Information processing apparatus, information processing method, and program

Abstract

To provide an information processor, an information processing method and a program for inspecting the presence / absence of the leakage of a key to be used for the encryption or decryption of secret data while keeping the key in a secret state.SOLUTION: Comparing encrypted candidate data obtained by encrypting verification data using key candidate data with the encrypted verification data or comparing candidate verification data obtained by decrypting the encrypted verification data using the key candidate data with the verification data, the verification data being verification plaintext for detecting whether a key for encrypting confidential data and / or decrypting the encrypted confidential data has leaked from a key management device, and the encrypted verification data being verification data encrypted using the key in the key management device; And a verification unit that determines presence or absence of leakage of the key to the data group based on a comparison result.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a technique for determining whether a key that should be kept secret has been leaked. [Background technology]

[0002] Many companies store confidential data, such as customer names and credit card numbers, on their computers and strictly manage it to prevent it from being made public. For example, companies limit the employees who can access confidential data and implement security measures to prevent unauthorized access to their computers from outside. Even with these measures, if malware is embedded in electronic data received from outside, confidential data may be leaked from its storage location on the computer onto a publicly available network. In this case, if a company does not detect the leak of confidential data as soon as possible, the amount of leaked confidential data will increase.

[0003] To address this issue, a system has been proposed that compares private files with various files available over a public network to determine whether the contents of the private files have been leaked (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-170036 Summary of the Invention [Problem to be solved by the invention]

[0005] Not only confidential data, but also keys such as encryption keys for encrypting confidential data and decryption keys for decrypting encrypted confidential data are information that should be kept secret, just like private files. When checking whether a key has been leaked onto a public network using the system disclosed in Patent Document 1, the key needs to be retrieved from its storage location in order to compare the key with various files. This increases the risk of the key being leaked onto a public network. With the technology disclosed in Patent Document 1, it is difficult to check whether a key has been leaked to the public while keeping the key confidential.

[0006] One objective of the present disclosure is to provide an information processing device, an information processing method, and a program that can check whether a key used to encrypt or decrypt confidential data has been leaked while keeping the key secret. [Means for solving the problem]

[0007] An information processing device according to one aspect included in the present disclosure includes a memory unit that stores verification data, which is plaintext for verification purposes, for detecting whether a key for encrypting confidential data and / or decrypting encrypted confidential data has been leaked from a key management device, and encrypted verification data, in which the verification data has been encrypted using the key in the key management device; a key candidate data acquisition unit that extracts key candidate data that are candidates for the key from a data group to be inspected; and a verification unit that compares the encrypted candidate data, in which the verification data has been encrypted using the key candidate data, with the encrypted verification data, or compares the candidate verification data, in which the encrypted verification data has been decrypted using the key candidate data, with the verification data, and determines whether the key has been leaked to the data group based on the comparison result. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to check whether a key has been leaked to the outside while keeping the key secret. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a block diagram showing a configuration example of a key leakage determination system including an information processing device according to a first embodiment. [Figure 2] 1 is a block diagram illustrating a configuration example of an information processing device according to a first embodiment. [Figure 3] 3 is a block diagram showing a data flow in the key leakage determination system according to the first embodiment. FIG. [Figure 4] 3 is a block diagram showing an example of a hardware configuration of a calculation unit shown in FIG. 2. FIG. [Figure 5] FIG. 3 is a sequence diagram illustrating an example of an operation procedure of the key leakage determination system according to the first embodiment. [Figure 6] 6 is a flowchart showing a specific example of the operation procedure of steps S102 to S103 shown in FIG. [Figure 7] 6 is a flowchart showing a specific example of the operation procedure of steps S104 to S106 shown in FIG. [Figure 8] FIG. 8 is a diagram showing an example of an image displayed by an output unit in step S305 shown in FIG. 7. [Figure 9] 6 is a flowchart showing a specific example of the operation procedure of steps S107 to S108 shown in FIG. [Figure 10] FIG. 10 is a diagram showing an example of an image displayed by an output unit in step S408 shown in FIG. [Figure 11] FIG. 10 is a block diagram showing a data flow in the key leakage determination system according to the second embodiment. [Figure 12] FIG. 10 is a sequence diagram illustrating an example of an operation procedure of the key leakage determination system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The information processing device of this embodiment determines whether a key for encrypting or decrypting confidential data has leaked to an area accessible by an unspecified number of people operating an information processing terminal. Types of keys for encrypting or decrypting confidential data include symmetric encryption keys and asymmetric encryption keys. Symmetric encryption keys include a common key that serves both to encrypt confidential data and to decrypt encrypted confidential data. Asymmetric encryption keys include a pair of public and private keys. The public key is made public, while the private key is kept secret. The private key serves to encrypt confidential data and to decrypt confidential data encrypted using the public key. In this embodiment, keys that need to be kept secret, such as a common key and a private key, are simply referred to as keys. An example of the information processing device of this embodiment will be described below. [Example]

[0011] The configuration of an information processing device according to the first embodiment will be described with reference to the drawing. Fig. 1 is a block diagram showing an example of the configuration of a key leakage determination system having an information processing device according to the first embodiment.

[0012] As shown in FIG. 1, the key leakage determination system 3 includes a key management device 2 that manages keys for encrypting and / or decrypting confidential data in a confidential state, and an information processing device 1 that determines whether the key has been leaked. The information processing device 1 is connected to the key management device 2 via a dedicated communication line 4. The information processing device 1 is connected to a server 5 via a network 100. The server 5 is, for example, a device used for business purposes by employees of the company that operates the key management device 2 and the information processing device 1. The server 5 includes a memory unit 6 that stores data shared by employees of the company. The memory unit 6 is a storage device that stores a group of data to be inspected for whether the key has been leaked. The network 100 is, for example, a network including the Internet.

[0013] 1 shows a configuration in which the information processing device 1 and the key management device 2 are connected via a dedicated communication line 4, but the connection configuration is not limited to that shown in Fig. 1. The information processing device 1 and the key management device 2 may transmit and receive data via the network 100 in a confidential state using a predetermined communication technology. The communication technology is, for example, a VPN (Virtual Private Network).

[0014] The key management device 2 is an information processing device such as a computer. The key management device 2 encrypts confidential data using a key and decrypts the encrypted confidential data using the key. When the key management device 2 receives plaintext confidential data and information requesting encryption, it encrypts the confidential data using the key and outputs the encrypted confidential data. When the key management device 2 receives encrypted confidential data and information requesting decryption, it decrypts the encrypted confidential data into plaintext and outputs the plaintext. The key management device 2 does not output the key from the device to an external device, so the key is kept confidential.

[0015] FIG. 2 is a block diagram showing an example of a configuration of an information processing device according to a first embodiment. FIG. 3 is a block diagram showing a data flow in the key leakage determination system according to the first embodiment. The information processing device 1 is, for example, a computer such as a personal computer. The information processing device 1 includes a storage unit 11, a calculation unit 12, a communication unit 13, an input unit 14, and an output unit 15. The storage unit 11 is a storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The communication unit 13 includes a communication circuit that transmits and receives data to and from other devices according to a communication protocol such as the Internet Protocol (IP). The input unit 14 is an input device such as a keyboard, a mouse, or a touch panel. The output unit 15 is an output device such as a display that displays information or a speaker that outputs sound. In this first embodiment, the output unit 15 is a display.

[0016] The storage unit 11 has a verification data storage unit 41 and a key candidate data storage unit 42. The verification data storage unit 41 stores verification data, which is plaintext for verification used to detect whether a key has leaked from the key management device 2, and encrypted verification data, which is data obtained by encrypting the verification data with a key. The key candidate data storage unit 42 stores key candidate data, which is data extracted from a data group to be inspected and is a key candidate.

[0017] The calculation unit 12 has a verification data creation unit 21, a key candidate data acquisition unit 22, and a key candidate data verification unit 23. The verification data creation unit 21 transmits verification data to the key management device 2 and acquires encrypted verification data from the key management device 2. The verification data creation unit 21 has a data generation unit 61 and an encryption unit 62. The data generation unit 61 generates verification data. The data generation unit 61 generates verification data corresponding to, for example, the algorithm and parameters of a key held by the key management device 2. Specific examples of the key algorithm and parameters will be described later. The data generation unit 61 stores the verification data in the storage unit 11 and passes the verification data to the encryption unit 62.

[0018] The encryption unit 62 transmits the verification data to the key management device 2 to request the key management device 2 to encrypt the verification data. When the encryption unit 62 receives the encrypted verification data from the key management device 2, it stores the encrypted verification data in the storage unit 11 and transmits the encrypted verification data to the key candidate data acquisition unit 22 and the output unit 15. The encryption unit 62 also transmits information on the key algorithm and parameters acquired from the key management device 2 to the key candidate data acquisition unit 22. If the key is a common key for symmetric encryption, the key algorithm is, for example, the RSA (Rivest, Shamir, Adleman) encryption. If the key is a private key for asymmetric encryption, the key algorithm is, for example, the AES (Advanced Encryption Standard) encryption. The parameter is, for example, the key bit length. If the key algorithm is the AES encryption and the parameter is the key bit length, the parameter can be selected from 128, 192, or 256 bits. The verification data generating unit 21 may obtain the key algorithm and parameter information from the key management device 2 in advance, or may obtain the information from the key management device 2 when the key management device 2 updates the key.

[0019] The key candidate data acquisition unit 22 extracts key candidate data, which is data that will become key candidates, from a data group to be inspected. The key candidate data acquisition unit 22 has a data acquisition unit 71 and a data processing unit 72. The data acquisition unit 71 sequentially reads out inspection data, which is data to be inspected, from the data group stored in the storage unit 6, and passes the read inspection data to the data processing unit 72.

[0020] The data processing unit 72 sets a search format for extracting key candidate data from a data group based on the key algorithm and parameters. The search format is, for example, a PEM (Privacy-Enhanced Mail) file format. The search format may also have a bit length corresponding to the key. If the key has a bit length of 128 bits for AES encryption, the key algorithm is AES encryption, and the parameters are the same 128 bits as the key bit length, the data processing unit 72 sets the format to 128 bits. To improve search efficiency, the data processing unit 72 may set the search format based on the key algorithm and parameters, or the search format may be specified by the user.

[0021] Each time the data processing unit 72 receives test data from the data acquisition unit 71, it checks whether the format of the received test data matches the search format. For example, if the search format has the same bit length as the key, the data processing unit 72 performs a text search on the data group to search for test data with the same bit length as the search format. The text to be searched is not limited to numbers, but may also be characters in a natural language. If the text is characters in a natural language, the data processing unit 72 may, for example, convert a character string into a bit string according to a predetermined rule. The data processing unit 72 stores the test data that matches the search format as key candidate data in the key candidate data storage unit 42 of the memory unit 11. The data processing unit 72 transmits the key candidate data to the key candidate data verification unit 23 and the output unit 15. When the data processing unit 72 receives encrypted verification data from the verification data creation unit 21, it transfers the encrypted verification data to the key candidate data verification unit 23.

[0022] The key candidate data verification unit 23 includes a verification unit 81. The verification unit 81 compares the encrypted verification data with encrypted candidate data obtained by encrypting verification data using the key candidate data, or compares the candidate verification data obtained by decrypting the encrypted verification data using the key candidate data with the verification data. Then, the verification unit 81 determines whether the key has leaked to the data group based on the comparison result. Specifically, if the comparison result shows that the encrypted candidate data and the encrypted verification data match, the verification unit 81 determines that the key has leaked to the data group. On the other hand, if the encrypted candidate data and the encrypted verification data do not match, the verification unit 81 determines that the key has not leaked to the data group. Furthermore, if the candidate verification data and the verification data match, the verification unit 81 determines that the key has leaked to the data group. On the other hand, if the candidate verification data and the verification data do not match, the verification unit 81 determines that the key has not leaked to the data group.

[0023] Here, a description will be given of the hardware configuration of the calculation unit shown in Fig. 2. Fig. 4 is a block diagram showing an example of the hardware configuration of the calculation unit shown in Fig. 2.

[0024] The calculation unit 12 has a memory 51 that stores a program, and a processor 52 that executes processing in accordance with the program. The processor 52 is, for example, a CPU (Central Processing Unit). The memory 51 is a non-volatile memory such as a flash memory. When the processor 52 executes the program, the functions of the verification data creation unit 21, the key candidate data acquisition unit 22, and the key candidate data verification unit 23 shown in FIG. 2 are executed. The program may be stored not only in the memory 51, but also in a portable recording medium.

[0025] Note that some or all of the functions of the calculation unit 12 may be executed by a dedicated circuit such as an ASIC (Application Specific Integrated Circuit). Furthermore, the hardware configurations of the key management device 2 and the server 5 are similar to the hardware configuration of the information processing device 1 described with reference to Figures 2 and 4, and therefore detailed description thereof will be omitted.

[0026] Next, the operation of the key leakage determination system 3 of the first embodiment will be described. Fig. 5 is a sequence diagram showing an example of the operation procedure of the key leakage determination system according to the first embodiment. In step S101, the verification data creation unit 21 transmits verification data to the key management device 2. In step S102, upon receiving the verification data from the information processing device 1, the key management device 2 creates encrypted verification data. In step S103, the key management device 2 transmits the created encrypted verification data to the information processing device 1.

[0027] In step S104, the key candidate data acquisition unit 22 sets a search format. In step S105, the key candidate data acquisition unit 22 searches for the data group to be inspected. In step S106, the key candidate data acquisition unit 22 extracts key candidate data from the data group to be inspected. In step S107, the key candidate data verification unit 23 determines whether or not a key has been leaked using the verification data, encrypted verification data, and key candidate data. In step S108, the key candidate data verification unit 23 causes the output unit 15 to output the determination result.

[0028] The operation of the key management device 2 will be described in detail with reference to Fig. 6. Fig. 6 is a flowchart showing a specific example of the operation procedure of steps S102 to S103 shown in Fig. 5. In the following, the key algorithm is defined as Ag1, the key as K1, and the key parameter as Pr1. In step S201, the key management device 2 encrypts confidential data using the algorithm Ag1, the key K1, and the parameter Pr1. In step S202, the key management device 2 receives verification data from the information processing device 1.

[0029] In step S203, the key management device 2 encrypts the verification data using the algorithm Ag1, the key K1, and the parameter Pr1 to create encrypted verification data. In step S204, the key management device 2 transmits information about the encrypted verification data, the algorithm Ag1, and the parameter Pr1 to the information processing device 1. In step S204, the information processing device 1 receives the information about the algorithm Ag1, the key K1, and the parameter Pr1 from the key management device 2, but may have previously acquired this information from the key management device 2.

[0030] 6 has been described as a case in which the key management device 2 creates encrypted verification data by using a key for verification data received from the information processing device 1 at the timing of encrypting confidential data, but this is not limited to this case. Although not shown in Fig. 6, the key management device 2 transmits the confidential data to another device (not shown) via the network 100. In the case of the flow shown in Fig. 6, when the key management device 2 transmits the encrypted confidential data to the network 100, the information processing device 1 determines whether the key has been leaked, which has the advantage of enabling confirmation of the security of the confidential data.

[0031] Next, the operation of the information processing device 1 will be described in detail. First, the operation of the key candidate data acquisition unit 22 will be described with reference to FIG. 7. FIG. 7 is a flowchart showing a specific example of the operation procedure of steps S104 to S106 shown in FIG. 5. In step S301, the key candidate data acquisition unit 22 creates a plurality of formats based on the algorithm Ag1 and parameters Pr1 as candidates for the search format Fm for extracting key candidate data, and outputs them to the output unit 15. In step S302, one or more search formats Fm are selected from the plurality of formats by the user. Here, it is assumed that the search format Fm1 is selected.

[0032] In step S303, the key candidate data acquisition unit 22 searches the data group to be inspected using the search format Fm1 selected by the user. In step S304, the key candidate data acquisition unit 22 searches the data group to be inspected and extracts inspection data in a format that matches the search format Fm1 as key candidate data. If the search target is a character string, the key candidate data acquisition unit 22 encodes the character string according to a predetermined rule. In this way, the key candidate data acquisition unit 22 may perform processing to convert the inspection data into a bit string as necessary. In step S305, the key candidate data acquisition unit 22 causes the output unit 15 to output the search result.

[0033] 8 is a diagram showing an example of an image displayed by the output unit in step S305 shown in FIG. 7. As shown in FIG. 8, information about the key used to generate the verification data is displayed on the output unit 15 as basic information about the verification data. Here, a case is shown in which there are two types of keys, key K1 and key K2. In addition, information about the location of the storage area for the data group to be inspected is displayed on the output unit 15. By referring to the image shown in FIG. 8, the user can understand, in accordance with the type of key, what key the verification data was generated based on and which storage area is the object of inspection.

[0034] Next, the operation of the key candidate data verification unit 23 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing a specific example of the operation procedure of steps S107 to S108 shown in Fig. 5. With reference to Fig. 9, it will be explained that the presence or absence of leakage can be determined not only when a common key of symmetric encryption is used as an encryption key or decryption key, but also when a private key of asymmetric encryption is used as an encryption key or decryption key.

[0035] In step S401, the key candidate data verification unit 23 encrypts verification data using the algorithm Ag1 and parameter Pr1, with the key candidate data as a key. This generates encrypted candidate data. In step S402, the key candidate data verification unit 23 determines whether the encrypted candidate data matches the encrypted verification data. If the determination result shows that the encrypted candidate data matches the encrypted verification data, the key candidate data verification unit 23 determines that key K1 has been leaked as an encryption key. This determination is made whether key K1 is a common key and is used as an encryption key, or whether key K1 is a private key and is used as an encryption key. On the other hand, if the determination result in step S402 shows that the encrypted candidate data does not match the encrypted verification data, the key candidate data verification unit 23 proceeds to processing in step S404.

[0036] In step S404, the key candidate data verification unit 23 decrypts the encrypted verification data using the algorithm Ag1 and the parameter Pr1, with the key candidate data as a key. This generates candidate verification data. In step S405, the key candidate data verification unit 23 determines whether the candidate verification data matches the verification data. If the result of the determination is that the candidate verification data matches the verification data, the key candidate data verification unit 23 determines that key K1 has been leaked as a decryption key. The determination of key leakage is made both when key K1 is a common key and is used as a decryption key, and when key K1 is a private key and is used as a decryption key. On the other hand, if the result of the determination in step S405 is that the candidate verification data does not match the verification data, the key candidate data verification unit 23 determines that key K1 has not been leaked (step S407). In step S408, the key candidate data verification unit 23 causes the output unit 15 to output the determination result.

[0037] FIG. 10 is a diagram showing an example of an image displayed by the output unit in step S408 shown in FIG. 9 . As shown in FIG. 10 , the setting information of the key candidate data and the verification result are displayed on the output unit 15 corresponding to the key type. Here, the case is shown where there are two types of keys, key K1 and key K2. Specifically, for the setting information of the key candidate data, the storage area to be inspected and the search format are displayed on the output unit 15 corresponding to the key type. As the verification result, the storage area to be inspected and the verification result are displayed on the output unit 15 corresponding to the key type. Both the setting information of the key candidate data and the verification result include an item for "storage area to be inspected," but the information for these storage areas may be the same or different. For example, if the key candidate data verification unit 23 determines that a key has been leaked as a result of the verification, the output unit 15 may display the storage area determined to have been leaked as "storage area to be inspected" in the verification result shown in FIG. 10 . By referring to the image shown in FIG. 10, the user can understand not only how the key candidate data is set according to the type of key, but also whether the key has been leaked.

[0038] The information shown in FIG. 8 and the information shown in FIG. 10 are examples of information output by the output unit 15. The output unit 15 may combine the information shown in FIG. 8 and the information shown in FIG. 10 into a single image and display it. The output unit 15 may not display all of the information shown in FIG. 8 and FIG. 10. For example, the output unit 15 displays at least the storage area of ​​the data group to be inspected and the determination result by the key candidate data verification unit 23. In this case, if it is determined that a key leak has occurred, the user can identify the storage area in which the key is stored. Therefore, the user can estimate how the key came to be leaked from the key management device to the identified storage area and take measures to prevent the key leak.

[0039] In addition, in the flow shown in Fig. 9, the order of determination in steps S402 and S405 is not limited to the order shown in Fig. 9. The key candidate data verification unit 23 may perform the process of step S405 before step S402. Furthermore, the key candidate data acquisition unit 22 may execute the processes of steps S303 to S304 shown in Fig. 7 at a predetermined cycle. In this case, the key candidate data acquisition unit 22 extracts key candidate data from the inspection target at a constant cycle, and the key candidate data verification unit 23 determines whether or not the key has been leaked using the extracted key candidate data. Therefore, the security of the key is maintained over time.

[0040] The information processing device 1 of the first embodiment includes a storage unit 11, a key candidate data acquisition unit 22, and a key candidate data verification unit 23. The storage unit 11 stores verification data, which is plaintext for verification, for detecting whether a key for encrypting confidential data and / or decrypting encrypted confidential data has been leaked from the key management device 2. The storage unit 11 stores encrypted verification data, which is verification data encrypted using a key in the key management device 2. The key candidate data acquisition unit 22 extracts key candidate data, which is a key candidate, from a data group to be inspected. The key candidate data verification unit 23 compares the encrypted verification data with encrypted candidate data obtained by encrypting the verification data using the key candidate data, or compares the verification data with candidate verification data obtained by decrypting the encrypted verification data using the key candidate data. The key candidate data verification unit 23 determines whether a key has been leaked to the data group based on the comparison result.

[0041] According to the first embodiment, it is assumed that the key candidate data extracted from the object to be inspected is the same as the legitimate key, and data obtained by encrypting verification data using the key candidate data is compared with the encrypted candidate data, or data obtained by decrypting encrypted verification data using the key candidate data is compared with the verification data. The comparison determines whether the assumption that the key candidate data is the legitimate key is correct. For example, if the compared data matches, it is determined that the assumption that the key candidate data is the legitimate key is correct. If the comparison result indicates that the assumption that the key candidate data is the legitimate key is correct, it means that data identical to the legitimate key has been leaked to the outside. Therefore, it is possible to determine whether the key has been leaked to the outside without extracting the key from the key management device 2 and directly comparing it with the data to be inspected. It is possible to inspect whether the key has been leaked while maintaining the confidentiality of the key.

[0042] There is a risk that the key may be leaked from the key management device 2 to the outside via the network 100 due to, for example, the key management device 2 receiving electronic data containing malware from the outside. In response to this, in the first embodiment, a part of the key that has been spread to the network 100 is stored in the storage unit 6 of the server 5, and the information processing device 1 determines whether the key has been leaked. This allows the user to quickly recognize that the key has been leaked, and to smoothly take steps to change the key. As a result, it is possible to prevent confidential data from being spread for a long period of time.

[0043] Moreover, the information processing device 1 of the present embodiment 1 includes a verification data generating unit 21. Since the verification data generating unit 21 generates the verification data, the processing load of the key management device 2 is reduced. Furthermore, since the user can generate the verification data by operating the information processing device 1, the range of selection of the verification data is increased. [Example]

[0044] The key leakage determination system of the present embodiment 2 has a different configuration from the key leakage determination system described in the embodiment 1. The configuration of the key leakage determination system of the present embodiment 2 will be described with reference to the drawings. In the present embodiment 2, the same components as those described in the embodiment 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0045] 11 is a block diagram showing a data flow in a key leakage determination system according to Example 2. The key leakage determination system 3 of Example 2 includes a key management device 2a and an information processing device 1a. In Example 2, the verification data creation unit 21 described with reference to FIG. 2 is provided in the key management device 2a instead of the information processing device 1a.

[0046] Next, a description will be given of the operation of the key leakage determination system 3 of the present embodiment 2. Fig. 12 is a sequence diagram showing an example of the operation procedure of the key leakage determination system according to the embodiment 2. The processes of steps S104 to S108 shown in Fig. 12 are the same as the processes described with reference to Fig. 5 and Fig. 7 to Fig. 10, and therefore detailed description thereof will be omitted.

[0047] In step S501, the verification data creation unit 21 of the key management device 2a generates verification data. The verification data creation unit 21 generates, for example, the verification data. The verification data is generated corresponding to the algorithm Ag1 and parameter Pr1 of the key K1. As a specific example, the verification data creation unit 21 sets the bit length of the verification data to be the same as the bit length of the key K1. In step S502, the verification data creation unit 21 encrypts the verification data using the algorithm Ag1, the key K1, and the parameter Pr1 to create encrypted verification data. In step S503, the verification data creation unit 21 transmits the verification data and the encrypted verification data to the information processing device 1a.

[0048] In the key leakage determination system of the second embodiment, a key management device 2a includes a verification data creation unit 21. When the storage unit 11 of the information processing device 1 receives the verification data and encrypted verification data generated by the key management device 2 from the key management device 2, the storage unit 11 stores the received verification data and encrypted verification data. According to the second embodiment, when the key management device 2 generates the verification data, the key management device 2 holds key information, and therefore, can efficiently generate verification data corresponding to the key.

[0049] The above-described embodiments are merely illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments alone. Those skilled in the art can implement the present invention in various other forms without departing from the scope of the present invention.

[0050] The above-described embodiment also includes the following features, but the features included in the present embodiment are not limited to those listed below.

[0051] (Item 1) a storage unit that stores verification data, which is plaintext for verification, for detecting whether a key for encrypting confidential data and / or decrypting the encrypted confidential data has been leaked from a key management device, and encrypted verification data, which is the verification data encrypted using the key in the key management device; a key candidate data acquisition unit that extracts key candidate data that are candidates for the key from a data group to be inspected; a verification unit that compares the encrypted verification data with encrypted candidate data obtained by encrypting the verification data using the key candidate data, or compares the encrypted verification data with candidate verification data obtained by decrypting the encrypted verification data using the key candidate data, and determines whether the key has been leaked to the data group based on the comparison result; An information processing device having the above.

[0052] Assuming that the key candidate data extracted from the object to be inspected is the same as the legitimate key, data obtained by encrypting verification data using the key candidate data is compared with the encrypted candidate data, or data obtained by decrypting encrypted verification data using the key candidate data is compared with the verification data. The comparison determines whether the assumption that the key candidate data is the legitimate key is correct. For example, if the compared data matches, it is determined that the assumption that the key candidate data is the legitimate key is correct. If the comparison results in a correct assumption that the key candidate data is the legitimate key, it means that data identical to the legitimate key has been leaked to the outside. Therefore, it is possible to determine whether the key has been leaked to the outside without extracting the key from the key management device and directly comparing it with the data to be inspected. Whether the key has been leaked can be inspected while maintaining the confidentiality of the key.

[0053] (Item 2) In the information processing device according to item 1, The verification unit If the encryption candidate data and the encryption verification data match, it is determined that the key has leaked to the data group, and if the encryption candidate data and the encryption verification data do not match, it is determined that the key has not leaked to the data group; If the candidate verification data and the verification data match, it is determined that the key has leaked to the data group, and if the candidate verification data and the verification data do not match, it is determined that the key has not leaked to the data group. Information processing device.

[0054] If the encrypted candidate data and the encrypted verification data match, it means that the verification data was encrypted with the same key. Also, if the candidate verification data and the verification data match, it means that the verification data encrypted with the legitimate key could be decrypted with the key candidate data. In either case, it becomes clear that the key was leaked as key candidate data to the data set being inspected.

[0055] (Item 3) In the information processing device according to item 1 or 2, The key candidate data acquisition unit extracting data in a format based on the algorithm and parameters of the key from the data group as the key candidate data; Information processing device.

[0056] As a result, data corresponding to the key algorithm and parameters is set as key candidate data, and data that is similar to the regular key is extracted as key candidate data from the data group to be inspected.

[0057] (Item 4) In the information processing device according to any one of items 1 to 3, a verification data generating unit that, upon generating the verification data, stores the verification data in the storage unit and transmits the verification data to the key management device, and, upon receiving the encrypted verification data, stores the received encrypted verification data in the storage unit; Information processing device.

[0058] (Item 5) In the information processing device according to any one of items 1 to 3, The storage unit when receiving the verification data and the encrypted verification data generated by the key management device from the key management device, storing the received verification data and the encrypted verification data; Information processing device.

[0059] (Item 6) In the information processing device according to any one of items 1 to 5, a display that displays a storage area for the data group and a determination result by the verification unit; Information processing device.

[0060] (Item 7) In the information processing device according to any one of items 1 to 6, The key candidate data acquisition unit extracting the key candidate data from the data group at a predetermined period; Information processing device. [Explanation of symbols]

[0061] 1, 1a: information processing device, 2, 2a: key management device, 3: key leakage determination system, 4: dedicated communication line, 5: server, 6: memory unit, 11: memory unit, 12: calculation unit, 13: communication unit, 14: input unit, 15: output unit, 21: verification data creation unit, 22: key candidate data acquisition unit, 23: key candidate data verification unit, 41: verification data storage unit, 42: key candidate data storage unit, 51: memory, 52: processor, 61: data generation unit, 62: encryption unit, 71: data acquisition unit, 72: data processing unit, 81: verification unit, 100: network.

Claims

1. a storage unit that stores verification data, which is plaintext for verification, for detecting whether a key for encrypting confidential data and / or decrypting encrypted confidential data has been leaked from a key management device, and encrypted verification data, which is the verification data encrypted using the key in the key management device; a key candidate data acquisition unit that extracts key candidate data that are candidates for the key from a data group to be inspected; a verification unit that compares the encrypted verification data with encrypted candidate data obtained by encrypting the verification data using the key candidate data, or compares the encrypted verification data with candidate verification data obtained by decrypting the encrypted verification data using the key candidate data, and determines whether the key has been leaked to the data group based on the comparison result; An information processing device having the above.

2. 2. The information processing device according to claim 1, The verification unit If the encryption candidate data and the encryption verification data match, it is determined that the key has leaked to the data group, and if the encryption candidate data and the encryption verification data do not match, it is determined that the key has not leaked to the data group; If the candidate verification data and the verification data match, it is determined that the key has leaked to the data group, and if the candidate verification data and the verification data do not match, it is determined that the key has not leaked to the data group. Information processing device.

3. 2. The information processing device according to claim 1, The key candidate data acquisition unit extracting data in a format based on the algorithm and parameters of the key from the data group as the key candidate data; Information processing device.

4. 2. The information processing device according to claim 1, a verification data generating unit that, upon generating the verification data, stores the verification data in the storage unit and transmits the verification data to the key management device, and, upon receiving the encrypted verification data, stores the received encrypted verification data in the storage unit; Information processing device.

5. 2. The information processing device according to claim 1, The storage unit when receiving the verification data and the encrypted verification data generated by the key management device from the key management device, storing the received verification data and the encrypted verification data; Information processing device.

6. 2. The information processing device according to claim 1, a display that displays a storage area for the data group and a determination result by the verification unit; Information processing device.

7. 2. The information processing device according to claim 1, The key candidate data acquisition unit extracting the key candidate data from the data group at a predetermined period; Information processing device.

8. An information processing method executed by an information processing device, storing verification data, which is plaintext for verification, for detecting whether or not a key for encrypting confidential data and / or decrypting encrypted confidential data has been leaked from a key management device, and encrypted verification data, which is the verification data encrypted using the key in the key management device; extracting key candidate data that are candidates for the key from the data group to be inspected; comparing the encrypted verification data with encrypted candidate data obtained by encrypting the verification data using the key candidate data, or comparing the encrypted verification data with candidate verification data obtained by decrypting the encrypted verification data using the key candidate data; determining whether the key has been leaked to the data group based on the comparison result; Information processing methods.

9. On the computer, storing verification data, which is plaintext for verification, for detecting whether or not a key for encrypting confidential data and / or decrypting encrypted confidential data has been leaked from a key management device, and encrypted verification data, which is the verification data encrypted using the key in the key management device; extracting key candidate data that are candidates for the key from the data group to be inspected; comparing the encrypted verification data with encrypted candidate data obtained by encrypting the verification data using the key candidate data, or comparing the encrypted verification data with candidate verification data obtained by decrypting the encrypted verification data using the key candidate data; determining whether the key has been leaked to the data group based on the comparison result; A program to make it happen.

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