Information processing systems and methods

Abstract

To achieve safer and more privacy-protected information management. [Solution] The information processing system comprises a location data acquisition unit 10 that periodically acquires location data, an encryption processing unit 12 that generates encrypted data by encrypting a value obtained by adding or subtracting a numerical value with a larger number of bits than the number of bits in the location data to the location data, an encryption data processing unit 21 that adds or subtracts multiple encrypted data generated from data acquired by the same location data acquisition unit 10, and a decryption unit 22 that decrypts the result of the addition or subtraction by the encryption data processing unit 21.

Description

Technical Field

[0001] The present invention relates to an information processing system and method for encrypting and transmitting position data and other data and decrypting it on the receiving side.

Background Art

[0002] In recent years, with the spread of smartphones, the collection of personal position data has become increasingly common (Patent Document 1). Position data greatly contributes to improving convenience, but on the other hand, there are remaining concerns regarding privacy. Position data is deeply related to an individual's daily life and privacy, and there is a possibility that it may be misused if the collected information leaks to a third party. When an individual is identified, there is also a risk of suffering criminal victimization such as stalking.

[0003] Currently, companies and service providers handling position data are required to comply with laws and regulations such as the Personal Information Protection Law, but they may be exposed to threats such as unauthorized access and cyberattacks. Therefore, advanced security technologies for more securely managing personal position data are required.

[0004] Therefore, the inventor has proposed a technique in which each mobile terminal encrypts its own position data, transmits the encrypted position data to an information processing device, and the information processing device calculates the average value of the position data (Japanese Patent Application Nos. 2023-158495 and 2023-158498). Thereby, position data can be used while protecting an individual's privacy. As an encryption method, for example, elliptic curve encryption is used. However, in the proposed technique, there is a possibility that the encrypted individual values can be decrypted, and there is a possibility that the individual information can be read by a malicious administrator. For this reason, a technique with even higher security is desired.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] This invention was made to solve the above problems and aims to provide an information processing system that enables safer and more privacy-protected information management. [Means for solving the problem]

[0007] The information processing system of the present invention is characterized by comprising: a data acquisition unit configured to periodically acquire data; an encryption processing unit configured to generate encrypted data by encrypting a value obtained by adding or subtracting a numerical value with a larger number of bits than the number of bits of the data to the data; an encrypted data processing unit configured to add or subtract a plurality of the encrypted data generated from data acquired by the same data acquisition unit; and a decryption unit configured to decrypt the result of the addition or subtraction by the encrypted data processing unit. Furthermore, one example of the configuration of the information processing system of the present invention is characterized by further comprising a random number generation unit configured to generate random numbers with a number of bits larger than the number of bits of the data, as numerical values ​​to be added to or subtracted from the data. Furthermore, in one example configuration of the information processing system of the present invention, the encryption processing unit is characterized by performing encryption using elliptic curve cryptography.

[0008] Furthermore, in one configuration example of the information processing system of the present invention, when the data is a, a first numerical value with a number of bits greater than the number of bits of data a is d, a second numerical value with a number of bits greater than the number of bits of data a is e, and a predetermined number of data is N (where N is an integer of 2 or more), if the count value of data a is not the number of data N, the encryption processing unit encrypts the value obtained by adding the numerical value d to data a to generate encrypted data G(a+d), and also encrypts the value obtained by adding the numerical value e to data a to generate encrypted data G(a+e), and the count value of data a When the number of data points is N, the encrypted data processing unit generates encrypted data G(a+d) by encrypting the value obtained by adding the numerical value d to the data point a, and generates encrypted data G(a-(N-1)e) by encrypting the value obtained by subtracting (N-1)e from the data point a, and performs this for every N data points. The encrypted data processing unit then multiplies N-1 encrypted data points G(a+e) and 1 encrypted data point G(a-(N-1)e), and calculates the difference between predetermined encrypted data points among the N encrypted data points G(a+d), and performs this for every N data points. Furthermore, in one example of the configuration of the information processing system of the present invention, the data acquisition unit, the random number generation unit, and the encryption processing unit are mounted on a data acquisition device, the encrypted data processing unit and the decryption unit are mounted on a server device, the data acquisition device further comprises a transmission unit configured to transmit encrypted data generated by the encryption processing unit to the server device, and the server device further comprises a receiving unit configured to receive encrypted data transmitted from the data acquisition device.

[0009] Furthermore, in one example of the configuration of the information processing system of the present invention, the decryption unit is characterized in that it refers to a table in which encrypted values ​​and plaintext values ​​are registered in association, and performs a first process in which it takes the encrypted value resulting from addition or subtraction by the encrypted data processing unit as the target for decryption, and obtains the plaintext value corresponding to this encrypted value from the table as the decryption result. Furthermore, in one example configuration of the information processing system of the present invention, the decryption unit is characterized in that, if the encrypted value to be decrypted is not registered in the table, it further performs a second process of changing the encrypted value to be decrypted, referring to the table based on the changed encrypted value, and obtaining a plaintext value corresponding to the changed encrypted value, and a third process of correcting the obtained plaintext value to obtain the decryption result of the encrypted value to be decrypted. Furthermore, in one example of the configuration of the information processing system of the present invention, the decryption unit changes the encrypted value to be decrypted by adding or subtracting an encrypted value obtained by encrypting the minimum unit value that changes the plaintext value to the encrypted value to be decrypted, and repeatedly performs the second process of referring to the table based on the changed encrypted value until the changed encrypted value matches the encrypted value in the table, and in the third process, corrects the plaintext value obtained from the table by repeating the second process with a correction value obtained by multiplying the number of times the second process was repeated by the minimum unit value.

[0010] Furthermore, the information processing method of the present invention is characterized by including a first step of periodically acquiring data, a second step of generating encrypted data by encrypting a value obtained by adding or subtracting a numerical value with a larger number of bits than the number of bits of the data to the data, a third step of adding or subtracting a plurality of the encrypted data generated from the data acquired in the first step by the same data acquisition device, and a fourth step of decrypting the result of the addition or subtraction in the third step. [Effects of the Invention]

[0011] According to the present invention, approximate values ​​of data can be obtained without decrypting individual data points. As a result, the present invention enables more secure and privacy-protected information management. [Brief explanation of the drawing]

[0012] [Figure 1]Figure 1 is a block diagram showing the configuration of an information processing system according to an embodiment of the present invention. [Figure 2] Figure 2 is a flowchart illustrating the operation of a mobile terminal according to an embodiment of the present invention. [Figure 3] Figure 3 is a flowchart illustrating the operation of a server device according to an embodiment of the present invention. [Figure 4] Figure 4 is a flowchart illustrating the operation of the decoding unit of a server device according to an embodiment of the present invention. [Figure 5] Figure 5 shows an example of a rainbow table. [Figure 6] Figure 6 illustrates the effects of an embodiment of the present invention. [Figure 7] Figure 7 is a diagram illustrating conventional encryption processing. [Figure 8] Figure 8 is a block diagram showing an example of the configuration of a computer that implements an information processing system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0013] [Principle of the invention] In this invention, a 256-bit random number is added to each value before it is encrypted using elliptic curve cryptography, thereby preventing the decryption of individual values ​​before calculations are performed between encrypted values. In elliptic curve cryptography's rainbow table decryption technique, encrypted values ​​can only be decrypted if the plaintext value is within a 32-bit range. This property is utilized. By adding a 256-bit random number to the plaintext before encryption, the encrypted value cannot be decrypted. After calculations are performed between encrypted values, the random number disappears, making decryption possible.

[0014] [Examples] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an information processing system according to an embodiment of the present invention. The information processing system includes a plurality of mobile terminals 1-1 to 1-3, which are data acquisition devices that periodically acquire position data, a server device 2 that receives encrypted position data from the mobile terminals 1-1 to 1-3, a higher-level device 3 that receives the decryption result of the encrypted position data from the server device 2, and a communication network 4 that interconnects the mobile terminals 1-1 to 1-3, the server device 2, and the higher-level device 3.

[0015] The mobile terminal 1-1 includes a position data acquisition unit 10, a random number generation unit 11, an encryption processing unit 12, and a transmission unit 13. In FIG. 1, only the configuration of the mobile terminal 1-1 is described, but the configurations of the other mobile terminals 1-2 and 1-3 are the same as that of the mobile terminal 1-1. The server device 2 includes a reception unit 20, an encrypted data processing unit 21, a decryption unit 22, and a transmission unit 23.

[0016] FIG. 2 is a flowchart for explaining the operation of the mobile terminal 1-1. The position data acquisition unit 10 of the mobile terminal 1-1 periodically acquires the position data a of the mobile terminal 1-1 by, for example, GPS (Global Positioning System) (step S100 in FIG. 2). The number of bits of the position data a is, for example, 32 bits.

[0017] The random number generation unit 11 of the mobile terminal 1-1 generates a random number having a larger number of bits than the number of bits of the position data a, for example, a 256-bit random number (step S101 in FIG. 2). At this time, the random number generation unit 11 generates two 256-bit random numbers: a 256-bit random number d for the difference of the position data and a 256-bit random number e for the addition of the position data.

[0018] The encryption processing unit 12 of the mobile terminal 1-1 encrypts the value obtained by adding or subtracting a random number generated by the random number generation unit 11 to the location data a acquired by the location data acquisition unit 10 using elliptic curve cryptography. If the data count value i is not the predetermined number of data N (NO in step S102 of Figure 2), the encryption processing unit 12 encrypts the value a+d obtained by adding the random number d to the location data a, generating encrypted data G(a+d), and also encrypts the value a+e obtained by adding the random number e to the location data a, generating encrypted data G(a+e) (step S103 of Figure 2). The initial value of the count value i is 1, and the number of data N is an integer of 2 or more. The encryption processing unit 12 increments the data count value i by 1 (step S104 of Figure 2).

[0019] The transmission unit 13 of the mobile terminal 1-1 wirelessly transmits encrypted data G(a+d) and G(a+e) to the server device 2 (Figure 2, step S105). Furthermore, if the data count value i is a predetermined number of data points N (YES in step S102), the encryption processing unit 12 encrypts the value a+d obtained by adding a random number d to the position data a, generating encrypted data G(a+d), and also encrypts the value a-(N-1)e obtained by subtracting (N-1)e from the position data a, generating encrypted data G(a-(N-1)e) (Figure 2, step S106). The encryption processing unit 12 initializes the data count value i to 1 (Figure 2, step S107).

[0020] The transmitting unit 13 wirelessly transmits the encrypted data G(a+d) and G(a-(N-1)e) to the server device 2 (step S105). The transmitting unit 13 adds its own terminal's unique ID to the encrypted data before transmitting it.

[0021] Mobile terminal 1-1 performs the above steps S100 to S107 at each data transmission cycle. In Figure 2, the random number generation process in step S101 is shown for clarity, but it is not necessary to perform the process in step S101 at each data transmission cycle. Random numbers d and e may be the same value. However, random number d must remain the same value until N encrypted data G(a+d) have been sent (until the count value i is initialized to 1). Similarly, random number e must remain the same value until N-1 encrypted data G(a+e) and 1 encrypted data G(a-(N-1)e) have been sent (until the count value i is initialized to 1). The operation of mobile terminal 1-1 has been described, but the operation of the other mobile terminals 1-2 and 1-3 is the same as that of mobile terminal 1-1.

[0022] Figure 3 is a flowchart illustrating the operation of server device 2. The receiving unit 20 of server device 2 receives encrypted data G(a+d), G(a+e), or encrypted data G(a+d), G(a-(N-1)e) from each mobile terminal 1-1 to 1-3 (Figure 3, step S200).

[0023] The encrypted data processing unit 21 of the server device 2 integrates N-1 encrypted data G(a+e) and 1 encrypted data G(a-(N-1)e) acquired by the receiving unit 20 for the same mobile terminal (Figure 3, step S201). The encrypted data processing unit 21 of the server device 2 also calculates the difference between predetermined encrypted data from the N number of encrypted data G(a+d) acquired by the receiving unit 20 for the same mobile terminal (Figure 3, step S202). As described above, since the encrypted data sent from the mobile terminal has a terminal ID attached to it, it is possible to process the encrypted data for each mobile terminal.

[0024] The encrypted data processing unit 21 increments the data count value j by 1 (Figure 3, step S203). The initial value of the count value j is 1. When the data count value j reaches a predetermined number of data points N, i.e., when the summation of N-1 encrypted data points G(a+e) and 1 encrypted data point G(a-(N-1)e) is completed (YES in step S204 of Figure 3), the decryption unit 22 of the server device 2 decrypts the summation value and the difference value calculated by the encrypted data processing unit 21 (step S205 of Figure 3).

[0025] Assuming a predetermined number of data points N=6, and the N location data points acquired by the mobile terminal's location data acquisition unit 10 are a1 to a6, the cumulative value σ of N-1 encrypted data points G(a+e) and 1 encrypted data point G(a-(N-1)e) is given by equation (1). σ=G(a1+e)+G(a2+e)+G(a3+e)+G(a4+e)+G(a5+e) +G(a6-5e) =G(a1+e+a2+e+a3+e+a4+e+a5+e+a6-5e) =G(a1+a2+a3+a4+a5+a6) ···(1)

[0026] Furthermore, if the encrypted data processing unit 21 calculates the difference between the first encrypted data G(a1+d) and the second encrypted data G(a2+d) among the N encrypted data G(a+d), the difference value S will be given by equation (2). S = G(a1+d) - G(a2+d) =G(a1+d-a2-d) =G(a1-a2) ···(2)

[0027] The encrypted data G(a+d), G(a+e), and G(a-(N-1)e) are obtained by adding or subtracting 256-bit random numbers d and e to a 32-bit position data a, and since these encrypted values ​​cannot be decrypted, they cannot be decrypted. On the other hand, as shown in equations (1) and (2), in the integrated value σ and difference value S after processing by the encrypted data processing unit 21, the 256-bit random numbers d and e have disappeared, so the encrypted data consists of 32-bit values. Therefore, it is possible to decrypt the integrated value σ and the difference value S.

[0028] An example of the decryption process in step S205 will be explained with reference to Figure 4. Below, the method for decrypting the cumulative value σ will be described, but the difference value S will also be decrypted in the same way as described below. In the process in Figure 4, the decryption unit 22 refers to a rainbow table like the one in Figure 5 that has been registered internally in advance. The rainbow table registers the correspondence between the encrypted value and the plaintext value obtained when the encrypted value is decrypted. In the example in Figure 5, the encrypted value and the plaintext value are represented in hexadecimal. The rainbow table does not register all possible values ​​that can be taken as plaintext values, that is, continuous values ​​that change by 1 each time, but only some plaintext values, that is, discrete values, are registered as plaintext values. This reduces the size of the table. The intervals for each plaintext value are set to 0x00001000 here, but these intervals are arbitrary. The rainbow table may be set up in common for the cumulative value σ and the difference value S, or separate tables may be prepared for the cumulative value σ and the difference value S.

[0029] First, the decryption unit 22 refers to the rainbow table. If an encrypted value matching the cumulative value σ to be decrypted is registered in the rainbow table (YES in step S300 of Figure 4), it retrieves the plaintext value corresponding to the encrypted value matching the cumulative value σ from the rainbow table (step S301 of Figure 4). This means that the cumulative value σ has been decrypted.

[0030] Furthermore, if the decryption unit 22 does not have an encrypted value that matches the cumulative value σ registered in the rainbow table (NO in step S300), it changes (adds or subtracts) the cumulative value σ by an encrypted value P obtained by encrypting the smallest unit value A (here, 0x00000001) when the plaintext value changes (Figure 4, step S302). The changed value is σ + (P × k) or σ - (P × k). k is the count value of the number of changes, and its initial value is 1. Whether to perform addition or subtraction is predetermined by prior settings. The encrypted value P may be a fixed value prepared in advance, or it may be a value encrypted by the decryption unit 22 using the same algorithm as the encryption of the location data. After changing the cumulative value σ, the decryption unit 22 increments the count value k of the number of changes by 1 (Figure 4, step S303).

[0031] Next, the decryption unit 22 refers to the rainbow table and determines whether an encrypted value matching the value obtained by changing the cumulative value σ in the previous step S302 is registered in the rainbow table (Figure 4, step S304). If an encrypted value matching the value obtained by changing the cumulative value σ is not registered in the rainbow table (NO in step S304), the process returns to step S302. In this way, the process of changing the cumulative value σ by the encrypted value P is repeated until it matches an encrypted value registered in the rainbow table. Here, if this process is repeated a maximum of (interval of plaintext value / A)-1 times, the changed cumulative value σ will match one of the encrypted values ​​in the rainbow table.

[0032] If the decryption unit 22 finds that an encrypted value matching the value obtained by changing the accumulated value σ in the previous step S302 is registered in the rainbow table (YES in step S304), it obtains the plaintext value corresponding to the encrypted value matching the value obtained by changing the accumulated value σ in the previous step S302 from the rainbow table (Figure 4, step S305).

[0033] The decryption unit 22 corrects the acquired plaintext value by the correction value A*k, and the corrected value is the value obtained by decrypting the integrated value σ (Figure 4, step S306). If the decryption unit 22 adds the encrypted value P to the integrated value σ in step S302, it subtracts the correction value A*k from the plaintext value acquired in step S305. Also, if the decryption unit 22 subtracts the encrypted value P from the integrated value σ in step S302, it adds the correction value A*k to the plaintext value acquired in step S305. In this way, an appropriate decrypted value can be obtained even if the integrated value σ is not directly registered in the rainbow table. This completes the processing of the decryption unit 22. Figure 4 describes the method of decrypting the integrated value σ, but as described above, the difference value S is decrypted in the same way.

[0034] Next, the transmission unit 13 of the server device 2 transmits the decoded integrated value and the decoded differential value to the host device 3 via the communication network 4 (Figure 3, step S206). In the example in Figure 1, the mobile terminals 1-1 to 1-3 and the server device 2, and the server device 2 and the host device 3 are connected by the same communication network 4, but they may be connected by different communication networks. Also, the communication between the server device 2 and the host device 3 may be wired communication or wireless communication.

[0035] The transmitted cumulative and differential values ​​are used in the higher-level device 3 for purposes such as aggregating location information. For example, the average location information can be calculated by dividing the decoded cumulative value by a predetermined number of data points N. How the average location information is used is arbitrary, but for example, the higher-level device 3 can aggregate the average location (approximate location) of people working from home and monitor whether those working from home are slacking off in locations far from their homes. The higher-level device 3 can also monitor which areas salespeople are currently active in to detect overlaps or omissions in activity areas. Furthermore, the distance traveled over a certain period of time can be calculated from the differential value. Alternatively, the average location information may be calculated on the server device 2 side and transmitted to the higher-level device 3 instead of being calculated on the higher-level device 3.

[0036] After data transmission, the encrypted data processing unit 21 resets the cumulative value σ and the difference value S to 0, and initializes the data count value j to 1. The decryption unit 22 then initializes the count value k, which represents the number of changes in the cumulative value σ, to 1 (Figure 3, step S207). The server device 2 repeatedly executes the processes in steps S200 to S207.

[0037] Figure 6 illustrates the effects of this embodiment, and Figure 7 illustrates the encryption process proposed in Japanese Patent Application No. 2023-158495 and Japanese Patent Application No. 2023-158498. As described above, the encrypted data G(a1+d), G(a2+d), G(a3+d), G(a4+d), G(a5+d), G(a6+d), G(a1+e), G(a2+e), G(a3+e), G(a4+e), G(a5+e), G(a6-5e) arriving at server device 2 are encrypted values ​​obtained by adding or subtracting 256-bit random numbers d and e to 32-bit position data a, and therefore cannot be decrypted as is. On the other hand, the integrated value σ=G(a1+a2+a3+a4+a5+a6) and the difference value S=G(a1-a2) can be decrypted because the random numbers d and e have been removed.

[0038] In contrast, the conventional encryption method shown in Figure 7 can decrypt not only the cumulative value σ = G(a1+a2+a3+a4+a5+a6) and the differential value S = G(a1-a2), but also the encrypted data G(a1), G(a2), G(a3), G(a4), G(a5), and G(a6) that arrive at the server device. Therefore, there is a possibility that a malicious administrator could decrypt the data and read the individual pieces of information.

[0039] As described above, in this embodiment, approximate location information can be obtained without decrypting individual location information. As a result, this embodiment enables more secure and private information management. Furthermore, since this embodiment uses a rainbow table for decrypting encrypted values, complex calculations are not required in the decryption process, reducing the processing load for decrypting encrypted values. In addition, since a private key is not required for decryption using a rainbow table, the leakage of private keys is eliminated.

[0040] In this embodiment, a mobile terminal is used as an example of a data acquisition device, but the data acquisition device is not limited to a mobile terminal. For example, if a person's location detection sensor in a building is used as the data acquisition device, it is possible to obtain an individual's approximate activity location and activity level while concealing their real-time location, thereby providing value for person-centered air conditioning control and health management. Furthermore, while this embodiment describes an example where a value obtained by adding or subtracting a random number from location information is encrypted, the information before adding the random number can be any information and is not limited to location information. For example, the value obtained by adding or subtracting a random number from power consumption data for each tenant in a building or control data between buildings could be encrypted. This can enhance security.

[0041] Each of the mobile terminals 1-1 to 1-3 and the server device 2 described in this embodiment can be realized by a computer equipped with a CPU (Central Processing Unit), storage device, and interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 8.

[0042] The computer comprises a CPU 200, a storage device 201, and an interface device (I / F) 202. In the case of mobile terminals 1-1 to 1-3, the I / F 202 is connected to the hardware of the location data acquisition unit 10 and the hardware of the transmission unit 13, etc. In the case of server device 2, the I / F 202 is connected to the hardware of the receiving unit 20 and the hardware of the transmission unit 23, etc. In such a computer, the program for realizing the information processing method of the present invention is stored in the storage device 201. The CPU 200 of each device executes the processing described in this embodiment according to the program stored in the storage device 201. [Explanation of Symbols]

[0043] 1-1 to 1-3... Mobile terminal, 2... Server device, 3... Higher-level device, 4... Communication network, 10... Location data acquisition unit, 11... Random number generation unit, 12... Encryption processing unit, 13, 23... Transmission unit, 20... Receiving unit, 21... Encrypted data processing unit, 22... Decryption unit 22.

Claims

1. A data acquisition unit configured to periodically acquire data, An encryption processing unit is configured to generate encrypted data by encrypting a value obtained by adding or subtracting a numerical value with a larger number of bits than the number of bits in the aforementioned data to the aforementioned data, An encrypted data processing unit configured to add or subtract multiple encrypted data generated from data acquired by the same data acquisition unit, An information processing system characterized by comprising a decryption unit configured to decrypt the result of addition or subtraction performed by the encrypted data processing unit.

2. In the information processing system described in claim 1, An information processing system further comprising a random number generation unit configured to generate a random number with a number of bits greater than the number of bits of the aforementioned data, as a numerical value to be added to or subtracted from the aforementioned data.

3. In the information processing system described in claim 1, The encryption processing unit is characterized by performing encryption using elliptic curve cryptography.

4. In the information processing system described in claim 1, The encryption processing unit, when the data is a, a first numerical value with a number of bits greater than the number of bits of data a is d, a second numerical value with a number of bits greater than the number of bits of data a is e, and a predetermined number of data is N (where N is an integer of 2 or more), if the count value of data a is not the number of data N, it encrypts the value obtained by adding the numerical value d to data a to generate encrypted data G(a+d), and also encrypts the value obtained by adding the numerical value e to data a to generate encrypted data G(a+e). If the count value of data a is the number of data N, it encrypts the value obtained by adding the numerical value d to data a to generate encrypted data G(a+d), and also encrypts the value obtained by subtracting (N-1)e from data a to generate encrypted data G(a-(N-1)e), and does this for every number of data N. The encrypted data processing unit is characterized by performing the following operations for each N data point: integrating N-1 encrypted data points G(a+e) with one encrypted data point G(a-(N-1)e), and calculating the difference between predetermined encrypted data points among the N encrypted data points G(a+d).

5. In the information processing system described in claim 2, The data acquisition unit, the random number generation unit, and the encryption processing unit are mounted on the data acquisition device. The encrypted data processing unit and the decryption unit are mounted on the server device. The data acquisition device further comprises a transmission unit configured to transmit encrypted data generated by the encryption processing unit to the server device, The information processing system is characterized by further comprising a receiving unit configured to receive encrypted data transmitted from the data acquisition device.

6. In the information processing system described in claim 1, The information processing system is characterized in that the decryption unit refers to a table in which encrypted values ​​and plaintext values ​​are registered in association, and performs a first process in which the encrypted value resulting from addition or subtraction by the encrypted data processing unit is the target of decryption, and the plaintext value corresponding to this encrypted value is obtained from the table as the decryption result.

7. In the information processing system described in claim 6, The decoding unit, If the encrypted value to be decrypted is not registered in the table, a second process is performed to change the encrypted value to be decrypted, refer to the table based on the changed encrypted value, and obtain the plaintext value corresponding to the changed encrypted value. An information processing system characterized by further performing a third process of correcting the acquired plaintext value to obtain the decryption result of the encrypted value to be decrypted.

8. In the information processing system described in claim 7, The decryption unit changes the encrypted value to be decrypted by adding or subtracting an encrypted value obtained by encrypting the minimum unit value that changes the plaintext value to the encrypted value to be decrypted, and repeatedly performs the second process of referring to the table based on the changed encrypted value until the changed encrypted value matches the encrypted value in the table, and in the third process, corrects the plaintext value obtained from the table by repeating the second process with a correction value obtained by multiplying the number of times the second process was repeated by the minimum unit value.

9. The first step is to periodically acquire data, A second step involves generating encrypted data by encrypting a value obtained by adding or subtracting a numerical value with a larger number of bits than the number of bits in the aforementioned data to the aforementioned data, A third step of adding or subtracting a plurality of encrypted data generated from the data acquired in the first step by the same data acquisition device, An information processing method characterized by comprising a fourth step of decoding the result of the addition or subtraction performed in the third step.

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