JP4539952B2 - Information distributed storage system, apparatus, program and recording medium - Google Patents

Description

  The present invention provides information using a secret sharing method in which secret information such as passwords and personal information is distributed and stored in a plurality of databases, and the original secret information can be restored by using some or more of these pieces of information. It relates to storage technology.

  When storing various types of information such as passwords, personal information, and encryption key information, it is important to ensure safety against leakage and damage of information. Conventionally, when storing with one information storage device, for example, encryption technology for encrypting and storing the information to be stored and authentication technology for restricting users who can acquire the information to be stored are used, but the information storage device itself There is a possibility that information is illegally acquired by hacking or decrypting the code, and it cannot be said that the security against information leakage is high. In addition, if the information storage device is damaged, the original secret information cannot be restored, so that there is no safety against damage.

  On the other hand, there is a technique for storing secret information with a plurality of information storage devices. For example, after secret information is subdivided, it is randomly divided into several groups and stored together with arrangement information that describes the order and method of information (Patent Document 1), or secret information is distributed There is a method of storing in a distributed manner using a function (Patent Document 2). According to these techniques, it is possible to completely restore the original secret information by aggregating all the shared information or some predetermined shared information. In either case, since the original secret information is not known at all from the information stored in the single information storage device, the security against information leakage is high. In addition, with these technologies, it is possible to restore the original secret information even when several information storage devices are damaged by adopting a redundant configuration, and it can be said that the safety against the information damage is high.

International Publication No. 00/45358 Pamphlet JP 2003-188867 A

  In the conventional information distributed storage technology, the original secret information can be completely restored by collecting all or a prescribed number of shared information necessary for restoring the secret information. However, since the information to be restored is the complete original secret information itself, it is necessary to safely store, for example, personal information and transaction information, and distribution and restoration to retrieve only the necessary information when necessary. It is not suitable for distributed storage of necessary information. In other words, partial restoration of confidential information, such as partial restoration to confirm what is stored as confidential information, partial restoration that may be made public, and rest not to be restored. There is a problem that you can not do.

The present invention has been made in view of the conventional problems as described above, and information that is highly safe against leakage and damage of information and is capable of partial restoration of secret information in the distributed storage of secret information. An object is to realize a distributed storage system , an apparatus, a program, and a recording medium.

In the present invention, the restoration control type secret information distribution method described in Japanese Patent Application No. 2003-366538 filed earlier by the present applicant is used. This is basically because the secret information S is a partial number of the secret information S with respect to the threshold value k, which is an integer of 2 or more, which is the minimum number of distributed information necessary for complete restoration of the secret information S. 2 and more k an integer number of divisions d that determines the number of lack of shared information that allows the restoration, d pieces of divided information S ₀ of the secret information _S, S _{1, ...,} secret information, such as S _d-1 S Enter the conditions for distributing
A prime number p larger than the maximum division information S _t (0 ≦ t ≦ d−1), and a random number r _i (1 ≦ 1 ≦ k−d) smaller than the prime number p and not 0 (k−d), (K (k−1) / 2) random numbers a _j (1 ≦ j ≦ k (k−1) / 2) are generated,
f (x) = S ₀ + S ₁ (x−a ₁ ) +... + S _d−1 (x−a _{(d 1) (d−2) / 2 + 1} ) (x−a _{(d−1) (d− 2) / 2 + 2) ...} (x-a (d-1) (d-2) / 2 + d-1) + r 1 (x-a d (d-1) / 2 + 1) (x-a d (d-1) _{/ 2 + 2)} ... (x- _{ad (d-1) / 2 + d} ) + ... + rk _-d (x-a _{(k-1) (k-2) / 2 + 1} ) (x-a _{(k-1) ( k-2) / 2 + 2} ) (x-a _{(k-1) (k-2) / 2 + k-1} ) mod p
The distribution function f (x) of the secret information S expressed by the following formula is generated.

This restoration control-type secret information distribution method is a method in which the conventional secret information distribution technique (k, n) threshold secret distribution method and (d, k, n) threshold secret distribution method are extended. If the k pieces of distributed information are available, the original secret information S can be restored by solving simultaneous equations relating to f (x). However, up to (k−d) pieces of shared information are provided. Since the simultaneous equations relating to f (x) cannot be solved, the original secret information S cannot be restored. However, by defining a dispersion function for dispersing information in a specific format, f (x) when any (k−d + 1) to (k−1) pieces of distributed information are arranged in a specific combination. ), Specific division information S ₀ , S ₁ ,..., S _d−1 can be obtained, and the original secret information S can be partially restored.

  For details on the (k, n) threshold secret sharing method and the (d, k, n) threshold secret sharing method, see “A. Shamir,“ How to Share a Secret ”, Commun. Of ACM, Vol. 22, No. 11, pp. 612-613, 1979 ”and“ GR Blakley, C. Meadows, “Security of ramp schemes”, Proc. Of Crypto '84, Lecure Notes on Computer. Sci, 196, pp242 -268, 1984 ".

For example, when k = 3 and d = 2, the dispersion function f (x) is
f (x) = S ₀ + S ₁ (x−a ₁ ) + r (x−a ₂ ) (x−a ₃ ) modp
The simultaneous equations for any two pieces of distributed information W _x and W _x + b can be expressed by the following determinant.

となり、ａ_ｌ，ａ_２，ａ_３の値によっては−ｘ ^２ ＋（２ａ _１ −ｂ）ｘ＋ａ _１ ｂ−ａ _１ ａ _２ −ａ _１ ａ _３ ＋ａ _２ ａ _３ ≡０，２ｘ＋ｂ−ａ _２ −ａ _３ ≡０を満たすｘとｂがある場合に、連立方程式から分割情報のＳ_０のみ、もしくはＳ_１のみを求めることができる。 When the left term of the determinant is transformed by the sweep method,

Depending on the values of a ₁ , a ₂ , and a ₃ , −x ² + (2a ₁ −b) x + a ₁ b−a ₁ a ₂ −a ₁ a ₃ + a ₂ a ₃ ≡0, 2x + b−a ₂ −a _When there are x and b satisfying 3≡0 , only S _{0 of the} division information or only S ₁ can be obtained from the simultaneous equations.

  The information distributed storage system of the present invention basically includes an information distribution device that distributes and encodes secret information into a plurality of pieces of distributed information, an information storage device that stores and manages the distributed information, and the original secret information or its The information restoration device restores the presentation information portion.

The information distribution apparatus includes an information input unit that receives input of secret information to be stored, a presentation information portion that encodes the input secret information, and allows partial presentation as determined in advance, and a partial presentation Information dividing means that divides the information into non-presentation information parts that do not allow the information, and a plurality of secret information divided into the presentation information part and the non-presentation information part so that the presentation information part can be restored from a combination of specific shared information Shared information generating means for generating shared information, and distributed information communication means for distributing the generated shared information to the information storage device. As a result, the presentation information part can be restored from a specific combination of shared information, and the non-presentation information part is distributed and encoded so that it can be restored only after a predetermined number of pieces of shared information are collected. be able to.

  The information storage device includes a distributed information communication unit that transmits and receives scattered information to and from the information distribution device or the information restoration device, and a distributed information storage unit that stores the distributed information distributed.

  The information storage apparatus includes a shared information arrangement unit that determines an arrangement location in a distributed information storage unit that stores distributed distributed information. As a result, for example, even when shared information is illegally acquired from a plurality of information storage devices, it is not possible to specify a combination of shared information among devices, and therefore it is possible to store information with increased safety against leakage. It becomes possible.

The information restoration device receives a designation of information to be restored, and a shared information selection means for selecting a combination of fixed shared information necessary for restoring the original secret information or its presentation information part as determined in advance , Distributed information communication means for acquiring shared information from each information storage device for storing the selected shared information, and information restoring means for restoring the original secret information or its presentation information part from the acquired distributed information using a predetermined distributed function And information output means for outputting the restored information.

  As a result, for the presentation information part of the private information of the individual who wants to restore, it becomes possible to identify the combination of the shared information necessary for restoration, acquire the shared information, and restore the presentation information part.

  In the information distributed storage system of the present invention, at least some of the information distribution device, the information storage device, and the information restoration device encrypt the original secret information, the presentation information portion, the non-presentation information portion, and the distribution information. Information encrypting means for encrypting the original secret information, the presentation information part and the non-presentation information part, and the information decrypting means for decrypting the distributed information. Thereby, it is possible to prevent the information from leaking even if the information is obtained illegally. That is, it is possible to further increase the security against information leakage and to distribute, store and restore secret information and distributed information.

  In the information distributed storage system of the present invention, at least a part of the information distribution device, the information storage device, and the information restoration device must have appropriate qualifications for mutual devices or users when transmitting / receiving distributed information. It is characterized by comprising authentication means for authenticating that it has The information dispersal device, the information storage device, and the information restoration device perform authentication between devices at the time of transmission / reception of the disperse information, so that it is possible to prevent the dispersal information from being acquired by an unauthorized device and information leakage. In other words, it is possible to transmit and receive distributed information with improved safety against information leakage in the communication circuit. Also, by authenticating the user of the device, the distributed information generated in the information distribution device and stored in the information storage device, or the secret information restored in the information recovery device, the presentation information part thereof, and the non-presentation information Only appropriate users can use the part. That is, it is possible to improve safety against information leakage during use of the apparatus.

  As described above, according to the present invention, the secret information S is distributedly encoded in the information distribution device, stored securely in a plurality of information storage devices, and only a specific part of the secret special information S is restored in the information recovery device. Thus, it is possible to securely distribute and store secret information.

  FIG. 1 shows an overall configuration diagram of an information distribution system according to an embodiment of the present invention. In FIG. 1, the information distribution device 100, the information restoration device 200, and the information storage devices 300 to 304 are connected via a communication line 500 in a network manner. The external recording medium 400 is an arbitrary external storage device attached to the information distribution device 100. The information distribution apparatus 100 includes an information input unit 110, an information division unit 120, a distributed information generation unit 130, and a distributed information communication unit 140. The information restoration apparatus 200 includes a shared information selection unit 210, a distributed information communication unit 220, and information restoration. The information storage device 300 includes a distributed information communication unit 310 and a distributed information storage unit 320. The information storage devices 301, 302, 303, and 304 have the same functions as the information storage device 300.

  In the information dispersal apparatus 100, the information input unit 110 accepts input of secret information to be stored, and the information dividing unit 120 encodes the input secret information and allows a partial presentation and a partial part of the presentation information. Divided into non-presentation information parts that do not allow unsatisfactory presentation, and the shared information generation unit 130 generates a plurality of shared information from the divided secret information so that the presented information part can be restored from a specific combination of shared information Then, the distributed information communication unit 140 distributes the generated distributed information to the information storage devices 300 to 304 and the external recording medium 400.

  In the information storage apparatus 300, the distributed information communication unit 310 receives the distributed information distributed from the information distributing apparatus 100, and the distributed information storage unit 320 stores the distributed information. Further, the shared information communication unit 310 transmits the shared information stored in the shared information storage unit 320 to the information storage device 200 when requested by the information restoration device 200. The operations of the distributed storage devices 301 to 304 are the same as those of the information storage device 300.

  In the information restoration apparatus 200, the shared information selection unit 210 receives designation of information to be restored, selects a combination of specific shared information necessary for restoring the original secret information or the presentation information part thereof, and the shared information communication unit 220 receives and acquires the shared information from each of the information storage devices 300 to 304 that store the selected shared information and the external recording medium 400, and the information restoration unit 230 obtains the original secret information from the acquired shared information or The presentation information part is restored, and the information output unit 240 outputs the restored information.

  In the following embodiment, personal information of a plurality of users is distributed and stored as secret information S in the five information storage devices 300 to 304 and the external recording medium 400, and a specific distribution stored in the plurality of information storage devices. The presentation information parts S1 and S2 and the original secret information S can be restored by a combination of information. Specifically, the secret information S to be distributed in the embodiment is made up of personal address information and telephone number information, the presentation information part S1 is a municipal part of the address information, and the presentation information part S2 is a telephone number. Of the information, the area code, the city code, and the non-presentation information part S3 are composed of the remaining address part of the address information and the remaining subscriber number part of the telephone number information.

  The information dispersal device 100 generates the disperse information W1 to W6 for the secret information S of each individual, and dispersively stores them in the information storage devices 300 to 304 and the external recording medium 400. From the shared information W1 stored in the information storage device 300 and the shared information W2 stored in the information storage device 301, the presentation information portion S1, that is, the municipality portion of the address information, is shared with the distributed information W3 stored in the information storage device 302. From the shared information W4 stored in the information storage device 303, it is assumed that the presentation information portion S2, that is, the area code and the local area number portion of the telephone number information, is restored in the information restoration device 200. However, the combination of shared information stored in any two information storage devices other than these combinations or three information storage devices that do not include the above combinations includes the presentation information portion S1, the presentation information portion S2, and the non-presentation information portion S3. It is assumed that the original secret information S cannot be restored. In addition, the presentation information part S1, the embankment information part S2, and the non-presentation information part S3 can be restored from the combination of the distributed information stored in any four information storage devices. It shall be fully recoverable.

  Hereinafter, operations of the information distribution apparatus 100, the information storage apparatuses 300 to 304, and the information restoration apparatus 200 in the present embodiment will be described.

<Information distribution apparatus 100>
In the information distribution apparatus 100, first, the information input unit 110 accepts input of personal information of each individual as the secret information S. The received personal information is preferably stored in, for example, an internal memory. In this embodiment, it is assumed that telephone number information “0234-56-7890” and address information “A city B town Cl-2-3” are input as personal information of the user AAA. Hereinafter, in order to distinguish from the secret information S of other users, the secret information S of the user AAA is described as SA. FIG. 2 is an input example of personal information of the user AAA to the user DDD in the present embodiment.

  Note that the present invention does not particularly define the type or content of information that is accepted as confidential information S in the information input unit 110. Any information may be used as long as it can be calculated by a distributed function by encoding numerical information, a character string, and the like, and may be a multimedia such as a document or image data. Further, the present embodiment does not define the method and format for inputting information. In addition to keyboard input and file input, input may be made from another device via a connection line such as the Internet.

  Next, the information dividing unit 120 encodes the secret information S and divides it into presentation information portions S1 and S2 and a non-presentation information portion S3. The encoded and divided information S1, S2, S3 is stored in, for example, an internal memory. It is desirable to delete the original secret information S itself from the internal memory. For example, the secret information SA of the user AAA includes the hexadecimal character string “303323343536” as the presentation information portion S1 as the encoding by the shift JIS code of the area code of the telephone number information + the local area number “023456” as the presentation information portion S1. The address information city A city B town is encoded as a hexadecimal character string “418E734292AC”, and the subscriber number of the telephone number information and the address information address “7890Cl-2-3” are encoded as the non-presentation information portion S16. The hexadecimal character string “373839330443312D322D33” is obtained. Hereinafter, in order to distinguish from the presentation information portions S1 and S2 and the non-presentation information portion S3 of other users, the presentation information portions S1 and S2 and the non-presentation information portion S2 of the user AAA are described as SAl, SA2, and SA3, respectively. FIG. 3 is an example of encoding personal information of the user AAA to the user DDD in the present embodiment.

  Note that this embodiment does not particularly define a method of dividing input information into a presentation information part and a non-presentation information part. In this embodiment, the area code is divided by a semantic delimiter such as an area code, a city code, a subscriber number, a municipality, and an address, but may be divided in units of length such as upper 50 bits and lower 50 bits. You may make it divide | segment according to the combination, after dividing | segmenting an information sequence finely.

  In the present embodiment, the secret information S is divided and encoded into the presentation information parts S1 and S2 and the non-presentation information part S3. However, the number and combination of the presentation information part and the non-presentation information part can be changed. In the present embodiment, the method of encoding each information and the result of encoding are not particularly specified. In the present embodiment, the hexadecimal representation by the shift JIS encoding of the input information is used as the encoding method and the encoding result is the hexadecimal character string. However, other code tables, original codes, and encoding methods are used. The encoding may be used, or the encoding result is not limited to a hexadecimal character string, and a bit string of 0 and 1 may be used in decimal notation. Furthermore, the security of information can be enhanced by encrypting the encoded result.

Next, the shared information generation unit 130 stores the information in the information storage devices 300 to 304 and the external recording medium 400 from the presentation information portions S1 and S2 and the non-presentation information portion S3 using a special distribution function f (x). The six pieces of distributed information W are created. The dispersion function f (x) in the present embodiment is expressed by the following expression.
f (x) = S1 + S2 (x-3) + S3 (x-31) (x-28) + r (x-27) (x-33) (x-38)
(Modp)
Note that x in this expression is an information number x for generating the shared information W, r is an arbitrary random number character string r having the same size as S1, S2 and S3, and P is a fixed character larger than S1, S2 and S3. Column p.

  The above function f (x) is calculated by substituting S1 from f (28) calculated by substituting 28 for x and f (31) calculated by substituting 31 for x, and substituting 29 for x. S2 is a dispersion function of the secret information S that can be restored from f (29) and f (30) calculated by substituting 30 for x. Such a special distribution function f (x) can be obtained by the restoration control type secret information distribution method described in Japanese Patent Application No. 2003-366538 filed earlier, and is not limited to the equation described in the present embodiment.

  An example of generation of shared information W for secret information SA of user AAA is shown below. In order to distinguish the six shared information W, they are described as shared information W1 to W6, and in particular, the shared information generated from the secret information SA of the user AAA is described as WA and WAl to WA6.

  Upon receiving the SAl, SA2, and SA3 shown in FIG. 3 encoded by the information dividing unit 120, the shared information generating unit 130 first generates a random character string r. The random number r is preferably a random number character string having a size comparable to that of S1, S2, and S3. Here, it is assumed that “1A2B3C4D5E6F70819203” is obtained. The random number r is generated every time secret information is input, and thus varies depending on the user. Hereinafter, the random number r for the user AAA is described as rA in order to distinguish it from the random number r generated in response to the input of confidential information of other users.

  Since the fixed character string p is common to all user inputs and is a fixed character string larger than S1, S2, and S3, a 10-byte hexadecimal character string “FFFFFFFFFFFFFFFFFFFD” is used in this embodiment. . The fixed character string p is preferably a prime number, but in this embodiment, a character string that is not a prime number is used for simplicity. The fixed character string p = FFFFFFFFFFFFFFFFFFFD used in the present embodiment is a composite number whose minimum prime factor is 647. The size of the fixed character string p is assumed to be larger than the assumed sizes S1, S2, and S3. For example, the information input unit 100 limits the number of characters that can be input, and calculates the size from the limit value. May be specified.

  Next, the distributed information generation unit 130 calculates the distributed information W from S1, S2, S3, the generated random number character string r, and a predetermined information number x according to the previous distribution function f (x). Here, from the characteristic of the dispersion function f (x) in this embodiment, the predetermined information number x in this embodiment is assumed to be 28, 31, 29, 30, 32, 34, and the dispersion information Wl = f (28 ), W2 = f (31), W3 = f (29), W4 = f (30), W5 = f (32), and W6 = f (34).

For example, from the secret information SA of the user AAA, 303233433536 as S1, 418E734292AC as S2, 3738393043312D322D33 as S3, 1A2B3C4D5E6F70819203 as random number character string r, 28 as information number x, and distributed information WAl as follows: Is calculated.
WA1 = f (28) = 303323334536 + 418E734292AC × (28−3)
+ 3738393043312D322D33 × (28−31) × (28−28)
+ 1A2B3C4D5E6F70819203 x (28-27) x (28-33)
× (28-38)
≡ 1C71C72308DF6E030CA7
(ModFFFFFFFFFFFFFFFFFFFFD)
In this embodiment , WAl = f (28) = 1C71C72308DF6E030CA7 is obtained as the distributed information WAl generated from the secret information SA of the user AAA. Thereafter, similarly, 31, 29, 30, 32, and 34 are substituted as the information number x to calculate the shared information W2 to W6, respectively. FIG. 4 is an example of generating a random character string r and shared information W1 to W6 from the user AAA to the user DDD in the present embodiment.

  The shared information generation unit 130 stores the shared information W obtained from the above calculation process and the calculation result in, for example, an internal memory. However, after the shared information W is generated, it is desirable to discard the values of the secret information S, the presentation information portions S1, S2, S3, and the random number character string r.

  The shared information communication unit 140 transmits the shared information W1 to W6 among the shared information W1 to W6 generated by the shared information generation unit 130 to the information storage devices 300 to 304 via the communication line 500, and the shared information W6 is transmitted. Records in the external recording medium 400. For example, the shared information WAl of the user AAA is transmitted to the information storage apparatus 300 together with the user name such as “AAA”, “1C71C72308DF6E030CA7”.

  The present embodiment does not particularly define a protocol for transmitting and recording shared information in the shared information communication unit 140 and its format. For example, the user information may be transmitted using a code representing the user instead of the user name, or the information number x that generated the distributed information may be transmitted as the transmission item. Further, when the shared information is transmitted, the shared information is further encrypted, or when the shared information is transmitted, authentication is performed with the information storage apparatuses 300 to 304 on the other side. It is desirable to increase safety.

  In this embodiment, the information distribution apparatus 100 once generates all the distributed information W in the distributed information generation unit 130, and then the distributed information communication unit 140 distributes the information to the information storage apparatuses 300 to 304 and the external recording medium 400. Although the information W is described as being transmitted and recorded, the shared information generating unit 130 and the distributed information communication unit 140 work together to generate the shared information W every time the shared information generating unit 130 generates one shared information W. The communication unit 140 may transmit and record the distributed information W generated in the corresponding information storage device or external recording medium.

<Information storage devices 300 to 304>
Since the operations of the information storage devices 300 to 304 are the same, the storage of the distributed information in the information storage device 300 will be described below. Further, storage of the shared information in the external recording medium 400 is omitted.

  In the distributed information communication unit 310, the information storage device 300 stores the information transmitted from the information distribution device 100 in the distributed information storage unit 320. For example, the distributed information communication unit 310 receives “AAA” and “1C71C72308DF6E030CA7” transmitted from the information distribution apparatus 100 and stores them in the distributed information storage unit 320 as the user name “AAA” and the shared information “1C71C72308DF6E030CA7”. FIG. 5 is a storage example of shared information from user AAA to user DDD stored in the shared information storage unit 320 in the information storage device 300.

  Note that the present invention does not particularly define the realization of the distributed information storage unit 320. It is only necessary that the distributed information transmitted from the information distribution apparatus 100 can be stored in association with the user name.

  Further, in this embodiment, the shared information recording unit 320 describes that the user name and the shared information are associated with each other and stored in the order in which the information is transmitted. Absent. For example, when the information stored in the distributed information storage unit 320 in the information storage device 300 is illegally acquired, the information stored in the distributed information storage unit 321 in the information storage device 301 is associated with each individual user. The combination of the distributed information about can be easily identified. In the present invention, by determining the storage location of the shared information in the shared information storage unit 320 without depending on the communication order or association, the security of information storage can be improved. This is realized by means such as determining the recording position of the transmitted shared information in the shared information storage unit 320 by, for example, calculating a hash value with a hash function after encoding the user name AAA. Can do.

<Information Restoration Device 200>
In the information restoration apparatus 200, the shared information selection unit 210 first accepts, as an input, the user name of the individual who wants to restore the secret information S and the selection of the presentation information portions S1 and S2 or the secret information S as the restoration location. In the present embodiment, it is assumed that the presentation information portions S1 and S2 of the secret information S of the user BBB, that is, the area code of the telephone number information of the user BBB + the city code of the address information and the restoration of the municipality of the address information are designated.

  This embodiment does not particularly define the contents and method of input and selection in the shared information selection unit 210. In this embodiment, it is described that the user name and the restoration location are input and specified. However, the user information in the list can be restored by specifying the list of user names and the restoration location, or only the user name is accepted. The restoration location may not be specified. Further, as input means, in addition to keyboard input and file input, input from another device may be accepted via a connection line such as the Internet.

  Next, the shared information selection unit 210 identifies a combination of shared information necessary for restoring the restoration location designated for the secret information S and a combination of information storage devices that store the shared information. For example, in the present embodiment, when the restoration location is the presentation information portion S1, the information storage devices 300 and 301, and when the restoration location is the presentation information portion S2, the information storage devices 302 and 303 store the target shared information. Is a place. When the secret information S is completely restored, four pieces of enemy information are required. Therefore, the information storage devices 300 to 303 are determined as the storage locations of the distributed information.

  The shared information communication unit 220 communicates with the information storage device determined in the distributed information selection group 210, and acquires the target user's shared information stored in the information storage device. For example, the shared information communication unit 220 requests the information storage device 300 for shared information corresponding to the user name “BBB”. In the information storage device 300, the shared information communication unit 310 acquires the shared information of the corresponding user name from the shared information storage unit 320 and transmits “71C71C785B14C3392202” as a response to the request to the information restoration device 200. This is acquired by the distributed information communication unit 220 and stored in the internal memory or the like as the distributed information Wl, for example. Similarly, the shared information communication unit 220 acquires “7530ECAFBC63266CEC81” as the shared information W2 corresponding to the user BBB from the information storage device 301, and stores this in the internal memory or the like. Similarly, “BA8555033A9E9FEA19E07” is acquired as the shared information W3 from the information storage device 302, and “BA8555033EB7871E430B3” is acquired as the shared information W4 from the information storage device 303, and stored in the internal memory or the like.

  The information restoration unit 230 restores the secret information S or the presentation information portions S1 to S2 from the acquired shared information. Information is restored as follows.

First, the dispersion function in this embodiment is f (x) = S1 + S2 (x−3) + S3 (x−31) (x−28) + r (x−27) (x−33) (x−38).
(Modp)
Therefore, simultaneous equations relating to two pieces of distributed information can be expressed by the following determinant.

Therefore, a determinant for obtaining the presentation information portions S1 and S2, the non-presentation information portion S3, and the random number character string r from the two pieces of shared information can be written as follows.

  When obtaining S1, the information restoration unit 230 substitutes x = 28, y = 31, Wx = Wl = 71C71C785B14C3392202, Wy = W2 = 7530ECAFBC63266CEC81 in the above determinant, and performs S1 as a result. = 303323334536 is obtained. Note that the combination of the shared information W1 and W2 is to calculate S1, and it is not possible to obtain a calculation result for S2, S3, and r. Similarly, when obtaining S2, in the above determinant, x = 29, y = 30, Wx = W3 = BA8555033A9E9FEA19E07, Wy = W4 = BA8555033EB7871E430B3 is substituted, and as a result, S2 = 418E734292AC Get. From this combination, it is not possible to obtain calculation results for S1, S3 and r. The information restoration unit 230 stores the calculation result in an internal memory or the like, and deletes the stored shared information W1, W2, W3, and W4.

In the present embodiment, the calculation of S1 and S2 from the distributed information is performed by matrix operation, but the calculation may be performed by other means. For example, the following simultaneous equations for the distributed information W1, W2, W3, and W4 can be established from the expression of the distributed idle number f (x) and the information number x.
W1 ≡ f (28) = S1 + S2 × (28−3) + S3 × (28−31) (28−28) + r × (28−27) × (28−33) × (28−38)
= S1 + 25S2 + 50r (modFFFFFFFFFFFFFFFFFFFD)
W2 ≡ f (31) = S1 + S2 × (31−3) + S3 × (31−31) × (31−28) + r × (31−27) × (31−33) × (31-38)
= S1 + 28S2 + 56r (modFFFFFFFFFFFFFFFFFFFD ) W3 ≡ f (29) = S1 + S2 × (29-3) + S3 × (29-31) × (29-28) + r × (29-27) × (29-33) × (29-38 )
= S1 + 26S2-2S3 + 72r
(ModFFFFFFFFFFFFFFFFFFFFD)
W4 ≡ f (30) = S1 + S2 × (30−3) + S3 × (30−31) × (30−28) + r × (30−27) × (30−33) × (30−38)
= S1 + 27S2-2S3 + 72r
(ModFFFFFFFFFFFFFFFFFFFFD)

By transforming the above formula, the following formula for obtaining S1 and S2 can be obtained.
S1 ≡ (28 × W1-25 × W2) ÷ 3 (modFFFFFFFFFFFFFFFFFFFD)
S2 ≡ W4-W3 (modFFFFFFFFFFFFFFFFFFFFD)
Therefore, the information restoration unit 230 can be mounted so that S1 and S2 can be easily restored from the shared information W1 and W2 and W3 and W4 by the above formulas. However, it is desirable to implement the information restoration unit 230 that performs matrix operation so that the dispersion function f (x) can be changed or the combination of the dispersion information can be changed.

  The information output unit 240 decrypts the secret information S or the presentation information part S1 or S2 restored by the information restoration unit 230, and outputs it together with the user name. In this embodiment, since S1 = 303233334356 and S2 = 418E734292AC, the area code + city code “023456” and the municipality “A city B town” are output as a result for the user name “BBB”.

  The present embodiment does not limit the format of information output by the information output unit 240 and the output method. The presentation information portion corresponding to the user name may be displayed in a list format, or may be output to other devices via a network in addition to screen output and file output.

  As described above, the information dispersal apparatus 100 according to the present embodiment divides and encodes the private secret information S from the six disperse information W1 to W6, and transmits or records the information to the information storage apparatuses 300 to 304 and the external recording medium 400. To do. The information restoring device 200 acquires specific shared information combinations W1 and W2 and W3 and W4 stored in a plurality of information storage devices for the secret information S of a specific individual, and obtains partial information of the secret information S. Only S1 and S2 are restored.

  The original secret information S cannot be completely restored unless four pieces of shared information are collected from the shared information W1 to W6 generated in the information sharing apparatus 100. Therefore, for example, even when information is illegally acquired from one of the information storage devices, the original secret information S, S1, S2, and S3 cannot be restored, and therefore it can be said that the security against the fullness of the information is high. In addition, since the six pieces of shared information are generated, the original secret information S can be restored even when one of the information storage devices is damaged, for example, and it can be said that the safety against loss of information is high. The information storage device 304 and the external recording medium 400 in the present embodiment are configured to increase the safety of information storage.

  Note that the processing functions of some or all of the units in the information distribution apparatus, information storage apparatus, and information restoration apparatus shown in FIG. 1 are configured by a computer program, and the program is executed using the computer to execute the method of the present invention. Needless to say, the system can be realized, or the processing procedure can be configured by a computer program and the program can be executed by the computer. In addition, a computer-readable recording medium such as an FD, MO, ROM, memory card, CD, or the like is stored in the computer. In addition, the program can be recorded and stored on a DVD, a removable disk, etc., and the program can be distributed through a network such as the Internet.

1 is an overall configuration diagram of an information distributed storage system according to an embodiment of the present invention. It is an input example of the personal information in an Example. It is an example of an encoding of the personal information in an Example. It is an example of the production | generation of the distribution information in an Example. It is a memory | storage example of the distributed information in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Information distribution apparatus 110 Information input part 120 Information division part 130 Distributed information generation part 140 Distributed information communication part 200 Information restoration apparatus 210 Distributed information selection part 220 Distributed information communication part 230 Information restoration part 240 Information output part 300, 301, 302, 303, 304 Information storage device 310 Distributed information communication unit 320 Distributed information storage unit 400 External recording medium 500 Communication line

Claims (13)

Consists of an information distribution device that distributes and encodes secret information into a plurality of pieces of shared information, an information storage device that stores and manages the shared information, and an information restoration device that restores the original secret information or its presentation information part from the shared information An information distributed storage system,
The information distribution apparatus includes an information input unit that receives input of secret information to be stored, a presentation information portion that encodes the input secret information, and allows partial presentation as determined in advance, and a partial presentation Information dividing means that divides the information into non-presentation information parts that do not allow the information and a predetermined information from the secret information divided into the presentation information part and the non-presentation information part so that the presentation information part can be restored from a combination of specific shared information A shared information generating unit that generates a plurality of shared information using a distributed function, and a distributed information communication unit that distributes the generated distributed information to an information storage device;
The information storage device includes a distributed information communication unit that transmits / receives shared information to / from the information distribution device or the information restoration device, and a distributed information storage unit that stores the distributed information distributed from the information distribution device,
The information restoration device receives designation of information to be restored, and selects a shared information selection means for selecting a combination of specific shared information necessary for restoring the original secret information or its presentation information part as determined in advance, and a selection Distributed information communication means for acquiring shared information from each information storage device for storing the distributed information, and information restoring means for recovering the original secret information or its presentation information part from the acquired distributed information using a predetermined distribution function; An information distributed storage system comprising: information output means for outputting the restored information. The information distributed storage system according to claim 1,
The information storage apparatus includes a distributed information arrangement unit that determines an arrangement location in the distributed information storage unit that stores the distributed information that has been distributed. The information distributed storage system according to claim 1 or 2,
At least some of the information dispersal device, the information storage device, and the information restoration device may include the original secret information, the presentation information portion and the non-presentation information portion, the information encryption means for encrypting the distributed information, and / or the encryption. An information distributed storage system comprising: information decoding means for decoding the original secret information, the presentation information part and the non-presentation information part, and the distributed information. The information distributed storage system according to any one of claims 1 to 3,
At least a part of the information distribution device, the information storage device, and the information device includes an authentication unit that authenticates that each other device or the user has appropriate qualifications when transmitting / receiving the distributed information. An information distributed storage system characterized by that. The information distribution apparatus used for the information distribution storage system of any one of Claims 1 thru | or 4. An information storage device used in the information distributed storage system according to any one of claims 1 to 4. An information restoration apparatus used in the information distributed storage system according to any one of claims 1 to 4. A program for causing a computer to execute a processing function of an information distribution apparatus used in the information distribution storage system according to any one of claims 1 to 4. A program for causing a computer to execute a processing function of an information storage device used in the information distributed storage system according to any one of claims 1 to 4. A program for causing a computer to execute the processing function of the information restoration apparatus used in the information distributed storage system according to any one of claims 1 to 4. A recording medium on which a program for causing a computer to execute a processing function of an information distribution apparatus used in the information distribution storage system according to claim 1 is recorded. The recording medium which recorded the program for performing the processing function of the information storage apparatus used for the information distributed storage system of any one of Claim 1 thru | or 4 with a computer. The recording medium which recorded the program for performing the processing function of the information restoration apparatus used for the information dispersion | distribution storage system of any one of Claim 1 thru | or 4 with a computer.

Images