JP2008097549A - Content playback device and content playback program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a content playback device capable of flexibly providing a user with a special privilege while achieving proper charging to the user in a content distribution service, and a content playback program. <P>SOLUTION: A portable terminal 10 is provided with: a communicating part 11 for acquiring encrypted content information composed of a plurality of content blocks; a decrypting part 17 for decrypting the encrypted content information in each encrypted block; a storing part 13 for storing held amount information; a determining part 14 for comparing a usage amount of an encrypted block of a playback object with the held amount to determine whether to allow the decryption of the encrypted block of the playback object; and an updating part 15 for updating the held amount information in accordance with the usage amount of the encrypted block of the playback object when the decryption of the encrypted block of the playback object is allowed, wherein block usage amount information includes information for reducing the held amount and information for increasing the held amount, in accordance with the type of a content block. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a content playback apparatus and a content playback program that receive content information including content such as video and usage amount information, and charge the content according to the usage amount information to reproduce the content.

  2. Description of the Related Art Conventionally, there is known a charging system that performs charging according to content usage by distributing content information including content such as video and usage amount information indicating the usage amount of content (for example, Patent Document 1 and Patent Document 2).

  Specifically, the content information includes a plurality of content blocks, and each content block includes a block that is a part of the content and block usage amount information that indicates the usage amount of the block.

In the billing system described above, holding amount information indicating the amount of money held by the user (holding amount) is managed, and the usage amount corresponding to the content block used by the user is subtracted from the holding amount. In this way, by charging for each content block, excessive charging is suppressed in the case where only a part of the content is used, and convenience for the user is improved.
JP-A-2004-287996 (for example, claim 1, FIG. 3) Japanese Patent Application Laid-Open No. 2004-341744 (for example, claim 1, FIG. 3, etc.)

  By the way, in general business customs, a point system that gives a user points that can be exchanged for goods or services according to the amount of use of the goods or services, a cash back system that returns money to the users, or the like is used. . In the following, the point system and the cash back system are collectively referred to as a privilege grant system.

  In the content distribution service described above, there is a need to apply the privilege grant system, but there is no framework for flexibly realizing the privilege grant system.

  Accordingly, the present invention has been made to solve the above-described problems, and in a content distribution service, it is possible to flexibly give a privilege to a user while realizing appropriate charging for the user It is an object to provide a playback device and a content playback program.

  One feature of the present invention is that an acquisition unit (extraction unit 12) acquires encrypted content information including a plurality of content blocks including an encrypted block and block usage amount information indicating the usage amount of the encrypted block. A decryption unit (decryption unit 17) that decrypts the encrypted content information for each encrypted block, and a storage unit (storage unit 13) that stores retained amount information indicating the retained amount that is the amount of money held by the user ) And the usage amount of the encryption block to be reproduced and the possessed amount of the plurality of encryption blocks are compared, and it is determined whether or not the decryption of the encryption block to be reproduced is permitted. When the determination unit (determination unit 14) and decryption of the encryption block to be reproduced are permitted, the holding amount information is determined according to the usage amount of the encryption block to be reproduced. The content playback device (portable terminal 10) includes an updating unit (updating unit 15) for updating the information, and the block usage amount information includes information for decreasing the holding amount according to the type of the content block, and the holding Including information that increases the amount of money.

  According to this feature, when the update unit is permitted to decrypt the encryption block to be played back, the updating unit updates the holding amount information according to the usage amount of the encryption block to be played back, thereby Excessive charging is suppressed in the case where only a portion is used.

  Depending on the type of content block, the block usage amount information includes information that reduces the amount of money held and information that increases the amount of money held, so even if only a part of the content is used, A privilege can be flexibly given to a user.

  One feature of the present invention is that, in the one feature described above, the storage unit stores use record information indicating a use record of the content block, and the update unit stores the encrypted block to be reproduced. When the decryption is permitted, the gist is to update the usage record information according to the usage amount of the encryption block to be reproduced.

  One feature of the present invention is that, in the one feature described above, the acquisition unit acquires the encrypted content information from a content storage unit (content storage unit 19) in which the encrypted content information is stored. And

  One feature of the present invention is that in one feature described above, payment amount information indicating a payment amount corresponding to the amount of money paid by a user is received, and the holding amount information is updated according to the payment amount. The content reproduction device further includes a communication unit (communication unit 11) that transmits the usage record information updated by the update unit.

  One aspect of the present invention is characterized in that, in the above-described one aspect, the device further includes a housing portion that houses a tamper-resistant device, and the device is provided with at least the update portion.

  One feature of the present invention is that a content reproduction program used in a device that stores holding amount information indicating a holding amount, which is the amount of money held by a user, stores an encryption block and a usage amount of the encryption block in a computer. Obtaining encrypted content information composed of a plurality of content blocks including block usage amount information indicating, a step of decrypting the encrypted content information for each encrypted block, and the plurality of encrypted blocks Comparing the usage amount of the encryption block to be played back with the held amount to determine whether or not to permit the decryption of the encryption block to be played back, and encryption of the playback target When the block decryption is permitted, the holding amount information is determined according to the usage amount of the encrypted block to be reproduced. To execute the steps of updating, the block usage amount information is, depending on the type of the content block, the information reducing the holdings amount, and summarized in that including the information for increasing the held amount.

  ADVANTAGE OF THE INVENTION According to this invention, in the content delivery service, the content reproduction apparatus and content reproduction program which can give a privilege flexibly to a user can be provided, implement | achieving appropriate charge with respect to a user.

  Hereinafter, a communication system according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[First Embodiment]
(Configuration of communication system)
The configuration of the communication system according to the first embodiment will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a communication system according to the first embodiment.

  As illustrated in FIG. 1, the communication system includes a mobile terminal 10, a management server 100, and a content distribution server 200.

  The mobile terminal 10 is a device that reproduces content such as video distributed from the content distribution server 200. Specifically, the mobile terminal 10 decrypts the encrypted content information received from the content distribution server 200 and reproduces the content. Note that content reproduction is a concept including video display and audio output.

  Here, it should be noted that the user of the mobile terminal 10 needs to pay money to a collection agent such as a mobile communication carrier in order to use the content. In this embodiment, it is assumed that the usage amount of content is paid in advance.

  The mobile terminal 10 receives payment amount information indicating the payment amount corresponding to the amount of money paid by the user from the management server 100, and updates the holding amount information indicating the amount of money (held amount) held by the user. . Specifically, the mobile terminal 10 adds the payment amount to the possession amount. Note that the payment amount may be the amount of money actually paid by the user and a predetermined amount adjusted according to the user's attributes (gender, age group, occupation, etc.).

  On the other hand, the mobile terminal 10 updates the held amount information according to the usage amount of the content used by the user. Specifically, the mobile terminal 10 subtracts the usage amount from the held amount (or adds the usage amount to the held amount).

  The portable terminal 10 transmits usage record information indicating the usage record of the content to the management server 100. Here, it should be noted that the usage record information includes the name (identifier) of the user, the name (identifier) of the content used by the user, the name (identifier) of the content block, the usage amount of the content block, and the like. The usage record information is used, for example, to calculate the number of points that can be exchanged for products or services, and the amount of money (including discount amount) that is returned to the user.

  The management server 100 is a server managed by a collection agent such as a mobile communication carrier. Specifically, the management server 100 manages holding amount information indicating the holding amount held by the user of the mobile terminal 10. The management server 100 manages usage record information indicating the usage record of content by the user of the mobile terminal 10.

  Here, the holding amount information and the usage record information managed by the management server 100 are synchronized with the holding amount information and the usage record information managed by the mobile terminal 10. Although it is preferable that the synchronization processing of the holding amount information and the usage record information is performed every time the user uses the content, the present invention is not limited to this.

  For example, the synchronization processing of the possessed amount information and the usage record information may be performed when the mobile terminal 10 is connected to the management server 100 to pay money, and the mobile terminal 10 manages the management server to settle the retained amount. It may be performed when connected to 100.

  The management server 100 pays the entire amount of money received from the user of the mobile terminal 10 (or the amount excluding the fee) as a usage fee to a content distributor such as a broadcaster. The management server 100 may transmit the usage record information received from the mobile terminal 10 to the content distribution server 200. In this case, the management server 100 may collect the usage history information statistically and transmit the statistically summarized usage history information to the content distribution server 200 from the viewpoint of protecting the privacy of the user. .

  The content distribution server 200 is a server managed by a content distributor such as a broadcaster. Specifically, the content distribution server 200 is a server that distributes encrypted content information to the mobile terminal 10.

(Configuration of mobile device)
Hereinafter, the configuration of the mobile terminal according to the first embodiment will be described with reference to the drawings. FIG. 2 is a block diagram illustrating a configuration of the mobile terminal 10 according to the first embodiment.

  As illustrated in FIG. 2, the mobile terminal 10 includes a communication unit 11, an extraction unit 12, a storage unit 13, a determination unit 14, an update unit 15, a key generation unit 16, a decryption unit 17, and a reproduction unit. 18.

  The communication unit 11 has a function of communicating with the management server 100 and the content distribution server 200. Specifically, the communication unit 11 receives encrypted content information from the content distribution server 200. The communication unit 11 receives the payment amount information from the management server 100, and updates the retained amount information stored in the storage unit 13 described later according to the payment amount information. The communication unit 11 transmits usage record information stored in the storage unit 13 described later to the management server 100.

  Here, the encrypted content information includes a plurality of content blocks as shown in FIG. Each content block includes an encrypted block and block usage amount information. The encrypted block is a block in which a part of the content is encrypted, and the block usage amount information is information indicating the usage amount of the encrypted block.

  It should be noted that the block usage amount information may indicate not only a positive usage amount but also a negative usage amount depending on the type of content block. For example, when the content block is a movie or the like, the block usage amount information is information indicating a positive usage amount (that is, information for reducing the holding amount). On the other hand, when the content block is CM (Commercial Message) or the like, the block usage amount information is information indicating a negative usage amount (that is, information for increasing the holding amount).

  The block usage amount information indicating the positive usage amount may indicate a different usage amount depending on the type of the content block. For example, if the block usage amount information corresponds to a scene in which the content block is more exciting than a normal scene, the block usage amount information indicates a higher usage amount than the normal scene (that is, a usage amount with a large amount for reducing the holding amount). Is preferred.

  The block usage amount information indicating the negative usage amount may indicate a different usage amount depending on the type of the content block. For example, when the content block corresponds to a scene in which the content block has a higher sponsor fee than a normal CM, the block usage amount information is smaller than the normal scene (that is, a usage amount that increases the amount of money held). It is preferable to show.

  Here, when all the content blocks included in one content are played back, the positive usage amount and the negative usage amount are offset, and the usage amount of the content becomes 0 (free) Block usage amount information may be defined. In such a case, if the content block corresponding to the CM is skipped without being played back, the holding amount decreases due to the playback of the content, but if the content block corresponding to the CM is not skipped, Revenue does not decrease due to content playback.

  The extraction unit 12 extracts a content block from the encrypted content information. Subsequently, the extraction unit 12 extracts the encrypted block and the block usage amount information from the content block. The extraction unit 12 inputs the block usage amount information to the determination unit 14 and the key generation unit 16, and inputs the encrypted block to the decryption unit 17.

  The memory | storage part 13 memorize | stores the amount-of-holding information which shows the amount of money which a user holds, and the utilization track record information which shows the utilization track record of the content by a user. Specifically, as shown in FIG. 4, the storage unit 13 associates holding amount information (holding amount) with usage record information (use content name, use content block name, use amount, accumulated amount). Remember.

  The holding amount information (holding amount) is updated according to the payment amount (payment amount information) paid by the user. Also, the retained amount information (held amount) is updated according to the usage amount of the content used by the user. Here, it should be noted that the held amount information (held amount) is updated in units of content blocks.

  The used content name is the name of the content used by the user.

  The used content block name is the name of the content block used by the user. That is, the use content block name is the name of the content block reproduced by the reproduction unit 18 described later.

  The usage amount is a usage amount corresponding to the content block used by the user. That is, the usage amount is the usage amount of the content block reproduced by the reproduction unit 18 described later.

  The accumulated amount is a value obtained by accumulating the usage amount corresponding to the content block used by the user.

  Note that, as described above, when the retained amount information is transmitted to the management server 100, the mobile terminal 10 should transmit the retained amount information including the user name (identifier).

  The determination unit 14 refers to the stored amount information stored in the storage unit 13 to determine whether or not to permit decryption of the encryption block to be reproduced. Specifically, when the held amount is equal to or greater than the usage amount of the encryption block to be played back, the determination unit 14 permits the decryption of the encryption block to be played back, and the held amount is the encryption block to be played back. If it is less than the usage amount, the decryption of the encrypted block to be reproduced is prohibited.

  Here, it should be noted that the encrypted block to be reproduced is an encrypted block requested to be reproduced by the user. Therefore, an encrypted block that the user has not requested to play is skipped without being played back.

  The update unit 15 updates the retained amount information and the usage record information stored in the storage unit 13 when the decryption of the encryption block to be reproduced is permitted. Specifically, the update unit 15 adds or subtracts the held amount information in accordance with the usage amount of the encryption block to be reproduced that is permitted to be decrypted. The update unit 15 adds the name of the encryption block to be reproduced that is permitted to be decrypted, the usage amount of the encryption block that is permitted to be decrypted, the accumulated amount of the usage amount, and the like to the usage record information.

  The key generation unit 16 generates a decryption key used for decryption of the encryption block to be reproduced. The decryption unit 17 decrypts the encrypted block to be reproduced using the decryption key generated by the key generation unit 16.

  Specifically, as shown in FIG. 5, for the first encrypted block (block 1), the key generation unit 16 uses the usage amount information 1 corresponding to the encrypted block (block 1) and the initial amount. A decryption key 1 used for decryption of the encrypted block (block 1) is generated using an initialization vector (IV). Subsequently, the decryption unit 17 decrypts the encrypted block (block 1) using the decryption key 1 generated by the key generation unit 16 to obtain a plaintext block (block 1). The initialization vector is included in encrypted content information, for example.

  For the encrypted block (block 2) to be decrypted second, the key generation unit 16 uses the usage amount information 2 corresponding to the block 2, the decryption key 1 used for decrypting the encrypted block (block 1), Using the hash value of the plaintext block (block 1), a decryption key 2 used for decrypting the encrypted block (block 2) is generated. Subsequently, the decryption unit 17 decrypts the encrypted block (block 2) using the decryption key 2 generated by the key generation unit 16 to obtain a plaintext block (block 2).

  The encrypted block decrypted after the third is decrypted in the same procedure as the encrypted block decrypted second (block 2).

  As described above, the decryption key used for decryption of the encrypted block decrypted after the second is generated using the hash value of the plaintext block corresponding to the previous encrypted block. That is, the second and subsequent encrypted blocks are not decrypted unless the previous encrypted block is decrypted.

  Here, the encrypted block skipped without the user requesting reproduction is not reproduced, but is skipped in order to obtain a decryption key used for decryption of the encrypted block to be reproduced following the skipped encrypted block. It should be noted that the encrypted block is decrypted. Of course, the usage amount of the skipped encrypted block is not used for updating the holding amount information and the usage record information.

  The reproduction unit 18 is a video display device such as a liquid crystal panel or an audio output device such as a speaker. The playback unit 18 plays back the content block decrypted by the decryption unit 17.

  The mobile terminal 10 includes a card slot 20 that accommodates tamper resistance (here, an IC card 21). The IC card 21 is provided with at least the update unit 15 and the key generation unit 16 described above. The IC card 21 may be a contact type IC card or a non-contact type IC card. A signal transmitted and received between the IC card 21 and the main body of the mobile terminal 10 may be encrypted as necessary.

(Operation of communication system)
Hereinafter, the operation of the communication system according to the first embodiment will be described with reference to the drawings. FIG. 6 is a sequence diagram showing the operation of the communication system according to the first embodiment.

  As shown in FIG. 6, in step 10, the user of the mobile terminal 10 pays an arbitrary amount of money to the collection agent.

  In step 20, the management server 100 transmits payment amount information indicating the amount of money (payment amount) paid by the user to the mobile terminal 10.

  In step 30, the mobile terminal 10 updates the held amount information according to the payment amount information received from the management server 100. Specifically, the mobile terminal 10 adds the payment amount to the possession amount.

  In step 40, the content distribution server 200 distributes encrypted content information including a plurality of content blocks to the mobile terminal 10.

  In step 50, the mobile terminal 10 compares the usage amount of the encryption block to be reproduced with the possession amount and determines whether or not the decryption of the encryption block to be reproduced is permitted. If the possessed amount is equal to or greater than the usage amount of the encryption block to be played back, the portable terminal 10 permits the decryption of the encryption block to be played back and proceeds to the process of step 60. On the other hand, when the possessed amount is less than the usage amount of the encryption block to be reproduced, the mobile terminal 10 prohibits the decryption of the encryption block to be reproduced and ends the series of processes.

  In step 60, the mobile terminal 10 generates a decryption key according to the procedure shown in FIG. 5, and decrypts the encrypted block to be reproduced. As described above, it should be noted that the method for generating the decryption key used for decrypting the first encrypted block is different from the method for generating the decryption key used for decrypting the second and subsequent encrypted blocks.

  In step 70, the mobile terminal 10 reproduces the content block decrypted in step 60.

  In step 80, the mobile terminal 10 updates the retained amount information stored in the storage unit 13 in accordance with the usage amount of the content block decrypted in step 60.

  In step 90, the mobile terminal 10 updates the usage record information stored in the storage unit 13 in accordance with the usage amount of the content block decrypted in step 60.

  In step 100, the mobile terminal 10 determines whether or not the content reproduction has ended. The portable terminal 10 proceeds to the process of step 110 when the reproduction of the content is finished, and returns to the process of step 50 when the reproduction of the content is not finished.

  In step 110, the mobile terminal 10 transmits the usage record information stored in the storage unit 13 to the management server 100. Note that the processing of step 110 may be performed when the usage record information is updated, not after the reproduction of the content ends. Further, the process of step 110 may be performed when the mobile terminal 10 is connected to the management server 100 in order to pay money, or when the mobile terminal 10 is connected to the management server 100 in order to settle the amount held. It may be done.

(Function and effect)
According to the mobile terminal 10 according to the first embodiment, when the update unit 15 is permitted to decrypt the encryption block to be reproduced, the updating unit 15 displays the retained amount information according to the usage amount of the encryption block to be reproduced. By updating, excessive charging is suppressed when only a part of the content is used.

  Depending on the type of content block, the block usage amount information includes information that reduces the amount of money held and information that increases the amount of money held, so even if only a part of the content is used, A privilege can be flexibly given to a user.

  When the update unit 15 is permitted to decrypt the encryption block to be reproduced, only a part of the content is used by updating the usage record information according to the usage amount of the encryption block to be reproduced. Even in such a case, a privilege can be flexibly given to the user.

  According to the mobile terminal 10 according to the first embodiment, the communication unit 11 updates the holding amount information according to the payment amount information received from the management server 100 and transmits the usage record information to the management server 100. The management server 100 side (that is, the collection agent side) can easily monitor whether or not the content is normally used.

  According to the mobile terminal 10 according to the first embodiment, since the update unit 15 is provided in the IC card 21, unauthorized reproduction of content due to falsification of the retained amount information is suppressed. Since the key generation unit 16 is provided in the IC card 21, unauthorized decryption of the encrypted block is suppressed.

[Second Embodiment]
The second embodiment will be described below with reference to the drawings. In the following, differences between the first embodiment and the second embodiment described above will be mainly described.

  Specifically, in the first embodiment described above, the extraction unit 12 extracts content blocks from the encrypted content information received by the communication unit 11.

  On the other hand, the extraction unit 12 reads the encrypted content information from the content storage unit that stores the encrypted content information, and extracts a content block from the encrypted content information.

(Configuration of mobile device)
Hereinafter, the configuration of the mobile terminal according to the second embodiment will be described with reference to the drawings. FIG. 7 is a block diagram illustrating a configuration of the mobile terminal 10 according to the second embodiment.

  As illustrated in FIG. 7, the mobile terminal 10 includes a content storage unit 19 in addition to the configuration illustrated in FIG. 2.

  The content storage unit 19 is a memory in which the encrypted content information received by the communication unit 11 is stored. That is, the content storage unit 19 temporarily stores the encrypted content information received when the mobile terminal 10 can communicate. Therefore, the extraction unit 12 can read the encrypted content information from the content storage unit 19 even when the mobile terminal 10 is in a state where communication is not possible (offline).

  Here, the content storage unit 19 may be a storage medium (SD card, memory stick, compact flash (registered trademark), etc.) in which encrypted content information is stored, and the encrypted content read from the storage medium. It should be noted that it may be a memory (such as a flash memory) in which information is stored.

(Function and effect)
According to the mobile terminal 10 according to the second embodiment, since the mobile terminal 10 has the content storage unit 19 in which the encrypted content information is stored, the mobile terminal 10 is in a state where communication is not possible (offline). However, the content can be reproduced, and the convenience for the user is improved.

  In addition, since the content stored in the content storage unit 19 is encrypted, and the possessed amount information is updated when the decryption of the encrypted block to be played back is permitted, The user can be charged appropriately.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the operation of the mobile terminal 10 shown in the above-described embodiment may be provided as a program.

  In the above-described embodiment, the mobile terminal 10 is described as an example of the content reproduction apparatus, but the present invention is not limited to this. Of course, the present invention is applicable to any apparatus that reproduces content.

  In the embodiment described above, the update unit 15 and the key generation unit 16 are provided in the IC card 21, but the present invention is not limited to this. Specifically, the update unit 15 and the key generation unit 16 are provided in the main body of the mobile terminal 10, and the card slot 20 that accommodates the IC card 21 may not be provided in the mobile terminal 10.

  Although not particularly mentioned in the above-described embodiment, a memory for storing usage amount information may be provided in the IC card 21 in order to prevent falsification of the usage amount information. Similarly, a memory for storing usage record information may be provided in the IC card 21 in order to prevent falsification of the usage record information.

  Although not specifically mentioned in the above-described embodiment, the usage amount information may be information that can specify the usage amount of the content (content block). Accordingly, the usage amount information may be the usage amount itself of the content (content block) or may include a calculation logic for the usage amount of the content (content block).

It is a figure which shows the structure of the communication system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the portable terminal 10 which concerns on 1st Embodiment. It is a figure which shows an example of the encryption content information which concerns on 1st Embodiment. It is a figure which shows the information memorize | stored in the memory | storage part 13 which concerns on 1st Embodiment. It is a figure which shows an example of the decoding method which concerns on 1st Embodiment. It is a sequence diagram which shows operation | movement of the communication system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the portable terminal 10 which concerns on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Portable terminal, 11 ... Communication part, 12 ... Extraction part, 13 ... Memory | storage part, 14 ... Determination part, 15 ... Update part, 16 ... Key generation part, DESCRIPTION OF SYMBOLS 17 ... Decoding part, 18 ... Reproduction part, 19 ... Content memory | storage part, 20 ... Card slot, 21 ... IC card, 100 ... Management server, 200 ... Content delivery server

Claims (6)

An acquisition unit that acquires encrypted content information including a plurality of content blocks including an encrypted block and block usage amount information indicating a usage amount of the encrypted block;
A decryption unit for decrypting the encrypted content information for each encrypted block;
A storage unit for storing holding amount information indicating a holding amount which is an amount of money held by the user;
A determination unit that determines whether or not to permit decryption of the encryption block to be reproduced by comparing the usage amount of the encryption block to be reproduced and the held amount among the plurality of encryption blocks; ,
An update unit that updates the holding amount information according to the usage amount of the encryption block to be played back when decryption of the encryption block to be played back is permitted,
The block usage amount information includes information for decreasing the retained amount and information for increasing the retained amount according to the type of the content block. The storage unit 13 stores use record information indicating a use record of the content block,
The update unit updates the usage record information according to the usage amount of the encryption block to be played back when decryption of the encryption block to be played back is permitted. 2. The content reproduction apparatus according to 1.   2. The content reproduction apparatus according to claim 1, wherein the acquisition unit acquires the encrypted content information from a content storage unit in which the encrypted content information is stored.   The payment amount information indicating the payment amount corresponding to the amount of money paid by the user is received, the holding amount information is updated according to the payment amount, and the usage record information updated by the updating unit is transmitted. The content reproduction apparatus according to claim 2, further comprising a communication unit. It further comprises an accommodating portion for accommodating a device having tamper resistance,
The content playback apparatus according to claim 1, wherein at least the update unit is provided in the device. A content reproduction program used in a device for storing holding amount information indicating a holding amount, which is the amount of money held by a user,
Obtaining encrypted content information composed of a plurality of content blocks including an encrypted block and block usage amount information indicating the usage amount of the encrypted block;
Decrypting the encrypted content information for each encrypted block;
Comparing the usage amount of the encryption block to be reproduced and the possessed amount among the plurality of encryption blocks, and determining whether or not to permit the decryption of the encryption block to be reproduced;
When the decryption of the encryption block to be played is permitted, updating the held amount information according to the usage amount of the encryption block to be played,
The block usage amount information includes information for decreasing the retained amount and information for increasing the retained amount according to the type of the content block.

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