JP7580185B2 - Providing device, providing method, and providing program - Google Patents

Description

The present invention relates to a provision device, a provision method, and a provision program.

Conventionally, there is a technology called compressed sensing as a data compression technology that can be applied to sparse data. With this technology, data can be restored from sampled data by using an observation matrix.

JP 2018-32252 A

However, the above techniques do not take into consideration providing an observation matrix that corresponds to the accuracy required for the data to be restored.

The present application has been made in view of the above, and aims to provide a providing device, a providing method, and a providing program that can provide an observation matrix according to the accuracy required for the data to be restored.

The providing device according to the present application includes a division unit, an encryption unit, and a providing unit. The division unit divides an observation matrix into a plurality of divided regions. The encryption unit encrypts the divided regions divided by the division unit into encryption keys based on a predetermined secret sharing scheme. The providing unit provides the encryption key encrypted by the encryption unit.

According to one aspect of the embodiment, it is possible to provide an observation matrix according to the accuracy required for the data to be restored.

FIG. 1 is a diagram illustrating an example of a providing process according to an embodiment. FIG. 2 is a diagram illustrating an example of a configuration of a providing device according to an embodiment. FIG. 3 is a diagram illustrating an example of the observation matrix database. FIG. 4 is a diagram showing an example of the user information database. FIG. 5A is a diagram (part 1) showing an example of divided regions. FIG. 5B is a diagram (part 2) showing an example of the divided regions. FIG. 6 is a diagram showing the relationship between the number of encryption keys and the observation matrix. FIG. 7 is a flowchart illustrating a procedure of a process executed by the providing device according to the embodiment. FIG. 8 is a hardware configuration diagram illustrating an example of a computer that realizes the functions of the providing device according to the embodiment.

Below, the provision device, provision method, and provision program according to the present application will be described in detail with reference to the drawings. Note that the provision device, provision method, and provision program according to the present application are not limited to these embodiments. In addition, the same parts in the following embodiments will be given the same reference numerals, and duplicated descriptions will be omitted.

[1. Information Processing]
First, an example of information processing performed by a providing device according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of information processing according to an embodiment. Fig. 1 illustrates a providing device 10 and a user terminal 100 according to an embodiment.

By the way, there is a technology called compressed sensing, which is disclosed in Non-Patent Document 1 (http://www.ieice.org/~netsci/wp-content/uploads/2016/05/NetSci201605_Kabashima.pdf).

In such compressed sensing, it is possible to restore the restored data corresponding to the sampling data from the sampling data by using the observation matrix. Here, even if only a part of the observation matrix is used, it is possible to restore the restored data from the sampling data with a certain degree of accuracy.

The providing device 10 has focused on this point and decided to divide the observation matrix into multiple divided regions, encrypt the divided regions with a predetermined encryption key, and provide the encryption key. In other words, the providing device 10 decides to divide the observation matrix and provide it according to the accuracy required by the user for the restored data.

Specifically, as shown in FIG. 1, the providing device 10 divides the observation matrix F into a number of divided regions f1 to fn (step S1). For example, when the divided region f1 of the observation matrix F is used, the restored data can be restored from the sampling data with a certain degree of accuracy, and the accuracy of the restored data can be improved as the divided regions f2, f3, and so on are increased. Note that in the following, when the divided regions f1 to fn are not particularly distinguished from each other, they may be simply referred to as divided region f.

Next, the providing device 10 encrypts each divided area f into an encryption key based on a predetermined encryption method (step S2). In this embodiment, each divided area f is encrypted using a ramp threshold secret sharing scheme.

The ramp threshold sharing method is a secret sharing method that cannot completely decrypt the secret information (corresponding to the observation matrix F), but can obtain some information about the secret information depending on the number of encryption keys. In other words, as the number of encryption keys increases, it becomes possible to obtain the secret information more accurately.

In general, in the ramp threshold distribution method, when k or more encryption keys exist, some information about the secret information can be obtained. For example, in the above observation matrix F, if the divided region f1 does not exist, the restored data cannot be restored.

For this reason, the providing device 10 encrypts, for example, the divided area f1 so that it can be restored with k encryption keys, and thereafter, as the number of encryption keys increases, encryption is performed so that the divided areas f2 and subsequent divided areas f can be restored.

When the providing device 10 receives a request for an encryption key from the user terminal 100 (step S3), the providing device 10 provides the corresponding encryption key to the user terminal 100 (step S4). This allows the user terminal 100 to restore an observation matrix F corresponding to the number of encryption keys based on the encryption key, and to obtain restored data based on the observation matrix F.

If user U needs more accurate restored data, he or she can use the user terminal 100 to request an additional encryption key from the providing device 10 again. In other words, user U can request an encryption key as appropriate depending on the accuracy required for the restored data.

In other words, user U can try out the observation matrix F of divided region f1, and if the user U determines that the observation matrix F is valid, the user U can obtain a more accurate observation matrix F.

In this way, the providing device 10 divides the observation matrix F into multiple divided regions f, encrypts it using an encryption key, and provides the encryption key, making it possible to provide the observation matrix F according to the accuracy required for the restored data.

2. Configuration of the providing device
Next, a configuration example of the providing device 10 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram of the providing device 10 according to the embodiment. Note that Fig. 2 also illustrates a plurality of user terminals 100.

The user terminal 100 is realized by an information processing device such as a smart device, such as a smartphone or tablet, a desktop PC (Personal Computer), a notebook PC, or a server device.

The user terminal 100 requests an encryption key from the providing device 10 via a specific network N, and obtains the encryption key. The user terminal 100 can also restore the observation matrix F from the encryption key, and can restore the restored data from the sampling data using the restored observation matrix F.

As shown in FIG. 2, the providing device 10 includes a communication unit 20, a storage unit 30, and a control unit 40. The communication unit 20 is realized, for example, by a network interface card (NIC). The communication unit 20 is connected to the network N by wire or wirelessly, and transmits and receives information between the network N and the user terminal 100.

The storage unit 30 is realized by, for example, a semiconductor memory element such as a random access memory (RAM) or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 30 also stores an observation matrix database 31 and a user information database 32.

Information about the observation matrix F is registered in the observation matrix database 31. FIG. 3 is a diagram showing an example of the observation matrix database 31. As shown in FIG. 3, the observation matrix database 31 registers a "matrix," a "first region," a "second region," an "encryption key," and the like, each associated with another.

Here, "matrix" refers to the observation matrix F, and "first region" and "second region" refer to the corresponding divided regions f. Furthermore, "encryption key" refers to the encryption key for the corresponding observation matrix F.

In the example shown in FIG. 3, conceptual values such as "F1", "f1-1", "f1-2", "k1-1", etc. are described, but in reality, character strings, numerical values, etc. will be registered. Also, the information shown in FIG. 3 is merely an example, and any information other than the information shown in FIG. 3 may be registered in the observation matrix database 31.

Returning to FIG. 2, the user information database 32 will be described. Information regarding the encryption key owned by the user U is registered in the user information database 32. FIG. 4 shows an example of the user information database 32.

As shown in FIG. 4, the user information database 32 registers a "user ID," "purchase amount," and "encryption key" in association with one another. Here, the "user ID" is an identifier for identifying the user U, and the "purchase amount" indicates the amount that the corresponding user U paid for the encryption key. As will be described later, the providing device 10 divides the observation matrix F, constructs a new business model for selling the divided observation matrix, and provides the encryption key according to the purchase amount. Furthermore, the "encryption key" indicates the encryption key provided to the corresponding user U.

Returning to the explanation of FIG. 2, the control unit 40 will be described. The control unit 40 is a controller, and is realized, for example, by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs stored in a storage device inside the providing device 10 using a RAM or the like as a working area. The control unit 40 is also a controller, and may be realized, for example, by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

As shown in FIG. 2, the control unit 40 includes a division unit 41, an encryption unit 42, and a provision unit 43. The division unit 41 divides the observation matrix F into a plurality of division regions f. FIGS. 5A and 5B are diagrams showing examples of the division regions f.

As shown in FIG. 5A, for example, the division unit 41 divides the observation matrix F into division regions f1 to fn, which are obtained by dividing the observation matrix F by rows. For example, the division region f1 is composed of the minimum number of rows that can restore the restored data.

The divided regions f2 to fn are, for example, a matrix with one row. The divided regions f2 to fn may each include multiple rows. The dividing unit 41 may also determine how many rows each divided region f should have, as appropriate, depending on the properties of the observation matrix F.

In addition, as shown in FIG. 5A, when the observation matrix F is divided, the user terminal 100 can use the least squares method to complement and use the missing observation matrix F.

Also, as shown in FIG. 5B, the division unit 41 may divide the observation matrix F by treating a set of rows and columns of the observation matrix F as a division region f. Here, the number of rows and columns constituting the division region f2 and subsequent division regions f is, for example, 1 each, but may be changed as appropriate by settings.

Returning to the explanation of FIG. 2, the encryption unit 42 will be described. The encryption unit 42 encrypts the divided area f divided by the division unit 41 using an encryption key based on a predetermined secret sharing method. In this embodiment, the encryption unit 42 performs encryption based on a ramp-type threshold sharing method.

Figure 6 shows the relationship between the number of encryption keys and the observation matrix F. The vertical axis in Figure 6 indicates the entropy, and the horizontal axis indicates the number of encryption keys. As shown in Figure 6, when the number of encryption keys exceeds (k - L), the entropy decreases, and when k encryption keys are collected, the entropy becomes "0." In other words, when there are (k - L) or fewer encryption keys, the entropy is H(s), but when there are more than (k - L), the ambiguity decreases.

In other words, when the number of encryption keys exceeds (k-L), it becomes possible to restore a portion of the observation matrix F, and when k encryption keys are collected, it becomes possible to completely restore the observation matrix F. For this reason, for example, the encryption unit 42 encrypts the divided region f1 so that it can be restored with (k-L) encryption keys.

The encryption unit 42 then performs encryption so that each of the divided regions f2 and subsequent divided regions f can be restored according to the number of encryption keys. This allows the user terminal 100 to gradually restore the observation matrix F according to the number of encryption keys.

Returning to the explanation of FIG. 2, the provision unit 43 will be described. The provision unit 43 provides each user terminal 100 with the encryption key used by the encryption unit 42. The provision unit 43 provides each encryption key according to the amount paid by each user U.

In other words, by purchasing additional encryption keys, user U can increase the accuracy of the restored data, enabling the data to be restored to the accuracy desired by the user. The payment method is not particularly limited, but may be, for example, online payment such as credit card payment.

In this way, the provider 43 can create a new business model by selling encryption keys to users U.

[3. Information processing flow]
Next, a process procedure executed by the providing device 10 according to the embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a process procedure executed by the providing device 10 according to the embodiment.

As shown in FIG. 7, the providing device 10 first divides the observation matrix F into multiple divided regions f (step S101), and then encrypts the divided regions f into encryption keys (step S2). Next, the providing device 10 provides the encryption key in response to a request from the user terminal 100 (step S103), and ends the process.

As described above, the providing device 10 according to the embodiment includes a dividing unit 41, an encryption unit 42, and a providing unit 43. The dividing unit 41 divides the observation matrix F into a plurality of divided regions f. The encryption unit 42 encrypts the divided regions f divided by the dividing unit 41 using an encryption key based on a predetermined secret sharing scheme. The providing unit 43 provides the encryption key used by the encryption unit 42. Therefore, according to the providing device 10 according to the embodiment, it is possible to provide an observation matrix F according to the accuracy required for the data to be restored.

4. Hardware Configuration
The providing device 10 according to the embodiment described above is realized by a computer 1000 having a configuration as shown in Fig. 8. Fig. 8 is a hardware configuration diagram showing an example of the computer 1000 that realizes the functions of the providing device 10. The computer 1000 has a CPU 1100, a RAM 1200, a ROM 1300, a HDD 1400, a communication interface (I/F) 1500, an input/output interface (I/F) 1600, and a media interface (I/F) 1700.

The CPU 1100 operates based on a program stored in the ROM 1300 or the HDD 1400, and controls each component. The ROM 1300 stores a boot program executed by the CPU 1100 when the computer 1000 is started, and programs that depend on the hardware of the computer 1000, etc.

HDD 1400 stores programs executed by CPU 1100 and data used by such programs. Communication interface 1500 receives data from other devices via communication network 500 and sends it to CPU 1100, and transmits data generated by CPU 1100 to other devices via communication network 500.

The CPU 1100 controls output devices such as a display and a printer, and input devices such as a keyboard and a mouse, via the input/output interface 1600. The CPU 1100 acquires data from the input devices via the input/output interface 1600. The CPU 1100 also outputs data generated via the input/output interface 1600 to the output devices.

The media interface 1700 reads a program or data stored in the recording medium 1800 and provides it to the CPU 1100 via the RAM 1200. The CPU 1100 loads the program from the recording medium 1800 onto the RAM 1200 via the media interface 1700 and executes the loaded program. The recording medium 1800 is, for example, an optical recording medium such as a DVD (Digital Versatile Disc) or a PD (Phase change rewritable Disc), a magneto-optical recording medium such as an MO (Magneto-Optical disk), a tape medium, a magnetic recording medium, or a semiconductor memory.

For example, when the computer 1000 functions as the providing device 10 according to the embodiment, the CPU 1100 of the computer 1000 executes a program loaded onto the RAM 1200 to realize the functions of the control unit 40. In addition, the data in the storage unit 30 is stored in the HDD 1400. The CPU 1100 of the computer 1000 reads and executes these programs from the recording medium 1800, but as another example, these programs may be obtained from another device via the communication network 500.

5. Effects
As described above, the providing device 10 according to the embodiment includes the division unit 41, the encryption unit 42, and the providing unit 43. The division unit 41 divides the observation matrix F into a plurality of divided regions f. The encryption unit 42 encrypts the divided regions f divided by the division unit 41 into encryption keys based on a predetermined secret sharing scheme. The providing unit 43 provides the encryption key encrypted by the encryption unit 42.

Therefore, according to the providing device 10 of the embodiment, it is possible to provide an observation matrix F according to the accuracy required for the data to be restored.

In addition, in the providing device 10 according to the embodiment, the encryption unit 42 encrypts the data into an encryption key based on a ramp-type secret sharing scheme.

Therefore, according to the providing device 10 of the embodiment, the observation matrix F can be divided and provided.

In addition, in the providing device 10 according to the embodiment, the division unit 41 divides the observation matrix F into rows as the division region f.

Therefore, according to the providing device 10 of the embodiment, the observation matrix F can be appropriately divided according to the required accuracy.

In addition, in the providing device 10 according to the embodiment, the division unit 41 divides the observation matrix into pairs of rows and columns as division regions f.

Therefore, according to the providing device 10 of the embodiment, the observation matrix F can be appropriately divided according to the required accuracy.

In addition, in the providing device 10 according to the embodiment, the providing unit 43 provides an encryption key according to the purchase amount.

Therefore, according to the providing device 10 of the embodiment, it is possible to create a new business model in which the observation matrix F is divided and sold.

[6. Other]
In addition, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified. For example, the various information shown in each drawing is not limited to the illustrated information.

In addition, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

In addition, the processes described in the above embodiments can be combined as appropriate to the extent that they do not cause any contradictions in the process content.

The above-mentioned "section, module, unit" can be read as "means" or "circuit". For example, the division unit 41 can be read as division means or division circuit.

REFERENCE SIGNS LIST 10 Providing device 20 Communication unit 30 Storage unit 31 Observation matrix database 32 User information database 40 Control unit 41 Division unit 42 Encryption unit 43 Providing unit 100 User terminal F Observation matrix f Division area

Claims (5)

A division unit that divides an observation matrix used for restoring restored data corresponding to the sampling data from the sampling data in a compressed sensing technique into a plurality of divided regions including a reference matrix that is a minimum submatrix capable of restoring the restored data ;
an encryption unit that encrypts the divided areas divided by the division unit with encryption keys based on a predetermined secret sharing scheme and corresponding to each divided area ;
a providing unit that, when receiving a request for an encryption key corresponding to an accuracy required for the restored data from a user terminal that restores the restored data using the observation matrix, provides the user terminal with an encryption key corresponding to a divided region corresponding to the accuracy, in addition to the encryption key corresponding to the reference matrix . The encryption unit includes:
The providing device according to claim 1 , wherein the encryption is performed with the encryption key based on the secret sharing scheme of a ramp type. The providing unit is
The providing device according to claim 1 or 2 , wherein the encryption key is provided in accordance with a purchase amount. 1. A computer-implemented method for providing a method comprising:
A division step of dividing an observation matrix used for restoring restored data corresponding to the sampling data from the sampling data in a compressed sensing technique into a plurality of divided regions including a reference matrix which is a minimum submatrix capable of restoring the restored data ;
an encryption step of encrypting the divided areas obtained by the division step with encryption keys based on a predetermined secret sharing scheme and corresponding to each of the divided areas ;
and a providing step of, when a request for an encryption key corresponding to the accuracy required for the restored data is received from a user terminal that restores the restored data using the observation matrix, providing to the user terminal an encryption key corresponding to the divided region corresponding to the accuracy in addition to the encryption key corresponding to the reference matrix . A division step of dividing an observation matrix used for restoring restored data corresponding to the sampling data from the sampling data in a compressed sensing technique into a plurality of divided regions including a reference matrix which is a minimum submatrix capable of restoring the restored data ;
an encryption step of encrypting the divided areas obtained by the division step with encryption keys based on a predetermined secret sharing scheme and corresponding to each divided area ;
and a providing procedure for, when a request for an encryption key corresponding to the accuracy required for the restored data is received from a user terminal that restores the restored data using the observation matrix, providing to the user terminal an encryption key corresponding to the divided region corresponding to the accuracy in addition to the encryption key corresponding to the reference matrix .

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