JP2008016014A - Confidential information protection system, confidential information restoring device, and tally generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect confidential information with higher security. <P>SOLUTION: This tally generation device 10 generates a plurality of tally data in accordance with confidential information S and tally generation instructing information. The tally data include tally main data and tally sub data. The tally sub data show conditions relating to each confidential information restoring device when restoring the confidential information S. Each confidential information restoring device restores the confidential information S while collecting a required number of tally data and determining whether the restoration is possible or impossible in accordance with the tally sub data. Each confidential information restoring device restores the confidential information S when the determination result shows that "the restoration is possible", but cannot restore the confidential information S when the determination result shows that "the restoration is impossible". <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for protecting confidential information using a secret sharing method, and more particularly to a technique for improving security of confidential information.

Patent Document 1 discloses a technique for protecting confidential information by a secret sharing method.
In the secret sharing method, N pieces of data (hereinafter referred to as “electronic tally”) are generated from confidential information, and the N pieces of electronic tally are distributed and held by a plurality of terminal devices. When restoring confidential information, it is possible to restore confidential information by using K (≦ N) electronic tally out of N electronic tally distributed and held by a plurality of terminal devices. The secret information cannot be restored from less than K electronic tallys.

Patent Document 2 discloses a technique for improving confidentiality of confidential information by distributing management information for managing storage locations of electronic tally.
JP 2002-351845 A JP 2004-147218 A

In the above prior art, if the terminal device has a function of restoring the confidential information from the electronic tally, as long as the number of electronic tally necessary for the restoration is collected, the processing capability of the terminal device and the user who owns the terminal device It was possible to restore confidential information without considering reliability. However, it has a problem of lack of security from the viewpoint of protecting confidentiality of confidential information.
Accordingly, the present invention has been made in view of the above-described problems, and an object thereof is to provide a confidential information protection system, a confidential information restoration device, and a tally generation device that can protect confidential information with higher security. And

  In order to achieve the above object, the present invention is a confidential information protection system that includes a tally generating device and a plurality of terminal devices, and holds confidential information in a distributed manner in the plurality of terminal devices. The tally generating device includes, for each terminal device, tally generating means for generating a plurality of electronic tallys based on the confidential information, and restoration control information indicating conditions relating to the restoration of the confidential information in each terminal device. Each of the terminal devices includes a storage unit that stores the electronic tally generated by the tally generation device and the recovery control information, a tally collection unit that collects a necessary number of electronic tallys, Based on the restoration control information, a determination unit that determines whether or not the confidential information can be restored, and the electronic tally stored in the storage unit only when it is determined by the determination unit that restoration is possible. Based on the electronic tally the tally collecting means collects, characterized by comprising a restoring means for restoring said confidential information.

  According to the above configuration, the tally generating device distributes the restoration control information together with the electronic tally to each terminal device. Therefore, even if each terminal device acquires the number of electronic tally necessary for restoration. Depending on the result of the determination as to whether or not the restoration control information is used, the confidential information may not be restored. The restoration control information is, for example, information indicating permission / non-permission of restoration, information indicating processing performance required for the terminal device, and the like.

The present invention makes it possible to appropriately manage a terminal device that restores confidential information and to protect confidential information with high security by performing restoration feasibility determination based on the restoration control information as described above.
Further, the present invention is a confidential information restoration device having a function of restoring the confidential information from a plurality of electronic tally generated based on the confidential information, wherein one electronic tally generated by the tally generating device and Based on the restoration control information stored in the storage means, storage means for storing restoration control information indicating a condition relating to restoration of the confidential information, tally collection means for collecting a necessary number of electronic tally, and the storage control information stored in the storage means, The determination means for determining whether or not the confidential information can be restored, and the electronic tally stored in the storage means and the electronic tally collected by the tally collection means only when it is determined that the confidential information can be restored. And a restoring means for restoring the confidential information.

According to this configuration, the confidential information restoration device determines whether or not restoration is possible based on the restoration control information even if the necessary number of electronic tally is collected. Information restoration processing cannot be performed, and highly secure confidential information can be protected.
Here, the tally collecting means acquires the electronic tally and the restoration control information acquired from the tally generating apparatus by each other confidential information restoring apparatus from the same number of other confidential information restoring apparatuses as the necessary number, and the restoration is performed. The means is configured to restore the confidential information using the electronic tally and the restoration control information stored in the storage means, and the electronic tally and the restoration control information acquired by the tally collection means. May be.

  According to this configuration, the confidential information cannot be restored using only the electronic tally, but can be restored only using the restoration control information. That is, since the electronic tally is information associated with the restoration control information, the confidential information restoration apparatus cannot restore the correct confidential information unless both the electronic tally and the restoration control information are correct information. Of course, even if only the electronic tally is acquired, the confidential information cannot be restored.

Here, information indicating whether or not the restoration of the confidential information is permitted is set in the restoration control information, and the determination unit determines that restoration is possible when the restoration control information indicates restoration permission. If the restoration control information indicates that restoration is not permitted, it may be determined that restoration is impossible.
According to this configuration, when the restoration control information indicates that restoration is not permitted, the confidential information restoration apparatus is prohibited from restoring confidential information even if the number of electronic tally necessary for restoration is collected. . Therefore, compared with the conventional restoration device from the viewpoint of protection of confidential information, the present invention can realize protection of confidential information with higher security.

  Here, the restoration control information is set with information indicating the property of the device that permits the restoration of the confidential information, and the confidential information restoring device further stores device characteristic information indicating the property of the device itself. The device characteristic storage means, and the determination means reads the device characteristic information, determines that the read device characteristic information satisfies the property indicated by the restoration control information, determines that restoration is possible, and reads the read The apparatus characteristic information may be determined to be unrecoverable when the property indicated by the restoration control information is not satisfied.

According to this configuration, the confidential information restoration device is prohibited from restoring the confidential information when the device characteristics of the own device do not satisfy the device characteristics indicated by the restoration control information. Therefore, compared with the conventional restoration device from the viewpoint of protection of confidential information, the present invention can realize protection of confidential information with higher security.
Here, the property indicated by the restoration control information is information indicating the processing performance of the device necessary for restoring the confidential information, and the device characteristic information is configured to indicate the processing performance of the own device. Also good.

According to this configuration, the confidential information restoration device is prohibited from restoring the confidential information when the device does not have the performance necessary for the restoration processing of the confidential information. That is, according to the present invention, when it is not guaranteed that the confidential information is correctly restored, the restoration of the confidential information can be prohibited.
Here, the determination unit is configured to perform the determination by comparing the restoration control information stored in the storage unit and the restoration control information acquired by the tally collection unit. Also good.

According to this configuration, since the confidential information restoration device determines whether or not restoration is possible using the restoration control information of the other device, in a system in which confidential information is distributed and held by a plurality of confidential information restoration devices, a plurality of confidential information restoration devices are used. It is determined that an appropriate device can be restored among the confidential information restoration devices.
Here, in the restoration control information, information indicating a priority for performing the confidential information restoration processing in a plurality of confidential information restoration apparatuses holding the plurality of electronic tallys is set, and the determination unit includes If the priority indicated by the restoration control information stored in the storage means is higher than the priority indicated by the restoration control information acquired by the tally collecting means, it is determined that restoration is possible, and is stored in the storage means If the priority indicated by the restored restoration control information is lower than the priority indicated by the restoration control information acquired by the tally collecting means, it may be determined that restoration is impossible.

  According to this configuration, the confidential information restoration device is prohibited from restoring the confidential information when the priority of the own device is set lower than the priority of the other device. Here, when the priority is set based on the reliability of the confidential information restoration device itself, the reliability of the user who owns the confidential information restoration device, etc., the confidential information is given to the device or the user with low reliability. Can be prohibited.

Here, the confidential information restoring device further restores the priority indicated by the restoration control information stored in the storage means when it is judged that the judgment means can restore. You may comprise so that an update means may be provided.
According to this configuration, since the restoration control information is updated, the level of priority between the confidential information restoring devices changes as the confidential information is restored. Therefore, it is possible to prevent the situation in which the confidential information restoration processing is permitted only to the confidential information restoration device decided every time, and to perform the restoration processing without any bias in a plurality of confidential information restoration devices. It becomes.

Here, the receiving means further receives a falsification detection value generated by performing a predetermined operation on the restoration control information from the tally generation device, and the determination means uses the falsification detection value, It may be configured to determine whether or not the restoration control information has been tampered with and to determine that restoration is not possible when tampering with the restoration control information is detected.
Since the restoration control information in the present invention is information that controls whether restoration is possible in order to protect the security of confidential information, the reliability of the information itself is important. Therefore, according to this configuration, it is possible to prevent the restoration possibility determination process from being performed based on the unauthorized restoration control information that has been tampered with.

Here, each electronic tally is information generated by performing secret sharing processing using a plurality of restoration control information on the confidential information, and the restoration means is stored in the storage means. The confidential information may be restored from a plurality of electronic tally using the restoration control information and the restoration control information acquired by the collection means.
When the restoration control information is used to control the restoration process, it is assumed that the restoration control information is falsified to receive an attack that enables restoration of confidential information by an unauthorized device.

  However, according to the above configuration, the electronic tally is information generated by performing secret sharing processing using the restoration control information on the confidential information. Therefore, the restoration control information is temporarily falsified and can be restored. Even if the determination process is broken, an unauthorized device cannot restore correct confidential information in the subsequent confidential information restoration process. Therefore, it is possible to neutralize an attack that falsifies the restoration control information.

Here, the confidential information restoration device may further include a data control unit that discards the electronic tally collected by the collection unit when the determination unit determines that restoration is impossible.
According to this configuration, by discarding the electronic tally acquired from the other device, it is possible to prevent the confidential information from being restored due to an erroneous operation of the user or the like, and to reliably prohibit the restoration of the confidential information.

Here, the tally collection means may be configured to collect the necessary number of electronic tallys when the determination means determines that restoration is possible.
According to this configuration, the confidential information restoring device can suppress transmission / reception of unnecessary data when it is determined that “restoration is impossible”, and can reduce the amount of data transmitted / received between the confidential information restoring devices.

  In addition, the present invention is a tally generating device, comprising tally generating means for generating a plurality of electronic tallys based on confidential information, and a plurality of terminal devices to which the plurality of electronic tallys are distributed. A restoration control information generating unit that generates restoration control information indicating a condition relating to restoration of the confidential information in each terminal device, and a distribution unit that distributes the electronic tally and the restoration control information to each corresponding terminal device. It is characterized by.

According to this configuration, the tally generating device can set restoration conditions for the confidential information restoring device to which the electronic tally is distributed, so that the restoration of confidential information is allowed unconditionally. Thus, it is possible to protect confidential information with higher security.
Here, the restoration control information generating means generates the restoration control information based on the number of electronic tally to be generated, the number of electronic tally necessary for restoring the confidential information, and tally generation instruction information including the condition. The tally generation means may be configured to generate the electronic tally based on the confidential information, the tally generation instruction information, and the restoration control information.

According to this configuration, the tally generating device generates the electronic tally based on the restoration control information, so that the once created restoration control information can be prevented from being tampered with by an unauthorized user. This is because correct confidential information cannot be restored using the altered restoration control information.
Here, the restoration control information generation means may be configured to generate the restoration control information indicating whether or not the confidential information can be restored in each terminal device.

According to this configuration, it is possible to individually set whether or not to restore confidential information to a plurality of confidential information restoring apparatuses that hold and distribute confidential information.
Here, the restoration control information generation means may be configured to generate the restoration control information indicating a priority of restoration of the confidential information in each terminal device.
According to this configuration, the tally generating device of the present invention sets priority for a plurality of confidential information restoring devices, and realizes control of restoring confidential information according to the priority. For example, by setting priorities based on the reliability of the confidential information restoration device itself, the reliability of the user who owns the confidential information restoration device, etc., the confidential information is restored to a device or user with low reliability. Can be prohibited. Therefore, compared with the conventional tally generating device from the viewpoint of security protection of confidential information, the present invention can realize protection of confidential information with higher security.

Here, the restoration control information generation means may be configured to generate the restoration control information indicating a property of a device that permits restoration of the confidential information.
According to this configuration, the tally generating device realizes control for restoring confidential information in consideration of the device characteristics of each confidential information restoring device.
Here, the property indicated by the restoration control information may be configured so as to be a processing performance of an apparatus necessary for restoring the confidential information.

According to this configuration, the tally generating device does not have the performance necessary for the restoration processing of the confidential information, that is, for the confidential information restoring device that cannot guarantee that the confidential information is correctly restored, the restoration of the confidential information is performed. Can be prohibited.
Here, the restoration control information generation means may be configured to use the value of the number of electronic tally necessary for restoration of the confidential information included in the tally generation instruction information as the restoration control information.

  In the secret sharing method in which electronic tally is generated from confidential information and the electronic tally is distributed and held by a plurality of devices, the restoration process is performed depending on the number of electronic tally (restoration threshold) necessary for restoring the confidential information. The amount of calculation required is different. Therefore, in the present invention, it is possible to represent the processing performance of the device necessary for restoring the confidential information by the value of the restoration threshold value, so that the tally generating device can use the existing data as the restoration control information. it can.

Here, the tally generating device further includes a falsification detection value generation unit that performs a predetermined calculation on each restoration control information and generates a falsification detection value corresponding to each restoration control information, and the distribution unit includes In addition to the electronic tally and the restoration control information, the falsification detection value may be distributed to each terminal device.
Since the restoration control information in the present invention is information that controls whether restoration is possible in order to protect the security of confidential information, the reliability of the information itself is important. Therefore, according to this configuration, the tally generating device can prevent the restoration possibility determination process from being performed based on the unauthorized restoration control information that has been falsified by transmitting the falsification detection value to the confidential information restoration device. it can.

Here, the tally generation unit may be configured to generate the plurality of electronic tallys based on the plurality of restoration control information generated by the restoration control information generation unit and the confidential information. .
In addition, the tally generating unit may be configured to generate the plurality of electronic tally by performing secret sharing processing using the plurality of restoration control information on the confidential information.

When the restoration control information is used to control the restoration process, it is assumed that the restoration control information is falsified to receive an attack that enables restoration of confidential information by an unauthorized device.
However, according to the above configuration, the electronic tally generated by the tally generating device is information generated by performing secret sharing processing using the recovery control information on the confidential information. Even if falsification is made and the restoration possibility determination process is broken, an unauthorized device cannot restore correct confidential information in the subsequent confidential information restoration process. Therefore, it is possible to neutralize an attack that falsifies the restoration control information.

Hereinafter, as an embodiment of the present invention, a confidential information protection system 1 will be described in detail with reference to the drawings.
<Overview>
Here, an outline of the confidential information protection system 1 will be described.
FIG. 1 is a diagram showing a configuration of the confidential information protection system 1. As shown in the figure, the confidential information protection system 1 includes a tally generating device 10 and five confidential information restoring devices 21, 22, 23, 24, and 25.

  In the present embodiment, as a specific example, the tally generating device 10 is a personal computer, the confidential information restoring devices 21 and 24 are mobile phones, the confidential information restoring device 22 is a PDA (Personal Digital Assistant), The confidential information restoring device 23 is a laptop computer, and the confidential information restoring device 25 is a memory card that is used by being attached to the tally generating device 10 and other confidential information restoring devices.

The tally generating device 10 and the confidential information restoring devices 21, 22, 23, 24, and 25 are connected via the network 30, and transmit / receive information via the network 30.
In this embodiment, the number of confidential information restoring devices is five, but the number of confidential information restoring devices in the present invention is not limited to five, and varies depending on how many devices the confidential information S is distributed and held. .

The tally generating device 10 generates five tally main data using the secret sharing method based on the confidential information S and tally generation instruction information described later. Further, the tally generating device 10 generates five tally sub data including a condition relating to the restoration of the confidential information S in each confidential information restoring device.
Then, the tally generating device 10 distributes tally data composed of tally main data and tally sub data to the confidential information restoring devices 21, 22, 23, 24, and 25 one by one.

When the confidential information S is restored from the tally data, each confidential information restoration device collects the tally data necessary for restoring the confidential information S and then determines whether or not restoration is possible using the tally sub data.
As a result of determining whether or not each confidential information is restored, each confidential information restoration device restores the confidential information S when it is judged that restoration is possible, and performs restoration processing of the confidential information S when it is judged that restoration is impossible. First, the tally data acquired from another confidential information restoration device is discarded.

<Configuration of Tally Generation Device 10>
FIG. 2 is a functional block diagram showing a functional configuration of the tally generating device 10. As shown in the figure, the tally generating device 10 includes a data input unit 101, a data extracting unit 102, a tally main data generating unit 103, a tally data generating unit 104, and a tally data transmitting unit 105.
Specifically, the tally generating device 10 is a computer system including a microprocessor, a ROM, a RAM, a hard disk unit, a network connection unit, and the like. The tally generating device 10 achieves its function by the microprocessor operating according to the computer program.

(1) Data input unit 101
The data input unit 101 receives external data input. Specifically, the data input unit 101 receives input of confidential information S and tally generation instruction information.
Confidential information S is required to be confidential, such as address book, sent / received mail, other personal information, customer information, company product information, sales performance information and other company confidential information, key information for decrypting encrypted content, etc. Information. In the present invention, the content of the confidential information S is not limited.

(Data structure of tally generation instruction information)
FIG. 3 shows a specific example of tally generation instruction information.
The tally generation instruction information 110 shown in the figure includes tally generation basic information 120 and five pairs of device identification information and tally restoration permission information.
Specifically, the five pairs include device identification information ID_0001 (130) and tally restoration permission information 131, device identification information ID_0002 (140) and tally restoration permission information 141, device identification information ID_0003 (150) and tally restoration permission. Information 151, device identification information ID_0004 (160) and tally restoration permission information 161, and device identification information ID_0005 (170) and tally restoration permission information 171.

The tally generation basic information 120 includes a tally generation number N (120a), a restoration threshold K (120b), and tally restoration permission rule information 120c.
The tally generation number N is information indicating how many tally data are generated from the confidential information S. In the present embodiment, since there are five confidential information restoring devices, tally data to be generated is five. Therefore, N = 5. At this time, the tally generation instruction information 110 includes N (= 5) pairs of device identification information and tally restoration permission information.

The restoration threshold value K is information indicating how many tally data are generated so that the secret information S can be restored from the tally data. In this embodiment, as an example, K = 3.
The tally restoration permission rule information 120c indicates any one of rule 1, rule 2, rule 3, and rule 4. The tally restoration permission rule information 120c means which rule from rule 1 to rule 4 the tally restoration permission information 131, 141, 151, 161, and 171 is set. Details of each rule will be described later.

  The device identification information is an identifier for identifying the confidential information restoring device. That is, the device identification information ID_0001 (130) is an identifier of the confidential information restoration device 21. The device identification information ID_0002 (140) is an identifier of the confidential information restoring device 22. The device identification information ID_0003 (150) is an identifier of the confidential information restoring device 23. The device identification information ID_0004 (160) is an identifier of the confidential information restoration device 24. The device identification information ID_0005 (170) is an identifier of the confidential information restoration device 25.

  The tally restoration permission information indicates a condition relating to restoration of the confidential information S in the confidential information restoring device identified by the device identification information associated with itself. That is, the tally restoration permission information 131 indicates a condition relating to restoration of the confidential information S in the confidential information restoring device 21. The tally restoration permission information 141 indicates a condition relating to restoration of the confidential information S in the confidential information restoring device 22. The tally restoration permission information 151 indicates a condition relating to restoration of the confidential information S in the confidential information restoring device 23. The tally restoration permission information 161 indicates a condition relating to restoration of the confidential information S in the confidential information restoring device 24. The tally restoration permission information 171 indicates a condition relating to restoration of the confidential information S in the confidential information restoring device 25.

FIG. 4 is a diagram showing a data structure of the tally restoration permission information 131. As shown in FIG. As shown in the figure, the tally restoration permission information 131 is 128-bit data, an effective information bit size of 8 bits indicating a numerical value n (where n ≦ 120), a random number of (120−n) bits, and It consists of n bits of effective information.
The effective information bit size indicates the data length (bit size) of the effective information. Of the tally restoration permission information 131, only effective information has a substantial meaning. In the effective information, a different value is set according to the rule (any one of rule 1 to rule 4) set in the tally restoration permission rule information 120c.

When acquiring effective information from the tally restoration permission information 131, first, the effective information bit size (= n) is read from the first 8 bits of the tally restoration permission information 131, and then n bits from the end of the tally restoration permission information 131. Effective information can be acquired by extracting the length.
The tally restoration permission information 141, 151, 161, and 171 also have the same data structure as the tally restoration permission information 131, and the effective information included in each tally restoration permission information is tally restoration permission rule information 120c. Different values are set according to the rule indicated by (any one of rule 1 to rule 4).

In the present embodiment, after this, “setting the tally restoration permission information to X.” means “setting the effective information of the tally restoration permission information to X and setting the execution information bit size n to the bit size of X. It is set and a random number is set in the remaining (120−n) bits ”.
Hereinafter, with reference to FIG. 5, a rule indicated by the tally restoration permission rule information 120c and each tally restoration permission information set according to the rule will be described.

(A) Rule 1
When the tally restoration permission rule information 120c indicates “Rule 1”, the tally restoration permission information 131, 141, 151, 161, and 171 includes the confidential information restoration devices 21, 22, 23, 24, and 25, respectively. Information indicating whether or not restoration of confidential information S is permitted is set.
In this embodiment, as a specific example,
Tally restoration permission information 131 = 1 (allowed)
Tally restoration permission information 141 = 0 (not permitted)
Tally restoration permission information 151 = 0 (not permitted)
Tally restoration permission information 161 = 1 (permitted)
Tally restoration permission information 171 = 0 (not permitted)
Suppose that Here, tally restoration permission information = 1 represents “permitted”, and tally restoration permission information = 0 represents “not permitted”. In this case, the confidential information restoring devices 21 and 24 are permitted to restore the confidential information S, and the confidential information restoring devices 22, 23, and 25 are not permitted to restore the confidential information S.

(B) Rule 2
When the tally restoration permission rule information 120c indicates “Rule 2”, the tally restoration permission information 131, 141, 151, 161, and 171 includes “secret information” in the confidential information restoration devices 21, 22, 23, 24, and 25. Information indicating "priority for restoring S" is set.
In this embodiment, as a specific example,
Tally restoration permission information 131 = 2
Tally restoration permission information 141 = 3
Tally restoration permission information 151 = 1
Tally restoration permission information 161 = 4
Tally restoration permission information 171 = 5
Suppose that Accordingly, the priority order of restoration of the confidential information S in the five confidential information restoration apparatuses is from the upper order to the lower order.
Confidential information restoration device 21
Confidential information restoration device 22
Confidential information restoration device 24
Confidential information restoration device 25
In the order.

Here, the priority order will be briefly described.
In the present embodiment, since the restoration threshold is set to K = 3, the restoration processing of the confidential information S involves three confidential information restoring devices, and the confidential information is based on the three tally data. Information S is restored. At this time, only the device with the highest priority indicated by the tally restoration permission information corresponding to the three confidential information restoring devices is permitted to restore the confidential information S, and the other two devices receive the confidential information S. It cannot be restored.

(C) Rule 3
When the tally restoration permission rule information 120c indicates “Rule 3”, the tally restoration permission information 131, 141, 151, 161, and 171 includes information indicating “processing performance of a device that permits restoration of the confidential information S”. Is set.
Here, the calculation amount necessary for the restoration process of the confidential information S is determined by the value of the restoration threshold K. Specifically, the larger the value of the restoration threshold K, the greater the calculation amount of the restoration process. Therefore, in rule 3, the value of the restoration threshold value K is uniformly set for each tally restoration permission information.

Therefore, in this embodiment, as a specific example,
Tally restoration permission information 131 = 3
Tally restoration permission information 141 = 3
Tally restoration permission information 151 = 3
Tally restoration permission information 161 = 3
Tally restoration permission information 171 = 3
Suppose that In this case, only the confidential information restoration device having the calculation processing capacity to restore the confidential information S generated based on the restoration threshold K = 3 is permitted to be restored.

Each confidential information restoration device internally stores a value obtained by converting the calculation processing performance of its own device into a restoration threshold value K (a value indicating how many pieces of confidential information K can be decrypted). It shall be held. This will be described in detail later.
(D) Rule 4
When the tally restoration permission rule information 120 c indicates “rule 4”, the tally restoration permission information 131, 141, 151, 161, and 171 are given to the confidential information restoration devices 21, 22, 23, 24, and 25. Information indicating "restoration point for tally data restoration" is set.

In this embodiment, as a specific example,
Tally restoration permission information 131 = 3
Tally restoration permission information 141 = 2
Tally restoration permission information 151 = 3
Tally restoration permission information 161 = 4
Tally restoration permission information 171 = 1
Suppose that

Here, the restoration permission point is used in the following manner when the confidential information S is restored.
Only the device with the highest point number indicated by the tally restoration permission information corresponding to the three confidential information restoration devices involved in the restoration process is permitted to restore the confidential information S, and the other two devices are classified as confidential information S. Cannot be restored. However, the number of points indicated by the confidential information restoration permission information has a property that it is reduced by one point each time the confidential information restoring device restores the confidential information S.

(2) Data extraction unit 102
The data extraction unit 102 analyzes the tally generation instruction information 110 received by the data input unit 101.
Then, the data extraction unit 102 extracts each data from the tally generation instruction information 110 to generate tally main data generation control information 210, tally sub data generation control information 220, and tally destination information 230.

FIG. 6 is a diagram showing a data structure of the tally main data generation control information 210. As shown in FIG. As shown in the figure, the tally main data generation control information 210 includes a restoration threshold K (120b) and tally restoration permission information 131, 141, 151, 161, and 171.
The data extraction unit 102 outputs the generated tally main data generation control information 210 to the tally main data generation unit 103.

  FIG. 7 is a diagram showing a data configuration of the tally sub data generation control information 220. As shown in FIG. As shown in the figure, the tally sub-data generation control information 220 includes a restoration threshold K (120b), tally restoration permission rule information 120c, device identification information ID_0001 (130) and tally restoration permission information 131, and device identification information ID_0002 (140. ) And tally restoration permission information 141, apparatus identification information ID_0003 (150) and tally restoration permission information 151, apparatus identification information ID_0004 (160) and tally restoration permission information 161, and apparatus identification information ID_0005 (170) and tally restoration permission information. 171.

The data extraction unit 102 outputs the generated tally sub data generation control information 220 to the tally data generation unit 104.
FIG. 8 is a diagram showing a data configuration of the tally destination information 230. As shown in FIG. As shown in the figure, the tally destination information 230 is information in which device identification information of the confidential information restoration device that is the destination of the tally data is associated with the address of the confidential information restoration device. Specifically, the tally destination information 230 includes device identification information ID_0001 (130) and address 1 (132), device identification information ID_0002 (140) and address 2 (142), device identification information ID_0003 (150) and address 3 (152), device identification information ID_0004 (160), address 4 (162), and device identification information ID_0005 (170).

Here, the data extraction unit 102 previously holds a list in which device identification information and destination information are associated with each other for each of a plurality of confidential information restoration devices. The destination information is a network address necessary for transmitting data from the tally generating device 10 to each confidential information restoring device via the network 30 such as an IP address.
Then, the data extraction unit 102 is an address that is transmission destination information corresponding to each of the device identification information ID_0001 (130), ID_0002 (140), ID_0003 (150), and ID_0004 (160) extracted from the tally generation instruction information 110. 1 (132), address 2 (142), address 3 (152), and address 4 (162) are extracted from the previous list.

In the tally destination information 230, the destination information field corresponding to the device identification information ID_0005 (170) is blank. This indicates that the tally generating device 10 does not transmit the tally data via the network 30, but transfers the tally data to the memory card (that is, the confidential information restoring device 25) inserted into the tally generating device 10. .
The data extraction unit 102 outputs the generated tally destination information 230 to the tally data transmission unit 105.

(3) Tally main data generation unit 103
The tally main data generation unit 103 generates tally main data Y _i based on the confidential information S received from the data input unit 101 and the tally main data generation control information 210 received from the data extraction unit 102.
FIG. 9 is a functional block diagram showing a functional configuration of the tally main data generation unit 103. As shown in the figure, the tally main data generation unit 103 includes a tally random number generation unit 181, a first tally value generation unit 182, and a second tally value generation unit 183.

The confidential information S is input to the second tally value generation unit 183. Of the tally main data generation control information 210, the restoration threshold value K (120b) is input to the tally random number generation unit 181 and the tally restoration permission information 131, 141, 151, 161, and 171 are the first tally numerical values. Input to the generation unit 182.
The tally random number generation unit 181 generates a tally generation random number based on the restoration threshold K (120b). Specifically, the tally random number generation unit 181 reads the value of K and generates K (= 3) 1-byte random numbers R ₁ , R ₂ , and R ₃ . The tally random number generation unit 181 outputs the generated random numbers R ₁ , R ₂ , and R ₃ to the second tally value generation unit 182.

The first tally value generation unit 182 generates the first tally value X _i (i = 1, 2,..., 5) based on the tally restoration permission information 131, 141, 151, 161, and 171. Specifically, the first tally value generator 182
C ₁ = tally restoration permission information 131
C ₂ = Tally restoration permission information 141
C ₃ = tally restoration permission information 151
C ₄ = tally restoration permission information 161
C ₅ = tally restoration permission information 171
For each of the above, a hash value is calculated using a one-way hash function Hash,
X ₁ = Hash (C ₁ )
X ₂ = Hash (C ₂ )
X ₃ = Hash (C ₃ )
X ₄ = Hash (C ₄ )
X ₅ = Hash (C ₅ )
As a result, five first tally values X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ are generated.

Here, Hash (x) represents a 1-byte hash value calculated by the hash function Hash for the input x.
The first tally value generating unit 182 outputs the generated first tally value X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ to the second tally value generating unit 183.
The second tally value generation unit 183 generates the tally main data from the confidential information S, the random numbers R ₁ , R ₂ , R ₃ , and the first tally values X ₁ , X ₂ , X ₃ , X ₄ , and X _5. Y _i is generated.

First, the second tally value generation unit 183 divides the L-byte confidential information S into units of bytes, and sets S [1], S [2],.
Next, the second tally value generation unit 183 uses the following (Equation 1) for i = 1, 2,..., 5 and m = 1, 2,. Y ₁ [m], Y ₂ [m],..., Y ₅ [m] are obtained.

ここで、（数１）における加算、乗算、及びべき乗算の演算は、全て有限体ＧＦ（２＾８）上で行う（２＾８は、２の８乗を表す）。
第２割符数値生成部１８３は、上記のようにして計算された第２割符数値Ｙ_１［ｍ］、Ｙ_２［ｍ］、…、Ｙ_５［ｍ］（ｍ＝１、２、…、Ｌ）を、割符主データとして、割符データ生成部１０４へ出力する。

Here, the operations of addition, multiplication, and power multiplication in (Equation 1) are all performed on a finite field GF (2 ^ 8) (2 ^ 8 represents 2 to the 8th power).
The second tally value generator 183 calculates the second tally value Y ₁ [m], Y ₂ [m],..., Y ₅ [m] (m = 1, 2,..., L) calculated as described above. ) Is output to the tally data generation unit 104 as tally main data.

In the present embodiment, each tally main data may be described as Y ₁ , Y ₂ , Y ₃ , Y ₄ , and Y _{5 as} follows.
Tally main data Y ₁ = Y ₁ [m] = Y ₁ [1], Y ₁ [2],..., Y ₁ [L]
Tally main data Y ₂ = Y ₂ [m] = Y ₂ [1], Y ₂ [2],..., Y ₂ [L]
Tally main data Y ₃ = Y ₃ [m] = Y ₃ [1], Y ₃ [2],..., Y ₃ [L]
Tally main data Y ₄ = Y ₄ [m] = Y ₄ [1], Y ₄ [2],..., Y ₄ [L]
Tally main data Y ₅ = Y ₅ [m] = Y ₅ [1], Y ₅ [2],..., Y ₅ [L]
(4) Tally data generation unit 104
The tally data generation unit 104 receives the tally main data Y ₁ , Y ₂ , Y ₃ , Y ₄ , and Y ₅ from the tally main data generation unit 103.

Further, the tally data generation unit 104 receives the tally sub data generation control information 220 shown in FIG. 7 from the data extraction unit 102, and receives five tally sub data F ₁ and F ₂ from the tally sub data generation control information 220. , F ₃ , F ₄ , and F ₅ are generated.
Each tally sub-data has a one-to-one correspondence with each confidential information restoration device, and is information for controlling restoration processing of the confidential information S in each confidential information restoration device.

The tally sub data F ₁ corresponds to the confidential information restoration device 21 and includes a restoration threshold K (120b), tally restoration permission rule information 120c, device identification information ID — 0001 (130), and tally restoration permission information 131.
Tally sub data _{F 2} contains corresponds to the confidential information restoring unit 22, restores the threshold K (120b), the tally restoration permission rule information 120c, device identification information ID_0002 (140), and the tally restoration permission information 141.

Tally sub data _{F 3} corresponds to confidential information restoring device 23 includes restoring the threshold K (120b), the tally restoration permission rule information 120c, device identification information ID_0003 (150), and the tally restoration permission information 151.
The tally sub data F ₄ corresponds to the confidential information restoration device 24 and includes a restoration threshold K (120b), tally restoration permission rule information 120c, device identification information ID_0004 (160), and tally restoration permission information 161.

The tally sub-data F ₅ corresponds to the confidential information restoration device 25 and includes a restoration threshold K (120b), tally restoration permission rule information 120c, device identification information ID_0005 (170), and tally restoration permission information 171.
Tally data generation unit 104, a tally data W ₁ and the tally main data Y ₁ and tally sub data F ₁ in combination, the tally data W ₂ and the tally main data Y ₂ and tally sub data F ₂ a set The tally main data Y ₃ and the tally sub data F ₃ are combined into a tally data W ₃ , the tally main data Y ₄ and the tally sub data F ₄ are combined into a tally data W ₄ , and the tally main data Y ₅ and tally data W ₅ to the tally sub data F ₅ in combination with.

FIG. 10 is a diagram illustrating a data configuration of the tally data W ₁ (240). As shown in the figure, the tally data W ₁ (240) is composed of tally main data Y ₁ (241) and tally sub data F ₁ (242).
The tally data generation unit 104 outputs the tally data W ₁ , W ₂ , W ₃ , W ₄ , and W ₅ to the tally data transmission unit 105.

(5) Tally data transmission unit 105
The tally data transmission unit 105 includes a network connection unit and a memory card input / output unit.
The tally data transmission unit 105 receives the tally transmission destination information 230 illustrated in FIG. 8 from the data extraction unit 102. Also, the tally data transmission unit 105 receives tally data W ₁ , W ₂ , W ₃ , W ₄ , and W ₅ from the tally data generation unit 104.

The tally data transmission unit 105 determines device identification information included in each tally data, and acquires a corresponding address from the tally destination information 230. The tally data transmission unit 105 transmits each tally data via the network 30 with the acquired address as a transmission destination.
Here, the tally data transmission unit 105 cannot acquire the address corresponding to the device identification information ID_0005 (150) from the tally destination information 230. When the address cannot be acquired, the tally data transmission unit 105 determines that the confidential information restoration device 25 identified by the device identification information ID_0005 (150) is a memory card. In this case, tally data transmission unit 105, in a state in which the confidential information restoring device 25 is mounted in the memory card slot, the tally data W _5, and transfers to the confidential information restoring device 25.

<Operation of tally generation processing>
(1) Overall Operation Here, the operation of tally generation processing by the tally generation device 10 will be described using the flowchart shown in FIG.
The tally generation process starts when the data input unit 101 receives input of the confidential information S and the tally generation instruction information 110. The data input unit 101 outputs the confidential information S to the tally main data generation unit 103, and outputs the tally generation instruction information 110 to the data extraction unit 102.

The data extraction unit 102 analyzes the tally generation instruction information 110 (step S101). Then, the data extraction unit 102 generates the tally main data generation control information 210 shown in FIG. 6 (step S102), and further generates the tally sub data generation control information 220 shown in FIG. 7 (step S103).
The data extraction unit 102 outputs the tally main data generation control information 210 to the tally main data generation unit 103, and outputs the tally sub data generation control information 220 to the tally data generation unit 104.

Further, the data extraction unit 102 generates the tally destination information 230 illustrated in FIG. 8 based on the list in which the device identification information and the destination information are associated (step S104). The data extraction unit 102 holds the list in advance.
The data extraction unit 102 outputs the tally destination information 230 to the tally data transmission unit 105.

Subsequently, the tally main data generation unit 103 generates the tally main data Y _i based on the confidential information S and the tally main data generation control information 210 (step S105). Here, i = 1, 2,... The detailed operation of generating the tally main data Y _i will be described later.
The tally main data generation unit 103 outputs the generated tally main data Y _i to the tally data generation unit 104.

The tally data generation unit 104 generates the tally sub data F _i corresponding to each confidential information restoration device based on the tally sub data generation control information 220 (step S106).
Next, tally data generation unit 104 associates the tally main data _{Y i} generated in step S105, the tally sub data _{F i} generated in Step S106, generates the tally data _{W i} (step S107). Tally data generation unit 104, the generated tally data _{W i,} and outputs to the tally data transmission unit 105.

Tally data transmission unit 105, a tally data _{W i} received from the tally data generation unit 104, is distributed to each confidential information restoring device (step S108).
Specifically, tally data transmission unit 105 via the network 30, sends the tally data W ₁ to the confidential information restoring device 21, and transmits the tally data W ₂ to the confidential information restoring device 22, the confidential information restoring device It sends tally data _{W 3} to 23, and transmits the tally data _{W 4} to the confidential information restoring device 24. Further, tally data transmission unit 105 to the confidential information restoring device 25 mounted in the memory card slot of the own apparatus, and transfers the tally data W _5.

(2) Operation of Tally Main Data Generation Processing Here, the operation of the tally main data generation processing will be described using the flowchart shown in FIG. The operation shown here is the details of step S105 in FIG.
The tally random number generation unit 181 of the tally main data generation unit 103 generates the same number of restoration threshold K, that is, three 1-byte random numbers R ₁ , R ₂ , and R ₃ (step S201).

Next, the first tally numerical value generation unit 182 converts each tally restoration permission information that is 128-bit data,
C ₁ = tally restoration permission information 131
C ₂ = Tally restoration permission information 141
C ₃ = tally restoration permission information 151
C ₄ = tally restoration permission information 161
C ₅ = tally restoration permission information 171
In this case, X _i = Hash (C _i ) is calculated to generate a first tally value X _i (i = 1, 2,..., 5) (step S202).

Next, the second tally numerical value generation unit 183 divides the L-byte confidential information S into bytes, and sets them as S [1], S [2], ..., S [L] ( Step S203).
The second tally value generation unit 183 repeats the processing from step S205 to step S207 for i = 1, 2,..., 5 (step S204, step S208).
The second tally value generation unit 183 repeats the process of step S206 for m = 1, 2,..., L (steps S205 and S207).

  The second tally value generator 183

を計算して、第２割符数値Ｙ_ｉ[ｍ]を生成する（ステップＳ２０６）。
第２割符数値生成部１８３は、割符主データＹ_ｉを、割符データ生成部１０４へ出力する（ステップＳ２０９）。

Is calculated to generate the second tally value Y _i [m] (step S206).
The second tally value generation unit 183 outputs the tally main data Y _i to the tally data generation unit 104 (step S209).

Here, the tally main data Y _i is
Y ₁ = Y ₁ [m] = Y ₁ [1], Y ₁ [2],..., Y ₁ [L]
Y ₂ = Y ₂ [m] = Y ₂ [1], Y ₂ [2],..., Y ₂ [L]
Y ₃ = Y ₃ [m] = Y ₃ [1], Y ₃ [2],..., Y ₃ [L]
Y ₄ = Y ₄ [m] = Y ₄ [1], Y ₄ [2],..., Y ₄ [L]
Y ₅ = Y ₅ [m] = Y ₅ [1], Y ₅ [2],..., Y ₅ [L].

<Configuration of Confidential Information Restoration Device 21>
Here, the configuration of the confidential information restoring device 21 will be described.
FIG. 13 is a functional block diagram functionally showing the configuration of the confidential information restoring device 21. As shown in the figure, the confidential information restoration device 21 includes a data transmission / reception unit 201, a tally data storage unit 202, a data control unit 203, a device identification information storage unit 204, a device characteristic information storage unit 205, a restoration unit 206, and restoration availability. The determination unit 207 includes a tally sub-data update unit 208 and an input unit 209.

Specifically, the confidential information restoring device 21 is a computer system including a microprocessor, a ROM, a RAM, a hard disk unit, a network connection unit, and the like. The confidential information restoring device 21 achieves its function by the microprocessor operating according to the computer program.
The confidential information restoring devices 22, 23, and 24 have the same configuration as the confidential information restoring device 21. Further, since the confidential information restoring device 25 is a memory card, the confidential information restoring device 25 includes components corresponding to the tally data storage unit 202, the device identification information storage unit 204, and the device characteristic information storage unit 205 of the confidential information restoration device 21. The confidential information restoring device 25 is used by being mounted in a memory card slot of another device.

  In the present embodiment, since the restoration threshold value K = 3 is described, in the following, among the five confidential information restoring devices, three devices including the confidential information restoring devices 21, 22, and 23 are classified as confidential information. A description will be given on the assumption that it is involved in the restoration process of S. However, this is one specific example, and any combination of the five confidential information restoring devices that hold the tally data may be used.

(1) Data transmission / reception unit 201
The data transmission / reception unit 201 is a network connection unit, and performs data transmission / reception via the network 30 between the data control unit 203 and the tally generating device 10, and between the data control unit 203 and another confidential information restoring device.
Specifically, the data transmitting / receiving unit 201 receives tally data W ₁ from the tally generating device 10.

Further, the data transmitting / receiving unit 201 transmits the tally data W ₁ to the confidential information restoring devices 22 and 23, receives the tally data W ₂ from the confidential information restoring device 22, and receives the tally data W ₂ from the confidential information restoring device 23. to receive the data _{W 3.}
(2) Tally data storage unit 202
The tally data storage unit 202 stores the tally data W ₁ received from the tally generation device 10.

The tally data storage unit 202 receives the tally data W ₂ received from the confidential information restoration device 22 and the confidential information restoration device 23 while the restoration unit 206 and the restoration possibility determination unit 207 perform the confidential information restoration processing. and temporarily stores the tally data W ₃ was.
(3) Data control unit 203
When the data control unit 203 acquires the tally data W ₁ from the tally generating device 10 via the data transmitting / receiving unit 201, the device identification information and the device identification information included in the tally sub data F ₁ of the tally data W ₁ It is determined whether or not the device identification information stored in the storage unit 204 matches. If the device identification information matches, the data control unit 203 writes the acquired tally data W ₁ into the tally data storage unit 202. If the device identification information do not match, the data control unit 203 discards the tally data W ₁ acquired.

In addition, when the data control unit 203 receives the confidential information restoration request from the input unit 209, the data control unit 203 requests the tally data W ₂ and W ₃ to the confidential information restoration devices 22 and 23 via the data transmission / reception unit 201. Note that the network address of another confidential information restoration device may be stored in the data control unit 203 or may be stored in the data transmission / reception unit 201.
In addition, when the data control unit 203 receives information indicating “unrestorable” from the restoration permission determination unit 207 in the restoration permission determination process of the confidential information S, the tally data stored temporarily from the tally data storage unit 202 is stored. Data W ₂ and W ₃ are read and discarded.

Further, the data control unit 203 controls data input / output with respect to each unit of the confidential information restoring device 21. In the present embodiment, each unit of the confidential information restoring device 21 inputs and outputs data via the data control unit 203 even if not specifically described.
(4) Device identification information storage unit 204
As shown in FIG. 14, the device identification information storage unit 204 stores device identification information ID_0001 that is an identifier of the own device.

(5) Device characteristic information storage unit 205
The device characteristic information storage unit 205 stores information indicating the device characteristics of the own device.
In the present embodiment, as a specific example, device characteristic information storage unit 205 stores a restorable maximum threshold value K _m. The recoverable maximum threshold value _Km is a value obtained by converting the processing performance of the apparatus into a recovery threshold value.

That is, since the maximum recoverable threshold value K _m of the confidential information restoring device 21 is K _m = 4, the confidential information restoring device 21 has a processing performance capable of restoring confidential information whose restoration threshold value K is 4 or less. Means that.
(6) Restoring unit 206
When the restoration unit 206 receives information indicating “restoration is possible” from the restoration possibility determination unit 207, the restoration unit 206 uses the tally data W ₁ , W ₂ , and W ₃ stored in the tally data storage unit 202 as follows. As shown, the confidential information S is restored.

First, the restoration unit 206 extracts tally sub data F ₁ , F ₂ , and F ₃ from the tally data W ₁ , W ₂ , and W ₃ . Further, the restoration unit 206 extracts the tally restoration permission information 131, 141, and 151 included in the tally sub data F ₁ , F ₂ , and F ₃ .
here,
C ₁ = tally restoration permission information 131
C ₂ = Tally restoration permission information 141
C ₃ = tally restoration permission information 151
Then, the restoration unit 206 calculates a one-way hash Hash for C ₁ , C ₂ , and C ₃ and calculates three first tally values X ₁ = Hash (C ₁ ).
X ₂ = Hash (C ₂ )
X ₃ = Hash (C ₃ )
Is generated.

Then, the restoration unit 206 outputs the tally main data Y ₁ = Y ₁ [1], Y ₁ [2] included in the first tally values X ₁ , X ₂ , X ₃ , tally data W ₁ , W ₂ , and W _3. ], Y ₁ [L], Y ₂ = Y ₂ [1], Y ₂ [2],..., Y ₂ [L], and Y ₃ = Y ₃ [1], Y ₃ [2],. , Y ₃ [L], byte confidential information S [1], S [2],..., S [L] is calculated.
Here, the byte confidential information is a value obtained by dividing the confidential information S for each byte, and is calculated by the following (Equation 3) and (Equation 4). It should be noted that the addition / subtraction / multiplication / division operations in (Equation 3) and (Equation 4) are all performed on the finite field GF (2 ^ 8).

ここで、

here,

である。
復元部２０６は、生成したバイト機密情報Ｓ［１］、Ｓ［２］、…、Ｓ［Ｌ］を連結して、機密情報Ｓを生成する。復元部２０６は、生成した機密情報Ｓを出力する。

It is.
The restoration unit 206 concatenates the generated byte confidential information S [1], S [2],..., S [L] to generate confidential information S. The restoration unit 206 outputs the generated confidential information S.

(7) Restorability determination unit 207
The restoration possibility determination unit 207 uses the tally sub data F ₁ , F ₂ , F ₃ stored in the tally data storage unit 202 and the maximum threshold value K _m that can be restored stored in the device characteristic information storage unit 205. Then, a process for determining whether to restore the confidential information S is performed.
Restoration determination processing is different depending on the rules indicated by the tally restoration permission rule information 120c included in the tally sub data F _1.

Tally restoration permission rule information 120c is, indicating "Rule 1" restoration state determining unit 207 uses the tally restoration permission information 131 included in the tally sub data F _1, the restoration determination processing.
When the tally restoration permission rule information 120c indicates “Rule 2” or “Rule 4”, the restoration permission determination unit 207 includes the tally restoration permission information 131 and the tally sub data F ₂ included in the tally sub data F _1. using tally restoration permission information 151 included in the tally restoration permission information 141, and the tally sub data F _3, the restoration determination processing.

Tally restoration permission rule information 120c is, indicating "Rule 3" restoration state determining unit 207, a tally restoration permission information 131 included in the tally sub data F _1, by using the restorable maximum threshold value K _m, restore Performs availability determination processing.
When it is determined that “restoration is possible” as a result of the restoration possibility determination process, information indicating “restoration is possible” is output to the restoration unit 206 via the data control unit 203, and “restoration is impossible” is determined. The information indicating “unrestorable” is output to the data control unit 203.

(8) Tally sub data update unit 208
The tally subdata updating unit 208 permits the tally restoration when the tally restoration permission rule information 120c indicates “Rule 4” and the restoration unit 206 performs the restoration process of the confidential information S. The number of points is updated by subtracting 1 from the restoration permission points set in the information 131.

(9) Input unit 209
The input unit 209 includes an input device that receives an instruction from the user, and receives a confidential information restoration request from the user. The input unit 209 outputs the received confidential information restoration request to the data control unit 203.
<Operation of confidential information restoration processing>
Here, the operation of the confidential information restoration process will be described using the flowcharts shown in FIGS. 16 and 17. Here, the confidential information restoring process by the confidential information restoring device 21 will be described as a specific example, but the confidential information restoring devices 22, 23, and 24, and the device to which the confidential information restoring device 25 is attached are also described. The operation is similar to the operation described here.

(1) Overall Operation The confidential information restoration process starts when the input unit 209 receives a confidential information restoration request.
First, the data control unit 203 reads out from the tally sub data _{F 1} included in the tally data _{W 1} stored in the tally data storage unit 202, restoring the threshold K a (120b) (step S301).

In this embodiment, since K = 3, the restoration of the confidential information S requires three tally data including the tally data W ₁ held by the own device. Therefore, the data control unit 203 acquires tally data from the other two devices via the data transmission / reception unit 201 (step S302). Specifically, the data control unit 203 acquires the tally data W ₂ from the confidential information restoring device 22 and acquires the tally data W ₃ from the confidential information restoring device 23.

The data control unit 203 writes the acquired tally data W ₂ and W ₃ to the tally data storage unit 202.
Next, restore judging unit 207, the tally sub data _{F 1,} reads the tally restoration permission rule information 120c (step S303), and determines whether the tally restoration permission rule information 120c is set which of the rules.

When rule 1 is set in the tally restoration permission rule information (120c) (“rule 1” in step S304), the restoration possibility determination unit 207 performs restoration possibility determination processing 1 (step S305).
When rule 2 is set in the tally restoration permission rule information (120c) (“rule 2” in step S304), the restoration possibility determination unit 207 performs restoration possibility determination processing 2 (step S306).

When rule 3 is set in the tally restoration permission rule information (120c) (“rule 3” in step S304), the restoration possibility determination unit 207 performs restoration possibility determination processing 3 (step S307).
When the rule 4 is set in the tally restoration permission rule information (120c) (“rule 4” in step S304), the restoration possibility determination unit 207 performs the restoration possibility determination process 4 (step S308).

The data control unit 203 determines whether the information received from the restoreability determination unit 207 is “restoreable” or “unrecoverable”.
If “restoration is impossible” (NO in step S309), the data control unit 203 reads out the tally data W ₂ and W ₃ stored in the tally data storage unit 202 and discards them (step S310).

If “restorable” (YES in step S309), the data control unit 203 outputs information indicating “restorable” to the restoring unit 206. Thereafter, the restoration unit 206 performs confidential information restoration processing to generate confidential information S (step S311). The restoration unit 206 outputs the generated confidential information S (step S312).
Subsequently, the data control unit 203, the tally sub data _{F 1,} read the tally restoration permission rule information (120c), the tally restoration permission rule information (120c) is, determines whether or not showing the rules 4.

If the tally restoration permission rule information (120c) indicates a rule other than rule 4 (NO in step S313), the confidential information restoration process ends.
When the tally restoration permission rule information (120c) indicates rule 4 (YES in step S313), the data control unit 203 outputs an update instruction to the tally sub data update unit 208.
Tally sub data update unit 208, the data control unit 203, when receiving the instruction for updating the tally restoration permission information 131 from the tally data storage unit 202 reads the tally sub data F _1, the tally restoration contained in the tally sub data F ₁ The number of points indicated by the permission information 131 is updated by subtracting 1 (step S314).

(2) Operation of Restorability Determination Processing 1 Here, the operation of the restoration permission determination processing 1 will be described using the flowchart shown in FIG. The operation shown here is the details of step S305 in FIG.
The restoration permission determination unit 207 reads the tally restoration permission information 131 included in the tally sub data F ₁ (step S131), and the read tally restoration permission information 131 is “1 (permitted)” and “0 (not permitted)”. ] Is determined.

When the tally restoration permission information 131 is set to “1 (permitted)” (YES in step S402), the restoration permission determination unit 207 outputs information indicating “restoration possible” to the data control unit 203 ( Step S403).
When the tally restoration permission information 131 is set to “0 (not permitted)” (NO in step S402), the restoration permission determination unit 207 outputs information indicating “restoration impossible” to the data control unit 203 ( Step S404).

In the example shown in FIG. 5, the tally restoration permission information 131 is set to “1 (permitted)”. Therefore, in this example, the restoration permission determination unit 207 notifies the data control unit 203 that “restoration is possible”. Is output.
(3) Restorability determination process 2
Here, the operation of the restoration possibility determination process 2 will be described using the flowchart shown in FIG. The operation shown here is the details of step S306 in FIG.

The restoration permission / non-permission determination unit 207 reads the tally restoration permission information 131 from the tally sub data F ₁ included in the tally data W ₁ of the own device (step S501).
Next, the restoration possibility determination unit 207 reads the tally restoration permission information 141 and 151 from the tally sub data F ₂ and F ₃ included in the tally data W ₂ and W ₃ of the other device (step S502).

The restoration possibility determination unit 207 compares the priority levels set in the tally restoration permission information 131, 141, and 151, and determines whether or not the priority order of the own device is the highest.
When the priority order of the own device is the highest (YES in step S503), the restoration possibility determination unit 207 outputs information indicating “restoration is possible” to the data control unit 203 (step S504).
When the priority order of the own apparatus is not the highest (NO in step S503), the restoration possibility determination unit 207 outputs information indicating “unrestorable” to the data control unit 203 (step S505).

In the example shown in FIG. 5, the tally restoration permission information 131 is set to “2”, the tally restoration permission information 141 is set to “3”, and the tally restoration permission information 151 is set to “1”. Therefore, in this example, since the priority order of the confidential information restoration device 21 is not the highest, the restoration possibility determination unit 207 outputs information indicating “unrestorable” to the data control unit 203.
(4) Restorability determination processing 3
Here, the operation of the restoration possibility determination process 3 will be described using the flowchart shown in FIG. The operation shown here is the details of step S307 in FIG.

Restoration determination unit 207 reads the value of the tally restoration permission information 131 included in the tally sub data _{F 1} (step S601). According to rule 3, the value of the restoration threshold K is set in the tally restoration permission information 131.
Next, restoration determination unit 207 reads the restorable maximum threshold value _{K m} stored in the device characteristic information storage unit 205 (step S602).

Restoration determination unit 207 compares the value of K that is set in the tally restoration permission information 131, the value of restorable maximum threshold value K _m.
When K _m ≧ K (YES in step S603), the restoration possibility determination unit 207 outputs information indicating “restoration is possible” to the data control unit 203 (step S604).
When K _m <K (NO in step S603), the restoration possibility determination unit 207 outputs information indicating “no restoration” to the data control unit 203 (step S404).

In the example shown in FIGS. 5 and 15, K = 3 and K _m = 4. Therefore, in this example, the restoration possibility determination unit 207 outputs information indicating “restoration is possible” to the data control unit 203.
(5) Restorability determination process 4
Here, the operation of the restoration possibility determination process 4 will be described using the flowchart shown in FIG. The operation shown here is the details of step S308 in FIG.

The restoration permission / non-permission determination unit 207 reads the tally restoration permission information 131 from the tally sub data F ₁ included in the tally data W ₁ of the own device (step S701).
Next, the restoration possibility determination unit 207 reads the tally restoration permission information 141 and 151 from the tally sub data F ₂ and F ₃ included in the tally data W ₂ and W ₃ of the other device (step S702).

The restoration permission determination unit 207 compares the restoration permission points set in the tally restoration permission information 131, 141, and 151, and determines whether or not the number of points of the own device is the maximum.
When the number of points of the own device is the maximum (YES in step S703), the restoration possibility determination unit 207 outputs information indicating “restoration is possible” to the data control unit 203 (step S704).
When the number of points of the own device is not the maximum (NO in step S703), the restoration possibility determination unit 207 outputs information indicating “no restoration” to the data control unit 203 (step S705).

  In the example shown in FIG. 5, the tally restoration permission information 131 is set to “3”, the tally restoration permission information 141 is set to “2”, and the tally restoration permission information 151 is set to “3”. Therefore, in this example, the number of points held by the confidential information restoration device 21 has the maximum number of points “3” of the number of points held by the three confidential information restoration devices. , Information indicating “restorable” is output to the data control unit 203.

(6) Confidential Information Restoration Process Here, the operation of the confidential information restoration process will be described using the flowchart shown in FIG. The operation shown here is the details of step S311 in FIG.
Restoring unit 206, the tally data _{W i} which is stored in the tally data storage unit 202, reads the tally main data _{Y i} (step S801). Here, i = 1, 2, and 3.

Subsequently, the restoration unit 206 obtains tally restoration permission information from the tally sub data F ₁ , F ₂ , and F ₃ included in the tally data W ₁ , W ₂ , and W ₃ stored in the tally data storage unit 202. 131, 141, and 151 are read out. Here, C ₁ = tally restoration permission information 131, C ₂ = tally restoration permission information 141, and C ₃ = tally restoration permission information 151 (step S802).
The restoration unit 206
First tally value X ₁ = Hash (C ₁ )
X ₂ = Hash (C ₂ )
X ₃ = Hash (C ₃ ) is generated (step S803).

Subsequently, the restoration unit 206 repeats step S805 and step S806 for m = 1, 2,..., L (steps S804 and S807).
First, the restoration unit 206

を算出し（ステップＳ８０５）、続いて、Ｐ_ｉ[ｍ]から

Is calculated (step S805), and then from P _i [m]

を算出する（ステップＳ８０６）。
最後に、復元部２０６は、Ｓ[１]、Ｓ[２] 、…、Ｓ[ｍ]を連結して、機密情報Ｓを生成する（ステップＳ８０８）。

Is calculated (step S806).
Finally, the restoration unit 206 concatenates S [1], S [2],..., S [m] to generate confidential information S (step S808).

<Summary>
In the above embodiment, when the tally restoration permission rule information is set to “Rule 1”, whether or not restoration of the confidential information S is permitted can be individually set for each confidential information restoration device.
When the tally restoration permission rule information is set to “rule 2”, the restoration of the confidential information S can be permitted only to the apparatus having the highest priority among the confidential information restoration apparatuses participating in the restoration process. Here, in the case of “Rule 1”, if all of the tally restoration permission information of the confidential information restoration device participating in the restoration process is “not permitted”, the confidential information S cannot be restored by any device. Could happen. However, in the case of “Rule 2”, any one of the confidential information restoration devices is always the highest priority device, and thus such a situation does not occur.

  When the tally restoration permission rule information is set to “Rule 3”, the restoration of the confidential information S can be permitted only to the confidential information restoration apparatus having a processing performance sufficient to restore the confidential information S. Here, the number of calculations required in (Equation 2) and (Equation 3) in the above embodiment is addition / subtraction = K ^ 2-1 times, multiplication = K × (K−2) times, division = K × (K -1) times, which is determined by the restoration threshold K. Therefore, in this embodiment, the calculation amount of the confidential information restoration process and the calculation capability of the confidential information restoration apparatus are used as index values by the value of the restoration threshold K.

The maximum recoverable threshold value K _m of each confidential information restoration device is obtained, for example, from the number of calculations that each confidential information restoration device can execute within a predetermined time. That is, the restoration threshold value K that is equal to or less than the number of computations that can be executed within the predetermined time is set as the maximum threshold value K _m that can be restored.
When the tally restoration permission rule information is set to “Rule 4”, the restoration of the confidential information is permitted only to the apparatus having a high priority (the apparatus having a high number of points) among the confidential information restoration apparatuses participating in the restoration process. The priority can be changed according to the number of past restorations. As a result, it is possible to avoid a situation in which only the same confidential information restoring device restores the confidential information S each time.

Here, the correspondence between the means described in the claims and the components described in the above embodiment will be described.
The tally generating unit according to claim 1 corresponds to the tally main data generating unit 103 and the tally data generating unit 104 of the tally generating device 10, and the restoration control information generating unit corresponds to the tally data generating unit 104.

Further, the storage means according to claim 1 and claim 2 corresponds to the tally data storage unit 202 of the confidential information restoration device 21, and the tally collection means corresponds to the data control unit 203 and the data transmission / reception unit 201. The means corresponds to the restoration possibility determination unit 207, and the restoration means corresponds to the restoration unit 206.
The device characteristic information storage means described in claim 5 corresponds to the device characteristic information storage unit 205 of the confidential information restoration device 21.

The restoration control information update unit according to claim 9 corresponds to the tally sub data update unit 208 of the confidential information restoration device 21.
The falsification detection means described in claim 10 corresponds to the restoration possibility determination unit 207 of the confidential information restoration apparatus 21.
The data control means according to claim 11 corresponds to the data control unit 203 of the confidential information restoring device 21.

The tally generating unit according to claim 13 corresponds to the tally main data generating unit 103 and the tally data generating unit 104 of the tally generating device 10, and the restoration control information generating unit corresponds to the tally data generating unit 104, and the distributing unit Corresponds to the tally data transmission unit 105.
The falsification detection value generation means according to claim 18 corresponds to the tally main data generation unit 103 of the tally generation device 10.

<Other variations>
So far, the present invention has been described based on the above embodiment, but the present invention is not limited to the above embodiment, and the following cases are also included in the present invention.
(1) In the above embodiment, the tally restoration permission information is 128-bit data including the effective information bit size and random number data, as shown in FIG. 4, and the tally data generation unit 104 stores the 128-bit data. Although the first tally value is generated by calculating the hash value for the tally restoration permission information, this configuration is not essential in the present invention. The case where the tally main data generation unit 104 generates a first tally value by calculating a hash value for only effective information is also included in the present invention.

  (2) In the above embodiment, the tally sub-data includes the restoration threshold K, but this is not essential. The number of tally data necessary for restoration of the confidential information S (value of the restoration threshold K) is notified in advance to each confidential information restoration device included in the system, and each confidential information restoration device transmits how many tally data. The tally sub-data does not have to include the restoration threshold value K if it is understood that it should be obtained from another confidential information restoration device.

  (3) In the above embodiment, when the tally restoration permission rule information 120c indicates “Rule 2” and “Rule 4”, only the device with the highest priority and the highest number of points has a configuration in which restoration is permitted. The present invention is not limited to this configuration. For example, the restoration of the confidential information S may be permitted for a predetermined number of confidential information restoring devices, such as two from the higher priority and the highest number of points. .

In addition, when the tally restoration permission rule information 120c indicates “rule 4”, it is assumed that the restoration is permitted only for the confidential information restoration device having the largest number of points, and the restoration is permitted regardless of the number of points. Also good. In this case, the number of points represents the remaining number of times that the restoration process is permitted for each device.
In the above embodiment, when the tally restoration permission rule information 120c indicates “Rule 3,” each tally restoration permission information is restored as information indicating the calculation capability of the apparatus necessary for the restoration processing of the confidential information S. Although the threshold value K is set, the present invention may use the number of clocks of the CPU, the size of the memory, or the like as a method of expressing the calculation capability of the apparatus.

  Further, in the case of “Rule 3”, the present invention is not limited to the calculation capability of the confidential information restoration device, and may be configured to show other device characteristics related to the confidential information restoration device. For example, when the confidential information S is image data, the resolution of the display device provided in the confidential information restoration apparatus is used as an index, and the confidential information is applied to an apparatus provided with a display device having only a predetermined resolution or less. You may comprise so that restoration of S may be prohibited. In addition, when the confidential information S is moving image data, the reproduction capability of the moving image data possessed by the confidential information restoring device is used as an index, and when the confidential information S is reproduced, an apparatus such as a frame dropping error may occur. May be configured to prohibit the restoration of the confidential information S.

Further, it may be used as an index whether or not the confidential information restoration device has a predetermined capability. For example, if an apparatus having a data replication capability is provided with a configuration that prohibits restoration of the confidential information S, unauthorized copying of the confidential information S can be suppressed and the confidential information S can be protected.
In the above embodiment, when the tally restoration permission rule information indicates “Rule 4”, the tally sub-data update unit 208 of the confidential information restoration device 21 subtracts 1 from the number of points of the own device. Is not limited to this configuration. The present invention may be configured, for example, to increase the number of points corresponding to other confidential information restoration apparatuses other than the confidential information restoration apparatus that restored the confidential information S from tally data. According to this configuration, the same effect as in the above embodiment can be obtained.

Further, each confidential information restoring device may be configured to weight the number of points to be increased or decreased. With this configuration, it is possible to distinguish and manage a device that is not easily prohibited from restoring the confidential information S and a device that is easily prohibited.
Furthermore, the degree of increase / decrease of points may be changed for each confidential information according to the intention of the creator of tally data. Thereby, the degree of increase / decrease of points can be adjusted for each confidential information according to the intention of the creator of the tally data. In this case, it is necessary to give the information on the number of points to be increased or decreased to the confidential information restoring device together with the tally main data. This can be realized, for example, by including information on the number of points to be increased or decreased with respect to the tally sub data.

  In the above embodiment, when the tally restoration permission rule information indicates “Rule 4”, the tally sub data update unit 208 of the confidential information restoration device 21 has a configuration of updating only the tally sub data of the own device. The present invention is not limited to this configuration. The tally sub-data updating unit 208 updates the tally sub-data of its own device, and sends the corresponding tally sub-data to the tally sub-data updating unit of another confidential information restoration device via the data transmitting / receiving unit 201. It may be configured to instruct to update.

In this case, since the tally sub-data is updated in all the confidential information restoration devices, the state of the tally sub-data corresponding to the tally data generated from the same confidential information can be synchronized in the system.
(4) In the above embodiment, the tally generating device 10 calculates 1 byte by calculating a hash value for each of the restoration permission information C _i (i = 1, 2,..., 5) that is 128-bit data. A first tally value X _i that is data is generated. The tally generating device 10 distributes the tally main data Y _i generated using the first tally value X _i to each confidential information restoration device, but the first tally value X _i is not distributed. is doing.

This is because each confidential information restoration device can generate the first tally numerical value X _i based on the tally restoration permission information C _i , so that this configuration is used to reduce the transmission data amount. have.
However, in the system of the present invention, the tally generating device 10 includes the first tally numerical value X _i itself generated by the first tally numerical value generating unit 182 in the tally main data Y _i and transmits it to each confidential information restoring device. You may comprise.

In each confidential information restoration device, the tally restoration permission information C _i included in the tally sub-data F _i is included in the restoration possibility judgment processing by the restoration possibility judgment unit 207 prior to restoration judgment using the tally restoration permission information C _i. Unidirectional hash is calculated, and the calculated value is compared with the first tally numerical value X _i included in the tally main data Y _i to determine whether the tally restoration permission information C _i has been tampered with. You may comprise.

When the tampering restoration permission information C _i is detected to be falsified, the restoration permission / non-permission determination unit 207 ends the restoration processing of the confidential information S, and when not detecting tampering of the tally restoration permission information C _i It may be configured to start the restoration permission / inhibition determination process described in (1). Note that the method of calculating the value used for the falsification detection process is not limited to the one for calculating the one-way hash value, and for example, encryption or the like may be used.

With this configuration, it is possible to prevent unauthorized confidential information restoration processing.
Here, in the configuration in which the first tally value X _i is not transmitted to the confidential information restoration device as in the above-described embodiment, tampering restoration detection processing of tally restoration permission information by hash value comparison cannot be performed. If the information is falsified, the confidential information restoration device cannot obtain the correct first tally value X _i and cannot restore the correct confidential information S. As a result, the confidential information S is prevented from being illegally restored. it can.

In the above embodiment, when the tally restoration permission information C _i is 1-byte information, the value of the tally restoration permission information C _i itself may be used as the first tally value X _i . Also in this case, similarly to the case where Hash (C _i ) is set to the first tally value X _i , if the tally restoration permission information C _i is falsified, the confidential information S cannot be restored correctly.
Further, the first tally value X _i may be generated without using the restoration permission information C _i . For example, a random number may be generated and used as the first tally value X _i . In this case, the first tally numerical value X _i needs to be included in the tally main data Y _i in order to use it for the restoration of the confidential information S.

For each i, the first tally value X _i generated using the restoration permission information C _i is used, and for some i, the first tally value X _i generated from a random number or the like is used. Whether to use the restoration permission information C _i for generating the first tally value X _i may be switched.
(5) In the above embodiment, each confidential information restoration device sends the entire tally data including the tally main data and the tally sub data to other confidential information restoration devices at the time of restoration feasibility determination processing. However, this configuration is not essential in the present invention.

  First, the confidential information restoration device sends only the tally sub-data necessary for the restoration feasibility judgment process, and when it is judged as “restorable” in the restoration feasibility judgment processing, The data may be requested and the tally main data may be obtained. As a result, transmission / reception of data that is unnecessary in the case of “unrestorable” can be suppressed, and the amount of data transmitted / received between the confidential information restoring devices can be reduced.

(6) In the above embodiment, the tally generating device 10 receives tally generation instruction information from the outside, and generates tally sub data corresponding to each confidential information restoration device based on the data extracted from the tally generation instruction information. However, the present invention is not limited to this configuration. The tally generation device 10 may have a configuration in which tally generation instruction information is stored in advance.
Further, according to the present invention, when each confidential information restoring device restores the confidential information by itself, the tally generating device 10 notifies the tally generating device 10, and the tally generating device 10 accepts the fact from each confidential information restoring device. The tally sub-data reflecting this may be generated.

According to this configuration, the tally generating device 10 can control the secret information restoring device that has restored the confidential information in the past to generate tally sub data that makes it difficult to restore the confidential information. .
(7) Although the memory card is shown as a specific example of the confidential information restoring device 25 in the above embodiment, the invention is not limited to this. For example, another recording medium such as an optical disk or a magnetic disk may be used.

  In the case of an optical disc or the like, it may be a write-once disc that cannot be overwritten with data. In this case, if the tally data received from another confidential information restoration device is temporarily recorded in the tally data storage unit 202 as in the above embodiment, the remaining capacity of the disk decreases each time tally data is restored. End up. Also, in the case of a read-only recording medium such as a BD-ROM, tally data received from another device cannot be temporarily recorded in the confidential information restoring device itself. Therefore, when the confidential information restoring device 25 is a write-once or read-only recording medium, a device that uses the information of the confidential information restoring device 25 provides a part of the memory as the tally data storage unit 202. Is desirable.

  Also, “Rule 4” accompanied by point update is not familiar to write-once and read-only recording media. Therefore, when the confidential information restoring device 25 is such a recording medium, the processing may be interrupted if the tally sub-permission information indicates “Rule 4”. However, in the case of the write-once type, “Rule 4” can be applied if it is allowed to reduce the free space by updating the points.

  In the above embodiment, the memory card that is an example of the confidential information restoring device 25 has only a configuration corresponding to the tally data storage unit 202, the device identification information storage unit 204, and the device characteristic information storage unit 205. . However, the present invention is not limited to this configuration, and other components can be realized on the memory card by adding an IC chip or the like for performing predetermined processing in the memory card. In this case, the confidential information restoration device 25 receives power supply from the device to which it is connected, but the confidential information restoration processing itself can be performed in the confidential information restoration device 25. As a result, the possibility of leakage of confidential information can be reduced.

  (8) In the above embodiment, one tally restoration permission information is assigned to each confidential information restoration device, but the present invention is not limited to this. A plurality of tally restoration permission information may be assigned to one device. In this case, the confidential information restoration device performs processing using one tally restoration permission information according to a predetermined standard. As a more specific example, in the case of “Rule 2”, the tally restoration permission information with the highest priority may be used.

  Further, in this case, the confidential information restoration apparatus may use a plurality of tally restoration permission information assigned to itself as information to be provided to the outside and information to be used for its own processing. Such control is effective, for example, when it is desired to permit a restoration by a device (self device) that provides tally data and a restoration by another device that collects the tally data as much as possible.

  That is, in the case of “Rule 2”, when it is desired to permit restoration by a device to which tally restoration permission information is assigned as much as possible, it is necessary to give as high priority as possible to the confidential information restoration device. is there. However, in this case, when another device attempts to restore confidential data using tally data collected from this confidential information restoration device, this high priority is an obstacle, and it is likely that restoration by another device is impossible. End up. Therefore, in such a case, it is assumed that a low priority is given as tally restoration permission information output to the outside. In this way, since the tally sub-authorization information included in the tally data has a low priority, other devices that collect the tally data and restore the confidential information are likely to be permitted to restore. .

  Contrary to the above, the condition of tally restoration permission information supplied to another apparatus is increased, and the condition of tally restoration permission information used by the own apparatus is lowered, so that confidential information can be restored by the apparatus. Restoration by other devices that have received tally data from can also be controlled to be difficult. Although the example in the case of “Rule 2” has been described here, the same control is possible in the case of other rules.

  (9) In the above embodiment, the apparatus that permits the restoration processing of the confidential information S is configured to be controlled by providing four rules from Rule 1 to Rule 4. However, from Rule 1 to Rule 4, It is only a concrete example. Therefore, the present invention is not limited to the above-described embodiments from Rule 1 to Rule 4, and is configured to control whether or not confidential information can be restored with a condition indicating whether or not confidential information can be restored for each device. I just need it.

(10) In the above embodiment, the confidential information restoration device has been described using a specific example that is realized by a mobile phone, a personal computer, or the like. However, the confidential information restoration device according to the present invention is a wireless tag or a sensor in a sensor network. You may implement | achieve with small modules, such as a node.
The sensor network is a system that forms a network using ultra-small sensors (sensor nodes) having a communication function and collects data acquired by each sensor. The sensor node is not fixed, and the sensor node itself can move when a person, a car, or the like moves with the sensor node, and the formed network changes dynamically.

The present invention may be configured such that a plurality of tally data is generated from a secret key held by a wireless tag and a sensor node, and is distributed and held by a plurality of wireless tags and sensor nodes.
In a network system using wireless tags, sensor nodes, and the like, each wireless tag and each sensor node needs to hold a secret key used for authentication processing between tags and between sensor nodes, encrypted communication, and the like. However, these small modules have a relatively low tamper resistance because of their low cost. Therefore, the security of the secret key can be protected by distributing the secret key using the present invention.

(11) The electronic tally system used in the above embodiment is merely an example, and can be applied to other electronic tally systems with the same configuration.
(12) The present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of the computer program.

  The present invention also provides a computer-readable recording medium such as a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray Disc). ), Recorded in a semiconductor memory or the like. The digital signal may be recorded on these recording media.

In the present invention, the computer program or the digital signal may be transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.
The present invention may be a computer system including a microprocessor and a memory, wherein the memory stores the computer program, and the microprocessor operates according to the computer program.

In addition, the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like, and executed by another independent computer system. It is good.
(13) A part or all of the constituent elements constituting each device of the present invention may be constituted by one system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on a single chip, and specifically, a computer system including a microprocessor, ROM, RAM, and the like. . A computer program is stored in the RAM. The system LSI achieves its functions by the microprocessor operating according to the computer program. Further, the method of circuit integration is not limited to LSI, and may be realized with a dedicated circuit. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied as a possibility.
(14) A part or all of the constituent elements constituting each device of the present invention may be constituted by an IC card or a single module that can be attached to and detached from each device. The IC card or the module is a computer system including a microprocessor, a ROM, a RAM, and the like. The IC card or the module may include the super multifunctional LSI described above. The IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.

  (15) The above embodiment and the above modifications may be combined.

  The confidential information protection system, the confidential information restoring device, and the tally generating device according to the present invention can be used in a service industry that provides a system having both security and flexibility of confidential information. Moreover, it can utilize in the industry which manufactures and sells the confidential information decompression | restoration apparatus and tally production | generation apparatus which concern on this invention.

It is a figure which shows the system configuration | structure of the confidential information protection system. 3 is a functional block diagram functionally showing the configuration of the tally generating device 10. FIG. It is a figure which shows the data structure of the tally production | generation instruction | indication information 110. FIG. It is a figure which shows the data structure of the tally recovery permission information 131. It is a figure for demonstrating the specific example of the tally restoration | recovery permission rule information in this embodiment, and the effective information contained in each tally restoration permission information. It is a figure which shows the data structure of the tally main data generation control information 210. It is a figure which shows the data structure of the tally sub data generation control information 220. It is a figure which shows the data structure of tally destination information 230. 3 is a functional block diagram functionally showing the configuration of a tally main data generation unit 103. FIG. Tally is a diagram showing the data structure of the data _W 1 (240). It is a flowchart which shows the operation | movement of a tally data generation process. It is a flowchart which shows the operation | movement of a tally main data generation process. 3 is a functional block diagram functionally showing the configuration of a confidential information restoring device 21. FIG. 6 is a diagram showing data stored in a device identification information storage unit 204. FIG. 6 is a diagram showing data stored in a device characteristic information storage unit 205. FIG. 18 is a flowchart showing an operation of confidential information restoration processing, continued from FIG. FIG. 17 is a flowchart showing an operation of confidential information restoration processing, continued from FIG. 16. 6 is a flowchart showing an operation of restoration permission / inhibition determination processing 1; It is a flowchart which shows operation | movement of the decompression | restoration possibility determination process 2. FIG. 6 is a flowchart showing an operation of restoration permission / inhibition determination processing 3; 10 is a flowchart showing an operation of restoration possibility determination processing 4; It is a flowchart which shows operation | movement of a confidential information restoration process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Confidential information protection system 10 Tally generation apparatus 21 Confidential information restoration apparatus 22 Confidential information restoration apparatus 23 Confidential information restoration apparatus 24 Confidential information restoration apparatus 25 Confidential information restoration apparatus 30 Network 101 Data input part 102 Data extraction part 103 Tally main data generation part 104 tally data generation unit 105 tally data transmission unit 181 tally random number generation unit 182 first tally value generation unit 183 second tally value generation unit 201 data transmission / reception unit 202 tally data storage unit 203 data control unit 204 device identification information storage unit 205 Device characteristic information storage unit 206 Restoration unit 207 Restorability judgment unit 208 Tally sub data update unit 209 Input unit

Claims (31)

A confidential information protection system that includes a tally generating device and a plurality of terminal devices, and holds confidential information in a distributed manner in the plurality of terminal devices,
The tally generator is
Tally generating means for generating a plurality of electronic tallys based on the confidential information;
A restoration control information generating means for generating, for each terminal device, restoration control information indicating a condition relating to restoration of the confidential information in each terminal device;
Each terminal device
Storage means for storing electronic tally and restoration control information generated by the tally generating device;
A tally collecting means for collecting a necessary number of electronic tallys;
Determination means for determining whether or not the confidential information can be restored based on the restoration control information;
Only when it is determined by the determination means that restoration is possible, the electronic tally stored in the storage means and the restoration means for restoring the confidential information based on the electronic tally collected by the tally collection means This is a confidential information protection system. A confidential information restoration device having a function of restoring the confidential information from a plurality of electronic tally generated based on the confidential information,
Storage means for storing one electronic tally generated by the tally generating device and restoration control information indicating conditions relating to restoration of the confidential information;
A tally collecting means for collecting a necessary number of electronic tallys;
Determination means for determining whether or not the confidential information can be restored based on the restoration control information stored in the storage means;
Only when it is determined by the determination means that restoration is possible, the electronic tally stored in the storage means, and the restoration means for restoring the confidential information based on the electronic tally collected by the tally collection means. This is a confidential information restoration device. The tally collecting means obtains the electronic tally and restoration control information obtained from the tally generating device by each other confidential information restoring device from the same number of other confidential information restoring devices as the required number,
The restoration means restores the confidential information using the electronic tally and the restoration control information stored in the storage means, and the electronic tally and the restoration control information acquired by the tally collection means. The apparatus for restoring confidential information according to claim 2. In the restoration control information, information indicating whether to permit restoration of the confidential information is set,
The determination unit determines that restoration is possible when the restoration control information indicates restoration permission, and determines that restoration is not possible when the restoration control information indicates restoration non-permission. The confidential information restoration device described in 1. In the restoration control information, information indicating a property of a device that permits restoration of the confidential information is set.
The confidential information restoring device further includes:
Device characteristic storage means for storing device characteristic information indicating the properties of the device itself,
The determination unit reads the device characteristic information, determines that the read device characteristic information satisfies the property indicated by the restoration control information, and determines that the restoration is possible. The confidential information restoring device according to claim 3, wherein it is determined that restoration is not possible when the indicated property is not satisfied. The property indicated by the restoration control information is information indicating processing performance of an apparatus necessary for restoring the confidential information,
6. The confidential information restoring device according to claim 5, wherein the device characteristic information is information indicating processing performance of the device itself. The determination unit performs the determination by comparing the restoration control information stored in the storage unit and the restoration control information acquired by the tally collection unit. The confidential information restoration device described in 1. In the restoration control information, information indicating a priority for performing the confidential information restoration processing in a plurality of confidential information restoration devices holding the plurality of electronic tallys is set,
The determination means determines that restoration is possible when the priority indicated by the restoration control information stored in the storage means is higher than the priority indicated by the restoration control information acquired by the tally collection means, The restoration control information stored in the storage unit is determined to be unrecoverable when the priority indicated by the restoration control information acquired by the tally collection unit is lower than the priority indicated by the restoration control information. Item 8. The confidential information restoring device according to Item 7. The confidential information restoring device further includes:
The restoration control information update means for updating the priority indicated by the restoration control information stored in the storage means when the judgment means determines that restoration is possible. The confidential information restoration device described in 1. The receiving means further receives, from the tally generating device, a falsification detection value generated by performing a predetermined calculation on the restoration control information,
The determination means determines whether or not the restoration control information has been falsified using the falsification detection value, and determines that restoration is impossible when falsification of the restoration control information is detected. The confidential information restoring device according to claim 3. Each electronic tally is information generated by performing a secret sharing process using a plurality of restoration control information on the confidential information,
The restoration means restores the confidential information from a plurality of electronic tallys using the restoration control information stored in the storage means and the restoration control information acquired by the collection means. The confidential information restoring device according to claim 3. The confidential information restoring device further includes:
The confidential information restoration apparatus according to claim 2, further comprising a data control unit that discards the electronic tally collected by the collection unit when the determination unit determines that the restoration is impossible. The confidential information restoration device according to claim 2, wherein the tally collection unit collects the necessary number of electronic tallys when the determination unit determines that restoration is possible. Tally generating means for generating a plurality of electronic tallys based on confidential information;
Restore control information generating means for generating, for each of a plurality of terminal devices to which the plurality of electronic tallys are distributed, restore control information indicating conditions relating to the restoration of the confidential information in each terminal device;
A tally generating apparatus comprising: a distribution unit that distributes electronic tally and restoration control information to each corresponding terminal apparatus. The restoration control information generating means generates the restoration control information based on the number of electronic tally to be generated, the number of electronic tally necessary for restoring the confidential information, and tally generation instruction information including the condition,
The tally generating device according to claim 14, wherein the tally generating unit generates the electronic tally based on the confidential information, the tally generation instruction information, and the restoration control information. The tally generation apparatus according to claim 15, wherein the restoration control information generation unit generates the restoration control information indicating whether or not the confidential information can be restored in each terminal device. The tally generating apparatus according to claim 15, wherein the restoration control information generating unit generates the restoration control information indicating a priority of restoration of the confidential information in each terminal device. The tally generating apparatus according to claim 15, wherein the restoration control information generating unit generates the restoration control information indicating a property of an apparatus that permits restoration of the confidential information. The tally generating apparatus according to claim 18, wherein the property indicated by the restoration control information is a processing performance of an apparatus necessary for restoring the confidential information. The tally according to claim 19, wherein the restoration control information generating means uses the value of the number of electronic tally required for restoring the confidential information included in the tally generation instruction information as the restoration control information. Generator. The tally generating device further includes:
A tamper detection value generating means for performing a predetermined calculation on each restoration control information and generating a tamper detection value corresponding to each restoration control information,
The tally generating apparatus according to claim 15, wherein the distribution unit distributes the tampering detection value to each terminal device in addition to the electronic tally and the restoration control information. 15. The tally generating unit generates the plurality of electronic tallys based on a plurality of restoration control information generated by the restoration control information generating unit and the confidential information. Tally generator. 23. The tally generating unit generates the plurality of electronic tallys by performing secret sharing processing using the plurality of restoration control information on the confidential information. Tally generator. A confidential information restoration method used in a confidential information restoration apparatus having a function of restoring the confidential information from a plurality of electronic tally generated based on the confidential information,
The confidential information restoring device includes:
A storage means for storing one electronic tally generated by the tally generating device and restoration control information indicating a condition relating to restoration of the confidential information;
The confidential information restoration method includes:
A tally collection step for collecting the required number of electronic tallys;
A determination step for determining whether or not the confidential information can be restored based on the restoration control information stored in the storage means;
A restoration step of restoring the confidential information based on the electronic tally stored in the storage means and the electronic tally collected by the tally collection means only when it is judged that restoration is possible in the determination step. A method for restoring confidential information. A computer program used in a confidential information restoring apparatus having a function of restoring the confidential information from a plurality of electronic tally generated based on the confidential information,
The confidential information restoring device includes:
A storage means for storing one electronic tally generated by the tally generating device and restoration control information indicating a condition relating to restoration of the confidential information;
The computer program is
A tally collection step for collecting the required number of electronic tallys;
A determination step for determining whether or not the confidential information can be restored based on the restoration control information stored in the storage means;
A restoration step of restoring the confidential information based on the electronic tally stored in the storage means and the electronic tally collected by the tally collection means only when it is judged that restoration is possible in the determination step. A computer program characterized by the above. A computer-readable recording medium recording a computer program used in a confidential information restoring apparatus having a function of restoring the confidential information from a plurality of electronic tally generated based on the confidential information,
The confidential information restoring device includes:
A storage means for storing one electronic tally generated by the tally generating device and restoration control information indicating a condition relating to restoration of the confidential information;
The computer program is
A tally collection step for collecting the required number of electronic tallys;
A determination step for determining whether or not the confidential information can be restored based on the restoration control information stored in the storage means;
A restoration step of restoring the confidential information based on the electronic tally stored in the storage means and the electronic tally collected by the tally collection means only when it is judged that restoration is possible in the determination step. A recording medium characterized by the above. An integrated circuit used in a confidential information restoration apparatus having a function of restoring the confidential information from a plurality of electronic tally generated based on the confidential information,
Storage means for storing one electronic tally generated by the tally generating device and restoration control information indicating conditions relating to restoration of the confidential information;
A tally collecting means for collecting a necessary number of electronic tallys;
Determination means for determining whether or not the confidential information can be restored based on the restoration control information stored in the storage means;
Only when it is determined by the determination means that restoration is possible, the electronic tally stored in the storage means and the restoration means for restoring the confidential information based on the electronic tally collected by the tally collection means An integrated circuit comprising: A tally generation method used in a tally generator,
A tally generating step for generating a plurality of electronic tallys based on the confidential information;
A restoration control information generating step for generating restoration control information indicating a condition relating to restoration of the confidential information in each terminal device for each of a plurality of terminal devices to which the plurality of electronic tallys are distributed;
A tally generation method comprising: a distribution step of distributing electronic tally and restoration control information to each corresponding terminal device. A computer program used in a tally generator,
A tally generating step for generating a plurality of electronic tallys based on the confidential information;
A restoration control information generating step for generating restoration control information indicating a condition relating to restoration of the confidential information in each terminal device for each of a plurality of terminal devices to which the plurality of electronic tallys are distributed;
A computer program comprising: a distribution step of distributing electronic tally and restoration control information to corresponding terminal devices. A computer-readable recording medium recording a computer program used in a tally generating device,
The computer program is
A tally generating step for generating a plurality of electronic tallys based on the confidential information;
A restoration control information generating step for generating restoration control information indicating a condition relating to restoration of the confidential information in each terminal device for each of a plurality of terminal devices to which the plurality of electronic tallys are distributed;
A distribution step of distributing electronic tally and restoration control information to each corresponding terminal device. An integrated circuit used in a tally generator,
Tally generating means for generating a plurality of electronic tallys based on confidential information;
Restore control information generating means for generating, for each of a plurality of terminal devices to which the plurality of electronic tallys are distributed, restore control information indicating conditions relating to the restoration of the confidential information in each terminal device;
An integrated circuit comprising: distribution means for distributing electronic tally and restoration control information to each corresponding terminal device.

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