JP2020141425A - Terminal equipment, key providing system, key generation method and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the confidentiality of a key used for encrypting a private key. SOLUTION: A plurality of keys generated from a first key used for encrypting a private key, an acquisition unit for acquiring identification information for identifying a user from another device, and a plurality of acquired keys. A terminal device including a key generator that generates a second key, which is the same key as the first key used for encrypting the private key, based on the key and the identification information. [Selection diagram] FIG. 4

Description

The present invention relates to a technique for transmitting a private key.

Conventionally, encryption technology has been used from the viewpoint of information protection and computer security. Normally, when using RSA (Rivest Shamir Adleman) technology such as SSL (Secure Sockets Layer) or S / MIME (Secure / Multipurpose Internet Mail Extensions), media (for example, personal computer, IC (Integrated Circuit) card, USB (Universal)) Since the key is generated by the application of Serial Bus) token etc.), the private key is not transmitted from the medium to the outside. Therefore, it is unlikely that the private key will be leaked to the outside.

However, when the key pair is generated by another device using the RSA technique, it is necessary to transmit the private key to the medium (see, for example, Patent Document 1). When transmitting a private key, security is low only by encrypting a communication path such as SSL. Therefore, it is conceivable to transmit the private key encrypted with the common key to the medium. Under such circumstances, when the application in the medium decrypts the private key encrypted with a certain common key, the secret is secured by storing the common key in the medium in advance.

Japanese Unexamined Patent Publication No. 2016-148919

However, when transmitting an encrypted private key to a medium that has already been distributed, a common key for decrypting the private key must also be transmitted. In such a case, there is a security problem even if the private key is encrypted unless the confidentiality of the common key is ensured. Such a problem is not limited to the common key used for encrypting the private key, but is a problem common to all the keys used for encrypting the private key.

In view of the above circumstances, an object of the present invention is to provide a technique capable of improving the confidentiality of a key used for encrypting a private key.

One aspect of the present invention is an acquisition unit that acquires a plurality of keys generated from a first key used for encrypting a private key and identification information for identifying a user from another device. A terminal including the plurality of keys and a key generation unit that generates a second key that is the same key as the first key used for encrypting the private key based on the identification information. It is a device.

One aspect of the present invention is the terminal device, in which some of the plurality of keys are set in the application, and the acquisition unit acquires the application to obtain the plurality of keys. Get some of the keys in.

One aspect of the present invention is the terminal device, in which logic relating to the second key generation method is further set in the application, and the key generation unit performs the second key according to the logic. Generate the key for.

One aspect of the present invention is the terminal device, in which the acquisition unit acquires the application via the first communication network and uses a part of the plurality of keys for the first communication. Obtained via a communication network different from the network.

One aspect of the present invention is the terminal device, wherein the key generation unit restores the first key by combining the plurality of keys according to predetermined conditions, and the restored first key. The second key is generated by encrypting the identification information with a predetermined algorithm.

One aspect of the present invention is the terminal device, further comprising a decryption unit that restores the private key by decrypting the encrypted private key using the generated second key. The decryption unit stores the restored private key in the tamper-resistant area in the own device.

One aspect of the present invention is among a key generator that generates a private key, a key that is a pair of the private key, and a plurality of keys generated from a first key used for encrypting the private key. Obtaining a key generation device including a communication unit that transmits transmission data including a part of keys and identification information for identifying a user to a terminal device, the plurality of keys, and the identification information from another device. A key that generates a second key, which is the same key as the first key used for encrypting the private key, based on the acquired unit, the plurality of acquired keys, and the identification information. It is a key providing system including a generation unit and a terminal device including the generation unit.

One aspect of the present invention is an acquisition step of acquiring a plurality of keys generated from a first key used for encrypting a private key and identification information for identifying a user from another device. A key having a key generation step of generating a second key which is the same key as the first key used for encrypting the private key based on the plurality of keys and the identification information. It is a generation method.

One aspect of the present invention is an acquisition step of acquiring a plurality of keys generated from a first key used for encrypting a private key and identification information for identifying a user from another device. A key generation step of generating a second key, which is the same key as the first key used for encrypting the private key, based on the plurality of keys and the identification information, is provided to the computer. It is a computer program to be executed.

According to the present invention, it is possible to improve the confidentiality of the key used for encrypting the private key.

It is a figure which shows the functional structure of the key providing system 100 of this invention. It is a schematic block diagram which shows the functional structure of the key generation apparatus 10. It is a schematic block diagram which shows the functional structure of the terminal apparatus 40. It is a schematic block diagram which shows the functional structure of the IC card 45. It is a sequence diagram which shows the process flow of a key providing system 100. It is a figure for demonstrating the generation process of a derived key. It is a figure for demonstrating the generation process of transmission data.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a functional configuration of the key providing system 100 of the present invention. The key providing system 100 includes a key generating device 10, an issuing server 20, an application providing device 30, and a terminal device 40. The issuing server 20 and the terminal device 40 are communicably connected via the first network 50. The first network 50 is composed of, for example, the Internet. The application providing device 30 and the terminal device 40 are communicably connected via the second network 60. The second network 60 is composed of, for example, a communication network (first communication network) provided by a telecommunications carrier. It is assumed that the communication between the key generation device 10 and the terminal device 40 is encrypted by SSL.

The key generation device 10 is provided in a manufacturing factory or a place where security control is performed. A place where security management is performed is a place where double or triple security is provided in a highly confidential building such as a building. The key generation device 10 generates a private key and a key pair of a public key based on a public key cryptosystem. Further, the key generation device 10 holds a plurality of keys generated from the master key (first key) and identification information for identifying the user. The master key is a key used to encrypt a private key. Also, a plurality of keys are generated by dividing the master key.

As an example, when the master key is divided in the present embodiment, when the master key is composed of a bit string of nbyte (n is an integer of 2 or more), the bit string of nbyte is divided into a plurality of bit strings (for example, a bit string of n_Abyte, n_Bbyte). It means to divide into bit strings of. In the following description, seed A (n_Abyte) and seed B (n_Bbyte) will be used as a plurality of keys generated from the master key. However, here, it is assumed that n = n_A + n_B. The values of n_A and n_B may be the same or different. The seed A and the identification information have different values for each user. The seed B is incorporated in the logic (hereinafter referred to as "first logic") relating to the method of generating the derived key (second key) and the method of encrypting the private key. The derived key is a key for encrypting the private key. The derived key is generated based on a plurality of keys and identification information. The seed A, the identification information and the first logic may be provided by another device. For example, the first logic is provided in the source file.

The key generation device 10 generates a derived key according to the first logic. Further, the key generation device 10 generates an encrypted secret key by encrypting the private key according to the first logic. The key generation device 10 transmits the transmission data in which the seed A and the identification information are stored and the transmission data in which the encrypted private key is stored to the issuing server 20.
The issuing server 20 transmits the transmission data transmitted from the key generation device 10 to the terminal device 40 via the first network 50.

The application providing device 30 provides an application. The application is software executed in the terminal device 40. The application provided by the application providing device 30 (hereinafter referred to as “providing application”) is, for example, a credit application, a PKI (Public Key Infrastructure) application, or the like. Further, in the source file of the provided application, the seed B and the logic related to the method of generating the derived key and the method of decrypting the private key (hereinafter referred to as "second logic") are embedded. The application providing device 30 transmits the provided application to the terminal device 40 in response to a request from the terminal device 40.

The terminal device 40 is configured by using an information processing device such as a smartphone or a tablet terminal. The terminal device 40 restores the private key by decrypting the encrypted private key using the provided application transmitted from the application providing device 30, the seed A transmitted from the issuing server 20, and the identification information. To do.

FIG. 2 is a schematic block diagram showing a functional configuration of the key generation device 10.
The key generation device 10 includes a CPU (Central Processing Unit), a memory, an auxiliary storage device, and the like connected by a bus, and executes a key generation program. By executing the key generation program, the key generation device 10 functions as a device including a key generation unit 11, a transmission data generation information storage unit 12, a transmission data generation unit 13, and a communication unit 14. All or part of each function of the key generator 10 may be realized by using hardware such as ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), and the like. .. Further, the key generation program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, flexible disks, magneto-optical disks, portable media such as ROM (READ ONLY MEMORY) and CD-ROM (CompactDisk-READ ONLY MEMORY), and storage of hard disks built into computer systems. It is a device. Further, the key generation program may be transmitted and received via a telecommunication line.

The key generation unit 11 generates a private key and a key pair of a public key based on a public key cryptosystem.
The transmission data generation information storage unit 12 is configured by using a storage device such as a magnetic hard disk device or a semiconductor storage device. The transmission data generation information storage unit 12 stores the identification information and seed A for each user and the source file in which the first logic is embedded as transmission data generation information.
The transmission data generation unit 13 generates transmission data based on the transmission data generation information stored in the transmission data generation information storage unit 12.
The communication unit 14 transmits the transmission data generated by the transmission data generation unit 13 to the issuing server 20.

FIG. 3 is a schematic block diagram showing a functional configuration of the terminal device 40.
The terminal device 40 includes a CPU, a memory, an auxiliary storage device, and the like connected by a bus, and executes a terminal device program. By executing the terminal device program, the terminal device 40 functions as a device including the first communication unit 41, the second communication unit 42, the terminal control unit 43, and the mounting unit 44.
A detachable IC card 45 is mounted on the mounting unit 44, and the IC card 45 is connected to the terminal control unit 43. In addition, all or a part of each function of the terminal device 40 may be realized by using hardware such as ASIC, PLD and FPGA. Further, the terminal device program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a flexible disk, a magneto-optical disk, a portable medium such as a ROM or a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, the terminal device program may be transmitted and received via a telecommunication line.

The first communication unit 41 communicates with the application providing device 30 via the second network 60. For example, the first communication unit 41 receives the provided application from the application providing device 30.
The second communication unit 42 communicates with the issuing server 20 via the first network 50. For example, the second communication unit 42 receives transmission data from the issuing server 20.
The terminal control unit 43 is realized by, for example, a processor including a CPU and the like. The terminal control unit 43 controls the entire terminal device 40. The terminal control unit 43 transmits a command to the IC card 45 mounted on the mounting unit 44, and receives a response as a processing result of the command.
The IC card 45 is, for example, a SIM (Subscriber Identity Module) card and includes an IC chip 451.

FIG. 4 is a schematic block diagram showing the functional configuration of the IC card 45.
The IC chip 451 includes a communication unit 452, a control unit 453, an application storage unit 454, an application processing unit 455, and a secret key storage unit 456.
The communication unit 452 communicates with the terminal control unit 43. For example, the communication unit 452 receives the command transmitted from the terminal control unit 43.
The control unit 453 executes processing according to a command received by the communication unit 452.
The application storage unit 454 stores the application (provided application) provided by the application providing device 30.
The application processing unit 455 functions as a key generation unit 457 and a decryption unit 458 by executing the program.
The key generation unit 457 generates a derived key according to the second logic embedded in the source file of the provided application.
The decryption unit 458 restores the private key by decrypting the encrypted private key according to the second logic embedded in the source file of the provided application.
The private key storage unit 456 stores the private key restored by the decryption unit 458.

FIG. 5 is a sequence diagram showing a processing flow of the key providing system 100.
The application providing device 30 transmits the requested provided application to the terminal device 40 in response to the request from the terminal device 40 (step S101). In addition to the application program, seed B and the second logic are embedded in the source file of the provided application. The provided application is provided by the application providing device 30 in the form of binary data or the like.
The first communication unit 41 of the terminal device 40 receives the provided application transmitted from the application providing device 30. The first communication unit 41 outputs the received provided application to the terminal control unit 43.

The terminal control unit 43 generates a command indicating that the output provided application is stored, and transmits the generated command to the IC card 45. The communication unit 452 of the IC card 45 receives the command transmitted from the terminal control unit 43. The control unit 453 stores the provided application in the application storage unit 454 in response to the command received by the communication unit 452 (step S102).
The transmission data generation unit 13 of the key generation device 10 includes information indicating that the seed A and the identification information are included (hereinafter referred to as “grant information”), and the seed stored in the transmission data generation information storage unit 12. Generate transmission data that stores A and identification information. The transmission data generation unit 13 outputs the generated transmission data to the communication unit 14. The communication unit 14 transmits the transmission data to the issuing server 20 (step S103).

The issuing server 20 receives the transmission data transmitted from the key generation device 10. The issuing server 20 transmits the received transmission data to the terminal device 40 via the first network 50 (step S104).
The second communication unit 42 of the terminal device 40 receives the transmission data transmitted from the issuing server 20. The second communication unit 42 outputs the received transmission data to the terminal control unit 43. The terminal control unit 43 confirms the source address of the output transmission data, and transmits the transmission data to the IC card 45 when the source address is the address of the issuing server 20. The communication unit 452 of the IC card 45 receives the transmission data transmitted from the terminal control unit 43, and outputs the received transmission data to the control unit 453. The control unit 453 determines whether or not the key generation condition is satisfied based on the output transmission data (step S105).

The condition for key generation is that the grant information and the provided application are complete. The key generation condition may be embedded in the logic of the provided application, or may be stored in advance by the control unit 453. If the key generation condition is not satisfied (step S105-NO), the control unit 453 waits until the key generation condition is satisfied.
On the other hand, when the key generation condition is satisfied (step S105-YES), the control unit 453 instructs the key generation unit 457 to generate the derived key, and also generates the seed A and the identification information included in the transmission data in the key generation unit. Output to 457.

The key generation unit 457 generates a derived key in response to an instruction from the control unit 453 (step S106). The process of generating the derived key will be described with reference to FIG. FIG. 6 is a diagram for explaining a process of generating a derived key. In the present embodiment, the derived key generation process by the key generation unit 457 follows the logic of the derived key generation method among the second logics embedded in the source file of the provided application stored in the application storage unit 454. It is performed in two steps shown in FIGS. 6 (A) and 6 (B). The logic of the derived key generation method is the derived key such as how to restore the master key by combining seeds A and B, and how to use the restored master key to generate the derived key. Includes the process up to the generation of.

In the following description, seed A is represented by ○○ ・ ・ ○○, seed B is represented by □□ ・ ・ □□, and identification information is represented by △△ ・ ・ ・ △△. As the first step, the key generation unit 457 combines the acquired seed A ○○ ・ ・ ○○ with the seed B □□ ・ ・ □□ embedded in the source file of the provided application to obtain a master key. Restore. Here, the master key restoration process will be described with an example. When the master key restoration method in the logic of the derived key generation method is the logic of combining the bit string of seed A after the bit string of seed B, the key generation unit 457 is the bit string of seed B □□ ・ ・ □□. Later, the master key □□ ・ ・ □□ ○○ ・ ・ ○○ is restored by combining the bit strings of seeds A ○○ ・ ・ ○○ (Fig. 6 (A)).

Next, as the second step, the key generation unit 457 encrypts the identification information △△ ・ ・ ・ △△ using the restored master key □□ ・ ・ □□ ○○ ・ ・ ○○. Generate a derived key by. Here, the process of generating the derived key by the key generation unit 457 will be described with an example. When the derived key generation method in the logic of the derived key generation method is the logic of encrypting the identification information by the first algorithm using the restored master key, the key generation unit 457 uses the master key □□ ... Derived key ◎◎ ・ ・ ・ ◎◎ is generated by encrypting the identification information △△ ・ ・ ・ △△ by the first algorithm using □□ ○○ ・ ・ ○○ (Fig. 6 (B)). ). The key generation unit 457 stores the generated derived key ◎ ◎ ... ◎ ◎ in the providing application (step S107).

The transmission data generation unit 13 of the key generation device 10 generates transmission data including an encryption secret key based on the transmission data generation information stored in the transmission data generation information storage unit 12. The transmission data generation process will be described with reference to FIG. FIG. 7 is a diagram for explaining a process of generating transmission data. First, the transmission data generation unit 13 restores the master key according to the logic of the method of generating the derived key among the first logics stored in the transmission data generation information storage unit 12. In the present embodiment, the process of generating the derived key by the transmission data generation unit 13 is executed in the two steps shown in FIGS. 7 (A) and 7 (B).

As the first step, the transmission data generation unit 13 includes seeds A ○○ ・ ・ ○○ stored in the transmission data generation information storage unit 12 and seeds B □□ ・ embedded in the first logic.・ Restore the master key in combination with □□. Here, the master key restoration process will be described with an example. When the restoration method of the master key is the logic of combining the bit string of seed A after the bit string of seed B, the transmission data generation unit 13 has the bit string of seed B □□ ・ ・ □□ followed by seed A ○○ ・. -The master key □□ ・ ・ □□ ○○ ・ ・ ○○ is restored by combining the bit strings of ○○ (Fig. 7 (A)).

Next, as the second step, the transmission data generation unit 13 encrypts the identification information △△ ・ ・ △△ using the restored master key □□ ・ ・ □□ ○○ ・ ・ ○○. Generate a derived key by. Here, the process of generating the derived key by the transmission data generation unit 13 will be described with an example. When the method of generating the derived key in the logic of the method of generating the derived key is the logic of encrypting the identification information by the first algorithm using the restored master key, the transmission data generation unit 13 uses the master key □□ ・・ □□ ○○ ・ ・ ○○ is used to encrypt the identification information △△ ・ ・ ・ △△ by the first algorithm to generate the derived key ◎◎ ・ ・ ・ ◎◎ (Fig. 7 (B)). )).

After that, the transmission data generation unit 13 encrypts the private keys XX ... XX using the generated derived keys ◎ ◎ ... ◎ ◎ according to the logic of the secret key encryption method in the first logic. Generate an encrypted private key by doing so. The logic of the private key encryption method includes the process up to the encryption of the private key, such as what kind of algorithm is used to encrypt the private key using the derived key.

Here, a method of encrypting the private key by the transmission data generation unit 13 will be described with an example. When the logic of the encryption method of the private key is the logic of encrypting the private key by the second algorithm using the generated derived key, the transmission data generation unit 13 uses the generated derived key ◎ ◎ ... The encrypted private key YY ... YY is generated by encrypting the private key XX ... XX with the second algorithm using ◎◎ (FIG. 7 (C)). Then, the transmission data generation unit 13 generates transmission data in which the generated encryption secret keys YY ... YY are stored. The transmission data generation unit 13 outputs the generated transmission data to the communication unit 14. The communication unit 14 transmits the output transmission data to the issuing server 20 (step S108).

The issuing server 20 receives the transmission data transmitted from the key generation device 10 and transmits the received transmission data to the terminal device 40 (step S109).
The second communication unit 42 of the terminal device 40 receives the transmission data transmitted from the issuing server 20. The second communication unit 42 outputs the received transmission data to the terminal control unit 43. The terminal control unit 43 confirms the source address of the output transmission data, and transmits the transmission data to the IC card 45 when the source address is the address of the issuing server 20. The communication unit 452 of the IC card 45 receives the transmission data transmitted from the terminal control unit 43, and outputs the received transmission data to the control unit 453. Since the control unit 453 includes the encryption secret key YY ... YY in the output transmission data, the control unit 453 instructs the decryption unit 458 to decrypt the secret key and the encryption secret key YY included in the transmission data. ... Outputs YY to the decoding unit 458.

The decryption unit 458 decrypts the private key according to the instruction of the control unit 453 (step S110). Specifically, the decryption unit 458 uses the derived key ◎◎ ・ ・ ・ ◎◎ stored in the provided application according to the logic of the secret key decryption method in the second logic, and encrypts the private key YY. ... Restore the private key by decrypting YY. The logic of the method of decrypting the private key includes a process up to decryption of the private key, such as what kind of algorithm is used to decrypt the encrypted private key using the derived key.

Here, an example of a method of decrypting the private key by the decryption unit 458 will be described. When the logic of the method of decrypting the private key is the logic of decrypting the encrypted private key by the second algorithm using the derived key, the decryption unit 458 uses the derived key ◎◎ ・ ・ ・ ◎◎. The secret keys XX ... XX are restored by decrypting the encrypted secret keys YY ... YY with the second algorithm. The decryption unit 458 stores the restored private key XX ... XX in the secret key storage unit 456 (step S111).

In the key providing system 100 configured as described above, the confidentiality of the key used for encrypting the private key can be improved. Specifically, the key generation device 10 transmits the seed A generated from the master key used for encrypting the private key and the identification information to the terminal device 40 via the first network 50. Further, the application providing device 30 transmits the seed B generated from the master key used for encrypting the private key to the terminal device 40 via the second network 60. The terminal device 40 restores the master key using the seed A and the seed B, and encrypts the identification information with the restored master key to generate a derived key in which the private key is encrypted. In this way, in the key providing system 100, the seed A and the seed B constituting the master key are transmitted separately. Therefore, it is possible to improve the confidentiality of the key used for encrypting the private key.

Further, the restored private key is stored in the anti-tamper area of the terminal device 40. As a result, it is unlikely that the private key will be leaked to the outside. Therefore, the security of the private key can be improved.
The seed B is embedded in the source file of the application. In addition, the application code is provided as a compiled BIN file. Therefore, it is difficult to identify the seed B even if it is eavesdropped. Therefore, since the security against the leakage of the seed B is high, the possibility that the derived key is generated can be reduced.

<Modification example>
In the present embodiment, the terminal device 40 including the IC card 45 has been described as an example, but it can also be applied to a storage medium having a CPU (for example, an IC card, a USB token with an IC chip, etc.).
In the present embodiment, the master key □□ ・ ・ □□ ○○ ・ ・ ○○ is halved to generate seed A ○○ ・ ・ ○○ and seed B □□ ・ ・ □□. Seed B may be generated according to the following criteria. For example, seed A may be generated by an odd-numbered byte string, and seed B may be generated by an even-numbered byte string. In this case, as the logic of the method of generating the derived key, for example, the bit string of the seed A and the bit string of the seed B are used, and the order is based on the seed A (for example, seed A, seed B, seed A). , Seed B, ...), and the logic to restore the master key is assumed. Further, the seed B may be generated by an odd-numbered byte string, and the seed A may be generated by an even-numbered byte string. In this case, as the logic of the method of generating the derived key, for example, a bit string of seed A and a bit string of seed B are used, and the order is based on seed B (for example, seed B, seed A, seed B). , Seed A, ...), and the logic to restore the master key is assumed. Further, the number of seeds generated from the master key (nbyte) may be three or more. Further, the number of bit strings of each seed may be appropriately set.

Further, in the description of FIG. 5, the key generation device 10 shows a configuration in which the transmission data storing the encryption private key is transmitted after the transmission data storing the seed A and the identification information. After transmitting the transmission data in which the seed A and the identification information are stored, the transmission data in which the seed A and the identification information are stored may be transmitted. In such a configuration, the terminal device 40 temporarily holds the encrypted private key, and when the transmission data storing the seed A and the identification information is received, the terminal device 40 generates the derived key and the secret key. Decryption processing is performed.
Further, in the present embodiment, the processes of steps S105 to 107 and steps S110 to 111 of FIG. 5 are performed in the IC card 45 of the terminal device 40, but these processes are performed by the terminal of the terminal device 40. It may be performed in the control unit 43. When configured in this way, the restored private key may be stored in any storage unit as long as it is stored in the tamper-resistant area.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design and the like within a range not deviating from the gist of the present invention are also included.

10 ... Key generation device, 20 ... Issuing server, 30 ... Application providing device, 40 ... Terminal device, 50 ... First network, 60 ... Second network, 11 ... Key generation unit, 12 ... Transmission data generation information storage unit, 13 ... Transmission data generation unit, 14 ... Communication unit, 41 ... 1st communication unit, 42 ... 2nd communication unit, 43 ... Terminal control unit, 44 ... Mounting unit, 45 ... IC card, 451 ... IC chip, 452 ... Communication unit , 453 ... Control unit, 454 ... Application storage unit, 455 ... Application processing unit, 456 ... Private key storage unit, 457 ... Key generation unit, 458 ... Decryption unit

Claims (9)

An acquisition unit that acquires a plurality of keys generated from the first key used for encrypting the private key and identification information for identifying the user from another device.
A key generation unit that generates a second key, which is the same key as the first key used for encrypting the private key, based on the acquired plurality of keys and the identification information.
A terminal device comprising. Some of the plurality of keys are set in the application, and
The terminal device according to claim 1, wherein the acquisition unit acquires a part of the plurality of keys by acquiring the application. In the application, the logic related to the second key generation method is further set.
The terminal device according to claim 2, wherein the key generation unit generates the second key according to the logic. The acquisition unit acquires the application via the first communication network, and acquires some of the keys among the plurality of keys via a communication network different from the first communication network, claim 2 or. 3. The terminal device according to 3. The key generation unit restores the first key by combining the plurality of keys according to a predetermined condition, and encrypts the identification information by a predetermined algorithm using the restored first key. The terminal device according to any one of claims 1 to 4, wherein the second key is generated thereby. Further provided with a decryption unit that recovers the private key by decrypting the encrypted private key using the generated second key.
The terminal device according to any one of claims 1 to 5, wherein the decryption unit stores the restored private key in a tamper-resistant area in the own device. A key generator that generates a private key and a key that is a pair of the private key,
A communication unit that transmits transmission data including a part of the keys generated from the first key used for encrypting the private key and identification information for identifying the user to the terminal device.
A key generator equipped with
An acquisition unit that acquires the plurality of keys and the identification information from another device, and
A key generation unit that generates a second key, which is the same key as the first key used for encrypting the private key, based on the acquired plurality of keys and the identification information.
With a terminal device equipped with
A key providing system equipped with. An acquisition step of acquiring a plurality of keys generated from a first key used for encrypting a private key and identification information for identifying a user from another device.
A key generation step of generating a second key, which is the same key as the first key used for encrypting the private key, based on the acquired plurality of keys and the identification information.
Key generation method having. An acquisition step of acquiring a plurality of keys generated from a first key used for encrypting a private key and identification information for identifying a user from another device.
A key generation step of generating a second key, which is the same key as the first key used for encrypting the private key, based on the acquired plurality of keys and the identification information.
A computer program that lets a computer run.

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