output from the adder 234-0 is output to samplers 232-0, 232-1,.
2- (n-1) and 232-n are PCM signals corresponding to signals sequentially output at a cycle substantially the same as the cycle of the PCM signal supplied to the analyzer 11.

The spectrum distribution of the PCM signal output from the adder 234-0 is obtained by decoding the spectrum of the original PCM signal supplied to the analyzer of the data output unit 1 for which the correct decryption key was not obtained. The distribution is substantially equal to the distribution of components excluding the component represented by the encrypted spectrum component supplied to the encrypting unit.

For example, the spectrum of the original PCM signal has the distribution shown in FIG. 4A, and the filter bank 113 of the data output unit 1 divides the spectrum distribution of the original PCM signal into 11 equal parts. It is assumed that 11 signals representing the obtained bands (bands B1 to B11) having the same bandwidth are supplied. In this case, the data reproducing unit 2
Decoding units 22-1, 22-2 and 22-7 to 22-1
If the correct decryption key is not supplied to the PC 1, the PC output from the data reproducing unit 2 (adder 234-0)
The spectrum distribution of the M signal is as shown in FIG. That is, this PCM signal does not substantially include spectrum components in the bands B1, B2, and B7 to B11.

Then, for example, the decoding units 22-3 to 22-22
-6, the decryption key to be supplied to the data reproducing unit 2 is provided free of charge to the owner, etc., while the decryption units 22-1, 22-
2 and the decryption keys to be supplied to 22-7 to 22-11 shall be provided for a fee. In this case, the owner of the data reproducing unit 2 operates the data reproducing unit 2 for free to reproduce a sound having a spectrum distribution shown in FIG. On the other hand, audio having the spectrum distribution shown in FIG. 4A (high-quality audio whose bandwidth is not limited) cannot be reproduced. However, the decoding units 22-1, 22
-2 and 22-7 to 22-11, it is possible to reproduce a high-quality sound whose band is not limited by purchasing a decryption key to be supplied. Furthermore, if the number of provided decryption keys is changed in two or more steps in accordance with the amount of the price or the like, the quality of the sound reproduced using the data reproducing unit 2 is also variable in three or more steps. can do.

The configuration of the content supply system is not limited to the above. For example, the delay unit 111-
0-111- (n-1) and 233-0-233- (n
-1) and samplers 112-0 to 112-n and 23
2-0 to 232-n and adders 234-0 to 234-
The function (n-1) may be performed by a DSP or CPU.

The signal to be encrypted by the data output unit 1 and the signal output by the data reproduction unit 2 need not be a PCM signal. Further, the band in which the spectrum represented by each signal generated by the filter bank 113 is distributed may be obtained by unequally dividing the spectrum distribution of the original PCM signal. Further, the data reproducing unit 2 may include a reproducing device that reproduces a sound represented by a signal output from the synthesizer 23.

The data output unit 1 is provided with an encryption unit 12-
The encrypted spectrum components generated by 0 to 12-n may be output in parallel. On the other hand, the data reproducing unit 2
Of the encrypted spectral components supplied in parallel from the data output unit 1 or the like, on a one-to-one basis.
May be obtained. Data output unit 1
Means CD (Compact Disc), CD-R (CD-Recordabl
e), DVD (Digital Versatile Disc), DVD-R
(DVD-Recordable) or a recording medium driver for recording data on any other recording medium. In this case, the data output unit 1 outputs
The data output from 12-n or the multiplexer 13 may be recorded on a recording medium set in its own recording medium driver.

The data output unit 1 may include a communication control device including a modem, a terminal adapter, and the like connected to an external communication line in place of or together with the recording medium driver. . In this case, the data output unit 1 may transmit data represented by a signal output from the encryption units 12-0 to 12-n or the multiplexer 13 to the outside via a communication line.

Further, the data reproducing section 2 is adapted to store CDs, CD-
A recording medium driver for reading data from R, DVD, DVD-R or any other recording medium may be provided. In this case, the data reproducing unit 2 reads data recorded on the recording medium by the data output unit 1 or any other device from the recording medium set in its own recording medium driver, and supplies the data to the demultiplexer 21 in serial. Or may be configured to supply the data to the decoding units 22-0 to 22-n in parallel.

Further, the data reproducing unit 2 may include a communication control device instead of the recording medium driver or together with the recording medium driver. In this case, the data reproducing unit 2
Receives the supplied signal when the data output from the data output unit 1 or the like is supplied to itself via a communication line, and receives the signal from the demultiplexer 21 or the decoding units 22-0 to 22-0.
22-n.

The encryption unit 12-0 of the data output unit 1
Some of the signals 12 to n may be supplied to the multiplexer 13 without encrypting the signal supplied thereto. Also, the decoding unit 22-0 of the data reproduction unit 2
22-n, to which the unencrypted signal is supplied, the signal may be supplied to the synthesizer 23 without performing the decryption process.

At least a part of the encryption units 12-0 to 12-n is included in a signal supplied to each of them.
Of the bit string representing the spectral intensity of each frequency component,
Each bit (upper bit) of a predetermined number of upper digits including an MSB (Most Significant Bit) may not be encrypted. Also, the upper bits and the other bits (lower bits) may be encrypted with different encryption keys. Then, of the decryption units 22-0 to 22-n, the decryption unit to which the data encrypted using the plurality of encryption keys is supplied receives the supply of the plurality of decryption keys,
This data may be decrypted using these decryption keys. However, in this case, the decoding unit
A value indicated by a part that cannot be decrypted using any of the decryption keys supplied thereto is treated as a predetermined value (for example, 0).

For example, a decryption key to be used for decoding the upper bits is provided free of charge to the owner of the data reproducing unit 2 and a decryption key to be used for decoding the lower bits is provided for a fee. Shall be performed. In this case, the owner of the data reproducing unit 2 can only use the data reproducing unit 2 to reproduce the voice having the inferior accuracy of the spectral intensity of each frequency component at no charge. On the other hand, if a decoding key for decoding the lower bits is purchased, a high-quality sound with unlimited spectral intensity accuracy can be reproduced.

Note that the encryption units 12-0 to 12-n may encrypt each part obtained by dividing the bit string representing the spectrum intensity into three or more with an encryption key different from each other. The part including the MSB may not be encrypted.

The signal to be encrypted by the data output unit 1 and the signal output by the data reproduction unit 2 do not need to be modulated waves obtained by modulating an audio signal. It may be a signal representing any content that can be represented in the form of a spectral distribution.

For example, the signal to be encrypted by the data output unit 1 (and the signal output by the data reproduction unit 2) represents the value of the gradation or color histogram component of the pixel constituting the image. A signal including a bit string,
The encryption units 12-0 to 12-n encrypt each part obtained by dividing the bit string into a plurality of parts using different encryption keys (however, the part including the MSB in each part is encrypted). (It is not necessary to convert it.) In this case, when the decryption units 22-0 to 22-n are supplied with data encrypted using a plurality of encryption keys, the data is decrypted using the plurality of decryption keys. In some cases, by changing the number of decoding keys supplied to the decoding units 22-0 to 22-n, the resolution and color distribution of an image represented by the signal output by the data reproduction unit 2 can be changed. .

The content supply system acquires data representing the amount of money charged to the owner of the data reproducing unit 2 from the outside, and obtains an encrypted spectrum component to be decrypted by the data reproducing unit 2. May be provided based on the determined data, and a device for supplying a decryption key for decrypting the determined encrypted spectrum component to a decryption unit for decrypting the determined encrypted spectrum component. The decryption unit supplied with the decryption key from this device may obtain the supplied decryption key and use it for decryption. In addition,
In this device, the decryption key to be supplied to the data reproducing unit 2 may be stored in advance, or may be obtained from outside. By providing the content supply system with this device, the quality of audio and the like reproduced using the data reproduction unit 2 changes according to data supplied from the outside.

Although the embodiments of the present invention have been described above, the variable quality data supply system, the variable quality data reproducing device, and the data protection device according to the present invention use ordinary computer systems, not dedicated systems. It is feasible. For example, the above-described analyzer 11 and the encryption unit 1 are installed in a personal computer or a microcomputer.
2-0 to 12-n and a medium storing a program for executing the operation of the multiplexer 13 (CD-ROM,
By installing the program from an MO, a floppy (registered trademark) disk, or the like, the data output unit 1 that executes the above-described processing can be configured. Also,
The above-described demultiplexer 21 and decoding units 22-0 to 22-n are added to a personal computer or a microcomputer.
By installing the program for executing the operation of the synthesizer 23 from a medium storing the program, the data reproducing unit 2 that executes the above-described processing can be configured.

Further, for example, a bulletin board (BB) of a communication line
These programs may be posted on S) and distributed via a communication line. Alternatively, a carrier wave is modulated by a signal representing these programs, the obtained modulated wave is transmitted, and this modulated wave is transmitted. The receiving device may restore the program by demodulating the modulated wave. The above-described processing can be executed by activating these programs and executing them in the same manner as other application programs under the control of the OS.

When the OS shares part of the processing,
Alternatively, when the OS constitutes a part of one component of the present invention, a program excluding the part may be stored in the recording medium. Also in this case, in the present invention, it is assumed that the recording medium stores a program for executing each function or step executed by the computer.

[0077]

As described above, according to the present invention, a variable quality data supply system and a variable quality data supply method for supplying content with low complexity while making the quality of the content variable are provided. A variable quality data reproducing device, a data protection device,
A variable quality data reproduction method and a data protection method are realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a content supply system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an analyzer.

FIG. 3 is a diagram illustrating a configuration of a synthesizer.

4A is a graph illustrating an example of a spectrum distribution of an original PCM signal, and FIG. 4B is a graph illustrating an example of a spectrum distribution of a PCM signal output from a data reproducing unit.

[Explanation of symbols]

1 Data Output Unit 11 Analyzer 111-0 to 111- (n-1), 233-0 to 233
-(N-1) delay unit 112-0 to 112-n, 232-0 to 232-n sampler 113,231 filter bank 12-0 to 12-n encryption unit 13 multiplexer 2 data reproduction unit 21 demultiplexer 22- 0 to 22-n decoding unit 23 synthesizer 234-0 to 234- (n-1) adder

Claims (18)

[Claims] 1. A partial data generating means for acquiring data representing a content and converting the data into a plurality of partial data representing at least a plurality of constituent parts of the data and at least one of which can be independently reproduced; Encrypting means for encrypting each of the partial data by using an encryption key associated with the partial data and outputting the encrypted partial data; acquiring each of the encrypted partial data; When a decryption key associated with any of them is supplied, the decryption key is acquired, and among the acquired partial data, the data associated with the acquired decryption key is used by using the decryption key. Decoding means for decoding the partial data; and data restoring means for generating data representing a portion represented by the decoded partial data in the content based on the decoded partial data. Variable quality data supply system comprising, characterized in that the. 2. The partial data generating means converts the data representing the content into each of the partial data representing a spectrum of the content for each band, and the data restoring means comprises: The method according to claim 1, further comprising: generating data representing the content having a spectrum represented by the partial data and substantially lacking a spectrum represented by the undecoded partial data. Variable quality data supply system. 3. The method according to claim 1, further comprising: acquiring charge amount data indicating a charge amount for a user of the content from outside; determining partial data to be decrypted based on the charge amount indicated by the acquired charge amount data; And a decryption key supply unit that supplies the decryption key associated with the partial data to the decryption unit, wherein the decryption unit acquires the decryption key supplied by the decryption key supply unit. The variable quality data supply system according to claim 1, wherein: 4. Representing a plurality of constituent parts of data representing contents, acquiring at least one of a plurality of partial data which can be independently reproduced and each of which is encrypted, and obtaining at least one of the plurality of partial data. When a decryption key associated with any is supplied, the decryption key is obtained,
Decryption means for decrypting, using the decryption key, the one associated with the obtained decryption key among the acquired partial data; and decrypting the content based on the decrypted partial data. And a data restoring means for generating data representing a portion represented by the converted partial data. 5. Each of said partial data represents a spectrum of said content for each band, and said data restoration means has a spectrum represented by said decoded partial data and said undecoded The variable quality data reproducing apparatus according to claim 4, wherein the apparatus generates data representing the content in which the spectrum represented by the partial data is substantially lacking. 6. The encrypted partial data includes a bit string representing the intensity of the spectrum of the content, and at least a part of the bit string is encrypted. Means for decrypting the part using the decryption key when obtaining a decryption key associated with the encrypted part, wherein the data restoring means comprises: The data representing the content is generated assuming that the value of the bit string is the intensity of the spectrum when a part that is not performed has a predetermined value. 3. The variable quality data reproducing apparatus according to claim 1. 7. The data according to claim 4, wherein the data representing the content is constituted by a PCM signal obtained by performing PCM (Pulse Code Modulation) modulation with an audio signal. Variable quality data playback device. 8. The decoding apparatus according to claim 4, wherein said decoding means includes means for acquiring said partial data by reading said partial data from an external recording medium on which each said partial data is recorded. The variable quality data reproducing device according to any one of the above items. 9. A partial data generating means for acquiring data representing a content and converting the data into a plurality of partial data representing a plurality of constituent parts of the data and at least one of which can be independently reproduced; Encrypting means for encrypting each of the partial data using an encryption key associated with the partial data, and outputting the encrypted partial data. 10. The apparatus according to claim 9, wherein said partial data generating means converts the data representing said content into each of said partial data representing a spectrum of said content for each band. Data protection device. 11. The partial data generating means converts the data representing the content into each of the partial data including a bit string representing the intensity of the spectrum of the content. 11. The data protection device according to claim 9, further comprising: means for encrypting at least a part of the data using an encryption key associated with the bit string. 12. 12. The data protection apparatus according to claim 9, wherein said encryption means comprises means for recording the encrypted partial data on an external recording medium. 13. Obtaining data representing a content, converting the data into a plurality of partial data representing a plurality of constituent parts of the data and at least one of which can be independently reproduced, and Is encrypted using the encryption key associated with the partial data and output, and the encrypted partial data is obtained, and the decryption associated with at least one of the partial data is performed. When the key is supplied, the decryption key is acquired, and among the acquired partial data, the data associated with the acquired decryption key is decrypted using the decryption key, and the decrypted A variable quality data supply method, comprising: generating data representing a portion represented by the decrypted partial data in the content based on the partial data. 14. A method for determining partial data to be decrypted on the basis of an amount charged to a user of the content, and supplying the decryption key associated with the determined partial data. 14. The variable quality data supply method according to claim 13, wherein: 15. Representing a plurality of components of data representing content, at least one of which can be independently reproduced,
Obtain a plurality of partially encrypted data, obtain a decryption key associated with at least one of the partial data, and obtain a decryption key corresponding to the obtained decryption key among the obtained partial data. The attached data is decrypted using the decryption key, and based on the decrypted partial data, data representing a portion represented by the decrypted partial data in the content is generated. Variable quality data playback method. 16. Acquiring data representing a content, converting the data into a plurality of partial data representing a plurality of constituent parts of the data and at least one of which can be independently reproduced, and Using a cryptographic key associated with the partial data and outputting the encrypted data. 17. A computer which represents a plurality of constituent parts of data representing a content, at least one of which can be independently reproduced, and obtains a plurality of encrypted partial data, and obtains each of the plurality of partial data. A decryption key that is associated with at least one of the obtained partial data, and among the acquired partial data, one that is associated with the acquired decryption key is decrypted using the decryption key. Means, and data restoring means for generating data representing a portion represented by the decrypted partial data in the content based on the decrypted partial data, and a computer-readable recording program for causing the program to function as Recording medium. 18. A partial data generator for acquiring data representing a content by a computer and converting the data into a plurality of partial data representing a plurality of constituent parts of the data and at least one of which can be independently reproduced. Means, encryption means for encrypting each of the partial data using an encryption key associated with the partial data and outputting the encrypted data, and a computer-readable recording medium storing a program for causing the partial data to function .