JP4193644B2 - Content distribution method and data supply station - Google Patents

Description

The present invention relates to a content distribution method and a data supply station. In particular, the content data is encrypted and transmitted to the reception terminal A so that only the reception terminal A can be used from the data supply station, and only the reception terminal B is received from the reception terminal A. There about the content distribution method and a data supply station for use therein to retransmit the content data so as to be available to the receiving terminal B.

  With the recent advancement and development of digital communication technology and computer technology, content data such as images, sounds and texts can be received and used via a communication network. Under such circumstances, the content data is digital information, and it is easy to copy, modify, etc., so that the copyright holder of the content data is protected, and at the same time, the content data acquired by the right holder can be Conventionally, a content distribution method has been proposed for ensuring the wide use of content data by allowing a user to use the content data properly for secondary use (see, for example, Patent Document 1).

  This conventional content distribution method includes an information supply station that distributes digital information, a plurality of information terminals that receive digital information, and an information transmission medium that connects the information supply station and the plurality of information terminals to each other. In addition, in the content distribution method in which the digital information distributed from the information supply station is secondarily distributed between the information terminals, the information supply station encrypts the information with a unique first encryption key for each information. Information and a distribution key obtained by encrypting a first decryption key corresponding to the first encryption key with a second encryption key unique to the information terminal are distributed, and each of the plurality of information terminals corresponds to the second encryption key. 2 Decrypt the distribution key with the first decryption key, decrypt the encrypted information transmitted from the information supply station or other information terminal with the first decryption key, and decrypt the encrypted distribution key with the second decryption key The first decryption key Of encrypted with a second encryption key specific to another information terminal transmission destination information, which is configured to output the encrypted distribution key and the encrypted information to the information transmission medium.

JP-A-8-8851

  However, in the above-described conventional content distribution method, of the plurality of information terminals, the information transmission source information terminal needs to have a second encryption key unique to the information transmission destination (secondary distribution destination) information terminal. Therefore, if the secondary distribution destination is not fixed, it is necessary to hold and manage the keys of all information terminals that may be distributed secondarily, and it is difficult to maintain the safety of the entire system There is a problem. Further, in the conventional content distribution method described above, the information supply station cannot know how and for which content data the secondary distribution has been performed.

The present invention has been made in view of the above points, and the receiving terminal manages only the identification information of the other receiving terminal without holding the encryption key information of the other receiving terminal, and the data supplying station. A content distribution method capable of constructing a secure system by exchanging identification information of a secondary distribution destination and a secondary distribution encryption key, so that a plurality of receiving terminals do not have and manage encryption keys of other receiving terminals, and The purpose is to provide a data supply station .

Another object of the present invention is to provide a transparent content distribution method and a data supply station that allow a data supply station to know how and for which content data secondary distribution has been performed. .

  In order to achieve the above object, a content distribution method according to a first aspect of the invention includes an encrypted content data obtained by encrypting content data with a content key and a content key decrypted with a terminal key associated with the first receiving terminal. In a content distribution method in which the encrypted content key encrypted so as to be combined and transmitted from the data supply station to the first receiving terminal, the encrypted content data is the first data, and the encrypted content key is the second data These first to third data are the third data that is the content encryption information that is encrypted with the supply station key associated with the data supply station by combining the content identification information for identifying the content data and the content key. A first data source station that generates a content data container that is combined with the first data terminal and transmits it to the first receiving terminal. A second step in which the first receiving terminal extracts the encrypted content key, the encrypted content data, and the first and third data from the received content data container, and the first receiving terminal A third step of combining secondary distribution destination identification information for identifying the second receiving terminal of the secondary distribution destination with the data of 2 and transmitting this as secondary distribution request information to the data supply station; Receives the secondary distribution request information and separates the secondary distribution destination identification information and the third data from the secondary distribution request information, and the data supply station separated in the fourth step. The fifth step of decrypting the third data with the supply station decryption key to obtain the content identification information and the content key, and the data supply station based on the secondary distribution destination identification information separated in the fourth step 2 Next distribution destination A sixth step of encrypting the content key obtained by decrypting in the fifth step with the secondary distribution destination encryption key associated with the second receiving terminal to create and transmit secondary distribution information; The first receiving terminal receives the secondary distribution information created and transmitted in the step, and combines the secondary distribution information with the first and third data extracted in the second step as the second data. And creating a new secondary distribution content data container, the secondary distribution content data container created in the seventh step as the second distribution destination second receiving terminal. It is characterized by being distributed to.

  In the present invention, when the first receiving terminal that receives the content data container created by the data supply station secondarily distributes the content data in the received content data container to another second receiving terminal, The first receiving terminal identifies the second receiving terminal of the secondary distribution destination in the third data which is the content encryption information encrypted with the supply station key by combining the content identification information for identifying the content data and the content key. The secondary distribution destination identification information to be combined is created as secondary distribution request information, transmitted to the data supply station, and the data supply station that has received the secondary distribution request information includes the secondary distribution request information. The secondary distribution related to the second receiving terminal of the secondary distribution destination is based on the content key obtained by decrypting the third data of the secondary distribution destination based on the secondary distribution destination identification information in the secondary distribution request information. Since encrypted in the previous encryption key was to create a secondary distribution information, first receiving terminal held the encryption key of the second receiving terminal of the secondary distribution destination, it can be made unnecessary to manage. Further, the data supply station receives the secondary distribution request information and can know which content data is secondarily distributed by the content identification information therein.

  In order to achieve the above object, a content distribution method according to a second aspect of the present invention provides encrypted content data obtained by encrypting content data with a content key, and a terminal key related to the first receiving terminal. In the content distribution method of transmitting the encrypted content key encrypted so that it can be decrypted by the data supply station to the first receiving terminal, the data supply station converts the encrypted content data and the session ID into data A digital signature is applied with a supply station signature key associated with the data supply station to obtain first data, and data obtained by applying a digital signature with the supply station signature key to data obtained by combining the encrypted content key and the session ID is second. The supply station key that combines the content identification information that identifies the content data and the content key Data obtained by digitally signing with the supply station signature key to the data obtained by combining the encrypted content encryption information and the session ID is used as third data, and a content data container is generated by combining the first to third data. The first step of transmitting to the first receiving terminal, and the first receiving terminal verifying the validity of the received content data container with the signature verification key using the supply station signature confirmation key related to the data supply station The second step of confirming by comparing and collating three session IDs included in the received content data container, and the content data received when the first receiving terminal can confirm the validity by the second step A third step of separating and extracting the encrypted content key, the encrypted content data, and the first and third data from the container. And the first receiving terminal decrypts the encrypted content key separated in the third step with the terminal key to obtain the content key, and decrypts the encrypted content data separated in the third step with the content key. The fourth step of obtaining the content data, the fifth step of the first receiving terminal temporarily storing the first and third data separated by the third step, and the first receiving terminal, Combining the third data separated in the third step with the secondary distribution destination identification information for identifying the second receiving terminal of the secondary distribution destination and the secondary distribution source identification information of the own terminal, Including a sixth step of creating data that has been digitally signed with the terminal signature key related to, as secondary distribution request information and transmitting it to the data supply station.

  Furthermore, in the second invention, the data supply station includes the seventh to eleventh steps, and the receiving terminal of the secondary distribution request source includes the twelfth to fourteenth steps. Here, in the seventh step, the secondary distribution request information is received, the secondary distribution destination identification information, the secondary distribution source identification information, and the third data are separated from the secondary distribution request information. The content encryption information and the session ID are separated from the third data. In the eighth step, the content encryption information separated in the seventh step is decrypted with the supply station decryption key to obtain the content identification information and the content key. In the ninth step described above, based on the secondary distribution source identification information separated in the seventh step, using the terminal signature confirmation key related to the receiving terminal of the secondary distribution source, the secondary distribution request information Verify signature.

  In the tenth step, when the signature is successfully verified in the ninth step, the receiving terminal of the secondary distribution destination is based on the secondary distribution destination identification information separated in the seventh step. The content key decrypted in the eighth step is encrypted using the terminal encryption key related to the. In the eleventh step, data obtained by adding a digital signature with the supply station signature key to data obtained by adding the session ID separated in the seventh step to the encrypted content key obtained in the tenth step is 2 Created as next distribution information and sent to the receiving terminal of the secondary distribution request source.

  In the twelfth step, the secondary distribution information is received, and the signature is confirmed with the supply station signature confirmation key related to the data supply station. In the thirteenth step, the session ID is extracted from the secondary distribution information. In the fourteenth step, the same session ID as the session ID extracted in the thirteenth step is added from the first data and the third data temporarily stored in the fifth step. The secondary distribution information whose signature has been successfully confirmed in the twelfth step is combined as the second data to create a new content data container for secondary distribution.

  In the present invention, when the receiving terminal secondary distributes the content data to the receiving terminal of the secondary distribution destination, the third data in the content data container transmitted and received from the data supply station is included in the secondary distribution destination. Data obtained by combining the secondary distribution destination identification information for identifying the receiving terminal and the secondary distribution source identification information of the own terminal and applying a digital signature with the terminal signature key related to the own terminal as the secondary distribution request information Send to the supply station.

  Thereby, the data supply station separates the secondary distribution destination identification information, the secondary distribution source identification information and the third data from the secondary distribution request information, and further decrypts the content encryption information in the third data. The content identification information and the content key are obtained by decrypting with the key, and the terminal signature confirmation key related to the receiving terminal of the secondary distribution source extracted from the receiving terminal information storage means is obtained based on the separated secondary distribution source identification information. The first signature verification unit that verifies the signature of the secondary distribution request information, and when the signature is successfully verified by the first signature verification unit, based on the separated secondary distribution destination identification information, Using the terminal encryption key related to the receiving terminal of the secondary distribution destination taken out from the receiving terminal information storage means, the decrypted content key is encrypted, and the separated session ID is added to the encrypted content key. The data, create and send data subjected to the digital signature at the feed station signature key as a secondary distribution information to secondary distribution requesting receiving terminal.

  Therefore, according to the present invention, it is unnecessary for the receiving terminal of the secondary distribution request source to hold and manage the encryption key of the receiving terminal of the secondary distribution destination. Further, the data supply station receives the secondary distribution request information and can know which content data is secondarily distributed by the content identification information therein. In addition, the security of data transmitted by the digital signature can be improved.

  In order to achieve the above object, the data supply station of the third invention is a data supply station used in the content distribution method of the second invention, and is separated by the seventh step of the second invention. Transmission history for storing secondary distribution destination identification information and secondary distribution source identification information obtained in this manner, and content identification information obtained by decoding in the eighth step of the second invention, as secondary distribution history information, respectively. A storage means is provided. In the present invention, the data supply station can store and manage the history of secondary distribution.

  In order to achieve the above object, a data supply station according to a fourth aspect of the present invention includes first encryption means for encrypting arbitrary content data so that it can be decrypted with an arbitrary content key, and obtaining encrypted content data. A second encryption unit that encrypts the content key so that the content key can be decrypted with a terminal key associated with the receiving terminal, and obtains an encrypted content key; content identification information that identifies content data; Create and transmit a content data container combining the third encryption means for encrypting with the supply station key related to the content to obtain the content encryption information, the encrypted content data, the encrypted content key and the content encryption information Content data container creation / transmission means.

  According to the present invention, since the content key is included in the secondary distribution request information transmitted from the first receiving terminal to the data supply station, the data supply station records the key on which the content data was previously encrypted. There is no need to keep it.

  Further, according to the present invention, the receiving terminal manages only the identification information of the other receiving terminal without holding the encryption key information of the other receiving terminal, and the secondary distribution destination with the data supply station. By exchanging the identification information and the secondary distribution encryption key, the received content data container can be reconfigured into a secondary distribution content data container that can be decrypted by the secondary distribution destination receiving terminal. It is unnecessary to hold and manage the encryption key of the receiving terminal of the next distribution destination.

  Furthermore, according to the present invention, it is possible to construct a transparent data distribution system in which a receiving terminal that has received secondary distribution can perform secondary distribution to other receiving terminals by the same procedure.

  Further, according to the present invention, the data supply station can receive secondary distribution request information and know which content data is secondarily distributed based on the content identification information therein. According to the present invention, the receiving terminal transmits the secondary distribution request information with a digital signature and confirms the validity of the content data container received from the data supply station. Since the secondary distribution information is also sent after being digitally signed, the security of the content distribution system can be improved.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram of a content distribution system to which an embodiment of a content distribution method according to the present invention is applied. The content distribution system of the present embodiment shown in FIG. 1 receives a data supply station 1 that distributes a data group (content data container) 4 composed of content data and data related to the content data, and receives the content data container 4. The first receiving terminal A (2) and the second receiving terminal B (3) that receives the content data container 7 from the receiving terminal 2.

  The receiving terminal 2 transmits secondary distribution request information 5 to the data supplying station 1 for secondary distribution of the content data container 4 received from the data supplying station 1 to the receiving terminal 3. 6 is used to reconstruct the content data container 4 into the content data container 7 and then transmit to the receiving terminal 3. That is, in this embodiment, the content data is encrypted and transmitted to the first receiving terminal 2 so that only the first receiving terminal 2 can be used from the data supply station 1, and further, the first receiving terminal 2 The content data is retransmitted to the second receiving terminal 3 so that only another second receiving terminal 3 can be used.

  Next, the configuration and operation of the data supply station 1 and the receiving terminals 2 and 3 constituting the content distribution system of FIG. 1 will be described in more detail. 2 is a block diagram of an embodiment of the data supply station 1 in FIG. 1, FIG. 3 is a block diagram of an embodiment of the receiving terminal 2 in FIG. 1, and FIG. 4 is a validity confirmation means in FIG. 51 shows a block diagram of an embodiment of 51. FIG.

  First, the configuration and operation of the content data container 4 creation process by the data supply station 1 will be described in detail with reference to the block diagram of FIG. 2 and the flowchart of FIG. When the content data container 4 is created, the data supply station 1 in FIG. 2 encrypts the content data 11 with the content key 12 in the encryption means 14 to obtain the encrypted content data 15 (step S1 in FIG. 5). Further, the data supply station 1 encrypts the content key 12 with the receiving terminal encryption key 17 related to the receiving terminal 2 in the encryption means 16 to obtain the encrypted content key 18 (step S2 in FIG. 5).

  Further, the content key 12 and the content identification information 13 for identifying the content data 11 are combined by the packaging means 19, and this is encrypted with the supply station encryption key 21 associated with the data supply station 1 in the encryption means 20. Encrypted information 22 is created (step S3 in FIG. 5). On the other hand, the session ID generating means 23 generates a session ID 24 (step S4 in FIG. 5).

  Next, after the encrypted content data 15 and the session ID 24 are combined in the package unit 25, the signature unit 27 applies a digital signature with the supply station signature key 26 associated with the data supply station 1, and the first data D1. Is created (step S5 in FIG. 5). Similarly, after the encrypted content key 18 and the session ID 24 are combined in the package unit 25, the signature unit 27 applies a digital signature with the supply station signature key 26 associated with the data supply station 1, and the second data D2 Is created (step S6 in FIG. 5).

  Similarly, after the content encryption information 22 and the session ID 24 are combined in the package unit 25, the signature unit 27 applies a digital signature with the supply station signature key 26 associated with the data supply station 1, and the third data D3 Is created (step S7 in FIG. 5). Subsequently, the first data D1, the second data D2, and the third data D3 are combined by the package means 28 to create the content data container 4 (step S8 in FIG. 5). The content data container 4 is transmitted to the receiving terminal 2 shown in FIGS.

  Next, content data reproduction processing by the receiving terminal 2 will be described in detail with reference to the block diagrams of FIGS. 3 and 4 and the flowchart of FIG. In FIG. 3, when the receiving terminal 2 receives the content data container 4 from the data supply station 1 shown in FIGS. 1 and 2 by the validity confirmation means 51 (step S11 in FIG. 6), the validity confirmation means 51 Then, the content data container 4 is disassembled (step S12 in FIG. 6), and the contents of the data container 4 are confirmed using the supply station signature confirmation key 52 associated with the data supply station 1 (step S13 in FIG. 6).

  The configuration and operation of the validity confirmation unit 51 will be described in detail with reference to the block diagram of FIG. In FIG. 4, the content data container 4 input to the validity confirmation unit 51 is decomposed into the first data D1, the second data D2, and the third data D3 described above in the unpackaging unit 511, respectively. The digital signature verification is performed in the signature verification means 512 using the supply station signature verification key 52 for each data.

  Subsequently, the unpackaging unit 513 further decomposes the first data D1 from the signature confirmation unit 512 to obtain the encrypted content data 15 and the session ID 24. Similarly, the second data D2 from the signature confirmation unit 512 is further decomposed in the unpackage unit 513, and the encrypted content key 18 and the session ID 24 are obtained. Similarly, the third data D3 from the signature confirmation unit 512 is further decomposed in the unpackage unit 513, and the content encryption information 22 and the session ID 24 are obtained.

  The comparison unit 514 compares the three session IDs 24 from the unpackage unit 513. The logic circuit 515 receives the comparison result of the comparison unit 514 and the signature confirmation result 516 from the signature confirmation unit 512, and when the comparison results are all equal and all the signature confirmation results 516 indicate that the verification is successful, As a result 53, a value indicating success of the validity check is output. Otherwise, a value indicating failure of validity check is output. Also, the encrypted content data 15, the encrypted content key 18, the first data D1, and the third data D3 are output.

  Returning to FIG. 3, the description will be continued. In the figure, when the validity confirmation result 53 obtained by the validity confirmation means 51 by the method described with reference to FIG. 4 is a value indicating a failure of validity confirmation (the signature confirmation results of the data D1, D2 and D3 described above are If collation is unsuccessful or the three session IDs 24 do not match, the processing is stopped (steps S13, S14, S18 in FIG. 6).

  On the other hand, when the value is a value indicating the success of the validity check (when the signature check result of the data D1, D2, and D3 described above is a successful check and the three session IDs 24 match), the validity check means 51 The output encrypted content key 18 is input to the decrypting means 54, where it is decrypted with the receiving terminal decrypting key 55 associated with the receiving terminal 2 to obtain the content key 12 (step S15 in FIG. 6). Then, the encrypted content data 15 output from the validity confirmation unit 51 is decrypted by the content key 12 in the decryption unit 56 to obtain the content data 11 (step S16 in FIG. 6). The content data is supplied to and played back by playback means (not shown in FIG. 3) (step S17 in FIG. 6).

  Next, an operation when the receiving terminal 2 performs secondary distribution of content data to other receiving terminals 3 will be described. In this case, in FIG. 1, the receiving terminal 2 first creates secondary distribution request information 5 according to the flowchart shown in FIG. 7 and supplies it to the data supply station 1, and the data supply station that has received the secondary distribution request information 5 1 creates secondary distribution information 6 according to the flowchart shown in FIG. 8 and transmits it to the receiving terminal 2 of the secondary distribution request source. As a result, the receiving terminal 2 creates a secondary distribution content data container 7 based on the secondary distribution information 6 according to the flowchart shown in FIG. 9 and transmits it to the receiving terminal 3 that is the secondary distribution request destination.

  Therefore, first, the process of creating the secondary distribution request information 5 by the receiving terminal 2 having the configuration of FIG. 3 will be described with reference to the flowchart of FIG. In FIG. 3, the receiving terminal 2 records the first data D1 and the third data D3 output from the validity confirmation unit 51 in the temporary recording unit 57 (step S21 in FIG. 7). Further, the receiving terminal 2 inputs the third data D3 together with the secondary distribution destination terminal identification information 58 and the secondary distribution source terminal identification information 59 to the package means 60 and combines them to receive them at the signature means 61. A digital signature is applied with the receiving terminal signature key 62 associated with the terminal 2, and this is sent to the data supply station 1 of FIG. 2 as the secondary distribution request information 5 described above (step S22 of FIG. 7).

  Next, the creation process of the secondary distribution information 6 by the data supply station 1 having the configuration shown in FIG. 2 will be described with reference to the flowchart of FIG. In FIG. 2, the data supply station 1 receives the secondary distribution request information 5 (step S25 in FIG. 8), and the unpacking means 29 converts it into the third data D3, the secondary distribution destination terminal identification information 58, and the secondary data. The distribution source terminal identification information 59 is separated (step S26 in FIG. 8).

  Subsequently, the data supply station 1 confirms the digital signature of the third data D3 with the supply station signature confirmation key 31 associated with the data supply station 1 in the signature confirmation unit 30 (step S27 in FIG. 8). If the signature cannot be verified normally, the process is interrupted (step S35 in FIG. 8). If the signature can be verified normally, the third data D3 is separated into the session ID 24 and the content encryption information 22 in the unpackage means 32.

  Subsequently, the decryption means 34 decrypts the content encryption information 22 with the supply station decryption key 33 corresponding to the supply station encryption key 21, and the unpackaging means 36 stores the content identification information (ID) 13 and the content key 14. Separate (step S28 in FIG. 8). The content identification information 13 is recorded in the transmission history DB 36 together with the secondary distribution destination terminal identification information 58, the secondary distribution source terminal identification information 59, and the session ID 24 (step S29 in FIG. 8).

  The secondary distribution source terminal identification information 59 is input to the terminal key DB 37, and based on this, the terminal signature confirmation key 38 related to the receiving terminal 2 is read from the terminal key DB 37 (step S30 in FIG. 8). Using the terminal signature confirmation key 38, the signature of the secondary distribution request information 5 is verified by the signature confirmation means 39 (step S31 in FIG. 8). If the signature is not properly verified, the process is interrupted and the process ends (step S35 in FIG. 8). If the signature is successfully verified, the secondary distribution destination terminal identification information 58 is input to the terminal key DB 37, and the secondary distribution destination terminal encryption key 40 corresponding to the secondary distribution destination terminal identification information 58 is the terminal key DB 37. (Step S32 in FIG. 8).

  Using the secondary distribution destination terminal encryption key 40, the content key 12 is encrypted by the encryption means 41 (step S33 in FIG. 8), and the session ID 24 is added to the content key 12 by the package means 42. The digital signature is made using the supply station signature key 44 related to the data supply station 1 and created as the secondary distribution information 6 described above (step S34 in FIG. 8), and the reception shown in FIGS. Transmit to terminal 2.

  Next, a process of creating the secondary distribution content data container 7 by the receiving terminal 2 having the configuration of FIG. 3 will be described with reference to the flowchart of FIG. In FIG. 3, when the receiving terminal 2 receives the secondary distribution information 6 from the data supply station 1 (step S41 in FIG. 9), the signature confirmation means 63 uses the supply station signature confirmation key 64 related to the data supply station 1 in the signature confirmation means 63. The signature of the secondary distribution information 6 is confirmed (step S42 in FIG. 9). If the signature is not properly verified, the processing is interrupted (step S47 in FIG. 9). As for the next distribution information 6, the session ID extraction means 65 extracts the session ID 24 (step S43 in FIG. 9).

  Next, data having the same session ID as the session ID 24 is read from the first data D1 and the third data D3 recorded in the temporary recording means 57 (steps S44 and S45 in FIG. 9). The secondary distribution information data container 7 is created by combining the received secondary distribution information 6 with the package means 66 (step S46 in FIG. 9). The secondary distribution content data container 7 completes the secondary distribution by transmitting it to the receiving terminal 3 as the secondary distribution destination (step S47 in FIG. 9). The receiving terminal 3 as the secondary distribution destination uses this in the same manner as the content data container received from the data supply station 1.

  The receiving terminal 3 that has received the secondary distribution can also perform secondary distribution to other receiving terminals by the same procedure. In this case, the secondary distribution request information from the receiving terminal 3 is transmitted to the data supply station 1 via the receiving terminal 2 or directly.

  Thus, according to the present embodiment, the data supply station 1 uses the encrypted content data to encrypt the content encryption information 22 that is encrypted with the supply station key by combining the content identification information for identifying the content data and the content key. 15 and the encrypted content key 18 are transmitted to the receiving terminal 2 as the content data container 4, and the receiving terminal 2 stores the content encryption information 22 together with the secondary distribution destination terminal identification information 58 of the receiving terminal 3 of the secondary distribution destination. By sending it back to the supply station 1, the content key encrypted with the encryption key 40 related to the secondary distribution destination terminal identification information 58 is received from the data supply station 1 as the secondary distribution information 6, and this is received as the encrypted content data and the encryption Since it is distributed to the receiving terminal 3 together with the encrypted content key, it is used for encrypting the content data 11. Ntsu key 12 it is not necessary to record in the data supply station 1, also it can be made unnecessary retention of the encryption key information for all other receiving terminal as the secondary distribution destination in the receiving terminal 2.

  Further, according to the present embodiment, the receiving terminal 2 does not hold the encryption key information of the other receiving terminals 3 of the secondary distribution destination, and only the secondary distribution destination terminal identification information 58 of the other receiving terminals 3. And the secondary distribution destination terminal identification information 58 and the secondary distribution destination terminal encryption key 40 are exchanged with the data supply station 1, so that the other receiving terminals 3 store the received content data container 4. The content data container 7 can be reconstructed.

  In the present invention, signal transmission between the data supply station 1 and the receiving terminal 2 and signal transmission between the receiving terminal 2 and the receiving terminal 3 include wireless transmission (including optical wireless transmission) and wired transmission. Either can be used. Further, instead of the above signal transmission, a recording medium in which the content data container 4 or 7 is recorded can be distributed, and further, the content data container 4 transmitted from the data supply station 1 using the communication network is received. It is also possible to distribute it so that the terminal 2 can download it.

1 is a system configuration diagram of a content distribution system to which an embodiment of a content distribution method of the present invention is applied. It is a block diagram of one Embodiment of the data supply station in FIG. It is a block diagram of one embodiment of the receiving terminal in FIG. It is a block diagram of one Embodiment of the validity confirmation means in FIG. 5 is a flowchart for explaining a content data container creation method according to the present invention. It is a flowchart for content data reproduction processing description by this invention. 5 is a flowchart for explaining a secondary distribution request information creation method according to the present invention. It is a flowchart for explaining the secondary distribution information creation method according to the present invention. 6 is a flowchart for explaining a method of creating a secondary distribution content data container according to the present invention.

Explanation of symbols

1 Data supply station 2 Receiving terminal A
3 Receiving terminal B
4 Content Data Container 5 Secondary Distribution Request Information 6 Secondary Distribution Information 7 Secondary Distribution Content Data Container 11 Content Data 12 Content Key 13 Content Identification Information (ID)
14, 16, 20, 41 Encryption means 15 Encrypted content data 17 Receiving terminal encryption key 18 Encrypted content key 19, 25, 28, 42, 60, 66 Package means 21 Supply station encryption key 22 Content encryption information 23 Session ID generation means 24 Session ID
26, 44 Supply station signature key 27, 43, 61 Sign means 29, 32, 35 Unpackage means 30, 39, 63 Signature confirmation means 31, 52, 64 Supply station signature confirmation key 33 Supply station decryption key 34, 54, 56 Decoding means 36 Transmission history database (DB)
37 Terminal Key Database (DB)
38 Terminal signature confirmation key 40 Secondary distribution destination terminal encryption key 51 Validity confirmation means 53 Validity confirmation result 55 Receiving terminal decryption key 57 Temporary storage means 58 Secondary distribution destination terminal identification information 59 Secondary distribution source terminal identification information 62 Reception Terminal signature key 65 Session ID extraction means D1 1st data D2 2nd data D3 3rd data

Claims (4)

A data supply station that combines encrypted content data obtained by encrypting content data with a content key and an encrypted content key encrypted so that the content key can be decrypted with a terminal key associated with the first receiving terminal In the content distribution method for transmitting from the first to the first receiving terminal,
The encrypted content data is the first data, the encrypted content key is the second data, and the supply station key associated with the data supply station by combining the content identification information for identifying the content data and the content key As the third data which is the content encryption information encrypted in step 1, the data supply station generates a content data container combining the first to third data, and transmits the content data container to the first receiving terminal. And the steps
A second step in which the first receiving terminal extracts the encrypted content key, the encrypted content data, and the first and third data from the received content data container;
The first receiving terminal combines the second data with secondary distribution destination identification information for identifying the second receiving terminal of the secondary distribution destination, and uses this as secondary distribution request information to the data supply station. A third step of transmitting;
A fourth step in which the data supply station receives the secondary distribution request information and separates secondary distribution destination identification information and the third data from the secondary distribution request information;
A fifth step in which the data supply station decrypts the third data separated in the fourth step with a supply station decryption key to obtain the content identification information and the content key;
Based on the secondary distribution destination identification information separated in the fourth step, the data supply station uses the secondary distribution destination encryption key associated with the second receiving terminal of the secondary distribution destination, A sixth step of encrypting the content key obtained in the step of generating the secondary distribution information and transmitting it;
The first receiving terminal receives the secondary distribution information created and transmitted in the fifth step, and the second distribution information is extracted as the second data in the second step. And a seventh step of creating a new secondary distribution content data container in combination with the first and third data, and the secondary distribution content data container created by the seventh step is 2 A content distribution method for distributing to the second receiving terminal as a next distribution destination. A data supply station that combines encrypted content data obtained by encrypting content data with a content key and an encrypted content key encrypted so that the content key can be decrypted with a terminal key associated with the first receiving terminal In the content distribution method for transmitting from the first to the first receiving terminal,
The data supply station applies a digital signature to a combination of the encrypted content data and a session ID with a supply station signature key associated with the data supply station as first data, and the encrypted content key and the data Data obtained by digitally signing with the supply station signature key to the data combined with the session ID is used as second data, and the content identification information for identifying the content data and the content key are combined and encrypted with the supply station key. Data obtained by digitally signing the content encryption information and the session ID with the supply station signature key is used as third data, and a content data container is generated by combining the first to third data. A first step of transmitting to the first receiving terminal;
The first receiving terminal verifies the validity of the received content data container by verifying a signature using a supply station signature confirmation key associated with the data supply station, and the three content data containers received. A second step of checking by session ID comparison,
When the first receiving terminal confirms the validity in the second step, the encrypted content key, the encrypted content data, and the first and third data are received from the received content data container. A third step of separating and removing
The first receiving terminal decrypts the encrypted content key separated in the third step with a terminal key to obtain the content key, and the encrypted content separated in the third step with the content key A fourth step of decrypting the data to obtain content data;
A fifth step in which the first receiving terminal temporarily stores the first and third data separated in the third step;
The first receiving terminal identifies secondary distribution destination identification information identifying the second receiving terminal of the secondary distribution destination in the third data separated in the third step, and secondary distribution of the terminal itself A sixth step of combining the original identification information, creating data with a digital signature with a terminal signature key associated with the own terminal as secondary distribution request information, and transmitting the data to the data supply station;
The data supply station receives the secondary distribution request information, separates the secondary distribution destination identification information, the secondary distribution source identification information, and the third data from the secondary distribution request information; A seventh step of separating the content encryption information and the session ID from third data;
An eighth step in which the data supply station obtains the content identification information and the content key by decrypting the content encryption information separated in the seventh step with a supply station decryption key;
Based on the secondary distribution source identification information separated in the seventh step, the data supply station uses the terminal signature confirmation key associated with the receiving terminal of the secondary distribution source to specify the secondary distribution request information. A ninth step of verifying the signature;
When the data supply station has successfully verified the signature in the ninth step, the data supply station determines the secondary distribution destination receiving terminal based on the secondary distribution destination identification information separated in the seventh step. A tenth step of encrypting the content key decrypted in the eighth step using an associated terminal encryption key;
Data obtained by applying a digital signature with a supply station signature key to data obtained by adding the session ID separated in the seventh step to the encrypted content key obtained in the tenth step by the data supply station is 2 An eleventh step of creating as next distribution information and transmitting to the first receiving terminal of the secondary distribution request source;
A twelfth step in which the first receiving terminal receives the secondary distribution information and verifies the signature with a supply station signature verification key associated with the data supply station;
A thirteenth step in which the first receiving terminal extracts the session ID from the secondary distribution information;
The first receiving terminal has the same session ID as the session ID extracted in the thirteenth step from the first data and the third data temporarily stored in the fifth step. Is added, and the secondary distribution information whose signature has been successfully confirmed in the twelfth step is combined with the second data as a new content data container for secondary distribution. A second distribution terminal that distributes the content data container for secondary distribution created in the fourteenth step to the second receiving terminal that is the secondary distribution destination. A content distribution method characterized by: A data supply station used in the content distribution method according to claim 2,
Secondary distribution of the secondary distribution destination identification information and the secondary distribution source identification information obtained by separation in the seventh step and the content identification information obtained by decryption in the eighth step, respectively. A data supply station comprising transmission history storage means for storing history information. First encryption means for encrypting arbitrary content data so that it can be decrypted with an arbitrary content key, and obtaining encrypted content data;
A second encryption means for encrypting the content key so that it can be decrypted with a terminal key associated with the receiving terminal to obtain an encrypted content key;
Content identification information for identifying the content data; and a third encryption unit that obtains content encryption information by combining the content key and encrypting with a supply station key associated with the local station;
A data supply station comprising: content data container creation / transmission means for creating and transmitting a content data container combining the encrypted content data, the encrypted content key, and the content encryption information.

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