WO2019167126A1 - Content data distribution system, content reproduction system, content data distribution method and program - Google Patents

Content data distribution system, content reproduction system, content data distribution method and program Download PDF

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Publication number
WO2019167126A1
WO2019167126A1 PCT/JP2018/007284 JP2018007284W WO2019167126A1 WO 2019167126 A1 WO2019167126 A1 WO 2019167126A1 JP 2018007284 W JP2018007284 W JP 2018007284W WO 2019167126 A1 WO2019167126 A1 WO 2019167126A1
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WO
WIPO (PCT)
Prior art keywords
terminals
content data
distributed
pieces
restored
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PCT/JP2018/007284
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French (fr)
Japanese (ja)
Inventor
崇 園田
栗原　洋介
航洋 竹之下
将仁 谷口
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株式会社ウフル
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Priority to PCT/JP2018/007284 priority Critical patent/WO2019167126A1/en
Publication of WO2019167126A1 publication Critical patent/WO2019167126A1/en

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
    • G06F21/60—Protecting data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/238—Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams
    • H04N21/2387—Stream processing in response to a playback request from an end-user, e.g. for trick-play

Definitions

  • the present invention relates to a content data distribution system, a content reproduction system, a content data distribution method, and a program used in the field of IoT (Internet of Things).
  • IoT Internet of Things
  • Patent Document 1 a technique for shortening the waiting time until the start of reproduction in video distribution is provided.
  • Patent Document 1 With the technology of Patent Document 1, it is impossible to produce content such as video and music only when the situation is limited.
  • the present invention provides a technique for restoring content data from distributed pieces when a plurality of terminals that have received any of the distributed pieces generated from the content data satisfy a predetermined condition.
  • the content data distribution system includes a generating unit that generates different n pieces (n is an integer of 2 or more) from content data according to a secret sharing method, and a hash of the n pieces of distributed pieces A calculation means for calculating each value, a distribution means for distributing one or more of the n distributed pieces to each of a plurality of terminals, and two or more of the plurality of terminals to the terminal.
  • the dispersed pieces were respectively obtained from the two or more terminals, a contents data distribution system having a restoring means for restoring the contents data based on the dispersion piece.
  • the content data distribution system is the content data distribution system according to the first aspect, wherein the generating means is based on any different k pieces (k is an integer of 2 or more and n or less). The n pieces of distributed pieces are generated so that the content data can be restored, and the determination unit is configured so that each of the acquired different hash values is identical to any one of the calculated hash values. In the content data distribution system, if there are k or more, the content data is determined to be recoverable.
  • the content data distribution system according to claim 3 of the present invention is the content data distribution system according to claim 1 or 2, wherein the acquisition unit acquires position information indicating the position of the terminal from the two or more terminals.
  • the determination means determines that the content data from the distribution piece is determined that the two or more terminals satisfy a predetermined condition when the positions indicated by the position information of the two or more terminals are within a predetermined range.
  • a content data distribution system for determining whether or not restoration is possible.
  • the content data distribution system according to claim 4 of the present invention is the content data distribution system according to claim 1 or 2, wherein the acquisition means accesses the predetermined device from the two or more terminals via a communication line. Access information indicating whether or not each of the two or more terminals is accessing the device based on the access information. It is a content data distribution system that determines whether or not the content data can be restored from the distributed piece, assuming that the terminal satisfies a predetermined condition.
  • a content reproduction system uses the distribution system according to any one of claims 1 to 4 and the content data restored by the distribution system to handle the content data.
  • a content playback system having playback means for playing back the content to be played.
  • the content data distribution method includes a step of generating different n pieces (n is an integer of 2 or more) of distributed pieces from content data according to a secret sharing method, and hash values of the n pieces of distributed pieces.
  • n is an integer of 2 or more
  • Each of the plurality of terminals, one or more of the n distributed pieces distributed to each of the plurality of terminals, and two or more of the plurality of terminals distributed to the terminals Obtaining each hash value of the distributed pieces, and when the two or more terminals satisfy a predetermined condition, based on the obtained hash value and the calculated hash value, Determining whether or not the content data can be restored from the distributed pieces distributed to two or more terminals, and determining that the content data can be restored
  • the dispersed pieces were respectively obtained from the two or more terminals, a contents data distribution method and a step of restoring the contents data based on the dispersion piece.
  • Each of the plurality of terminals, one or more of the n distributed pieces distributed to each of the plurality of terminals, and two or more of the plurality of terminals distributed to the terminals Obtaining each hash value of the distributed pieces, and when the two or more terminals satisfy a predetermined condition, based on the obtained hash value and the calculated hash value, Determining whether the content data can be restored from the distributed pieces distributed to two or more terminals, and determining that the content data can be restored.
  • FIG. 7 is a sequence diagram showing a flow of operations of the content reproduction system 9. The figure for demonstrating determination of the restoration possibility of content data. The figure which shows the example of the message displayed on the terminal 2. FIG. The figure for demonstrating the dispersion piece in a modification. The figure which shows the example of the content table 121 in a modification.
  • FIG. 1 is a diagram showing a configuration of a content reproduction system 9 according to the present embodiment.
  • the content reproduction system 9 includes a distribution system C, a plurality of terminals 2, and a communication line 3 that connects these terminals so that they can communicate with each other.
  • the distribution system C is a so-called cloud in which a plurality of distribution apparatuses 1 communicate with each other and share resources provided in each of them, and is a content data distribution system in the present invention.
  • the content data distribution system according to the present invention is a system that supplies content data to terminals that satisfy a predetermined condition. The distribution data generated based on the content data is distributed and the content data itself is distributed. You don't have to.
  • the plurality of distribution apparatuses 1 constituting the distribution system C may communicate with each other using, for example, an ad hoc mode in IEEE 802.11. Further, these distribution apparatuses 1 may communicate with each other via the communication line 3.
  • the plurality of terminals 2 are terminal devices each possessed by a user, such as a personal computer and a smartphone. Each of the terminals 2 is connected to the distribution system C via the communication line 3 and receives a distributed piece from the distribution device 1.
  • the communication line 3 is a line that connects the distribution apparatus 1 and the terminal 2 so as to communicate with each other, and is, for example, the Internet.
  • the communication line 3 may include a relay device such as a gateway or a router that relays communication with the distribution apparatus 1 or the terminal 2.
  • FIG. 2 is a diagram illustrating an example of the configuration of the distribution apparatus 1.
  • the distribution apparatus 1 includes a control unit 11, a storage unit 12, and a communication unit 13.
  • any of the plurality of distribution devices 1 may include the display unit 15 or the sound emitting unit 16.
  • the control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and a computer program (hereinafter simply referred to as a program) in which the CPU is stored in the ROM and the storage unit 12. Are read out and executed to control each part of the distribution apparatus 1.
  • a CPU Central Processing Unit
  • ROM Read Only Memory
  • RAM Random Access Memory
  • the communication unit 13 is a communication circuit connected to the communication line 3 by wire or wireless.
  • the communication unit 13 may have a function of directly connecting to another distribution device 1 by wire or wireless.
  • the distribution apparatus 1 exchanges information with the terminal 2 connected to the communication line 3 by the communication unit 13.
  • the display unit 15 has a display screen such as a liquid crystal display, and displays an image under the control of the control unit 11.
  • the image displayed by the display unit 15 may be a still image such as a photograph or an illustration, or may be a moving image that changes over time.
  • the sound emitting unit 16 is a speaker or the like that emits sound under the control of the control unit 11.
  • the delivery apparatus 1 does not need to have the display part 15 and the sound emission part 16, and may have only one among these.
  • the storage unit 12 is a storage unit such as a solid state drive or a hard disk drive, and stores various programs, data, and the like read by the CPU of the control unit 11.
  • the storage unit 12 includes a content table 121, a distributed fragment table 122, and a hash value table 123.
  • FIG. 3 is a diagram showing an example of the content table 121.
  • the content table 121 stores a content ID, which is identification information for identifying content, and data indicating the content (referred to as content data) in association with each other.
  • the storage unit 12 stores a plurality of contents using the content table 121.
  • the content is information created for, for example, art, education, entertainment, etc., and is expressed by a character string, an image, music, a movie, a video, or the like.
  • the control unit 11 reads the content data, displays the video on the display unit 15, and releases the sound to the sound emitting unit 16, thereby reproducing the video work, the music work, and the like.
  • the storage unit 12 does not have to store the content table 121.
  • FIG. 4 is a diagram showing an example of the dispersion piece table 122.
  • the distributed piece table 122 stores a plurality of distributed pieces generated based on content data in association with content IDs.
  • each of the plurality of dispersion pieces is associated with a dispersion piece ID which is identification information for identifying each of the plurality of dispersion pieces.
  • the plurality of dispersed pieces are configured so that the original content data cannot be restored even if they are each alone. That is, the original content data is not restored unless at least two distributed pieces are used.
  • FIG. 5 is a diagram illustrating an example of the hash value table 123.
  • the hash value table 123 stores each hash value of each dispersion piece in association with each dispersion piece ID. As shown in FIG. 5, the hash value table 123 may be associated with the content ID of the content data for each content data that is the basis of each distributed piece.
  • the hash value stored in the hash value table 123 is a value calculated from the dispersion piece identified by the corresponding dispersion piece ID, and is a value representing the dispersion piece.
  • the hash value has a smaller data amount than the original distributed piece.
  • the same hash value is always calculated from the same distributed piece. On the other hand, it is extremely rare that the same hash value is calculated from different dispersion pieces, and this is practically impossible.
  • This hash value is calculated by, for example, a cryptographic hash function such as MD5 (Message Digest AlgorithmS5) or SHA (Secure Hash Algorithm). And it is impossible to restore the original distributed piece from this hash value.
  • the hash value since the hash value is actually different for each original distributed piece, it functions as identification information for identifying the distributed piece. Therefore, in the distributed piece table 122, a hash value may be used instead of the distributed piece ID. In this case, the distribution piece table 122 may also serve as the hash value table 123.
  • FIG. 6 is a diagram illustrating an example of the configuration of the terminal 2.
  • the terminal 2 includes a control unit 21, a storage unit 22, a communication unit 23, an operation unit 24, a display unit 25, a sound emitting unit 26, and a positioning unit 27.
  • the control unit 21 includes a CPU, a ROM, and a RAM, and controls each unit of the terminal 2 when the CPU reads and executes a program stored in the ROM and the storage unit 22.
  • the storage unit 22 is a storage unit such as a solid state drive or a hard disk drive, and stores various programs, data, and the like read by the CPU of the control unit 21.
  • the communication unit 23 is a communication circuit connected to the communication line 3 by wire or wireless.
  • the terminal 2 exchanges information with the distribution device 1 connected to the communication line 3 by the communication unit 23.
  • the operation unit 24 includes operation buttons such as operation buttons, a keyboard, and a touch panel for giving various instructions.
  • the operation unit 24 receives an operation by the user and sends a signal corresponding to the operation content to the control unit 21.
  • the display unit 25 has a display screen such as a liquid crystal display, and displays an image under the control of the control unit 21.
  • a transparent touch panel of the operation unit 24 may be disposed on the display screen.
  • the sound emitting unit 26 is a speaker or the like that emits sound under the control of the control unit 21.
  • the positioning unit 27 is a device that measures the position of itself (terminal 2).
  • the positioning unit 27 is a receiver that receives navigation signals from a plurality of navigation satellites based on a global positioning satellite system (GNSS: Global Navigation Satellite System).
  • GNSS Global Navigation Satellite System
  • the positioning unit 27 may include a processor that measures (calculates) the position of the terminal 2 based on the received navigation signal.
  • the control unit 21 may measure the position of the terminal 2 using a plurality of navigation signals received by the positioning unit 27.
  • the means by which the positioning unit 27 measures the position is not limited to GNSS.
  • the positioning unit 27 measures the position of the terminal 2 by receiving a beacon transmitted from a beacon transmitter installed at a predetermined location and extracting information on a position included in the beacon. Also good.
  • the positioning unit 27 may cooperate with an entrance / exit system that manages entrance / exit in a predetermined area such as a station or a commercial facility by short-range wireless communication such as RFID (radio frequency identifier).
  • the positioning unit 27 may measure the position of the terminal 2 using the entry record written by the entry / exit system. That is, the positioning unit 27 measures whether or not the terminal 2 exists inside a predetermined area where entry / exit is managed by the entrance / exit system as position information of the terminal 2.
  • the positioning unit 27 may measure the position of the terminal 2 using position information provided from the base station.
  • the terminal 2 is not located within the determined range and communication with the distribution system C is not possible, the distribution system C is communicating with one of the distribution devices 1 itself. Thus, it can be determined that the terminal 2 is located within the determined range. In this case, the terminal 2 may not have the positioning unit 27.
  • FIG. 7 is a diagram illustrating a functional configuration of the distribution apparatus 1.
  • the communication line 3 and the communication unit 13 are omitted.
  • the control unit 11 of the distribution apparatus 1 reads out and executes a program stored in the storage unit 12, thereby generating a generation unit 111, a calculation unit 112, a distribution unit 113, an acquisition unit 114, a determination unit 115, and a restoration unit 116. Function as. Further, as shown in FIG. 7, when at least one of the display unit 15 and the sound emitting unit 16 is provided in the distribution device 1, the control unit 11 may function as the reproducing unit 117 by controlling them.
  • control unit 11 of one distribution device may be realized by the control unit 11 of one distribution device 1, but the control units 11 of the plurality of distribution devices 1 constituting the distribution system C communicate with each other to perform mutual computation functions. Alternatively, it may be realized by sharing resources such as storage contents of the storage unit 12.
  • the generation unit 111 reads content data corresponding to the specified content ID from the content table 121 of the storage unit 12, and generates n different pieces of distribution from the content data according to the secret sharing method.
  • n is an integer of 2 or more.
  • the distributed piece is data used to restore the content data. As described above, the generation unit 111 generates n distributed pieces so that the original content data is not restored unless at least two or more distributed pieces are used.
  • the calculating means 112 reads the dispersion pieces from the dispersion piece table 122 and calculates the hash values of these dispersion pieces.
  • the calculated hash value is stored in the hash value table 123 in association with the dispersion piece ID for identifying the original dispersion piece.
  • the distribution unit 113 distributes at least one of the n distributed pieces to each of the plurality of terminals 2.
  • the distribution unit 113 may select and distribute a distributed piece that cannot be predicted by the user of the terminal 2 using, for example, a pseudo random number sequence.
  • the distribution unit 113 may determine the number of distributed pieces to be distributed to the user's terminal 2 according to the user's instruction, payment amount, class assigned in advance, or the like.
  • the terminal 2 that has received the distributed piece from the distribution apparatus 1 stores the distributed piece in the storage unit 22 and calculates a hash value of the distributed piece.
  • the hash function used for this calculation is the same as the hash function used when the control unit 11 of the distribution apparatus 1 functions as the calculation unit 112. Therefore, the hash values calculated by the distribution apparatus 1 and the terminal 2 for the common distributed piece are the same value.
  • the obtaining unit 114 obtains the hash values of the distributed pieces distributed to the terminals 2 from two or more terminals 2 among the plurality of terminals 2.
  • the hash value acquired by the acquisition unit 114 is a hash value calculated in the terminal 2.
  • the acquisition unit 114 acquires position information indicating the position where the terminal 2 exists in association with the hash value described above from the terminal 2.
  • the determination unit 115 distributes to the terminals 2 based on the hash value acquired by the acquisition unit 114 and the hash value calculated by the calculation unit 112. It is determined whether or not the content data can be restored from the distributed pieces.
  • the determination unit 115 specifies the position of each of the terminals 2 based on the position information acquired by the acquisition unit 114 from two or more terminals 2. And the determination means 115 determines whether those terminals 2 are gathering in the predetermined place by determining whether those positions are in the determined range.
  • the determination unit 115 When determining that two or more terminals 2 are gathered at a predetermined place, the determination unit 115 stores the hash value acquired by the acquisition unit 114 from those terminals 2 and the hash value table 123 of the storage unit 12. Compare the hash value with Thereby, the determination unit 115 determines whether or not the original content data can be restored from the distributed pieces distributed to the terminals 2 gathered at the predetermined location.
  • n different distributed pieces generated from one piece of content data by the generation unit 111 have a property that the original content data cannot be restored unless all of them are prepared. Therefore, the determination unit 115 matches the different hash values acquired from the two or more terminals 2 described above with one of the n hash values associated with one content ID in the hash value table 123. When the number is n, it is determined that the original content data can be restored.
  • the restoration unit 116 acquires the respective distributed pieces from the two or more terminals 2 and restores the content data based on the distributed pieces.
  • Reproduction means 117 reproduces content corresponding to the content data using the restored content data.
  • the content data restored by the restoration unit 116 may be supplied (distributed) to the terminal 2 and used for content reproduction in the terminal 2.
  • the control unit 21 of the terminal 2 displays the video on the display unit 25 among the content indicated by the content data, and sends the sound to the sound emitting unit 26. By outputting the content, the content is reproduced.
  • the control unit 21 functions as a playback unit that plays back the content corresponding to the content data using the content data restored by the distribution system C.
  • FIG. 8 is a sequence diagram showing a flow of operations of the content reproduction system 9.
  • FIG. 8A shows the operation until the distributed piece is distributed from the distribution system C to the terminal 2
  • FIG. 8B shows the operation until the content data is restored and the content is reproduced.
  • the operations performed by the distribution system C shown below are performed by any one of the distribution devices 1 constituting the distribution system C, but the operations of each step are performed by different distribution devices 1 even if performed by the same distribution device 1. Also good.
  • the distribution system C reads, for example, content data indicating content produced by a certain artist from the storage unit 12 of any of the distribution apparatuses 1 constituting the content system C. N different dispersion pieces are generated based on (Step S101). Further, the distribution system C calculates the hash values of the generated n distributed pieces (step S102).
  • the distribution system C distributes one or more of the generated n distributed pieces to the terminals 2 possessed by the plurality of fans (users) of the artist described above (step S103).
  • the terminal 2 that has received one or more distributed pieces calculates a hash value of the distributed piece (step S104), and stores the calculated hash value and the original distributed piece in the storage unit 22 in association with each other (step S104). S105).
  • the terminal 2 performs positioning for measuring its own position (step S200).
  • the distribution system C acquires position information indicating its own position obtained by positioning by the plurality of terminals 2 and a hash value of the distributed piece (step S201).
  • the distribution system C determines whether or not these terminals 2 are gathered at a predetermined location based on the position information of the plurality of terminals 2, and when determining that they are gathered, the hash acquired from these terminals 2 The value is compared with the hash value stored in the distribution system C to determine whether the content data can be restored from the distributed pieces distributed to these terminals 2 (step S202).
  • FIG. 9 is a diagram for explaining determination of whether or not content data can be restored.
  • the distribution system C generates five different distributed pieces from the distributed piece D1 to the distributed piece D5 from one content data, and randomly distributes one of the distributed pieces. Delivered to the terminal 2. Seven users U1 to U7 each have a terminal 2, and any one of the dispersion pieces D1 to D5 is distributed to each of these terminals 2. Distributed pieces D1, D2, D3, D4, and D5 are distributed to terminals 2 owned by users U1, U2, U3, U4, and U5, respectively. Also, distributed pieces D2 and D1 are distributed to terminals 2 owned by users U6 and U7, respectively.
  • the distribution system C determines that the content data can be restored from the distributed pieces acquired from the terminals 2 possessed by these users.
  • the distribution system C can restore the content data. judge.
  • the dispersion piece D1 is not stored in any of the terminals 2 possessed by these users. That is, since all five different dispersion pieces are not prepared, the distribution system C determines that the content data cannot be restored.
  • the distribution system C may send information indicating the dispersion piece ID for identifying the dispersion piece that is lacking to the terminals 2 of all users constituting the group G3.
  • the terminal 2 that has received this information may display a message corresponding to the number of the dispersed pieces that are insufficient and the identification information.
  • FIG. 10 is a diagram illustrating an example of a message displayed on the terminal 2.
  • the five different dispersion pieces described above are associated with the five pieces constituting the puzzle shown in FIG. 10 in advance.
  • the user terminal 2 displays a character string representing a message “one piece is not enough!” Together with the image shown in FIG.
  • the image shown in FIG. 10 since only one piece at the lower right is displayed in a color different from the other four pieces, the user who sees this image knows which dispersion piece is lacking. .
  • the message displayed on the terminal 2 is not limited to that described above.
  • the message may display, for example, a picture of a musical instrument such as a piano, a drum, a guitar, or a bass, and express a lack of dispersed pieces by their colors.
  • this message may notify the user only of the fact that the distribution pieces necessary for restoring the content data are insufficient, and may not notify the user of the number of distribution pieces that are insufficient.
  • a user who gathered at the above-mentioned place and viewed the above-mentioned image can use other social networking services (social networking service, social networking service, etc.)
  • social networking service social networking service, etc.
  • a message such as “People who have a piece in the lower right, gather at the venue” can be called.
  • the distribution system C acquires the distributed pieces from these terminals 2 (step S203). Then, the distribution system C restores the content data based on the acquired plurality of dispersed pieces (step S204).
  • the distribution system C supplies the restored content data to each of the plurality of terminals 2 described above (step S205). These terminals 2 use the supplied content data to reproduce content corresponding to the content data (step S206).
  • step S206 may be performed in the distribution system C.
  • the distribution system C may not perform step S205.
  • ⁇ Modification 1> content such as video and music is played back only when a plurality of terminals 2 are gathered at a predetermined location, but the conditions for playing back the content are not limited to this. That is, the distribution system C only needs to be configured to reproduce content such as video and music only when two or more terminals satisfy a predetermined condition.
  • the acquisition unit 114 realized by the control unit 11 of the distribution apparatus 1 associates the hash value described above with each of the two or more terminals 2 and the terminal 2 accesses a predetermined apparatus via the communication line 3. You may acquire the access information which shows whether it is doing.
  • the determining unit 115 when it is determined that each of the terminals 2 is accessing the above-described device based on the access information acquired by the acquiring unit 114, the determining unit 115 satisfies the predetermined condition. It may be determined that If it is determined that the terminal 2 satisfies the predetermined condition, the determination unit 115 is distributed to the terminal 2 based on the hash value acquired by the acquisition unit 114 and the hash value calculated by the calculation unit 112. It may be determined whether or not the content data can be restored from the distributed pieces.
  • the generation unit 111 generates n distributed pieces that cannot be restored without using the original content data according to the secret sharing method. N pieces of distributed pieces may be generated so that the content data can be restored. In this case, the generation unit 111 may generate n distributed pieces from the content data using a so-called (k, n) threshold secret sharing method.
  • the (k, n) threshold secret sharing method is a secret sharing method using, for example, a Shamir polynomial or an exclusive OR.
  • the original content data can be decrypted from arbitrarily different k distributed pieces among the generated n distributed pieces, but arbitrarily different ( No information of the original content data can be obtained from k ⁇ 1) pieces of dispersion.
  • This k is an integer not less than 2 and not more than n.
  • the generation unit 111 may generate n distributed pieces so that the content data can be restored based on arbitrarily different k pieces (k is an integer of 2 or more and n or less). .
  • the determination unit 115 can restore the content data when the acquired plurality of different hash values match any one of the hash values calculated by the calculation unit 112 and there are k or more. Judge that there is.
  • the generation unit 111 may use the (k, L, n) threshold secret sharing method instead of the (k, n) threshold secret sharing method.
  • the original content data can be decoded from any of the k different distributed pieces, The original content data information cannot be obtained from any different (kL) distributed pieces.
  • the (k, L, n) threshold value secret sharing method information of the original content data is partially obtained from arbitrarily different (k ⁇ L + 1) to (k ⁇ 1) distributed pieces. Is obtained.
  • the generation unit 111 generates n distributed pieces so that the content data can be restored based on any two or more and n or less different distributed pieces.
  • the number of the dispersed pieces that can be restored when they are aligned does not have to be set to one.
  • FIG. 11 is a diagram for explaining a dispersion piece in this modification.
  • the generation unit 111 realized by the control unit 11 of the distribution apparatus 1 divides the content data into two or more different data (hereinafter referred to as divided data).
  • the content data is divided into six different pieces of divided data E1 to E6. These six pieces of divided data E1 to E6 are divided so that the original content data cannot be restored unless all of them are prepared.
  • the secret sharing method is used as a method for dividing content data, the different pieces of divided data obtained are pieces of information that do not make sense on their own. The security is ensured as compared with the case of using an algorithm that is considered to be safe.
  • the generation means 111 generates a dispersion piece identified by each dispersion piece ID as shown in FIG.
  • the dispersion piece D1 includes only the divided data E1, E2, and E3
  • the distribution piece D2 includes only the divided data E2, E3, and E4
  • the dispersion piece D3 includes only the divided data E3, E4, and E5.
  • the distributed piece D4 includes only the divided data E4, E5, and E6,
  • the distributed piece D5 includes only the divided data E1, E5, and E6.
  • the number of distributed pieces, the number of divided data, and the type and number of divided data included in each distributed piece are not limited to those shown in FIG.
  • the dispersion piece D1 and the dispersion piece D4 are gathered, all the six pieces of divided data E1 to E6 are obtained, so that the original content data can be restored.
  • the divided data E6 among the divided data E1 to E6 cannot be obtained. Therefore, as shown in FIG. 11, when generating dispersed pieces, the number of dispersed pieces that can be restored when they are aligned is not limited to one.
  • the distribution system C generates n different distributed pieces from one piece of content data.
  • the distribution system C generates encrypted data by encrypting the content data with the determined key data, and this key. N different distributed pieces may be generated from the data.
  • FIG. 12 is a diagram showing an example of the content table 121 in this modification.
  • the distribution system C individually generates key data that cannot be predicted by the user using, for example, a pseudo random number, for each piece of content data associated with the content ID, and performs encryption using the key data. Then, the distribution system C associates the key data used for encryption and the encrypted data generated by the encryption with the content ID.
  • the distribution system C generates n different distributed pieces from the key data and distributes one of them to the terminal 2.
  • the distribution system C acquires hash values of the distributed pieces distributed to the terminals 2 from the two or more terminals 2, and when the terminals 2 satisfy a predetermined condition, Based on the hash value calculated in the distribution system C, it is determined whether or not the original key data can be restored from the distributed pieces distributed to those terminals 2.
  • the distribution system C When determining that the original key data can be restored, the distribution system C obtains each distributed piece from the terminals 2 and restores the key data. The distribution system C reads the encrypted data from the content table 121 and applies the restored key data to restore the original content data.
  • the content data stored in the content table 121 may be deleted after the encrypted data is generated.
  • the key data stored in the content table 121 may be deleted after generating n distributed pieces from the key data.
  • the content data (content data in a narrow sense) of this modification can be said to be content data (content data in a broad sense) of the present invention in combination with key data.
  • the distribution apparatus 1 of this modification generates encrypted data by applying key data to content data (narrowly defined content data), and distributes n pieces of data from the key data (widely defined content data) according to a secret sharing method. It is possible to determine whether or not the content data can be restored from the obtainable distributed pieces by generating pieces and comparing the hash values calculated by the distribution device 1 and the terminal 2 for each of the pieces. When it is determined that the content data (in a narrow sense) is obtained by acquiring the distributed pieces, restoring the key data from the distributed pieces and applying the data to the encrypted data.
  • the process executed by the control unit 11 of the distribution apparatus 1 can be considered as a distribution method of content data (including distributed pieces generated from the content data). That is, according to the present invention, the generation unit generates different n pieces (n is an integer of 2 or more) from the content data according to the secret sharing method, and the calculation unit obtains the hash values of the n pieces.
  • the step of acquiring the hash value of each distributed piece distributed to the terminal and the determination means are calculated by the calculation means and the hash value acquired by the acquisition means when two or more terminals satisfy a predetermined condition.
  • the program executed by the control unit 11 of the distribution apparatus 1 is a recording medium readable by a computer device, such as a magnetic recording medium such as a magnetic tape and a magnetic disk, an optical recording medium such as an optical disk, a magneto-optical recording medium, or a semiconductor memory. Can be provided in a stored state.
  • the program may be downloaded via a communication line such as the Internet.
  • various devices other than the CPU may be applied as the control means exemplified by the control unit 11 described above. For example, a dedicated processor or the like is used.

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Abstract

Provided is a system used in the field of the Internet of Things (IOT), more specifically, a distribution system for reconstructing content data from a plurality of dispersion pieces when a plurality of terminals that have respectively received arbitrary dispersion pieces satisfy a predetermined condition. A generation means 111 generates, from content data, n dispersion pieces different from each other according to a secret sharing method. A calculation means 112 calculates the hash values of the respective dispersion pieces. A distribution means 113 distributes an arbitrary dispersion piece from among the plurality of dispersion pieces to each of a plurality of terminals 2. An acquisition means 114 acquires each of the hash values of the dispersion pieces from two or more terminals. When the terminals 2 satisfy a predetermined condition, a determination means 115 compares the hash values acquired from the terminals 2 with the hash values calculated by the calculation means 112 and determines whether the content data can be reconstructed. When it is determined that reconstruction is possible, a reconstruction means 116 reconstructs the content data by acquiring the dispersion pieces from the respective terminals 2.

Description

コンテンツデータ配信システム、コンテンツ再生システム、コンテンツデータ配信方法、及びプログラムContent data distribution system, content reproduction system, content data distribution method, and program
　本発明は、ＩｏＴ（Internet　of　Things）の分野で利用されるコンテンツデータ配信システム、コンテンツ再生システム、コンテンツデータ配信方法、及びプログラムに関する。 The present invention relates to a content data distribution system, a content reproduction system, a content data distribution method, and a program used in the field of IoT (Internet of Things).
　近年、映像や音楽の再生に関する技術が注目されている。例えば、映像配信における再生開始までの待ち時間を短縮する技術が提供されている（特許文献１）。 In recent years, technology related to video and music playback has attracted attention. For example, a technique for shortening the waiting time until the start of reproduction in video distribution is provided (Patent Document 1).
特開２０１６－１３４７０１号公報JP 2016-134701 A
　しかしながら、特許文献１の技術では、限られた状況にあるときにだけ映像や音楽等のコンテンツを再生する演出は出来ない。 However, with the technology of Patent Document 1, it is impossible to produce content such as video and music only when the situation is limited.
　本発明は、コンテンツデータから生成された複数の分散片のいずれかを受け取った複数の端末が決められた条件を満たしたときに、それらの分散片からコンテンツデータを復元する技術を提供する。 The present invention provides a technique for restoring content data from distributed pieces when a plurality of terminals that have received any of the distributed pieces generated from the content data satisfy a predetermined condition.
　本発明の請求項１に係るコンテンツデータ配信システムは、コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成する生成手段と、前記ｎ個の分散片のハッシュ値をそれぞれ算出する算出手段と、複数の端末のそれぞれに、前記ｎ個の分散片のいずれか１個以上を配信する配信手段と、前記複数の端末のうち２以上の端末から、該端末に配信された前記分散片のハッシュ値をそれぞれ取得する取得手段と、前記２以上の端末が所定の条件を満たしている場合に、前記取得されたハッシュ値と、前記算出されたハッシュ値と、に基づいて、前記２以上の端末に配信された前記分散片から前記コンテンツデータが復元可能か否かを判定する判定手段と、前記コンテンツデータが復元可能であると判定された場合に、前記２以上の端末から前記分散片をそれぞれ取得して、該分散片に基づいて前記コンテンツデータを復元する復元手段と、を有するコンテンツデータ配信システムである。 The content data distribution system according to claim 1 of the present invention includes a generating unit that generates different n pieces (n is an integer of 2 or more) from content data according to a secret sharing method, and a hash of the n pieces of distributed pieces A calculation means for calculating each value, a distribution means for distributing one or more of the n distributed pieces to each of a plurality of terminals, and two or more of the plurality of terminals to the terminal. An acquisition means for acquiring a hash value of the distributed fragment, and when the two or more terminals satisfy a predetermined condition, the acquired hash value and the calculated hash value; And determining means for determining whether or not the content data can be recovered from the distributed pieces distributed to the two or more terminals, and determining that the content data can be recovered The case, the dispersed pieces were respectively obtained from the two or more terminals, a contents data distribution system having a restoring means for restoring the contents data based on the dispersion piece.
　本発明の請求項２に係るコンテンツデータ配信システムは、請求項１に記載の態様において、前記生成手段は、任意の異なるｋ個（ｋは２以上かつｎ以下の整数）の前記分散片に基づいて前記コンテンツデータを復元可能になるように、前記ｎ個の分散片を生成し、前記判定手段は、前記取得された複数の異なるハッシュ値が、いずれも前記算出されたハッシュ値のいずれかと一致し、かつ、ｋ個以上ある場合に、前記コンテンツデータが復元可能であると判定することを特徴とするコンテンツデータ配信システムである。 The content data distribution system according to a second aspect of the present invention is the content data distribution system according to the first aspect, wherein the generating means is based on any different k pieces (k is an integer of 2 or more and n or less). The n pieces of distributed pieces are generated so that the content data can be restored, and the determination unit is configured so that each of the acquired different hash values is identical to any one of the calculated hash values. In the content data distribution system, if there are k or more, the content data is determined to be recoverable.
　本発明の請求項３に係るコンテンツデータ配信システムは、請求項１又は２に記載の態様において、前記取得手段は、前記２以上の端末から該端末の位置を示す位置情報をそれぞれ取得し、前記判定手段は、前記２以上の端末の位置情報がそれぞれ示す位置が決められた範囲内にある場合に、該２以上の端末が所定の条件を満たしているとして、前記分散片から前記コンテンツデータが復元可能か否かを判定することを特徴とするコンテンツデータ配信システムである。 The content data distribution system according to claim 3 of the present invention is the content data distribution system according to claim 1 or 2, wherein the acquisition unit acquires position information indicating the position of the terminal from the two or more terminals. The determination means determines that the content data from the distribution piece is determined that the two or more terminals satisfy a predetermined condition when the positions indicated by the position information of the two or more terminals are within a predetermined range. A content data distribution system for determining whether or not restoration is possible.
　本発明の請求項４に係るコンテンツデータ配信システムは、請求項１又は２に記載の態様において、前記取得手段は、前記２以上の端末から、該端末が通信回線を介して所定の装置にアクセスしているか否かを示すアクセス情報をそれぞれ取得し、前記判定手段は、前記アクセス情報に基づいて前記２以上の端末のそれぞれが前記装置にアクセスしていると判定される場合に、該２以上の端末が所定の条件を満たしているとして、前記分散片から前記コンテンツデータが復元可能か否かを判定することを特徴とするコンテンツデータ配信システムである。 The content data distribution system according to claim 4 of the present invention is the content data distribution system according to claim 1 or 2, wherein the acquisition means accesses the predetermined device from the two or more terminals via a communication line. Access information indicating whether or not each of the two or more terminals is accessing the device based on the access information. It is a content data distribution system that determines whether or not the content data can be restored from the distributed piece, assuming that the terminal satisfies a predetermined condition.
　本発明の請求項５に係るコンテンツ再生システムは、請求項１から４までのいずれか１項に記載の配信システムと、前記配信システムにより復元された前記コンテンツデータを用いて、該コンテンツデータに対応するコンテンツを再生する再生手段と、を有するコンテンツ再生システムである。 A content reproduction system according to claim 5 of the present invention uses the distribution system according to any one of claims 1 to 4 and the content data restored by the distribution system to handle the content data. A content playback system having playback means for playing back the content to be played.
　本発明の請求項６に係るコンテンツデータ配信方法は、コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成するステップと、前記ｎ個の分散片のハッシュ値をそれぞれ算出するステップと、複数の端末のそれぞれに、前記ｎ個の分散片のいずれか１個以上を配信するステップと、前記複数の端末のうち２以上の端末から、該端末に配信された前記分散片のハッシュ値をそれぞれ取得するステップと、前記２以上の端末が所定の条件を満たしている場合に、前記取得されたハッシュ値と、前記算出されたハッシュ値と、に基づいて、前記２以上の端末に配信された前記分散片から前記コンテンツデータが復元可能か否かを判定するステップと、前記コンテンツデータが復元可能であると判定された場合に、前記２以上の端末から前記分散片をそれぞれ取得して、該分散片に基づいて前記コンテンツデータを復元するステップと、を有するコンテンツデータ配信方法である。 The content data distribution method according to claim 6 of the present invention includes a step of generating different n pieces (n is an integer of 2 or more) of distributed pieces from content data according to a secret sharing method, and hash values of the n pieces of distributed pieces Each of the plurality of terminals, one or more of the n distributed pieces distributed to each of the plurality of terminals, and two or more of the plurality of terminals distributed to the terminals Obtaining each hash value of the distributed pieces, and when the two or more terminals satisfy a predetermined condition, based on the obtained hash value and the calculated hash value, Determining whether or not the content data can be restored from the distributed pieces distributed to two or more terminals, and determining that the content data can be restored The dispersed pieces were respectively obtained from the two or more terminals, a contents data distribution method and a step of restoring the contents data based on the dispersion piece.
　本発明の請求項７に係るプログラムは、コンピュータに、コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成するステップと、前記ｎ個の分散片のハッシュ値をそれぞれ算出するステップと、複数の端末のそれぞれに、前記ｎ個の分散片のいずれか１個以上を配信するステップと、前記複数の端末のうち２以上の端末から、該端末に配信された前記分散片のハッシュ値をそれぞれ取得するステップと、前記２以上の端末が所定の条件を満たしている場合に、前記取得されたハッシュ値と、前記算出されたハッシュ値と、に基づいて、前記２以上の端末に配信された前記分散片から前記コンテンツデータが復元可能か否かを判定するステップと、前記コンテンツデータが復元可能であると判定された場合に、前記２以上の端末から前記分散片をそれぞれ取得して、該分散片に基づいて前記コンテンツデータを復元するステップと、を実行させるためのプログラムである。 According to a seventh aspect of the present invention, there is provided a program for generating different n pieces (n is an integer of 2 or more) of distributed pieces from content data according to a secret sharing method, and hash values of the n pieces of distributed pieces. Each of the plurality of terminals, one or more of the n distributed pieces distributed to each of the plurality of terminals, and two or more of the plurality of terminals distributed to the terminals Obtaining each hash value of the distributed pieces, and when the two or more terminals satisfy a predetermined condition, based on the obtained hash value and the calculated hash value, Determining whether the content data can be restored from the distributed pieces distributed to two or more terminals, and determining that the content data can be restored. To the dispersed pieces were respectively obtained from the two or more terminals, a program for executing the steps of: restoring the contents data based on the dispersion piece.
　本願に係る発明によれば、複数の端末が決められた条件を満たしたときにのみ、映像や音楽等のコンテンツが再生される、という演出ができる。 According to the invention according to the present application, it is possible to produce an effect that content such as video and music is reproduced only when a plurality of terminals satisfy a predetermined condition.
本実施形態に係るコンテンツ再生システム９の構成を示す図。The figure which shows the structure of the content reproduction system 9 which concerns on this embodiment. 配信装置１の構成の例を示す図。The figure which shows the example of a structure of the delivery apparatus. コンテンツ表１２１の例を示す図。The figure which shows the example of the content table. 分散片表１２２の例を示す図。The figure which shows the example of the dispersion | distribution piece table | surface 122. ハッシュ値表１２３の例を示す図。The figure which shows the example of the hash value table 123. FIG. 端末２の構成の例を示す図。The figure which shows the example of a structure of the terminal 2. FIG. 配信装置１の機能的構成を示す図。The figure which shows the functional structure of the delivery apparatus. コンテンツ再生システム９の動作の流れを示すシーケンス図。FIG. 7 is a sequence diagram showing a flow of operations of the content reproduction system 9. コンテンツデータの復元可否の判定を説明するための図。The figure for demonstrating determination of the restoration possibility of content data. 端末２に表示されるメッセージの例を示す図。The figure which shows the example of the message displayed on the terminal 2. FIG. 変形例における分散片を説明するための図。The figure for demonstrating the dispersion piece in a modification. 変形例におけるコンテンツ表１２１の例を示す図。The figure which shows the example of the content table 121 in a modification.
１…配信装置、１１…制御部、１１１…生成手段、１１２…算出手段、１１３…配信手段、１１４…取得手段、１１５…判定手段、１１６…復元手段、１１７…再生手段、１２…記憶部、１２１…コンテンツ表、１２２…分散片表、１２３…ハッシュ値表、１３…通信部、１５…表示部、１６…放音部、２…端末、２１…制御部、２２…記憶部、２３…通信部、２４…操作部、２５…表示部、２６…放音部、２７…測位部、３…通信回線、９…コンテンツ再生システム、Ｇ１～Ｇ３…グループ。 DESCRIPTION OF SYMBOLS 1 ... Distribution apparatus, 11 ... Control part, 111 ... Generation means, 112 ... Calculation means, 113 ... Distribution means, 114 ... Acquisition means, 115 ... Determination means, 116 ... Restoration means, 117 ... Reproduction means, 12 ... Storage part, 121 ... Contents table, 122 ... Distributed fragment table, 123 ... Hash value table, 13 ... Communication unit, 15 ... Display unit, 16 ... Sound emission unit, 2 ... Terminal, 21 ... Control unit, 22 ... Storage unit, 23 ... Communication , 24 ... operation part, 25 ... display part, 26 ... sound emitting part, 27 ... positioning part, 3 ... communication line, 9 ... content reproduction system, G1 to G3 ... group.
＜実施形態＞
＜システムの全体構成＞
　図１は、本実施形態に係るコンテンツ再生システム９の構成を示す図である。コンテンツ再生システム９は、配信システムＣと、複数の端末２と、これらを通信可能に接続する通信回線３と、を有する。 <Embodiment>
<Overall system configuration>
FIG. 1 is a diagram showing a configuration of a content reproduction system 9 according to the present embodiment. The content reproduction system 9 includes a distribution system C, a plurality of terminals 2, and a communication line 3 that connects these terminals so that they can communicate with each other.
　配信システムＣは、複数の配信装置１が相互に通信して、それぞれに備えられたリソースを共有する、いわゆるクラウドであり、本発明におけるコンテンツデータ配信システムである。なお、本発明におけるコンテンツデータ配信システムは、所定の条件を満たした端末に対してコンテンツデータを供給するシステムであるが、コンテンツデータに基づいて生成された分散片を配信し、コンテンツデータ自体を配信しなくてもよい。配信システムＣを構成する複数の配信装置１は、例えばＩＥＥＥ８０２．１１におけるアドホック・モード等を利用して相互に通信を行ってもよい。また、これらの配信装置１は、それぞれが通信回線３を介して相互に通信を行ってもよい。 The distribution system C is a so-called cloud in which a plurality of distribution apparatuses 1 communicate with each other and share resources provided in each of them, and is a content data distribution system in the present invention. The content data distribution system according to the present invention is a system that supplies content data to terminals that satisfy a predetermined condition. The distribution data generated based on the content data is distributed and the content data itself is distributed. You don't have to. The plurality of distribution apparatuses 1 constituting the distribution system C may communicate with each other using, for example, an ad hoc mode in IEEE 802.11. Further, these distribution apparatuses 1 may communicate with each other via the communication line 3.
　複数の端末２は、パーソナルコンピュータや、スマートフォン等、ユーザがそれぞれ所持している端末装置であり、それぞれが通信回線３を経由して配信システムＣと接続し、配信装置１から分散片を受け取る。 The plurality of terminals 2 are terminal devices each possessed by a user, such as a personal computer and a smartphone. Each of the terminals 2 is connected to the distribution system C via the communication line 3 and receives a distributed piece from the distribution device 1.
　通信回線３は、配信装置１と端末２とを通信可能に接続する回線であり、例えばインターネット等である。通信回線３は、配信装置１又は端末２との通信を中継するゲートウェイ、ルータ等の中継機器を含んでもよい。 The communication line 3 is a line that connects the distribution apparatus 1 and the terminal 2 so as to communicate with each other, and is, for example, the Internet. The communication line 3 may include a relay device such as a gateway or a router that relays communication with the distribution apparatus 1 or the terminal 2.
＜配信装置の構成＞
　図２は、配信装置１の構成の例を示す図である。配信装置１は、制御部１１、記憶部１２、及び通信部１３を有する。また、複数の配信装置１のうち、いずれかは、表示部１５、又は放音部１６を有していてもよい。 <Configuration of distribution device>
FIG. 2 is a diagram illustrating an example of the configuration of the distribution apparatus 1. The distribution apparatus 1 includes a control unit 11, a storage unit 12, and a communication unit 13. In addition, any of the plurality of distribution devices 1 may include the display unit 15 or the sound emitting unit 16.
　制御部１１は、ＣＰＵ（Central Processing Unit）、ＲＯＭ（Read Only Memory）、ＲＡＭ（Random Access Memory）を有し、ＣＰＵがＲＯＭ及び記憶部１２に記憶されているコンピュータプログラム（以下、単にプログラムという）を読み出して実行することにより配信装置１の各部を制御する。 The control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and a computer program (hereinafter simply referred to as a program) in which the CPU is stored in the ROM and the storage unit 12. Are read out and executed to control each part of the distribution apparatus 1.
　通信部１３は、有線又は無線により通信回線３に接続する通信回路である。通信部１３は、有線又は無線により直接、他の配信装置１と接続する機能を有していてもよい。配信装置１は、通信部１３により通信回線３に接続された端末２と情報をやり取りする。 The communication unit 13 is a communication circuit connected to the communication line 3 by wire or wireless. The communication unit 13 may have a function of directly connecting to another distribution device 1 by wire or wireless. The distribution apparatus 1 exchanges information with the terminal 2 connected to the communication line 3 by the communication unit 13.
　表示部１５は、液晶ディスプレイ等の表示画面を有しており、制御部１１の制御の下、画像を表示する。表示部１５が表示する画像は、写真やイラスト等の静止画であってもよいし、時間の経過にともなって変化する動画であってもよい。 The display unit 15 has a display screen such as a liquid crystal display, and displays an image under the control of the control unit 11. The image displayed by the display unit 15 may be a still image such as a photograph or an illustration, or may be a moving image that changes over time.
　放音部１６は、制御部１１の制御の下で音声を放出するスピーカ等である。なお、配信装置１は、表示部１５及び放音部１６を有しなくてもよく、また、これらのうち、一方のみを有していてもよい。 The sound emitting unit 16 is a speaker or the like that emits sound under the control of the control unit 11. In addition, the delivery apparatus 1 does not need to have the display part 15 and the sound emission part 16, and may have only one among these.
　記憶部１２は、ソリッドステートドライブ、ハードディスクドライブ等の記憶手段であり、制御部１１のＣＰＵに読み込まれる各種のプログラム、データ等を記憶する。 The storage unit 12 is a storage unit such as a solid state drive or a hard disk drive, and stores various programs, data, and the like read by the CPU of the control unit 11.
　また、記憶部１２は、コンテンツ表１２１、分散片表１２２、及びハッシュ値表１２３を有する。 In addition, the storage unit 12 includes a content table 121, a distributed fragment table 122, and a hash value table 123.
　図３は、コンテンツ表１２１の例を示す図である。コンテンツ表１２１は、コンテンツを識別する識別情報であるコンテンツＩＤと、そのコンテンツを示すデータ（コンテンツデータという）とを対応付けて記憶する。記憶部１２は、コンテンツ表１２１により、複数のコンテンツを記憶する。コンテンツとは、例えば芸術や教養、娯楽等のために創作された情報であり、文字列や画像、音楽、動画、映像等で表現される。 FIG. 3 is a diagram showing an example of the content table 121. The content table 121 stores a content ID, which is identification information for identifying content, and data indicating the content (referred to as content data) in association with each other. The storage unit 12 stores a plurality of contents using the content table 121. The content is information created for, for example, art, education, entertainment, etc., and is expressed by a character string, an image, music, a movie, a video, or the like.
　制御部１１は、コンテンツデータを読み出して映像を表示部１５に表示させ、また、音声を放音部１６に放出させることにより、映像作品や音楽作品等を再生する。なお、配信装置１が１つのコンテンツを記憶する場合、記憶部１２は、コンテンツ表１２１を記憶しなくてもよい。 The control unit 11 reads the content data, displays the video on the display unit 15, and releases the sound to the sound emitting unit 16, thereby reproducing the video work, the music work, and the like. When the distribution device 1 stores one content, the storage unit 12 does not have to store the content table 121.
　図４は、分散片表１２２の例を示す図である。分散片表１２２は、コンテンツデータに基づいて生成された複数の分散片を、コンテンツＩＤと対応付けて記憶する。分散片表１２２において、複数の分散片の各々には、それぞれを識別する識別情報である分散片ＩＤが対応付けられる。 FIG. 4 is a diagram showing an example of the dispersion piece table 122. The distributed piece table 122 stores a plurality of distributed pieces generated based on content data in association with content IDs. In the dispersion piece table 122, each of the plurality of dispersion pieces is associated with a dispersion piece ID which is identification information for identifying each of the plurality of dispersion pieces.
　複数の分散片は、それぞれが単独では、たとえ部分的であっても元のコンテンツデータを復元することが不可能であるように構成されている。すなわち元のコンテンツデータは、少なくとも２以上の分散片を用いない限り復元されない。 The plurality of dispersed pieces are configured so that the original content data cannot be restored even if they are each alone. That is, the original content data is not restored unless at least two distributed pieces are used.
　図５は、ハッシュ値表１２３の例を示す図である。ハッシュ値表１２３は、分散片の各々のハッシュ値を、それぞれの分散片ＩＤと対応付けて記憶する。ハッシュ値表１２３は、図５に示す通り、それぞれの分散片の基礎となったコンテンツデータごとに、そのコンテンツデータのコンテンツＩＤと対応付けられてもよい。 FIG. 5 is a diagram illustrating an example of the hash value table 123. The hash value table 123 stores each hash value of each dispersion piece in association with each dispersion piece ID. As shown in FIG. 5, the hash value table 123 may be associated with the content ID of the content data for each content data that is the basis of each distributed piece.
　ハッシュ値表１２３に記憶されるハッシュ値は、対応する分散片ＩＤで識別される分散片から算出される値であり、その分散片を代表する値である。ハッシュ値は、元の分散片よりもデータ量が小さい。 The hash value stored in the hash value table 123 is a value calculated from the dispersion piece identified by the corresponding dispersion piece ID, and is a value representing the dispersion piece. The hash value has a smaller data amount than the original distributed piece.
　同一の分散片からは、必ず同一のハッシュ値が算出される。一方、異なる分散片から同一のハッシュ値が算出されることは極めて稀であり、事実上、起こり得ない。このハッシュ値は、例えば、ＭＤ５（Message Digest Algorithm 5）やＳＨＡ（Secure Hash Algorithm）等の暗号学的ハッシュ関数等により算出される。そして、このハッシュ値から元の分散片を復元することは不可能である。 The same hash value is always calculated from the same distributed piece. On the other hand, it is extremely rare that the same hash value is calculated from different dispersion pieces, and this is practically impossible. This hash value is calculated by, for example, a cryptographic hash function such as MD5 (Message Digest AlgorithmＳ5) or SHA (Secure Hash Algorithm). And it is impossible to restore the original distributed piece from this hash value.
　なお、ハッシュ値は、上述した通り、事実上、元の分散片ごとにそれぞれ異なるので、分散片を識別する識別情報として機能する。したがって、分散片表１２２では、分散片ＩＤに代えてハッシュ値が用いられてもよい。この場合、分散片表１２２は、ハッシュ値表１２３を兼ねてもよい。 Note that, as described above, since the hash value is actually different for each original distributed piece, it functions as identification information for identifying the distributed piece. Therefore, in the distributed piece table 122, a hash value may be used instead of the distributed piece ID. In this case, the distribution piece table 122 may also serve as the hash value table 123.
＜端末の構成＞
　図６は、端末２の構成の例を示す図である。端末２は、制御部２１、記憶部２２、通信部２３、操作部２４、表示部２５、放音部２６、及び測位部２７を有する。 <Terminal configuration>
FIG. 6 is a diagram illustrating an example of the configuration of the terminal 2. The terminal 2 includes a control unit 21, a storage unit 22, a communication unit 23, an operation unit 24, a display unit 25, a sound emitting unit 26, and a positioning unit 27.
　制御部２１は、ＣＰＵ、ＲＯＭ、ＲＡＭを有し、ＣＰＵがＲＯＭ及び記憶部２２に記憶されているプログラムを読み出して実行することにより端末２の各部を制御する。 The control unit 21 includes a CPU, a ROM, and a RAM, and controls each unit of the terminal 2 when the CPU reads and executes a program stored in the ROM and the storage unit 22.
　記憶部２２は、ソリッドステートドライブ、ハードディスクドライブ等の記憶手段であり、制御部２１のＣＰＵに読み込まれる各種のプログラム、データ等を記憶する。 The storage unit 22 is a storage unit such as a solid state drive or a hard disk drive, and stores various programs, data, and the like read by the CPU of the control unit 21.
　通信部２３は、有線又は無線により通信回線３に接続する通信回路である。端末２は、通信部２３により通信回線３に接続された配信装置１と情報をやり取りする。 The communication unit 23 is a communication circuit connected to the communication line 3 by wire or wireless. The terminal 2 exchanges information with the distribution device 1 connected to the communication line 3 by the communication unit 23.
　操作部２４は、各種の指示をするための操作ボタン、キーボード、タッチパネル等の操作子を備えており、ユーザによる操作を受付けてその操作内容に応じた信号を制御部２１に送る。 The operation unit 24 includes operation buttons such as operation buttons, a keyboard, and a touch panel for giving various instructions. The operation unit 24 receives an operation by the user and sends a signal corresponding to the operation content to the control unit 21.
　表示部２５は、液晶ディスプレイ等の表示画面を有しており、制御部２１の制御の下、画像を表示する。表示画面の上には、操作部２４の透明のタッチパネルが重ねて配置されてもよい。放音部２６は、制御部２１の制御の下で音声を放出するスピーカ等である。 The display unit 25 has a display screen such as a liquid crystal display, and displays an image under the control of the control unit 21. A transparent touch panel of the operation unit 24 may be disposed on the display screen. The sound emitting unit 26 is a speaker or the like that emits sound under the control of the control unit 21.
　測位部２７は、自身（端末２）の位置を測定する機器等であり、例えば、全球測位衛星システム（ＧＮＳＳ：Global Navigation Satellite System）に基づき、複数の航法衛星からそれぞれ航法信号を受信する受信機等を有する。測位部２７は、受信した航法信号に基づいて端末２の位置を測定（計算）するプロセッサを有していてもよい。また、測位部２７が受信した複数の航法信号を用いて制御部２１が端末２の位置を測定してもよい。 The positioning unit 27 is a device that measures the position of itself (terminal 2). For example, the positioning unit 27 is a receiver that receives navigation signals from a plurality of navigation satellites based on a global positioning satellite system (GNSS: Global Navigation Satellite System). Etc. The positioning unit 27 may include a processor that measures (calculates) the position of the terminal 2 based on the received navigation signal. Further, the control unit 21 may measure the position of the terminal 2 using a plurality of navigation signals received by the positioning unit 27.
　なお、測位部２７が位置を測定する手段は、ＧＮＳＳに限られない。例えば、測位部２７は、決められた場所に設置されたビーコン発信機から発信されるビーコンを受信して、そのビーコンに含まれる位置の情報を抽出することで、端末２の位置を測定してもよい。 In addition, the means by which the positioning unit 27 measures the position is not limited to GNSS. For example, the positioning unit 27 measures the position of the terminal 2 by receiving a beacon transmitted from a beacon transmitter installed at a predetermined location and extracting information on a position included in the beacon. Also good.
　また、測位部２７は、例えばＲＦＩＤ（radio frequency identifier）等の近距離無線通信により駅や商業施設等の所定領域における入退場を管理する入退場システムと連携してもよい。この場合、測位部２７は、入退場システムによって書き込まれた入場の記録を用いて端末２の位置を測定してもよい。すなわち、この測位部２７は、入退場システムによって入退場を管理されている所定領域の内側に端末２が存在するか否かを、端末２の位置の情報として測定する。 Further, the positioning unit 27 may cooperate with an entrance / exit system that manages entrance / exit in a predetermined area such as a station or a commercial facility by short-range wireless communication such as RFID (radio frequency identifier). In this case, the positioning unit 27 may measure the position of the terminal 2 using the entry record written by the entry / exit system. That is, the positioning unit 27 measures whether or not the terminal 2 exists inside a predetermined area where entry / exit is managed by the entrance / exit system as position information of the terminal 2.
　また、端末２が携帯電話機等である場合、測位部２７は、基地局から提供される位置情報を用いて端末２の位置を測定してもよい。 Further, when the terminal 2 is a mobile phone or the like, the positioning unit 27 may measure the position of the terminal 2 using position information provided from the base station.
　なお、例えば、端末２が決められた範囲内に所在していないと、配信システムＣと通信が可能にならない場合等では、配信システムＣは、いずれかの配信装置１と通信していること自体によって、端末２が決められた範囲内に所在している、と判定することが可能である。この場合、端末２は、測位部２７を有しないでもよい。 Note that, for example, if the terminal 2 is not located within the determined range and communication with the distribution system C is not possible, the distribution system C is communicating with one of the distribution devices 1 itself. Thus, it can be determined that the terminal 2 is located within the determined range. In this case, the terminal 2 may not have the positioning unit 27.
＜配信装置の機能的構成＞
　図７は、配信装置１の機能的構成を示す図である。なお、図７において、通信回線３、及び通信部１３を省く。配信装置１の制御部１１は、記憶部１２に記憶されているプログラムを読み出して実行することにより、生成手段１１１、算出手段１１２、配信手段１１３、取得手段１１４、判定手段１１５、及び復元手段１１６として機能する。また、図７に示す通り、制御部１１は、表示部１５又は放音部１６の少なくとも一方が配信装置１に備えられている場合、これらを制御して再生手段１１７として機能してもよい。 <Functional configuration of distribution device>
FIG. 7 is a diagram illustrating a functional configuration of the distribution apparatus 1. In FIG. 7, the communication line 3 and the communication unit 13 are omitted. The control unit 11 of the distribution apparatus 1 reads out and executes a program stored in the storage unit 12, thereby generating a generation unit 111, a calculation unit 112, a distribution unit 113, an acquisition unit 114, a determination unit 115, and a restoration unit 116. Function as. Further, as shown in FIG. 7, when at least one of the display unit 15 and the sound emitting unit 16 is provided in the distribution device 1, the control unit 11 may function as the reproducing unit 117 by controlling them.
　これらの機能は、１台の配信装置１の制御部１１によって実現されてもよいが、配信システムＣを構成する複数の配信装置１の制御部１１が、相互に通信をして互いの演算機能や記憶部１２の記憶内容等のリソースを共有することによって実現されてもよい。 These functions may be realized by the control unit 11 of one distribution device 1, but the control units 11 of the plurality of distribution devices 1 constituting the distribution system C communicate with each other to perform mutual computation functions. Alternatively, it may be realized by sharing resources such as storage contents of the storage unit 12.
　生成手段１１１は、指定されたコンテンツＩＤに対応するコンテンツデータを記憶部１２のコンテンツ表１２１から読み出し、このコンテンツデータから秘密分散法に従って異なるｎ個の分散片を生成する。ここで、ｎは２以上の整数である。分散片は、コンテンツデータを復元するために用いられるデータである。生成手段１１１は、上述した通り、少なくとも２個以上の分散片を用いないと、元のコンテンツデータが復元されないように、ｎ個の分散片を生成する。 The generation unit 111 reads content data corresponding to the specified content ID from the content table 121 of the storage unit 12, and generates n different pieces of distribution from the content data according to the secret sharing method. Here, n is an integer of 2 or more. The distributed piece is data used to restore the content data. As described above, the generation unit 111 generates n distributed pieces so that the original content data is not restored unless at least two or more distributed pieces are used.
　なお、この実施形態では、生成手段１１１がｎ個の分散片を全て用いないと、元のコンテンツデータを復元できないように、これらの分散片を生成する場合について説明する。生成されたｎ個の分散片は、それぞれ個別の分散片ＩＤと対応付けて分散片表１２２に記憶される。 In this embodiment, a case will be described in which these distributed pieces are generated so that the original content data cannot be restored unless the generation unit 111 uses all n distributed pieces. The generated n dispersion pieces are stored in the dispersion piece table 122 in association with individual dispersion piece IDs.
　算出手段１１２は、分散片表１２２から分散片を読み出し、これら分散片のハッシュ値をそれぞれ算出する。算出したハッシュ値は、元の分散片を識別するための分散片ＩＤと対応付けて、ハッシュ値表１２３に記憶される。 The calculating means 112 reads the dispersion pieces from the dispersion piece table 122 and calculates the hash values of these dispersion pieces. The calculated hash value is stored in the hash value table 123 in association with the dispersion piece ID for identifying the original dispersion piece.
　配信手段１１３は、複数の端末２のそれぞれに、ｎ個の分散片のいずれか１個以上を配信する。この配信手段１１３は、例えば擬似乱数列等を用いて端末２のユーザに予測し得ない分散片を選択して配信してもよい。配信手段１１３は、ユーザの指示や支払い額、予め割当てられた階級等に応じて、そのユーザの端末２に向けて配信する分散片の個数を決めてもよい。 The distribution unit 113 distributes at least one of the n distributed pieces to each of the plurality of terminals 2. The distribution unit 113 may select and distribute a distributed piece that cannot be predicted by the user of the terminal 2 using, for example, a pseudo random number sequence. The distribution unit 113 may determine the number of distributed pieces to be distributed to the user's terminal 2 according to the user's instruction, payment amount, class assigned in advance, or the like.
　配信装置１から分散片を受け取った端末２は、この分散片を記憶部２２に記憶するとともに、この分散片のハッシュ値を計算する。この計算に用いるハッシュ関数は、配信装置１の制御部１１が算出手段１１２として機能するときに用いたハッシュ関数と同じである。したがって、共通の分散片について配信装置１及び端末２でそれぞれ算出されたハッシュ値は同じ値になる。 The terminal 2 that has received the distributed piece from the distribution apparatus 1 stores the distributed piece in the storage unit 22 and calculates a hash value of the distributed piece. The hash function used for this calculation is the same as the hash function used when the control unit 11 of the distribution apparatus 1 functions as the calculation unit 112. Therefore, the hash values calculated by the distribution apparatus 1 and the terminal 2 for the common distributed piece are the same value.
　取得手段１１４は、複数の端末２のうち２以上の端末２から、それらの端末２に配信された分散片のハッシュ値をそれぞれ取得する。取得手段１１４が取得するハッシュ値は、端末２において算出されたハッシュ値である。また、取得手段１１４は、端末２から上述したハッシュ値と対応付けて、その端末２が存在する位置を示す位置情報を取得する。 The obtaining unit 114 obtains the hash values of the distributed pieces distributed to the terminals 2 from two or more terminals 2 among the plurality of terminals 2. The hash value acquired by the acquisition unit 114 is a hash value calculated in the terminal 2. In addition, the acquisition unit 114 acquires position information indicating the position where the terminal 2 exists in association with the hash value described above from the terminal 2.
　判定手段１１５は、２以上の端末が所定の場所に集まっている場合に、取得手段１１４が取得したハッシュ値と、算出手段１１２が算出したハッシュ値と、に基づいて、それらの端末２に配信された分散片からコンテンツデータが復元可能か否かを判定する。 When two or more terminals are gathered at a predetermined place, the determination unit 115 distributes to the terminals 2 based on the hash value acquired by the acquisition unit 114 and the hash value calculated by the calculation unit 112. It is determined whether or not the content data can be restored from the distributed pieces.
　例えば、判定手段１１５は、２以上の端末２から取得手段１１４が取得した位置情報に基づいてそれら端末２のそれぞれの位置を特定する。そして、判定手段１１５は、それらの位置が決められた範囲内にあるか否かを判定することにより、それらの端末２が所定の場所に集まっているか否かを判定する。 For example, the determination unit 115 specifies the position of each of the terminals 2 based on the position information acquired by the acquisition unit 114 from two or more terminals 2. And the determination means 115 determines whether those terminals 2 are gathering in the predetermined place by determining whether those positions are in the determined range.
　２以上の端末２が所定の場所に集まっていると判定する場合、判定手段１１５は、取得手段１１４がそれらの端末２から取得したハッシュ値と、記憶部１２のハッシュ値表１２３に記憶されているハッシュ値とを比較する。これにより判定手段１１５は、上述した所定の場所に集まっている端末２に配信された分散片から元のコンテンツデータが復元可能か否かを判定する。 When determining that two or more terminals 2 are gathered at a predetermined place, the determination unit 115 stores the hash value acquired by the acquisition unit 114 from those terminals 2 and the hash value table 123 of the storage unit 12. Compare the hash value with Thereby, the determination unit 115 determines whether or not the original content data can be restored from the distributed pieces distributed to the terminals 2 gathered at the predetermined location.
　この実施形態では、生成手段１１１によって１つのコンテンツデータから生成された異なるｎ個の分散片は、その全てが揃わないと元のコンテンツデータを復元できない性質を有する。したがって、判定手段１１５は、上述した２以上の端末２から取得した互いに異なるハッシュ値が、ハッシュ値表１２３において１つのコンテンツＩＤに対応付けられているｎ個のハッシュ値のいずれかと一致しており、かつ、その数がｎ個である場合に、元のコンテンツデータが復元可能である、と判定する。 In this embodiment, n different distributed pieces generated from one piece of content data by the generation unit 111 have a property that the original content data cannot be restored unless all of them are prepared. Therefore, the determination unit 115 matches the different hash values acquired from the two or more terminals 2 described above with one of the n hash values associated with one content ID in the hash value table 123. When the number is n, it is determined that the original content data can be restored.
　復元手段１１６は、判定手段１１５によりコンテンツデータが復元可能であると判定された場合に、２以上の端末２から分散片をそれぞれ取得して、それらの分散片に基づいてコンテンツデータを復元する。 When the determination unit 115 determines that the content data can be restored, the restoration unit 116 acquires the respective distributed pieces from the two or more terminals 2 and restores the content data based on the distributed pieces.
　再生手段１１７は、復元されたコンテンツデータを用いて、そのコンテンツデータに対応するコンテンツを再生する。 Reproduction means 117 reproduces content corresponding to the content data using the restored content data.
　なお、復元手段１１６により復元されたコンテンツデータは、端末２に供給（配信）され、端末２においてコンテンツの再生に用いられてもよい。例えば、復元されたコンテンツデータを配信システムＣから供給されたとき、端末２の制御部２１は、このコンテンツデータが示すコンテンツのうち、映像を表示部２５に表示させ、音声を放音部２６に出力させることにより、そのコンテンツを再生する。この場合、制御部２１は、配信システムＣにより復元されたコンテンツデータを用いて、そのコンテンツデータに対応するコンテンツを再生する再生手段として機能する。 Note that the content data restored by the restoration unit 116 may be supplied (distributed) to the terminal 2 and used for content reproduction in the terminal 2. For example, when the restored content data is supplied from the distribution system C, the control unit 21 of the terminal 2 displays the video on the display unit 25 among the content indicated by the content data, and sends the sound to the sound emitting unit 26. By outputting the content, the content is reproduced. In this case, the control unit 21 functions as a playback unit that plays back the content corresponding to the content data using the content data restored by the distribution system C.
＜コンテンツ再生システムの動作＞
　図８は、コンテンツ再生システム９の動作の流れを示すシーケンス図である。配信システムＣから端末２に分散片が配信されるまでの動作を図８（ａ）に、コンテンツデータが復元され、コンテンツが再生されるまでの動作を図８（ｂ）に、それぞれ示す。 <Operation of content playback system>
FIG. 8 is a sequence diagram showing a flow of operations of the content reproduction system 9. FIG. 8A shows the operation until the distributed piece is distributed from the distribution system C to the terminal 2, and FIG. 8B shows the operation until the content data is restored and the content is reproduced.
　以下に示す配信システムＣが行う動作は、これを構成するいずれかの配信装置１が行うものであるが、各ステップの動作は、同じ配信装置１が行っても、異なる配信装置１が行ってもよい。 The operations performed by the distribution system C shown below are performed by any one of the distribution devices 1 constituting the distribution system C, but the operations of each step are performed by different distribution devices 1 even if performed by the same distribution device 1. Also good.
　図８（ａ）に示す通り、配信システムＣは、自身を構成するいずれかの配信装置１の記憶部１２から、例えば、或るアーティストが制作したコンテンツを示すコンテンツデータを読み出して、このコンテンツデータに基づいて異なるｎ個の分散片を生成する（ステップＳ１０１）。また、配信システムＣは、生成されたｎ個の分散片のハッシュ値をそれぞれ算出する（ステップＳ１０２）。 As shown in FIG. 8A, the distribution system C reads, for example, content data indicating content produced by a certain artist from the storage unit 12 of any of the distribution apparatuses 1 constituting the content system C. N different dispersion pieces are generated based on (Step S101). Further, the distribution system C calculates the hash values of the generated n distributed pieces (step S102).
　配信システムＣは、上述したアーティストの複数のファン（ユーザ）がそれぞれ所持する端末２に、生成されたｎ個の分散片のいずれか１個以上を配信する（ステップＳ１０３）。１個以上の分散片を受信した端末２は、この分散片のハッシュ値を算出し（ステップＳ１０４）、算出したハッシュ値と、元の分散片とを対応付けて記憶部２２に記憶する（ステップＳ１０５）。 The distribution system C distributes one or more of the generated n distributed pieces to the terminals 2 possessed by the plurality of fans (users) of the artist described above (step S103). The terminal 2 that has received one or more distributed pieces calculates a hash value of the distributed piece (step S104), and stores the calculated hash value and the original distributed piece in the storage unit 22 in association with each other (step S104). S105).
　図８（ｂ）に示す通り、端末２は、自身の位置を測定する測位を実行する（ステップＳ２００）。配信システムＣは、複数の端末２が測位によって得た自身の位置を示す位置情報と、分散片のハッシュ値とをそれぞれ取得する（ステップＳ２０１）。 As shown in FIG. 8B, the terminal 2 performs positioning for measuring its own position (step S200). The distribution system C acquires position information indicating its own position obtained by positioning by the plurality of terminals 2 and a hash value of the distributed piece (step S201).
　配信システムＣは、複数の端末２の位置情報に基づいて、これらの端末２が所定の場所に集まっているか否かを判定し、集まっていると判定する場合、これらの端末２から取得したハッシュ値と、配信システムＣにおいて記憶しているハッシュ値とを比較して、これらの端末２に配信された分散片からコンテンツデータが復元可能か否かを判定する（ステップＳ２０２）。 The distribution system C determines whether or not these terminals 2 are gathered at a predetermined location based on the position information of the plurality of terminals 2, and when determining that they are gathered, the hash acquired from these terminals 2 The value is compared with the hash value stored in the distribution system C to determine whether the content data can be restored from the distributed pieces distributed to these terminals 2 (step S202).
　図９は、コンテンツデータの復元可否の判定を説明するための図である。この図９に示す例において、配信システムＣは、分散片Ｄ１から分散片Ｄ５までの５個の異なる分散片を１つのコンテンツデータから生成し、それぞれランダムに１個ずつ、いずれかの分散片を端末２に配信する。ユーザＵ１からユーザＵ７までの７人は、それぞれ端末２を所持しており、これらの端末２には、それぞれ分散片Ｄ１から分散片Ｄ５までのいずれか１個が配信されている。ユーザＵ１、Ｕ２、Ｕ３、Ｕ４、及びＵ５の所有する端末２には、それぞれ、分散片Ｄ１、Ｄ２、Ｄ３、Ｄ４、及びＤ５が配信される。また、ユーザＵ６、及びＵ７の所有する端末２には、それぞれ、分散片Ｄ２、及びＤ１が配信される。 FIG. 9 is a diagram for explaining determination of whether or not content data can be restored. In the example shown in FIG. 9, the distribution system C generates five different distributed pieces from the distributed piece D1 to the distributed piece D5 from one content data, and randomly distributes one of the distributed pieces. Delivered to the terminal 2. Seven users U1 to U7 each have a terminal 2, and any one of the dispersion pieces D1 to D5 is distributed to each of these terminals 2. Distributed pieces D1, D2, D3, D4, and D5 are distributed to terminals 2 owned by users U1, U2, U3, U4, and U5, respectively. Also, distributed pieces D2 and D1 are distributed to terminals 2 owned by users U6 and U7, respectively.
　図９に示す通り、ユーザＵ１、Ｕ２、Ｕ３、Ｕ４、及びＵ５で構成されるグループＧ１が集まると、分散片Ｄ１から分散片Ｄ５までの５個の異なる分散片が全て揃う。したがって、この場合配信システムＣは、これらのユーザがそれぞれ所持する端末２から取得した分散片からコンテンツデータが復元可能であると判定する。 As shown in FIG. 9, when the group G1 composed of users U1, U2, U3, U4, and U5 gathers, all five different dispersion pieces from the dispersion piece D1 to the dispersion piece D5 are prepared. Therefore, in this case, the distribution system C determines that the content data can be restored from the distributed pieces acquired from the terminals 2 possessed by these users.
　同様に、 ユーザＵ３、Ｕ４、Ｕ５、Ｕ６、及びＵ７で構成されるグループＧ２が集まった場合でも、５個の異なる分散片が全て揃うので、配信システムＣは、コンテンツデータが復元可能であると判定する。 Similarly, even when the group G2 composed of the user users U3, U4, U5, U6, and U7 gathers, since all five different distributed pieces are prepared, the distribution system C can restore the content data. judge.
　一方、ユーザＵ２、Ｕ３、Ｕ４、Ｕ５、及びＵ６で構成されるグループＧ３が集まると、これらのユーザが所持する端末２のいずれにも、分散片Ｄ１が記憶されていない。つまり、５個の異なる分散片が全て揃わないから、配信システムＣは、コンテンツデータが復元可能でないと判定する。 On the other hand, when the group G3 composed of the users U2, U3, U4, U5, and U6 is gathered, the dispersion piece D1 is not stored in any of the terminals 2 possessed by these users. That is, since all five different dispersion pieces are not prepared, the distribution system C determines that the content data cannot be restored.
　このとき、配信システムＣは、グループＧ３を構成する全ユーザの端末２に向けて、不足している分散片を識別する分散片ＩＤを示す情報を送ってもよい。この情報を受け取った端末２は、不足している分散片の個数とその識別情報とに応じたメッセージを表示してもよい。 At this time, the distribution system C may send information indicating the dispersion piece ID for identifying the dispersion piece that is lacking to the terminals 2 of all users constituting the group G3. The terminal 2 that has received this information may display a message corresponding to the number of the dispersed pieces that are insufficient and the identification information.
　図１０は、端末２に表示されるメッセージの例を示す図である。上述した５個の異なる分散片は、予め図１０に示すパズルを構成する５つのピースのそれぞれに対応付けられている。分散片Ｄ１のみが揃わない場合、ユーザの端末２にはそれぞれ図１０で示した画像とともに「１つのピースが足りていません！」というメッセージを表した文字列が表示される。図１０で示す画像では、右下の１つのピースのみ、他の４つのピースと異なる色で表示されているため、この画像を見たユーザは、どの分散片が不足しているのかを把握する。 FIG. 10 is a diagram illustrating an example of a message displayed on the terminal 2. The five different dispersion pieces described above are associated with the five pieces constituting the puzzle shown in FIG. 10 in advance. When only the dispersion pieces D1 are not prepared, the user terminal 2 displays a character string representing a message “one piece is not enough!” Together with the image shown in FIG. In the image shown in FIG. 10, since only one piece at the lower right is displayed in a color different from the other four pieces, the user who sees this image knows which dispersion piece is lacking. .
　なお、端末２に表示されるメッセージは上述したものに限られない。メッセージは、例えば、ピアノ、ドラム、ギター、ベース等の楽器の絵を表示して、それらの色によって不足している分散片を表現してもよい。また、このメッセージは、コンテンツデータを復元するために必要な分散片が不足しているという事実だけをユーザに伝え、不足している分散片の個数をユーザに伝えないものであってもよい。 Note that the message displayed on the terminal 2 is not limited to that described above. The message may display, for example, a picture of a musical instrument such as a piano, a drum, a guitar, or a bass, and express a lack of dispersed pieces by their colors. In addition, this message may notify the user only of the fact that the distribution pieces necessary for restoring the content data are insufficient, and may not notify the user of the number of distribution pieces that are insufficient.
　この演出によれば、上述した場所に集まって上述した画像を見たユーザが、例えば、ソーシャル・ネットワーキング・サービス（social networking service, SNS）等を使って、この場所に集まっていない他のユーザに向けて、「右下のピースを持っているファンの人、○○会場に集まって」等のメッセージを呼びかけることができる。 According to this presentation, a user who gathered at the above-mentioned place and viewed the above-mentioned image can use other social networking services (social networking service, social networking service, etc.) A message such as “People who have a piece in the lower right, gather at the venue” can be called.
　上述した複数の端末２に配信された分散片からコンテンツデータが復元可能である、と判定する場合、配信システムＣは、これらの端末２から分散片をそれぞれ取得する（ステップＳ２０３）。そして、配信システムＣは、取得した複数の分散片に基づいてコンテンツデータを復元する（ステップＳ２０４）。 If it is determined that the content data can be restored from the distributed pieces distributed to the plurality of terminals 2 described above, the distribution system C acquires the distributed pieces from these terminals 2 (step S203). Then, the distribution system C restores the content data based on the acquired plurality of dispersed pieces (step S204).
　コンテンツデータを復元すると、配信システムＣは、復元したコンテンツデータを上述した複数の端末２のそれぞれに供給する（ステップＳ２０５）。これらの端末２は、供給されたコンテンツデータを用いて、このコンテンツデータに対応するコンテンツを再生する（ステップＳ２０６）。 When the content data is restored, the distribution system C supplies the restored content data to each of the plurality of terminals 2 described above (step S205). These terminals 2 use the supplied content data to reproduce content corresponding to the content data (step S206).
　なお、ステップＳ２０６は、配信システムＣにおいて行われてもよい。この場合、配信システムＣは、ステップＳ２０５を行わなくてもよい。 Note that step S206 may be performed in the distribution system C. In this case, the distribution system C may not perform step S205.
　以上の動作により、複数の端末２が所定の場所に集まっているときに限り、映像や音楽等のコンテンツを再生される、という演出が実現される。また、例えば、複数の端末２のそれぞれに、ｎ個の分散片のうちのいずれかをランダムに配信する場合、端末２を１つずつ所持するユーザが何人集まれば、元のコンテンツデータが復元可能であるかという期待値は、統計的に計算可能である。 By the above operation, an effect that content such as video and music is reproduced only when a plurality of terminals 2 are gathered in a predetermined place is realized. In addition, for example, when any one of the n distributed pieces is randomly distributed to each of the plurality of terminals 2, the original content data can be restored if any number of users each having one terminal 2 gather. The expected value of whether or not can be calculated statistically.
＜変形例＞
　以上が実施形態の説明であるが、この実施形態の内容は以下のように変形し得る。また、以下の変形例を組合せてもよい。 <Modification>
The above is the description of the embodiment, but the contents of this embodiment can be modified as follows. Further, the following modifications may be combined.
＜変形例１＞
　上述した実施形態において、複数の端末２が所定の場所に集まっているときに限り、映像や音楽等のコンテンツが再生されていたが、コンテンツが再生される条件は、これに限られない。すなわち、配信システムＣは、２以上の端末が所定の条件を満たしている場合に限り、映像や音楽等のコンテンツを再生する構成であればよい。 <Modification 1>
In the above-described embodiment, content such as video and music is played back only when a plurality of terminals 2 are gathered at a predetermined location, but the conditions for playing back the content are not limited to this. That is, the distribution system C only needs to be configured to reproduce content such as video and music only when two or more terminals satisfy a predetermined condition.
　例えば、配信装置１の制御部１１によって実現される取得手段１１４は、２以上の端末２の各々から上述したハッシュ値と対応付けて、その端末２が通信回線３を介して所定の装置にアクセスしているか否かを示すアクセス情報を取得してもよい。 For example, the acquisition unit 114 realized by the control unit 11 of the distribution apparatus 1 associates the hash value described above with each of the two or more terminals 2 and the terminal 2 accesses a predetermined apparatus via the communication line 3. You may acquire the access information which shows whether it is doing.
　この場合、判定手段１１５は、取得手段１１４が取得したアクセス情報に基づいて端末２のそれぞれが上述した装置にアクセスしていると判定される場合に、これらの端末２が所定の条件を満たしていると判定してもよい。端末２が所定の条件を満たしていると判定すると、判定手段１１５は、取得手段１１４が取得したハッシュ値と、算出手段１１２が算出したハッシュ値と、に基づいて、それらの端末２に配信された分散片からコンテンツデータが復元可能か否かを判定すればよい。 In this case, when it is determined that each of the terminals 2 is accessing the above-described device based on the access information acquired by the acquiring unit 114, the determining unit 115 satisfies the predetermined condition. It may be determined that If it is determined that the terminal 2 satisfies the predetermined condition, the determination unit 115 is distributed to the terminal 2 based on the hash value acquired by the acquisition unit 114 and the hash value calculated by the calculation unit 112. It may be determined whether or not the content data can be restored from the distributed pieces.
　この変形例によれば、複数の端末２が物理的に所定の場所に集まっていなくても、それらの端末２と、そのそれぞれに配信された分散片とが決められた条件を満たしていれば、コンテンツが復元される。 According to this modification, even if a plurality of terminals 2 are not physically gathered at a predetermined place, if the terminals 2 and the distributed pieces distributed to each of the terminals 2 satisfy a predetermined condition. , The content is restored.
＜変形例２＞
　上述した実施形態において、生成手段１１１は、秘密分散法に従って全て用いないと元のコンテンツデータを復元できないｎ個の分散片を生成していたが、２以上かつｎ未満の分散片に基づいて元のコンテンツデータを復元できるようにｎ個の分散片を生成してもよい。この場合、生成手段１１１は、いわゆる（ｋ，ｎ）しきい値秘密分散法を用いて、コンテンツデータからｎ個の分散片を生成してもよい。 <Modification 2>
In the above-described embodiment, the generation unit 111 generates n distributed pieces that cannot be restored without using the original content data according to the secret sharing method. N pieces of distributed pieces may be generated so that the content data can be restored. In this case, the generation unit 111 may generate n distributed pieces from the content data using a so-called (k, n) threshold secret sharing method.
　（ｋ，ｎ）しきい値秘密分散法とは、例えばシャミア（Shamir）の多項式や排他的論理和等を用いた秘密分散法である。（ｋ，ｎ）しきい値秘密分散法によれば、生成されたｎ個の分散片のうち、任意の相異なるｋ個の分散片から元のコンテンツデータが復号できるが、任意の相異なる（ｋ－１）個の分散片からは、元のコンテンツデータの情報が全く得られない。このｋは、２以上かつｎ以下の整数であり、ｋ＝ｎの場合は、上述した実施形態で示した通り、ｎ個の全てを用いないと元のコンテンツデータを復元できない。ｋ＜ｎの場合は、ｎ個に満たなくても、任意のｋ個の分散片が揃った場合に、元のコンテンツデータが復元できる。 The (k, n) threshold secret sharing method is a secret sharing method using, for example, a Shamir polynomial or an exclusive OR. According to the (k, n) threshold secret sharing scheme, the original content data can be decrypted from arbitrarily different k distributed pieces among the generated n distributed pieces, but arbitrarily different ( No information of the original content data can be obtained from k−1) pieces of dispersion. This k is an integer not less than 2 and not more than n. When k = n, as shown in the above-described embodiment, the original content data cannot be restored unless all n are used. In the case of k <n, the original content data can be restored when any k distributed pieces are prepared even if it is less than n.
　すなわち、生成手段１１１は、任意の異なるｋ個（ｋは２以上かつｎ以下の整数）の分散片に基づいてコンテンツデータを復元可能になるように、ｎ個の分散片を生成してもよい。そして、この場合、判定手段１１５は、取得した複数の異なるハッシュ値が、いずれも算出手段１１２が算出したハッシュ値のいずれかと一致し、かつ、ｋ個以上ある場合に、コンテンツデータが復元可能であると判定する。 That is, the generation unit 111 may generate n distributed pieces so that the content data can be restored based on arbitrarily different k pieces (k is an integer of 2 or more and n or less). . In this case, the determination unit 115 can restore the content data when the acquired plurality of different hash values match any one of the hash values calculated by the calculation unit 112 and there are k or more. Judge that there is.
　なお、生成手段１１１は、（ｋ，ｎ）しきい値秘密分散法に代えて（ｋ，Ｌ，ｎ）しきい値秘密分散法を用いてもよい。（ｋ，Ｌ，ｎ）しきい値秘密分散法においてコンテンツデータから生成されるｎ個の分散片は、それらのうち、任意の相異なるｋ個の分散片から元のコンテンツデータが復号できるが、任意の相異なる（ｋ－Ｌ）個の分散片からは、元のコンテンツデータの情報が全く得られない、という性質を持つ。そして、（ｋ，Ｌ，ｎ）しきい値秘密分散法において、任意の相異なる（ｋ－Ｌ＋１）個以上（ｋ－１）個以下の分散片からは、部分的に元のコンテンツデータの情報が得られる、という性質を持つ。 Note that the generation unit 111 may use the (k, L, n) threshold secret sharing method instead of the (k, n) threshold secret sharing method. Among the n distributed pieces generated from the content data in the (k, L, n) threshold secret sharing method, the original content data can be decoded from any of the k different distributed pieces, The original content data information cannot be obtained from any different (kL) distributed pieces. In the (k, L, n) threshold value secret sharing method, information of the original content data is partially obtained from arbitrarily different (k−L + 1) to (k−1) distributed pieces. Is obtained.
＜変形例３＞
　上述した変形例において、生成手段１１１は、任意の異なる２個以上かつｎ個以下の分散片に基づいてコンテンツデータを復元可能になるように、ｎ個の分散片を生成していたが、生成される分散片は、揃ったときに復元可能になる個数が１つに定まっていなくてもよい。 <Modification 3>
In the above-described modification, the generation unit 111 generates n distributed pieces so that the content data can be restored based on any two or more and n or less different distributed pieces. The number of the dispersed pieces that can be restored when they are aligned does not have to be set to one.
　図１１は、この変形例における分散片を説明するための図である。配信装置１の制御部１１によって実現する生成手段１１１は、コンテンツデータを２以上の相異なるデータ（以下、分割データという）に分割する。例えば、図１１に示す例では、コンテンツデータは６個の相異なる分割データＥ１～Ｅ６に分割される。これらの６個の分割データＥ１～Ｅ６は、全てが揃わないと元のコンテンツデータが復元できないように分割されている。分割の方法は、上述した（ｋ，ｎ）しきい値秘密分散法をｋ＝ｎの条件下で用いてもよいし、端末２のユーザに予め配布している鍵データでコンテンツデータを暗号化し、暗号化されたデータを順序がわかるように分割してもよい。なお、コンテンツデータの分割の方法に秘密分散法を用いると、得られる複数の相異なる分割データは、それぞれ単独では意味をなさない情報であるから、例えば、上述した分割の方法に他の計算量的に安全とされているアルゴリズムを用いる場合に比べて安全性が担保される。 FIG. 11 is a diagram for explaining a dispersion piece in this modification. The generation unit 111 realized by the control unit 11 of the distribution apparatus 1 divides the content data into two or more different data (hereinafter referred to as divided data). For example, in the example shown in FIG. 11, the content data is divided into six different pieces of divided data E1 to E6. These six pieces of divided data E1 to E6 are divided so that the original content data cannot be restored unless all of them are prepared. As the division method, the above-described (k, n) threshold secret sharing method may be used under the condition of k = n, or the content data is encrypted with the key data distributed in advance to the user of the terminal 2 The encrypted data may be divided so that the order can be understood. If the secret sharing method is used as a method for dividing content data, the different pieces of divided data obtained are pieces of information that do not make sense on their own. The security is ensured as compared with the case of using an algorithm that is considered to be safe.
　生成手段１１１は、図１１に示す通り、それぞれの分散片ＩＤで識別される分散片を生成する。これにより、例えば、分散片Ｄ１は、分割データＥ１、Ｅ２、Ｅ３だけを含み、分散片Ｄ２は、分割データＥ２、Ｅ３、Ｅ４だけを含み、分散片Ｄ３は、分割データＥ３、Ｅ４、Ｅ５だけを含み、分散片Ｄ４は、分割データＥ４、Ｅ５、Ｅ６だけを含み、分散片Ｄ５は、分割データＥ１、Ｅ５、Ｅ６だけを含むように、それぞれが生成される。なお、分散片の数、分割データの数、及び、各分散片に含ませる分割データの種類及び数等は、図１１に示したものに限られない。 The generation means 111 generates a dispersion piece identified by each dispersion piece ID as shown in FIG. Thus, for example, the dispersion piece D1 includes only the divided data E1, E2, and E3, the distribution piece D2 includes only the divided data E2, E3, and E4, and the dispersion piece D3 includes only the divided data E3, E4, and E5. Are respectively generated so that the distributed piece D4 includes only the divided data E4, E5, and E6, and the distributed piece D5 includes only the divided data E1, E5, and E6. Note that the number of distributed pieces, the number of divided data, and the type and number of divided data included in each distributed piece are not limited to those shown in FIG.
　この場合、分散片Ｄ１と、分散片Ｄ４とが集まると、６個の分割データＥ１～Ｅ６の全てが得られるため、元のコンテンツデータが復元可能である。しかし、分散片Ｄ１、Ｄ２、Ｄ３の３個が集まっても、分割データＥ１～Ｅ６のうち、分割データＥ６が得られない。したがって、図１１に示す通り、分散片を生成する場合には、揃ったときに復元可能になる分散片の個数は１つに定まらない。 In this case, when the dispersion piece D1 and the dispersion piece D4 are gathered, all the six pieces of divided data E1 to E6 are obtained, so that the original content data can be restored. However, even if the three dispersion pieces D1, D2, and D3 are collected, the divided data E6 among the divided data E1 to E6 cannot be obtained. Therefore, as shown in FIG. 11, when generating dispersed pieces, the number of dispersed pieces that can be restored when they are aligned is not limited to one.
＜変形例４＞
　上述した実施形態において、配信システムＣは、１つのコンテンツデータからｎ個の異なる分散片を生成していたが、コンテンツデータを決められた鍵データで暗号化して暗号化データを生成し、この鍵データからｎ個の異なる分散片を生成してもよい。 <Modification 4>
In the embodiment described above, the distribution system C generates n different distributed pieces from one piece of content data. However, the distribution system C generates encrypted data by encrypting the content data with the determined key data, and this key. N different distributed pieces may be generated from the data.
　図１２は、この変形例におけるコンテンツ表１２１の例を示す図である。配信システムＣは、コンテンツＩＤに対応付けられたコンテンツデータのそれぞれに、例えば、擬似乱数等によりユーザに予測し得ない鍵データを個別に生成し、この鍵データを適用して暗号化を行う。そして、配信システムＣは、暗号化に用いた鍵データと、暗号化より生成された暗号化データとをコンテンツＩＤに対応付ける。 FIG. 12 is a diagram showing an example of the content table 121 in this modification. The distribution system C individually generates key data that cannot be predicted by the user using, for example, a pseudo random number, for each piece of content data associated with the content ID, and performs encryption using the key data. Then, the distribution system C associates the key data used for encryption and the encrypted data generated by the encryption with the content ID.
　配信システムＣは、鍵データからｎ個の異なる分散片を生成して、そのうちのいずれかを端末２に配信する。配信システムＣは、２以上の端末２から、それらの端末２に配信された分散片のハッシュ値を取得し、それらの端末２が所定の条件を満たしている場合に、取得したハッシュ値と、配信システムＣにおいて算出されたハッシュ値と、に基づいて、それらの端末２に配信された分散片から元の鍵データが復元可能であるか否かを判定する。 The distribution system C generates n different distributed pieces from the key data and distributes one of them to the terminal 2. The distribution system C acquires hash values of the distributed pieces distributed to the terminals 2 from the two or more terminals 2, and when the terminals 2 satisfy a predetermined condition, Based on the hash value calculated in the distribution system C, it is determined whether or not the original key data can be restored from the distributed pieces distributed to those terminals 2.
　そして、元の鍵データが復元可能である判定する場合、配信システムＣは、それらの端末２からそれぞれ分散片を取得し、鍵データを復元する。配信システムＣは、コンテンツ表１２１から暗号化データを読み出して、復元した鍵データを適用することにより、元のコンテンツデータを復元する。 When determining that the original key data can be restored, the distribution system C obtains each distributed piece from the terminals 2 and restores the key data. The distribution system C reads the encrypted data from the content table 121 and applies the restored key data to restore the original content data.
　この変形例では、暗号化データを生成した後において、コンテンツ表１２１に記憶したコンテンツデータを削除してもよい。また、この変形例では、鍵データからｎ個の分散片を生成した後において、コンテンツ表１２１に記憶した鍵データを削除してもよい。また、この変形例のコンテンツデータ（狭義のコンテンツデータ）は、鍵データと組合せて、本願発明のコンテンツデータ（広義のコンテンツデータ）と言える。 In this modification, the content data stored in the content table 121 may be deleted after the encrypted data is generated. In this modification, the key data stored in the content table 121 may be deleted after generating n distributed pieces from the key data. In addition, the content data (content data in a narrow sense) of this modification can be said to be content data (content data in a broad sense) of the present invention in combination with key data.
　すなわち、この変形例の配信装置１は、コンテンツデータ（狭義のコンテンツデータ）に鍵データを適用して暗号化データを生成し、鍵データ（広義のコンテンツデータ）から秘密分散法に従ってｎ個の分散片を生成し、それぞれの分散片について配信装置１及び端末２で算出されたハッシュ値を比較することで、取得可能な分散片からコンテンツデータが復元可能であるか否かを判定し、復元可能であると判定した場合に、分散片を取得して、それらの分散片から鍵データを復元して暗号化データに適用することでコンテンツデータ（狭義）を復元する。 That is, the distribution apparatus 1 of this modification generates encrypted data by applying key data to content data (narrowly defined content data), and distributes n pieces of data from the key data (widely defined content data) according to a secret sharing method. It is possible to determine whether or not the content data can be restored from the obtainable distributed pieces by generating pieces and comparing the hash values calculated by the distribution device 1 and the terminal 2 for each of the pieces. When it is determined that the content data (in a narrow sense) is obtained by acquiring the distributed pieces, restoring the key data from the distributed pieces and applying the data to the encrypted data.
＜変形例５＞
　配信装置１の制御部１１が実行する処理は、コンテンツデータ（コンテンツデータから生成された分散片を含む）の配信方法として観念され得る。すなわち、本発明は、生成手段が、コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成するステップと、算出手段が、ｎ個の分散片のハッシュ値をそれぞれ算出するステップと、配信手段が、複数の端末のそれぞれに、ｎ個の分散片のいずれか１個以上を配信するステップと、取得手段が、複数の端末のうち２以上の端末から、その端末に配信された分散片のハッシュ値をそれぞれ取得するステップと、判定手段が、２以上の端末が所定の条件を満たしている場合に、取得手段が取得したハッシュ値と、算出手段が算出したハッシュ値と、に基づいて、２以上の端末に配信された分散片からコンテンツデータが復元可能か否かを判定するステップと、復元手段が、判定手段によりコンテンツデータが復元可能であると判定された場合に、２以上の端末から分散片をそれぞれ取得して、その分散片に基づいてコンテンツデータを復元するステップと、を有するコンテンツデータ配信方法として提供されてもよい。 <Modification 5>
The process executed by the control unit 11 of the distribution apparatus 1 can be considered as a distribution method of content data (including distributed pieces generated from the content data). That is, according to the present invention, the generation unit generates different n pieces (n is an integer of 2 or more) from the content data according to the secret sharing method, and the calculation unit obtains the hash values of the n pieces. Each of the calculating step, the distributing means distributing one or more of the n distributed pieces to each of the plurality of terminals, and the acquiring means from two or more terminals among the plurality of terminals; The step of acquiring the hash value of each distributed piece distributed to the terminal and the determination means are calculated by the calculation means and the hash value acquired by the acquisition means when two or more terminals satisfy a predetermined condition. Based on the hash value, a step of determining whether or not the content data can be restored from the distributed pieces distributed to two or more terminals, and a restoring means restores the content data by the judging means. If it is determined that possible, two or more terminals distributed pieces acquired respectively, and restoring the contents data based on the dispersion piece may be provided as content data distribution method having.
＜変形例６＞
　配信装置１の制御部１１によって実行されるプログラムは、磁気テープ及び磁気ディスク等の磁気記録媒体、光ディスク等の光記録媒体、光磁気記録媒体、半導体メモリ等の、コンピュータ装置が読取り可能な記録媒体に記憶された状態で提供し得る。また、このプログラムを、インターネット等の通信回線経由でダウンロードさせてもよい。なお、上述した制御部１１によって例示した制御手段としてはＣＰＵ以外にも種々の装置が適用される場合があり、例えば、専用のプロセッサ等が用いられる。 <Modification 6>
The program executed by the control unit 11 of the distribution apparatus 1 is a recording medium readable by a computer device, such as a magnetic recording medium such as a magnetic tape and a magnetic disk, an optical recording medium such as an optical disk, a magneto-optical recording medium, or a semiconductor memory. Can be provided in a stored state. The program may be downloaded via a communication line such as the Internet. Note that various devices other than the CPU may be applied as the control means exemplified by the control unit 11 described above. For example, a dedicated processor or the like is used.

Claims (7)

  1. 　コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成する生成手段と、
    　前記ｎ個の分散片のハッシュ値をそれぞれ算出する算出手段と、
    　複数の端末のそれぞれに、前記ｎ個の分散片のいずれか１個以上を配信する配信手段と、
    　前記複数の端末のうち２以上の端末から、該端末に配信された前記分散片のハッシュ値をそれぞれ取得する取得手段と、
    　前記２以上の端末が所定の条件を満たしている場合に、前記取得されたハッシュ値と、前記算出されたハッシュ値と、に基づいて、前記２以上の端末に配信された前記分散片から前記コンテンツデータが復元可能か否かを判定する判定手段と、
    　前記コンテンツデータが復元可能であると判定された場合に、前記２以上の端末から前記分散片をそれぞれ取得して、該分散片に基づいて前記コンテンツデータを復元する復元手段と、
    　を有するコンテンツデータ配信システム。     Generating means for generating different n pieces (n is an integer of 2 or more) from the content data according to the secret sharing method;
    A calculation means for calculating a hash value of each of the n distributed pieces;
    Distribution means for distributing one or more of the n distributed pieces to each of a plurality of terminals;
    Obtaining means for obtaining the hash values of the distributed pieces distributed to the terminals from two or more terminals among the plurality of terminals;
    When the two or more terminals satisfy a predetermined condition, based on the acquired hash value and the calculated hash value, from the distributed pieces distributed to the two or more terminals Determining means for determining whether or not the content data can be restored;
    When it is determined that the content data can be restored, the restoration unit obtains the distributed pieces from the two or more terminals, and restores the content data based on the distributed pieces;
    A content data distribution system.
  2. 　前記生成手段は、任意の異なるｋ個（ｋは２以上かつｎ以下の整数）の前記分散片に基づいて前記コンテンツデータを復元可能になるように、前記ｎ個の分散片を生成し、
    　前記判定手段は、前記取得された複数の異なるハッシュ値が、いずれも前記算出されたハッシュ値のいずれかと一致し、かつ、ｋ個以上ある場合に、前記コンテンツデータが復元可能であると判定する
    　ことを特徴とする請求項１に記載のコンテンツデータ配信システム。     The generation means generates the n distributed pieces so that the content data can be restored based on any different k pieces (k is an integer of 2 or more and n or less).
    The determination unit determines that the content data can be restored when the acquired plurality of different hash values all match any one of the calculated hash values and there are k or more. The content data distribution system according to claim 1.
  3. 　前記取得手段は、前記２以上の端末から該端末の位置を示す位置情報をそれぞれ取得し、
    　前記判定手段は、前記２以上の端末の位置情報がそれぞれ示す位置が決められた範囲内にある場合に、該２以上の端末が所定の条件を満たしているとして、前記分散片から前記コンテンツデータが復元可能か否かを判定する
    　ことを特徴とする請求項１又は２に記載のコンテンツデータ配信システム。     The acquisition means acquires position information indicating the position of the terminal from the two or more terminals,
    The determination unit determines that the two or more terminals satisfy a predetermined condition when the positions indicated by the position information of the two or more terminals are within a predetermined range, and determines that the content data from the distribution piece The content data distribution system according to claim 1, wherein whether or not can be restored is determined.
  4. 　前記取得手段は、前記２以上の端末から、該端末が通信回線を介して所定の装置にアクセスしているか否かを示すアクセス情報をそれぞれ取得し、
    　前記判定手段は、前記アクセス情報に基づいて前記２以上の端末のそれぞれが前記装置にアクセスしていると判定される場合に、該２以上の端末が所定の条件を満たしているとして、前記分散片から前記コンテンツデータが復元可能か否かを判定する
    　ことを特徴とする請求項１又は２に記載のコンテンツデータ配信システム。     The acquisition means respectively acquires access information indicating whether or not the terminal is accessing a predetermined device via a communication line from the two or more terminals,
    The determination unit determines that the two or more terminals satisfy a predetermined condition when it is determined that each of the two or more terminals is accessing the device based on the access information. The content data distribution system according to claim 1, wherein it is determined whether or not the content data can be restored from a piece.
  5. 　請求項１から４までのいずれか１項に記載の配信システムと、
    　前記配信システムにより復元された前記コンテンツデータを用いて、該コンテンツデータに対応するコンテンツを再生する再生手段と、
    　を有するコンテンツ再生システム。     The distribution system according to any one of claims 1 to 4,
    Reproduction means for reproducing content corresponding to the content data using the content data restored by the distribution system;
    A content reproduction system comprising:
  6. 　コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成するステップと、
    　前記ｎ個の分散片のハッシュ値をそれぞれ算出するステップと、
    　複数の端末のそれぞれに、前記ｎ個の分散片のいずれか１個以上を配信するステップと、
    　前記複数の端末のうち２以上の端末から、該端末に配信された前記分散片のハッシュ値をそれぞれ取得するステップと、
    　前記２以上の端末が所定の条件を満たしている場合に、前記取得されたハッシュ値と、前記算出されたハッシュ値と、に基づいて、前記２以上の端末に配信された前記分散片から前記コンテンツデータが復元可能か否かを判定するステップと、
    　前記コンテンツデータが復元可能であると判定された場合に、前記２以上の端末から前記分散片をそれぞれ取得して、該分散片に基づいて前記コンテンツデータを復元するステップと、
    　を有するコンテンツデータ配信方法。     Generating different n pieces (n is an integer of 2 or more) from the content data according to the secret sharing method;
    Calculating a hash value of each of the n distributed pieces;
    Delivering one or more of the n distributed pieces to each of a plurality of terminals;
    Obtaining the hash values of the distributed pieces distributed to the terminals from two or more terminals among the plurality of terminals;
    When the two or more terminals satisfy a predetermined condition, based on the acquired hash value and the calculated hash value, from the distributed pieces distributed to the two or more terminals Determining whether the content data can be restored;
    When it is determined that the content data can be restored, obtaining each of the distributed pieces from the two or more terminals, and restoring the content data based on the distributed pieces;
    A content data distribution method comprising:
  7. 　コンピュータに、
    　コンテンツデータから秘密分散法に従って異なるｎ個（ｎは２以上の整数）の分散片を生成するステップと、
    　前記ｎ個の分散片のハッシュ値をそれぞれ算出するステップと、
    　複数の端末のそれぞれに、前記ｎ個の分散片のいずれか１個以上を配信するステップと、
    　前記複数の端末のうち２以上の端末から、該端末に配信された前記分散片のハッシュ値をそれぞれ取得するステップと、
    　前記２以上の端末が所定の条件を満たしている場合に、前記取得されたハッシュ値と、前記算出されたハッシュ値と、に基づいて、前記２以上の端末に配信された前記分散片から前記コンテンツデータが復元可能か否かを判定するステップと、
    　前記コンテンツデータが復元可能であると判定された場合に、前記２以上の端末から前記分散片をそれぞれ取得して、該分散片に基づいて前記コンテンツデータを復元するステップと、
    　を実行させるためのプログラム。     On the computer,
    Generating different n pieces (n is an integer of 2 or more) from the content data according to the secret sharing method;
    Calculating a hash value of each of the n distributed pieces;
    Delivering one or more of the n distributed pieces to each of a plurality of terminals;
    Obtaining the hash values of the distributed pieces distributed to the terminals from two or more terminals among the plurality of terminals;
    When the two or more terminals satisfy a predetermined condition, based on the acquired hash value and the calculated hash value, from the distributed pieces distributed to the two or more terminals Determining whether the content data can be restored;
    When it is determined that the content data can be restored, obtaining each of the distributed pieces from the two or more terminals, and restoring the content data based on the distributed pieces;
    A program for running
PCT/JP2018/007284 2018-02-27 2018-02-27 Content data distribution system, content reproduction system, content data distribution method and program WO2019167126A1 (en)

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