JP6302592B2 - Information processing apparatus, information processing method, and program - Google Patents

Description

  The present invention relates to an information processing apparatus, an information processing method, and a program.

  In recent years, commercial transactions using a virtual currency such as Bitcoin (registered trademark) have been performed. In the commercial transaction using the virtual currency, a technique called block chain is used in order to prevent fraud without requiring centralized management. In blockchain, multiple transactions, previous hash values, and other information are defined as “blocks”, and the reliability of the information in these “blocks” is determined by a consensus building process in the network formed by all participants. Is secured.

  For example, Patent Literature 1 discloses a technology for realizing a commercial transaction using a virtual currency by such a block chain technology.

JP, 2006-218633, A

  Here, since the block chain indicates the contents of the transaction for all the participants, the block chain is not limited to the transaction of virtual currency such as Bitcoin (registered trademark), and can be applied to various transactions. For example, a method of using a block chain as a trail when a contract is exchanged between a plurality of persons can be considered. However, due to the nature of the contract, there arises a problem that the contents of the contract can be referred to only by a specific participant and kept secret from others. In such a case, simply applying the technique described in Patent Document 1 as it is cannot solve the problem, and it is not yet sufficient from the aspect of ensuring confidentiality of specific information.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an information processing apparatus, an information processing method, and a program capable of ensuring confidentiality with respect to specific information.

In order to achieve the above object, an information processing apparatus according to the first aspect of the present invention provides:
Data storage means for encrypting and storing the generated data with a common key in blocks connected by a block chain constructed in the network (for example, the encryption / decryption unit 124 that executes the processing of step S207 and step S208, and Data registration unit 121);
Public key acquisition means (for example, another public key acquisition unit 126 that executes the process of step S204) for acquiring a second public key different from the first public key stored in advance from the blocks connected by the block chain; ,
Common key storage means for encrypting the common key with the second public key acquired by the public key acquisition means, and storing the encrypted common key in blocks connected by the block chain (for example, step S205 and step An encryption / decryption unit 124 and a data registration unit 121) that execute the process of S206;
A common key generation unit configured to generate a new common key different from the common key after the common key encrypted by the common key storage unit is stored in a block connected by the block chain. ,
The data storage means encrypts and stores the generated data with a common key corresponding to a predetermined condition among the common key or the new common key in blocks connected by the block chain. ,
And wherein a call.

In order to achieve the above object, an information processing apparatus according to the second aspect of the present invention provides:
Data acquisition means (for example, the block integration unit 125 that executes the process of step S301) for acquiring data encrypted with a common key from blocks connected in a block chain constructed in the network;
When the common key is not stored, an encrypted common key acquisition unit (for example, the process of step S301) that acquires the common key encrypted with the public key stored in advance from the blocks connected by the block chain Block integration unit 125) for executing
A common key decryption means for decrypting the common key obtained by the encrypted common key obtaining means with a secret key corresponding to the public key (for example, an encryption / decryption unit 124 for executing the process of step S305);
A data decryption means for decrypting the data acquired by the data acquisition means with the common key (for example, an encryption / decryption unit 124 that executes the process of step S306);
Display means for displaying the data decrypted by the data decryption means (for example, the block integration unit 125 for executing the process of step S307);
It is characterized by providing.

The common key storage means encrypts the common key with the first public key, and stores the encrypted common key in blocks connected by the block chain (for example, execute the processes of step S103 and step S104) Encryption / decryption unit 124 and data registration unit 121),
You may do it.

  Further, the generated data includes low-importance data less than a predetermined importance and high-importance data higher than the predetermined importance,
  Further comprising importance data storage means for storing the high importance data in a database connected via the network, which is different from the blocks connected by the block chain,
  The data storage means stores the low importance data in blocks connected by the block chain, and performs a predetermined calculation on the high importance data with storage destination information indicating a storage destination of the high importance data. Stored in the block connected with the block chain together with the calculated value calculated by
  You may do it.

In order to achieve the above object, an information processing method according to a third aspect of the present invention includes:
An information processing method in an information processing apparatus,
A data storage step (for example, a step of executing the processing of step S207 and step S208) for encrypting the generated data with a common key and storing it in the blocks connected by the block chain constructed in the network;
A public key acquisition step of acquiring a second public key different from the first public key stored in advance from the blocks connected by the block chain (for example, the step of executing step S204);
A common key storage step (for example, step S205 and step S) that encrypts the common key with the second public key acquired in the public key acquisition step, and stores the encrypted common key in blocks connected by the block chain. Step of executing the process of S206),
A common key generation step of generating a new common key different from the common key after the encrypted common key is stored in the block connected by the block chain in the common key storage step. ,
In the data storing step, the generated data is encrypted and stored in a block connected by the block chain with a common key corresponding to a predetermined condition among the common key or the new common key. ,
And wherein a call.

In order to achieve the above object, a program according to the fourth aspect of the present invention provides:
Computer
Data storage means for encrypting and storing the generated data with a common key in blocks connected by a block chain constructed in the network (for example, the encryption / decryption unit 124 that executes the processing of step S207 and step S208, and Data registration unit 121),
Public key acquisition means for acquiring a second public key different from the first public key stored in advance from the blocks connected by the block chain (for example, another public key acquisition unit 126 that executes the process of step S204),
Common key storage means for encrypting the common key with the second public key acquired by the public key acquisition means, and storing the encrypted common key in blocks connected by the block chain (for example, step S205 and step Encryption / decryption unit 124 and data registration unit 121) that execute the process of S206,
After the common key encrypted by the common key storage means is stored in the block connected by the block chain, it functions as a common key generation means for generating a new common key different from the common key. ,
The data storage means encrypts and stores the generated data with a common key corresponding to a predetermined condition among the common key or the new common key in blocks connected by the block chain. ,
And wherein a call.

  According to the present invention, confidentiality with respect to specific information can be ensured.

It is a block diagram showing an example of an information processing system concerning an embodiment of the present invention. It is a block diagram which shows an example of the information processing apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the contract document to produce. It is a flowchart which shows an example of a prior registration process. It is a figure which shows an example of the specific content registered by a prior registration process. It is a flowchart which shows an example of a block registration process. It is a flowchart which shows an example of a reference process. It is a figure which shows an example of the specific registration content of the block registration process in the pattern 1. FIG. It is a figure which shows the example of the concrete reference content in case the content of a block chain is in the state shown in FIG. It is a figure which shows an example of the specific registration content of the block registration process in the pattern 2. FIG. It is a figure which shows the example of the concrete reference content in case the content of a block chain is in the state shown in FIG. It is a figure which shows an example of the specific registration content of the block registration process in the pattern 3. FIG. It is a figure which shows the example of the concrete reference content in case the content of a block chain is in the state shown in FIG. It is a figure which shows the specific content of the block chain in a modification. It is a block diagram which shows an example of the information processing system in a modification.

  First, the outline of the block chain will be described by taking the information processing system 1 shown in FIG. 1 as an example. In the information processing system 1, as shown in FIG. 1, information processing apparatuses 100 </ b> A to 100 </ b> C (the information processing apparatuses 100 </ b> A to 100 </ b> C are also simply referred to as information processing apparatuses 100) are connected to be communicable via a network 210. .

  The information processing apparatus 100 is an information terminal such as a mobile phone, a smartphone, a tablet, or a PC (Personal Computer), and constructs a distributed network 210 such as P2P (Peer to Peer). Note that the information processing system 1 is not limited to a P2P type system, and may be a cloud computing type, for example.

  The information processing apparatus 100 functions as a transaction generation apparatus having a function of generating data related to a contract by a user operation and distributing it to the network 210. The information processing apparatus 100 also functions as a block chain generation apparatus that verifies the validity of the transaction distributed by the transaction generation apparatus, generates a new block, and connects existing block chains. The result verified by the block chain generation device is shared by each information processing device 100 via the network 210. In the illustrated example, in order to facilitate understanding, an example in which the information processing apparatus 100 has both the function of the transaction generation apparatus and the function of the block chain generation apparatus is shown. It may be. Usually, data handled by a certain number of transactions is stored in one block (the block chain generation device collects a certain number of transactions in one block and puts a plurality of data handled by that transaction into one block. In this embodiment, it is assumed that data handled by one transaction is stored in one block in order to facilitate understanding.

  In this embodiment, data relating to a contract handled by a transaction generated by a function as a transaction generation device (simply referred to as data) is stored in one unit called a block, and the block is a block obtained by connecting the blocks in time series Managed by a chain. Specifically, the data is stored in a block newly generated by a function as a block chain generation device, and then linked to an existing block chain and shared by each information processing device 100. For example, when a transaction that is not included in the block chain is distributed, the function of the block chain generation device verifies the transaction and generates a new block (nth block). Then, the hash value (256 bits) of the last block (n-1th block) of the current block chain is included in the data and stored in a new block (nth block). As a result, data is stored in the block and is managed in time series by the block chain. In other words, the block chain has a role as a ledger that records data (contract contents) related to the contract. In the following, a contract performed by the user A, the user B, and the user C will be described as an example.

  Next, the configuration of the information processing apparatus 100 in this embodiment will be described with reference to FIG. In the illustrated example, the information processing apparatus 100A that is the user A terminal is taken as an example, but the same applies to the information processing apparatus 100B that is the user B terminal and the information processing apparatus 100C that is the user C terminal. The description is omitted.

  As shown in FIG. 2, the information processing apparatus 100A (hereinafter referred to as the information processing apparatus 100) includes a storage unit 110, a control unit 120, an input / output unit 130, a communication unit 140, and a system bus that interconnects them. (Not shown).

  The storage unit 110 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a program executed by the CPU of the control unit 120 and data necessary for executing the program in advance. Specifically, in this embodiment, a program for causing the information processing apparatus 100 to function as a transaction generation apparatus, a program for causing the information processing apparatus 100 to function as a block chain generation apparatus, a program for generating various keys, and the like are installed in advance. ing. The RAM stores data that is created or changed during program execution. The storage unit 110 includes user A's private key 111, user A's public key 112, first common key 113, block integration data 114, and other users' public key 115 as main information used by the program executed by the control unit 120. , Remember.

  User A's private key 111 and user A's public key 112 are keys used for encryption and decryption generated by a pair key generation unit 122 described later. Data encrypted with the public key 112 of the user A can be decrypted only with the private key 111 of the user A. In the illustrated example, the public key 112 of the user A and the private key 111 of the user A are stored, but the public key 112 and the private key 111 are generated and stored for each user by the pair key generation unit 122. The

  The first common key 113 is a key generated by a common key generation unit 123 described later, and is a key used in common for both encryption and decryption. In the illustrated example, the first common key 113 is stored, but the common key may not be stored, and a new common key different from the first common key 113 is generated. It may be stored (details will be described later). The block integration data 114 is data indicating the contents of each block integrated by the block integration unit 125 described later. The public key 115 of another user is a public key of another user acquired by the other public key acquisition unit 126 described later.

  The block information DB 116 is a database that stores information about the generated blocks.

  The control unit 120 includes a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), and the like. The control unit 120 operates according to a program stored in the storage unit 110 and executes processing according to the program. The control unit 120 includes, as main functional units provided by programs stored in the storage unit 110, a data registration unit 121, a pair key generation unit 122, a common key generation unit 123, and an encryption / decryption unit 124. The block integration unit 125 and the other public key acquisition unit 126 are provided.

  The data registration unit 121 is a functional unit that implements the functions as the transaction generation device and the block chain generation device described above. The data registration unit 121 has a function of generating a new transaction based on a user operation on the input / output unit 130 (a function of a transaction generation device), a function of verifying that the new transaction is valid, and a new A function for generating a block chain by generating a block and storing data handled in a verified transaction (function of a block chain generation device). That is, the data registration unit 121 has a general function related to block chain data registration. As described above, in this embodiment, in order to facilitate understanding, the information processing apparatus 100 (user A's terminal) functions as a data generation unit 121 as a transaction generation apparatus and as a block chain generation apparatus. Although described as having a function, for example, the data registration unit 121 in the terminal of the user A has a function as a transaction generation device, and the data registration unit 121 in the terminal of the user B functions as a block chain generation device. You may have. That is, the data registration unit 121 does not necessarily have both functions, and may have different functions according to conditions (situations).

  The pair key generation unit 122 has a function of generating the public key and secret key of the user. Specifically, the pair key generation unit 122 generates the public key and secret key of the user according to the pair key generation program stored in the storage unit 110 (in the example illustrated in FIG. 2, the public key 112 of the user A and the user A private key 111 of A is generated). In this embodiment, a public key and a secret key for each user are generated in advance by the pair key generation unit 122 and stored in the storage unit 110.

  The common key generation unit 123 has a function of generating a common key according to the common key generation program stored in the storage unit 110 (in the example illustrated in FIG. 2, the first common key 113 is generated). In this embodiment, an example in which a common key is generated by a common key generation program is shown, but the common key may be acquired from the outside via the network 210.

  The encryption / decryption unit 124 has a function of performing various encryptions and decryptions. As will be described in detail later, the encryption / decryption unit 124 in this embodiment has a function of encrypting a common key with its own or another person's public key, a function of encrypting data with a common key, and an encrypted common It has a function of decrypting a key with its own secret key and a function of decrypting encrypted data with a common key.

  The block integration unit 125 has a function of generating the block integrated data 114 by integrating the contents (each data) of the blocks connected as a block chain.

  The other public key acquisition unit 126 has a function of acquiring another user's public key. The other public key acquisition unit 126 acquires a public key generated in another user's terminal and registered in the block chain.

  The input / output unit 130 includes a keyboard, a mouse, a camera, a microphone, a liquid crystal display, an organic EL (Electro-Luminescence) display, and the like, and is a device for inputting and outputting data.

  The communication unit 140 is a device for communicating with another information processing apparatus 100 via the network 210.

  The above is the configuration of the information processing apparatus 100. Next, the operation of the information processing apparatus 100 will be described with reference to FIGS. In this embodiment, a case where “document A” shown in FIG. 3 is created as a contract between users A, B, and C will be described as an example. In this embodiment, group information that can be uniquely identified by the type of document (document name) is predetermined, and a block chain is generated for each group (in the example shown, document A is group A). The block chain of document A is generated). The contents of items 1 to 3 shown in FIG. 3 correspond to one piece of data. In this embodiment, in order to facilitate understanding, the contents of items 1 to 3 (that is, data 1 to 3) are sequentially stored in blocks 1 to 3 and managed as a block chain. (One data is handled in one transaction, and the one data is sequentially stored in one block).

  First, the pre-registration process shown in FIG. 4 is performed based on an operation by the user. The pre-registration process is a process for setting the data of the group of documents shown in FIG. 3 as a block chain to be managed by the block chain. Note that the public key 112 and the private key 111 of each user are generated in advance by the function of the pair key generation unit 122 in each information terminal (information processing apparatus 100) of the user A, the user B, and the user C, and are stored in the storage unit 110. Assume that it is stored. In this embodiment, it is assumed that the pre-registration process is executed by user A's operation. The user who performs the pre-registration process is determined in advance, and may be performed by a user other than the user A.

  In the pre-registration process shown in FIG. 4, first, the information processing apparatus 100 creates group information using the function of the data registration unit 121 (step S <b> 101). Specifically, in the process of step S101, the group managed by the block chain is “document A” (group A), and the group includes items 1 to N (N is an integer and the last item of the document A). This is defined by creating (registering) block 1. Block 1 is the first block in the block chain. Thus, by performing the process of step S101, as shown in FIG. 5, the content of the group A indicating the document A is defined in the block 1 as the group information to be created. Note that the processing in step S101 may be performed by the user selecting group information to be created from a plurality of group information stored in advance in the storage unit 110. Further, the processing in step S101 may be performed by a dedicated server connected to the information processing apparatus 100 via a network instead of the information processing apparatus 100. In the dedicated server, the referable person described later is managed, and the dedicated server may have the function of the pair key generation unit 122 and the function of the common key generation unit 123. That is, the public key and secret key generated by the dedicated server may be managed in association with the identification information of each user and distributed to each user. The common key may be distributed from the dedicated server to the required users.

  Subsequently, the information processing apparatus 100 generates the first common key 113 by the function of the common key generation unit 123 (step S102), and the generated first common key 113 by the function of the encryption / decryption unit 124. It encrypts with the public key 112 of the user A (step S103). Then, using the function of the data registration unit 121, the encrypted first common key 113A is registered in the block 1 (step S104), and the pre-registration process is terminated. In the process of step S104, as shown in FIG. 5, the public key 112 of user A is also registered in block 1 in the same manner as the first common key 113A. The example shown in FIGS. 4 and 5 shows an example in which the public key 112 and the first common key 113A of the user A are registered in the block. This is because the user A manages only the secret key 111. This is because even if one common key 113 is not managed, it can be obtained from a block, and the key management burden can be reduced. When the key management burden is not taken into account, the public key 112 and the first common key 113A of the user A may not be registered in the block.

  In this embodiment, the contents of all transactions registered in the block are verified at regular timing by the function of the block chain generation device, as in the general block chain technology. If it is recognized as valid, the data handled in the transaction is registered in the block, connected to the existing block chain, and shared by each information processing apparatus 100 via the network 210. It becomes. Hereinafter, since the registration to the block is the same, description thereof will be omitted.

  Next, a block registration process for registering data (generated data or simply data) handled in a transaction generated by a user operation in a block will be described. The block registration process is executed by a user operation (an operation for generating a transaction and registering data). In this embodiment, as described above, since one block is created and registered for each item (one data), the number of items to be registered (the number of transactions) ), It may be executed repeatedly.

  FIG. 6 is a flowchart illustrating an example of the block registration process. Here, description will be made without designating an execution user. In the block registration process, first, the information processing apparatus 100 determines whether the data handled in the generated transaction (data to be registered) is an encryption target by the function of the data registration unit 121 (step S201). ). Whether or not it is an encryption target may be determined in advance together with a referable person (to be described later) when group information is registered (defined) in the pre-registration process (items and references for encryption). It is only necessary that information indicating whether or not the data is data to be encrypted is stored in the storage unit 110 together with information on the referable person.

  When the registration target data is not the encryption target (step S201; No), the information processing apparatus 100 registers the data in the target block by the function of the data registration unit 121 (step S202), and ends the block registration process. To do.

  On the other hand, when the data to be registered is the encryption target (step S201; Yes), it is determined whether or not the public key of the user (referenceable person) who can refer to the data is owned (step S203). As described above, the information regarding the referable person is predetermined and stored in the storage unit 110 when the group information is registered (defined) in the pre-registration process. Therefore, in the process of step S203, the storage unit 110 It is only necessary to identify the referable person based on the information stored in and to determine whether or not all of the identified referable persons have public keys. Note that identification information for identifying a user may be added to the public key, and it may be determined which user's public key is based on the identification information.

  When it is determined that the public key of the referable person is not owned (step S203; No), the information processing apparatus 100 acquires the public key of the referable person by the function of the other public key acquisition unit 126 (step S204). ). Although details will be described later, in the process of step S204, the public key of the referable person registered in the block is acquired. After executing the process of step S204, the information processing apparatus 100 uses the function of the encryption / decryption unit 124 to generate a common key with the acquired public key (the common key is generated in the process of step S102 in FIG. 4). ) Is encrypted (step S205) and registered in the block (step S206). By performing the process in step S206, the referable person can acquire the common key encrypted in the process in step S205. Then, the referable person only has to decrypt the acquired encrypted common key with the private key owned by himself / herself (step S305 described later). In addition, you may perform the process of the said step S204-step S206 after the process of step S208 mentioned later.

  After performing the process of step S206, or when it is determined in step S203 that the public key of the referable person is owned (step S203; Yes), the information processing apparatus 100 performs the function of the encryption / decryption unit 124. Thus, the data is encrypted with the common key owned (step S207). Then, the encrypted data is registered in the target block (step S208), and the block registration process is terminated. By performing the block registration process, data to be registered (data handled in the generated transaction) is managed by the block chain.

  Next, reference processing when referring to the contents of the blocks connected to the block chain by the block registration processing of FIG. 6 will be described with reference to FIG. The reference process is executed by a user operation. More specifically, it is executed by performing an operation for designating a group to be referred to. Note that the reference process can be executed for each user.

  When the reference process is started, the information processing apparatus 100 acquires all the contents (each data and key information) of the blocks connected by the block chain corresponding to the specified group by the function of the block integration unit 125. (Step S301). Then, it is determined whether or not encrypted data is included in the content of the acquired block (step S302). If encrypted data is included (step S302; Yes), it is determined whether or not the corresponding common key is owned (step S303). In this embodiment, when data is encrypted, it is encrypted with the common key by the process of step S207 in FIG. 6, and therefore the process of step S303 has a common key that can be decrypted. It is determined whether or not.

  When it is determined that the corresponding common key is not owned (step S303; No), the information processing apparatus 100 determines whether the acquired content includes an encrypted common key by the function of the block integration unit 125. Is determined (step S304). Specifically, in the process of step S304, it is determined whether or not the encrypted common key can be decrypted with the private key owned by itself. When the encrypted common key can be decrypted with the private key owned by itself (step S304; Yes), the information processing apparatus 100 uses the function of the encryption / decryption unit 124 to decrypt the encrypted key. The common key is decrypted with its own secret key (step S305).

  After determining that the corresponding common key is possessed in the process of step S303 after executing the process of step S305 (step S303; Yes), the information processing apparatus 100 functions the encryption / decryption unit 124. Thus, the encrypted data is decrypted with the common key (step S306). After executing the process of step S306, the information processing apparatus 100 outputs the decrypted data by the function of the block integration unit 125 (step S307), and ends the reference process.

  On the other hand, if it is determined in step S304 that the encrypted common key cannot be decrypted with the private key owned by itself (step S304; No), the encrypted data is in an encrypted state. The output is output as it is (step S307), and the reference process is terminated. When it is determined in step S302 that the encrypted data is not included (step S302; No), the information processing apparatus 100 outputs the data by the function of the block integration unit 125 (step S307). ) End the reference process.

  The above is the operation of the information processing apparatus 100. Subsequently, a more specific operation will be described separately for Pattern 1 to Pattern 3.

  First, a case where data corresponding to item 3 in the group of “document A” shown in FIG. 3 can be referred to only by user A (pattern 1) will be described. FIG. 8 is a diagram illustrating an example of specific registration contents of the block registration process in Pattern 1. In the following description, it is assumed that the pre-registration process shown in FIG. 4 is performed by the user A (that is, encryption is performed using the public key of the user A and the public key of the user A as shown in FIG. The description will be made on the assumption that the first common key is registered in block 1). Also, block registration processing is performed by user A, and data corresponding to items 1 to 3 is registered in the target block (the same applies to pattern 2).

  First, when the user A starts the block registration process shown in FIG. 6, the data corresponding to the item 1 is not an object to be encrypted, so it is determined No in step S <b> 201 of FIG. 6, and the item 1 is processed in the process of step S <b> 202. Is registered in block 1 (see block 1 in FIG. 8). As for item 2, the contents of item 2 are registered in block 2 in the process of step S202 as in item 1 (see block 2 in FIG. 8).

  On the other hand, since the data corresponding to item 3 is an encryption target, it is determined Yes in step S201 in FIG. 6 and the process proceeds to step S203. In step S203, since the referable person is the user A himself / herself, it is determined that the public key of the referable person is owned (determined as Yes). Then, in step S207, the data corresponding to the item 3 is encrypted with the first common key 113 (for example, 99999999 is set to MzYWdU0M as shown in FIG. 8), and the encrypted data in step S208 is Registered in block 3.

  The above is the specific registration contents of the block registration process in Pattern 1. Note that the case where only data that can be referred to by any user is registered is the same as the registration in block 1 and block 2 shown in FIG. Subsequently, specific reference contents of the reference process in the pattern 1 will be described. FIG. 9 shows an example of specific reference contents when the contents of the block chain are in the state shown in FIG.

  First, the case where the user A performs the reference process shown in FIG. 7 will be described. When the reference process is started, the contents of block 1 to block 3 shown in FIG. 8 are acquired by the process of step S301. Among them, since the data corresponding to item 3 is encrypted, it is determined Yes in step S302, and the process proceeds to step S303. In the process of step S303, since the first common key 113 corresponding to the encrypted data is owned, it is determined Yes and the process proceeds to step S306. Then, the data corresponding to item 3 is decrypted by the first common key 113 in the process of step S306. By subsequently executing the process of step S307, the data corresponding to item 3 is displayed in a decrypted state as shown in FIG. 9A (items 1 and 2 are encrypted). It will be displayed as it is).

  On the other hand, when the user B or the user C performs the reference process illustrated in FIG. 7, the contents of the blocks 1 to 3 illustrated in FIG. Although it is determined Yes in step S302 of FIG. 7, since user B and user C do not have the first common key 113, it is determined No in the process of step S303. Then, the process proceeds to step S304. However, since the encrypted common key is not included in the acquired contents of blocks 1 to 3, it is determined No in step S304. Then, the process of step S307 is executed, and as shown in FIG. 9B, the data corresponding to item 3 is displayed in an encrypted state (items 1 and 2 are not encrypted and thus remain as they are. Is displayed).

  In this way, the data corresponding to item 3 can be referred to only by user A by encrypting the data corresponding to item 3 with the first common key 113 and registering it in the block. it can. Therefore, confidentiality with respect to specific information can be ensured. Also, by encrypting the generated first common key 113 with the public key 112 of the user A and registering it in the block, the user A can obtain the first common key 113 from the block without owning the first common key 113. Therefore, the user A only has to manage the secret key 111, and the management burden of the first common key 113 can be reduced.

  Next, a case where the data corresponding to item 3 in the group of “document A” shown in FIG. 3 can be referred to only by user A and user B (pattern 2) will be described. FIG. 10 is a diagram illustrating an example of specific registration contents of the block registration process in the pattern 2. Note that description of the same parts as those of the pattern 1 is omitted. The first common key encrypted with the public key of user A is also registered in block 1 (not shown in FIG. 10) as in pattern 1 (similar to block 1 in FIG. 8). And

  When the user A starts the block registration process shown in FIG. 6, the data corresponding to the item 1 and the data corresponding to the item 2 are registered in each block in the same manner as the pattern 1 (see block 2 in FIG. 10). Since the data corresponding to item 3 is to be encrypted, it is determined Yes in step S201 in FIG. 6, and the process proceeds to step S203.

  In step S203, since the public key of the user B who can be referred to is not owned, it is determined No. And user A acquires the public key of user B who is a referable person by the process of step S204. As shown in FIG. 10, user B's public key is registered in advance in a block (block 3 in the illustrated example). For example, based on the fact that the block 2 is registered by the user A and shared among the users, the public key of the user B may be registered in the target block by the operation of the user B. In addition, an instruction for registering the public key in the target block may be transmitted from the user A to the user B, and the user B may register the public key based on the instruction. In the process of step S204 shown in FIG. 6, the public key of user B registered by user B in this way is acquired.

  Following the process of step S204, user A encrypts the first common key 113 with the public key of user B obtained by the process of step S205, and the encrypted first common key by the process of step S206. 113 is registered in block 4 as shown in FIG. Thereafter, similarly to the pattern 1, the data corresponding to the item 3 is encrypted with the first common key and registered in the block 5 (see steps S207 and S208 in FIG. 6 and block 5 in FIG. 10).

  The above is the specific registration contents of the block registration process in Pattern 2. Subsequently, specific reference contents of the reference process in the pattern 2 will be described. FIG. 11 shows an example of specific reference contents when the contents of the block chain are in the state shown in FIG. When user A who can be referred to performs the reference process, the process similar to the process described in pattern 1 (the process when the first common key 113 of pattern 1 is owned) is performed (FIG. 7). 11), the data corresponding to item 3 is displayed in a decrypted state as shown in FIG. 11A. . Further, even when the user C who is not a referable person performs the reference process, the process similar to the process described in the pattern 1 (the process when the first common key 113 of the pattern 1 is not owned) is performed (see FIG. 7, the data corresponding to item 3 is displayed in an encrypted state as shown in FIG. 11B. Therefore, here, a case where the reference process is performed by the user B will be described as an example.

  When user B starts the reference process, the contents of block 1 to block 5 shown in FIG. 10 are acquired by the process of step S301 (note that block 1 is omitted in the example shown in FIG. 10). Among them, since the data corresponding to item 3 is encrypted, it is determined Yes in step S302, and the process proceeds to step S303. In the process of step S303, since the first common key 113 corresponding to the encrypted data is not owned, it is determined No, and the process proceeds to step 304. Here, the first common key 113 encrypted with the public key of the user B is registered in the block 4 shown in FIG. 10, and the contents of the block are acquired in the process of step S301 in FIG. Therefore, in the process of step S304, it is determined that the first common key 113 can be decrypted with the private key owned by the user (the private key owned by the user B) (that is, Yes). .

  Subsequently, by the process of step S305, the encrypted first common key 113 is decrypted with the secret key of the user B, and the user B acquires the first common key 113. Then, in the process of step S306, the data corresponding to item 3 is decrypted by the first common key 113, and then the process of step S307 is executed, as shown in FIG. Data corresponding to 3 is displayed in a decrypted state (items 1 and 2 are displayed as they are because they are not encrypted).

  As described above, the user A obtains the public key of the user B, encrypts the first common key 113 with the public key of the user B who has obtained the first common key 113, and registers the data in the block. A and user B can be referred to. Therefore, the confidentiality with respect to specific information can be appropriately ensured with respect to users other than the referable person.

  Next, a case where data can be referred to only by the user B in the item 3 in the group of “document A” shown in FIG. 3 (pattern 3) will be described. Since pattern 3 is different from pattern 1 and pattern 2 in that only the user B can be referred to, the data corresponding to item 3 is different from item 1 and item 2 (item 1 and item 2). User A registers), and User B registers in the target block. FIG. 12 is a diagram illustrating an example of specific registration contents of the block registration process in the pattern 3. Note that description of the same parts as those of the pattern 1 is omitted. The first common key encrypted with the public key of user A is also registered in block 1 (not shown in FIG. 12), similarly to pattern 1 (similar to block 1 in FIG. 8). And

  When the user A starts the block registration process shown in FIG. 6, the data corresponding to the item 1 and the data corresponding to the item 2 are registered in each block in the same manner as the pattern 1 (see block 2 in FIG. 12). Subsequently, data corresponding to the item 3 is registered in the target block. The data corresponding to the item 3 is data that should be registered by the user B because it can be referred to only by the user B. Note that the data registrant may be determined in advance when the group information is registered (defined) in the pre-registration process.

  When the data corresponding to item 2 is registered in the target block (block 2 in this example) and shared among the users, user B executes the processing from step S102 to step S104 in FIG. 4 based on this. To do. Note that a signal that prompts the user A to register data corresponding to the item 3 may be transmitted from the user A to the user B. Specifically, the information processing apparatus 100 of the user B generates a second common key as a new common key different from the first common key 113 by the function of the common key generation unit 123 (step S102), and performs encryption / decryption. The generated second common key is encrypted with the public key 112 of the user B by the function of the generating unit 124 (step S103). Then, the function of the data registration unit 121 registers the encrypted second common key in the target block (block 3 in the example shown in FIG. 12) (step S104). Here, since the second common key is a key different from the first common key 113, only the owner of the second common key can decrypt the content encrypted with the second common key. . Further, since the second common key is encrypted with the public key of the user B, it can be decrypted only by the secret key of the user B.

  After registering the encrypted second common key in the target block, the user B is the user B himself as in the case of the pattern 1, so that the referenceable person is disclosed in step S203 of FIG. It is determined that the key is owned (Yes is determined), and the content of the data corresponding to the item 3 is encrypted with the second common key in step S207 (as shown in FIG. XI0tagBag). In step S208, the encrypted content is registered in block 4 (see block 4 in FIG. 12).

  The above is the specific registration contents of the block registration process in Pattern 3. After that, when it is possible to refer not only to the user B but also to the user C, the user B obtains the public key of the user C and uses the public key of the user C to obtain the second common key as in the case of the pattern 2 What is necessary is just to encrypt and register to the target block. In addition, after registering data corresponding to item 3 in the pattern 2 in the target block, for example, when registering data corresponding to the item 4 that can be referred to only by the user A in the target block, Similarly to pattern 3, user A who is a registrant generates a new common key, encrypts data corresponding to item 4 with the generated new common key, and registers it in the block. That is, when adding a referenceable person to the registration target data, as described in Pattern 2, the public key of the added participant is acquired, and the common key is encrypted with the acquired public key and blocked. While performing registration, when reducing the number of people who can refer to data to be registered, or when making a completely different referenceable person, a new common key may be generated as described in Pattern 3.

  The specific reference contents of the reference process in pattern 3 are the same as those in pattern 1 except that the first common key 113 is the second common key and the second common key owner is user B. Detailed description will be omitted. FIG. 13 shows an example of specific reference contents when the contents of the block chain are in the state shown in FIG.

  When user B who is a referable person performs the reference process, the process is the same as the process described in pattern 1 (the process when the first common key 113 of pattern 1 is owned) (step S303 in FIG. 7). If the result of the determination in step S306 is “Yes”, the data corresponding to item 3 is displayed in a decrypted state as shown in FIG. On the other hand, when user A and user C who are not referable users perform reference processing, processing similar to the processing described in pattern 1 (processing when the first common key 113 of pattern 1 is not owned) (No in step S304), the data corresponding to item 3 is displayed in an encrypted state as shown in FIG. 13B.

  Thus, when only the user B other than the user A who previously registered the common key in the block can be referred to, the referable person (user B) newly generates the second common key, and the second common key. Data encrypted with the key may be registered in the block. Therefore, the confidentiality with respect to specific information can be appropriately ensured with respect to users other than the referable person. Also, if the generated second common key is encrypted with the public key owned by itself and registered in the block, the management burden of the second common key can be reduced.

(Modification)
In addition, this invention is not limited to the said embodiment, A various deformation | transformation and application are possible. For example, the information processing apparatus 100 does not have to include all the technical features described in the above embodiment, and the one described in the above embodiment so as to solve at least one problem in the prior art. The structure of the part may be provided. Further, at least some of the following modifications may be combined.

  In the above embodiment, in order to facilitate understanding, an example in which data handled in one transaction in the same group is registered in one block and a block chain is generated for each group is shown. It is an example. For example, as shown in FIG. 14, data handled in transactions related to contracts of different groups may be registered in one block. In the example shown in the figure, a contract between user A, user B, and user C is shown for group A, and a contract between user A and user D is shown for group B. Although illustration is omitted, data handled by a plurality of transactions in the same group may be registered in one block. Also in this case, by the same processing as in the above embodiment, decryption can be appropriately performed for a referable person, and confidentiality of specific information can be appropriately ensured for users other than the referable person. .

  In the above-described embodiment, the example in which all data handled in the transaction is managed by the block chain in the information processing system 1 shown in FIG. 1 is an example. For example, highly confidential information for the future may be managed by the information processing system 2 shown in FIG. 15, for example. The information processing system 2 illustrated in FIG. 2 includes a center server 999 including a database 199, as compared with the information processing system 1 illustrated in FIG. In the information processing system 2 illustrated in FIG. 2, for example, highly confidential information (confidential information) is managed in the database 199 of the center server 999. Then, in the blocks connected by the block chain, the address information (address of the database 199 of the center server 999) where the confidential information is stored, the hash value of the confidential information, and the unique key specifying the confidential information are encrypted. Registered (encrypted as in the above embodiment). The referable person obtains information of each block by performing a reference process, and decrypts the storage address information, the hash value, and the unique key of the confidential information.

  Then, the database 199 of the center server 999 is accessed based on the decrypted address information, and whether or not the hash value and the unique key match is verified. Should be referred to. According to this, the confidential information is managed by the center server 999, the confidential information itself is not managed by the block chain, and the hash value of the confidential information is managed by the block chain. Therefore, safety can be ensured even if information on the key is leaked. Moreover, since it is impossible to restore confidential information based on the hash value, confidentiality can be ensured.

  In the above embodiment, the case where a contract is created has been described as an example. However, the present invention is not limited to the case where a contract is created, and various types of information that need to ensure confidentiality of specific information. This is applicable when various transactions are conducted.

  In the case where the above functions are realized by sharing an OS (Operating System) and an application, or by cooperation between the OS and the application, only a part other than the OS may be stored in the medium.

  It is also possible to superimpose a program on a carrier wave and distribute it via a communication network. For example, the program may be posted on a bulletin board (BBS, Bulletin Board System) on a communication network, and the program may be distributed via the network. Then, the above-described processing may be executed by starting these programs and executing them in the same manner as other application programs under the control of the operating system.

DESCRIPTION OF SYMBOLS 1 Information processing system, 2 Information processing system, 100A-C Information processing apparatus, 110 Storage part, 111 Secret key, 112 Public key, 113 1st common key, 113A Encrypted 1st common key, 114 Block integration data, 115 Public key of other user, 116 block information DB, 120 control unit, 121 data registration unit, 122 pair key generation unit, 123 common key generation unit, 124 encryption / decryption unit, 125 block integration unit, 126 other public key acquisition unit 130 Input / output unit 140 Communication unit 199 Database 210 Network 999 Center saver

Claims (5)

Data storage means for encrypting and storing the generated data with a common key in blocks connected by a block chain constructed in the network;
Public key acquisition means for acquiring a second public key different from the first public key stored in advance from the blocks connected by the block chain;
Common key storage means for encrypting the common key with the second public key acquired by the public key acquisition means, and storing the encrypted common key in blocks connected by the block chain;
A common key generation unit configured to generate a new common key different from the common key after the common key encrypted by the common key storage unit is stored in a block connected by the block chain. ,
The data storage means encrypts and stores the generated data with a common key corresponding to a predetermined condition among the common key or the new common key in blocks connected by the block chain. ,
The information processing apparatus according to claim and this. The common key storage means encrypts the common key with the first public key, and stores the encrypted common key in blocks connected by the block chain.
The information processing apparatus according to claim 1.   The generated data includes low-importance data less than a predetermined importance and high-importance data higher than the predetermined importance,
  Further comprising importance data storage means for storing the high importance data in a database connected via the network, which is different from the blocks connected by the block chain,
  The data storage means stores the low importance data in blocks connected by the block chain, and performs a predetermined calculation on the high importance data with storage destination information indicating a storage destination of the high importance data. Stored in the block connected with the block chain together with the calculated value calculated by
  The information processing apparatus according to claim 1, wherein the information processing apparatus is an information processing apparatus. An information processing method in an information processing apparatus,
A data storage step for encrypting and storing the generated data with a common key in blocks connected by a block chain constructed in the network;
A public key acquisition step of acquiring a second public key different from the first public key stored in advance from the blocks connected by the block chain;
A common key storing step of encrypting the common key with the second public key acquired in the public key acquiring step, and storing the encrypted common key in blocks connected by the block chain;
A common key generation step of generating a new common key different from the common key after the encrypted common key is stored in the block connected by the block chain in the common key storage step. ,
In the data storing step, the generated data is encrypted and stored in a block connected by the block chain with a common key corresponding to a predetermined condition among the common key or the new common key. ,
Information processing method, wherein a call. Computer
Data storage means for encrypting and storing the generated data with a common key in blocks connected by a block chain constructed in the network,
Public key acquisition means for acquiring a second public key different from the first public key stored in advance from the blocks connected by the block chain;
Common key storage means for encrypting the common key with the second public key acquired by the public key acquisition means, and storing the encrypted common key in blocks connected by the block chain;
After the common key encrypted by the common key storage means is stored in the block connected by the block chain, it functions as a common key generation means for generating a new common key different from the common key. ,
The data storage means encrypts and stores the generated data with a common key corresponding to a predetermined condition among the common key or the new common key in blocks connected by the block chain. ,
Program which is characterized a call.

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