JP2017204706A - Content distribution system, content distribution method, content generation apparatus, and content generation program - Google Patents

Abstract

Authenticity is ensured from the time content is generated.
When content is generated, a hash value of content and metadata accompanying the content are acquired, and the hash value and metadata are registered in the block chain. Accordingly, it is possible to guarantee systematically that the creator has not processed from the time when the content is generated to the time of distribution, and to ensure the authenticity of the content from the time of content generation to the time of distribution. Since hash values and metadata are registered in the blockchain, centralized management is not necessary.
[Selection] Figure 1

Description

  The present invention relates to a technique for ensuring the authenticity of content and metadata.

  Posting and sharing services for video and images are widespread. With these services, general users can post content such as videos and images, and can view the posted content. Users can freely post and view content, but it is difficult to confirm the authenticity of the content (that it has not been processed or tampered with), which may lead to unauthorized use of the content or infringement of copyright.

  An electronic signature is a means for proving authenticity when digital data is distributed. By ensuring authenticity, digital data can be used as contracts or public evidence.

  A non-patent document 1 service is known as a digital art work ownership management service. The service of Non-Patent Document 1 registers metadata such as work name, author name, year of creation, etc. and the address of the owner in the block chain, and records the transfer of rights.

  Blockchain technology is a technology that introduces a mechanism that can ensure reliability without requiring centralized management. In blockchain technology, the reliability of information exchanged between participants is ensured by a process of consensus building within the peer-to-peer (P2P) network formed by all participants, and tampering and double use By preventing fraud such as the entire system, the soundness of the blockchain is maintained. A blockchain is a collection of transaction information (transactions) between participants in units called blocks, in which information indicating the immediately preceding block is described in each block, and each block is linked. All transactions are recorded. Yes.

Trent McConaghy and David Holtzman, “Towards An Ownership Layer for the Internet”, [online], June 24, 2015, ascribe GmbH, Internet (URL: http://www.ascribe.io/)

  The method of using an electronic signature to prove the authenticity of the content has a problem that a centralization mechanism capable of ensuring reliability is required and the threshold is high. When a block chain is used, a transaction for registering content information is issued without using a centralized mechanism, and the content information can be distributed to the network by registering the transaction in the block chain.

  However, when the block chain is used, since the general user registers the content information without going through the centralization mechanism, there is a problem that the reliability of the registered content cannot be secured. Further, although authenticity at the time of distribution is guaranteed, authenticity from the moment the content is created to before distribution is not guaranteed. There is a possibility that the content is processed before distribution. For example, there is a problem in using the work certificate or the video of the in-vehicle camera at the time of the accident as evidence.

  In the service of Non-Patent Document 1, registration of works is organized by a service provider. The work name, author name, and creation year are self-reported, and the reliability of the information is not guaranteed. In addition, content created by secondary use is also newly handled, and there is a problem that it cannot be confirmed which content is based.

  The present invention has been made in view of the above, and an object thereof is to guarantee authenticity from the time of content generation.

  A content distribution system according to a first aspect of the present invention is a content distribution system for registering content information generated by a content generation device in a block chain, the content generation device generating content and a hash value of the content Content generation means for obtaining the metadata, metadata generation means for generating metadata of the content, and transmission means for transmitting the hash value and the metadata, the hash value and the metadata being the block chain And a block generation device that generates a block including the transaction and adds it to the end of the block chain before the transaction generation device issues the transaction. Previous Or hash value to check whether not registered in the block chain, or wherein the hash value prior to block generation unit generates the block characterized in that it sure not registered in the block chain.

  In the content distribution system, the metadata includes software and / or hardware information used for generating the content.

  In the content distribution system, the metadata includes information on a method for acquiring the metadata value.

  In the content distribution system, the content generation device includes an electronic signature unit that adds an electronic signature to the hash value and the metadata, and verifies the electronic signature before the transaction generation device issues the transaction. Alternatively, the electronic signature is verified before the block generation device generates the block.

  In the content distribution system, the metadata generation means encrypts at least a part of the values in the metadata with a secret key, and describes the hash value of the encrypted value in the metadata. In response to the acquisition request including the hash value and the public key described in the metadata, the content generation device encrypts a correct value corresponding to the hash value with the secret key, and further uses the public key. The encrypted correct answer value is returned.

  The content distribution method according to the second aspect of the present invention is a content distribution method executed by a computer, the step of generating content and obtaining a hash value of the content, the step of generating metadata of the content, Issuing the transaction for registering the hash value and the metadata in a block chain; and generating a block including the transaction and adding it to the end of the block chain, and issuing the transaction Alternatively, in any of the steps of registering in the block chain, it is confirmed whether the hash value is registered in the block chain.

  In the content distribution method, the step of generating the metadata includes encrypting the value of at least a part of the metadata with a secret key, and storing the hash value of the encrypted value in the metadata. In response to an acquisition request including the hash value and the public key described in the metadata, the correct value corresponding to the hash value is encrypted with the private key, and further encrypted with the public key. A step of returning a correct answer value.

  A content generation device according to a third aspect of the present invention is a content generation device for registering generated content information in a block chain, a content generation unit that generates content and obtains a hash value of the content, It has a metadata production | generation means which produces | generates metadata, The transmission means which transmits the said hash value and the said metadata, It is characterized by the above-mentioned.

  In the content generation apparatus, the metadata includes information on software and / or hardware used to generate the content, and includes electronic signature means for adding an electronic signature to the hash value and the metadata. And

  In the content generation apparatus, the metadata includes information on a method for acquiring the metadata value.

  A content generation program according to a fourth aspect of the present invention is characterized by operating a computer as each means of the content generation apparatus.

  According to the present invention, authenticity from the time of content generation can be guaranteed.

It is a whole lineblock diagram containing the contents generation device in this embodiment. It is a figure which shows the example of metadata. It is a figure which shows the range of an electronic signature. It is a flowchart which shows the flow of a process of the content generation apparatus in this Embodiment. It is a figure which shows the flow of a process which registers the hash value and metadata of a content into a block chain. It is a figure which shows the flow of another process which registers the hash value and metadata of a content into a block chain. It is a figure which shows a mode that the value in metadata is concealed. It is a sequence diagram which shows the flow of a process which acquires the correct value of metadata.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram including a content generation apparatus according to the present embodiment. When content is generated, the content generation device 1 shown in the figure calculates a hash value of the content, generates metadata of the content, attaches an electronic signature to the hash value and the metadata, and transmits it to the wallet 3. . The hash value and metadata are registered in the block chain by the wallet 3 and the minor 4 participating in the P2P network of the content management block chain.

  The content generation apparatus 1 illustrated in FIG. 1 includes a content generation unit 11, a metadata generation unit 12, an encryption unit 13, an electronic signature unit 14, and a transmission unit 15. Each unit included in the content generation device 1 may be configured by a computer including an arithmetic processing device, a storage device, and the like, and the processing of each unit may be executed by a program. This program is stored in a storage device included in the content generation apparatus 1, and can be recorded on a recording medium such as a magnetic disk, an optical disk, or a semiconductor memory, or provided through a network.

  The content generation unit 11 generates content such as video and images and calculates a hash value of the content. The content generation unit 11 is, for example, a smartphone camera application or a voice recorder. When an encoder chip for encoding video or the like is provided, the encoder chip functions as the content generation unit 11. The content is not limited to video and images, and may be audio. The time when the content is generated is when the content is written to a memory or a disk and becomes accessible. For example, when the user has taken a moving image or a still image using the content generation device 1.

  The metadata generation unit 12 generates content metadata. Content metadata includes metadata that can be acquired from within the content and metadata that is outside the content. The metadata in the content is data described in the content such as shooting date / time and position information. The metadata outside the content is information that is not described in the content but can be acquired by the content generation device 1. The metadata outside the content is, for example, data such as a terminal ID given to the content generation device 1, information on software and hardware used for content generation, and the name of the content creator. By including information on the software and hardware used to generate the content in the metadata, the authenticity of the content can be ensured if the software or hardware is sufficiently reliable. FIG. 2 shows an example of metadata. The metadata on the left side of FIG. 2 is an example of metadata described in the content, and the metadata on the right side is an example of metadata acquired and given by the metadata generation unit 12. Obtain multiple pieces of information that can be obtained from multiple sources, such as date, time, and location, and list the source. For example, the date and time acquisition source includes a clock in the terminal, a GPS, an NTP server, and the like, and the location acquisition source includes a GPS and a wireless base station.

  The encryption unit 13 encrypts the content on the basis of a license (public / limited publication) given to the content. If the content can be freely accessed, the content need not be encrypted.

  The electronic signature unit 14 adds an electronic signature to the hash value and metadata of the content. When the content is encrypted, a hash value of the encrypted content is calculated, and an electronic signature is attached together with the hash value and metadata of the original content. When the encoder chip supports the electronic signature, the electronic signature of the encoder chip for the hash value of the content and the metadata in the content is also obtained. FIG. 3 is a diagram showing the range of the electronic signature. When the encoder chip is compatible with the electronic signature, the electronic signature of the encoder chip is given to the hash value of the content generated by the encoder chip and the metadata described in the content. In addition to the metadata described in the content, the electronic signature unit 14 assigns an electronic signature including the metadata provided by the metadata generation unit 12 and, if the content is encrypted, the hash value of the encrypted content. To do.

  The transmission unit 15 transmits the hash value and metadata of the content attached with the electronic signature to the wallet 3. The content main body may be held by the content generation device 1 and the content may be distributed upon request. Alternatively, the content may be transmitted to the content server, and the content server may hold and distribute the content. The content acquisition destination may be recorded in the metadata.

  The hash value and metadata are registered in the block chain by the wallet 3 and the minor 4 participating in the P2P network of the block chain. The wallet 3 receives the hash value and metadata from the content generation device 1, issues a transaction describing a series of processes for registering the hash value and metadata, and broadcasts it to the network. The minor 4 generates a block including a transaction and adds it to the block chain. There are a large number of minors 4 on the network. The minor 4 that has generated the block that satisfies the predetermined condition earliest can add the block to the block chain. The blockchain that records all transactions is shared across the network. The contents of the transaction included in the blockchain can be confirmed by any participant, and it is virtually impossible to tamper with it.

  Note that the content generation apparatus 1 may have a wallet 3 function and issue a transaction for registering a hash value and metadata.

  Next, a processing flow of the content generation apparatus will be described.

  FIG. 4 is a flowchart showing the flow of processing of the content generation apparatus according to this embodiment.

  When the content generation unit 11 generates content (step S11), the metadata generation unit 12 generates metadata (step S12). The hash value of the content is calculated when the content is generated.

  If the content needs to be encrypted, the encryption unit 13 encrypts the content (step S13).

  If the content is encrypted, the hash value of the encrypted content is calculated (step S14).

  The electronic signature unit 14 attaches an electronic signature to the content hash value (including the encrypted content hash value) and metadata (step S15), and the transmission unit 15 transmits the hash value and metadata to the wallet 3 (step S15). Step S16).

  Next, processing of the wallet 3 and the minor 4 for registering the hash value and metadata in the block chain will be described.

  5 and 6 are flowcharts showing the flow of processing for registering the hash value and metadata of the content in the block chain. FIG. 5 is a flowchart of a process in which the wallet 3 checks whether or not the content is already registered in the block chain, and FIG. 6 is a flowchart of a process in which the minor 4 checks.

  First, the flowchart of FIG. 5 will be described.

  When receiving the hash value and the metadata, the wallet 3 checks whether the hash value is registered in the block chain (step S21). If the same hash value is already registered in the block chain, registration is stopped. Here, the electronic signature attached to the hash value and the metadata may be verified by the wallet 3.

  The wallet 3 issues a transaction for registering the hash value and metadata (step S22). Transactions are broadcast to nodes participating in the blockchain P2P network.

  The minor 4 receives the transaction, generates a block including the transaction, and adds it to the end of the block chain (step S23).

  Next, the flowchart of FIG. 6 will be described. The flowchart of FIG. 6 is a process for registering the hash value and metadata in the block chain as in FIG. 5, but the minor 4 is different in that it checks whether the hash value has already been registered in the block chain.

  The wallet 3 issues a transaction for registering the hash value and metadata (step S24). Transactions are broadcast to nodes participating in the blockchain.

  The minor 4 receives the transaction and checks whether the hash value included in the transaction is registered in the block chain (step S25). If the same hash value is already registered in the blockchain, the transaction is discarded. Here, the minor 4 may verify the hash value and the electronic signature attached to the metadata.

  The minor 4 generates a block including a transaction and adds it to the end of the block chain (step S26).

  Through the above process, the hash value and metadata of the content are registered in the block chain.

  Next, secrecy of metadata information will be described.

  All transactions are recorded in the block chain, and anyone can confirm the contents of the transactions included in the block chain. In this embodiment, the hash value and metadata of the content are registered in the block chain. The metadata includes items such as date and time and position information that make it clear when and where the creator was. From the viewpoint of privacy, there is a desire to keep metadata information confidential. If the data does not have a fixed format, the risk of being read only by hashing is reduced. However, in the case of the fixed format data, there is a high possibility that a correct value that produces the same hash value is searched for. Hashing with meaningless character strings before and after the fixed format data is also possible, but because the normal value is processed, the character string in the same format as the normal value was inserted. In some cases, there is a concern that it will be indistinguishable, reducing the reliability of the value.

  Therefore, in the present embodiment, as shown in FIG. 7, the metadata generation unit 12 encrypts the value of the item to be concealed in the metadata with the secret key of the creator, and then the hash value of the encrypted value Is calculated and described in the metadata.

  The concealed value can be known by the procedure shown in FIG. FIG. 8 is a sequence diagram showing a flow of processing in which a requester obtains a correct answer value of metadata from a creator. The processing shown in the figure is performed by the device used by the requester and the content generation device 1.

  First, the requester sends a request for obtaining a correct value including the hash value (hashed after encryption) and the public key of the requester described in the metadata that the correct value is desired to know (step) S71).

  The creator encrypts the correct answer value with the secret key of the creator, and further encrypts it with the public key of the requester (step S72).

  The creator transmits the correct value double-encrypted in step S72 to the requester (step S73).

  The requester decrypts with the requester's own private key and takes out the correct value encrypted with the creator's private key (step S74).

  The requester calculates a hash value of the value extracted in step S74 (correct value encrypted with the creator's private key), and whether the obtained hash value is the same as the hash value described in the metadata. It is confirmed whether or not (step S75).

  If the hash values are the same, the correct value is obtained by decrypting the value extracted in step S74 with the creator's public key (step S76).

  Through the above processing, the requester can know the correct value of the secret item in the metadata.

  As described above, according to the present embodiment, when content is generated, a hash value of content and metadata accompanying the content are acquired, and by registering the hash value and metadata in the block chain, It is possible to guarantee systematically that the creator has not processed from the time of content generation to the time of distribution, and to ensure the authenticity of the content from the time of content generation to the time of distribution. Since hash values and metadata are registered in the blockchain, centralized management is not necessary.

  According to the present embodiment, the content generation device 1 encrypts at least a part of the values in the metadata with the creator's private key, and describes the hash value of the encrypted value in the metadata. Upon receiving the acquisition request including the hash value described in the metadata and the requester's public key, the content generation apparatus 1 encrypts the correct value corresponding to the hash value with the creator's private key, and further requests By transmitting a value double-encrypted with the public key of the person, it is possible to conceal and limit the value described in the metadata while ensuring authenticity. The requester decrypts the double-encrypted value with the requester's private key, calculates its hash value, and confirms whether it is the same as the hash value described in the metadata, It can be confirmed that the received value is the same as that requested. The requester can know the correct value of the requested value by decrypting the double encrypted value with the requester's private key and the creator's public key.

DESCRIPTION OF SYMBOLS 1 ... Content production | generation apparatus 11 ... Content production | generation part 12 ... Metadata production | generation part 13 ... Encryption part 14 ... Digital signature part 15 ... Transmission part 3 ... Wallet 4 ... Minor

Claims (11)

A content distribution system for registering content information generated by a content generation device in a block chain,
The content generation device includes:
Content generating means for generating content and obtaining a hash value of the content;
Metadata generation means for generating metadata of the content;
Transmission means for transmitting the hash value and the metadata,
A transaction generation device that issues a transaction for registering the hash value and the metadata in the block chain;
A block generation device that generates a block including the transaction and adds the block to the end of the block chain, and
Before the transaction generation device issues the transaction, it is checked whether the hash value is registered in the block chain, or the hash value is added to the block chain before the block generation device generates the block. A content distribution system that checks whether it is registered.   The content distribution system according to claim 1, wherein the metadata includes information on software and / or hardware used to generate the content.   The content distribution system according to claim 1, wherein the metadata includes information on a method of acquiring the metadata value. The content generation device has an electronic signature means for giving an electronic signature to the hash value and the metadata,
4. The electronic signature is verified before the transaction generation device issues the transaction, or the electronic signature is verified before the block generation device generates a block. The content distribution system described in Crab. The metadata generation means encrypts the value with a secret key for at least a part of the value in the metadata, describes the hash value of the encrypted value in the metadata,
In response to the acquisition request including the hash value and the public key described in the metadata, the content generation device encrypts a correct value corresponding to the hash value with the private key, and further encrypts with the public key. 5. The content distribution system according to claim 1, wherein the encrypted correct answer value is returned. A content distribution method executed by a computer,
Generating content and determining a hash value of the content;
Generating metadata of the content;
Issuing a transaction for registering the hash value and the metadata in a blockchain;
Generating a block including the transaction and adding it to the end of the block chain, and
A content distribution method characterized by confirming whether or not the hash value is registered in the block chain in either the step of issuing the transaction or the step of registering in the block chain. The step of generating the metadata includes, for at least a part of the values in the metadata, encrypting the values with a secret key, and describing a hash value of the encrypted value in the metadata,
In response to an acquisition request including the hash value and public key described in the metadata, an encrypted correct value obtained by encrypting a correct value corresponding to the hash value with the private key and further encrypting with the public key The content distribution method according to claim 6, further comprising a step of replying. A content generation device for registering generated content information in a block chain,
Content generating means for generating content and obtaining a hash value of the content;
Metadata generation means for generating metadata of the content;
Transmitting means for transmitting the hash value and the metadata;
A content generation apparatus comprising: The metadata includes information on software and / or hardware used to generate the content,
The content generation apparatus according to claim 8, further comprising an electronic signature unit that adds an electronic signature to the hash value and the metadata.   The content generation apparatus according to claim 8, wherein the metadata includes information on a method for acquiring the metadata value.   A content generation program that causes a computer to operate as each unit of the content generation device according to claim 8.

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