Security system

Abstract

This security system provides a mechanism to prevent information secured by a management key in a specific area from being retrieved by applications that store that information in other areas. [Solution] When security management is requested, the security device performs a specific process to identify the other key in the key pair used for authentication, based on information indicating a specific area AS. If the security device fails to authenticate the authentication information AT using the other key in the key pair identified in the specific process, it does not perform security management for the target information TA. If the security device succeeds in authenticating the authentication information AT using the other key in the key pair identified in the specific process, it performs security management for the target information TA.

Description

Technical Field

[0001] The present invention relates to a security system.

Background Art

[0002] Patent Document 1 describes a security system including a target device and a security device. The security device stores an administrative key for managing information of the target device. The security device performs security management such as digital signature using the administrative key for the information of the target device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the security system as described in Patent Document 1, the storage device of the target device may store applications in each of a plurality of areas. In this case, it is required that the security device perform security management for each area regarding the information associated with executing the applications stored in different areas.

Means for Solving the Problems

[0005] A security system for solving the above problems comprises a target device having a storage device that stores applications in each of multiple areas, and an execution device that executes the applications, and a security device that performs security management on the information of the target device using different management keys for each area, wherein the execution device is a key pair for authenticating that the security management will be performed on the information associated with the execution of the applications, and includes an authentication information generation process that generates authentication information that can be authenticated by the other key pair for the specific area using one of the key pairs for a specific area in which one of the multiple applications is stored, and the security When requesting security management from the security device regarding target information associated with the execution of the specific application, the system performs an authentication request process that sends information indicating the specific area and the authentication information generated in the authentication information generation process to the security device. When the security device is requested to perform security management, it performs a specific process to identify the other half of the key pair used for authentication based on the information indicating the specific area. If the security device fails to authenticate the authentication information using the other half of the key pair identified in the specific process, it does not perform security management regarding the information of the target device. If it succeeds in authenticating the authentication information using the other half of the key pair identified in the specific process, it performs security management. [Effects of the Invention]

[0006] The security device described above performs security management only if it can authenticate the authentication information for each area, and does not perform security management if it can authenticate the authentication information. Therefore, the security device can prevent information that has been secured by the management key of a specific area from being obtained by the execution of an application stored in another area. [Brief explanation of the drawing]

[0007] [Figure 1]Figure 1 is a schematic diagram showing the security system of the first embodiment. [Figure 2] Figure 2 is an explanatory diagram showing a series of processes performed by the security system of the first embodiment. [Figure 3] Figure 3 is an explanatory diagram illustrating a series of processes performed by the security system of the second embodiment. [Figure 4] Figure 4 is an explanatory diagram illustrating a series of processes performed by the security system of the third embodiment. [Modes for carrying out the invention]

[0008] <First Embodiment> The first embodiment of the security system will be described below with reference to the drawings. <Overview of the security system> As shown in Figure 1, the security system 10 comprises a target device 20 and a security device 30. The security system 10 is mounted on a vehicle. The target device 20 and the security device 30 are able to communicate with each other.

[0009] The target device 20 is an ECU. The target device 20 establishes an in-vehicle network in the vehicle. In the in-vehicle network, the target device 20 communicates with other ECUs (not shown in the diagram).

[0010] The target device 20 is a device in the in-vehicle network that is subject to security management by the security device 30. The target device 20 comprises an execution device 21, RAM 22, and storage device 23.

[0011] The execution device 21 is the CPU. The execution device 21 performs various processes. The RAM 22 temporarily stores data generated by the processing performed by the execution device 21. The storage device 23 is ROM. The storage device 23 stores applications in each of its multiple areas. Specifically, the storage device 23 has a first area AR1 and a second area AR2.

[0012] The first area AR1 is an internal area. The internal area is an area that can be accessed in conjunction with the execution of applications stored in the internal area, but access is restricted in conjunction with the execution of applications stored outside the internal area. The storage device 23 stores the first application AP1 in the first area AR1.

[0013] The second area, AR2, is the entry point area. The entry point area is an area that can be accessed in conjunction with the execution of applications stored in the entry point area, and access to applications stored outside the entry point area is not restricted in conjunction with the execution of applications. The storage device 23 stores the second application AP2 in the second area, AR2.

[0014] Therefore, in this embodiment, the execution device 21 cannot access the first region AR1 when executing the second application AP2. On the other hand, the execution device 21 can access the second region AR2 when executing the first application AP1.

[0015] Furthermore, the execution device 21 requests security management from the security device 30 regarding information associated with the execution of each application. Security management includes digital signing, encryption, and decryption using the management key MK managed by the security device 30.

[0016] The security device 30 is a so-called HSM (Hardware Security Module). The security device 30 stores a management key MK for each area of ​​the target device 20, which is used to manage the security of information associated with the execution of applications stored in that area.

[0017] Specifically, the security device 30 includes an execution device 31, a RAM 32, and a storage device 33. The execution device 31 executes various processes. The RAM 32 temporarily stores data generated by the processes performed by the execution device 31. The storage device 33 is a ROM. The storage device 33 stores a first management key MK1 used for security management of information associated with the execution of an application stored in the first area AR1 of the target device 20. The storage device 33 stores a second management key MK2 used for security management of information associated with the execution of an application stored in the second area AR2 of the target device 20. The first management key MK1 is different from the second management key MK2.

[0018] As shown in FIG. 2, the security system 10 performs a series of processes related to access restriction for security management. Specifically, when the power of the target device 20 changes from the off state to the on state, that is, when the target device​​​​​​​In step S12, the execution device 31 performs a second key pair generation process. In the second key pair generation process, the execution device 31 generates a pair of a second secret key SK2 and a second public key PK2 as the key pair for the second area AR2. The key pair for the second area AR2 is used for authentication when security management is required for information associated with the execution of the second application AP2 stored in the second area AR2. Note that the key pair generation process includes the first key pair generation process and the second key pair generation process. Therefore, when the target device 20 is activated, the execution device 31 performs the key pair generation process. Thereafter, the execution device 31 advances the process to step S13.

[0021] In step S13, the execution device 31 performs an other-party storage process. In the other-party storage process, the execution device 31 stores each public key PK, which is the other party of the key pair, in association with the area. Specifically, the execution device 31 stores the first public key PK1 in association with the first area AR1. The execution device 31 stores the second public key PK2 in association with the second area AR2.

[0022] Thereafter, the execution device 31 performs a transmission process. In the transmission process, the execution device 31 transmits each secret key SK, which is one party of the key pair, to the target device 20. Specifically, the execution device 31 transmits the first secret key SK1 to the target device 20 in association with the first area AR1. Also, the execution device 31 transmits the second secret key SK2 to the target device 20 in association with the second area AR2.

[0023] When the target device 20 receives the first secret key SK1 and the second secret key SK2, the execution device 21 performs the process of step S14. In step S14, the execution device 21 performs a one-party storage process. In the one-party storage process, the execution device 21 stores the received plurality of secret keys SK in the storage device 23 so that the secret key SK of the corresponding area can be used only when executing the application stored in each area.

[0024] Specifically, the execution device 21 stores the first secret key SK1 in the storage device 23 so that the first secret key SK1 of the first area AR1 can be used only when executing the first application AP1 stored in the first area AR1. In addition, the execution device 21 stores the second secret key SK2 in the storage device 23 so that the second secret key SK2 of the second area AR2 can be used only when executing the second application AP2 stored in the second area AR2.

[0025] More specifically, the execution device 21 stores the first secret key SK1 in the first area AR1 of the storage device 23. The execution device 21 stores the second secret key SK2 in the second area AR2 of the storage device 23.

[0026] Subsequently, the execution device 21 performs a prohibition request process. In the prohibition request process, the execution device 21 sends a transmission prohibition request PD to the security device 30, which is a request to prohibit the transmission of the first secret key SK1 and the second secret key SK2.

[0027] Upon receiving the transmission prohibition request PD, the security device 30 performs the process in step S15. In step S15, the execution device 31 prohibits further transmission of the first secret key SK1 and the second secret key SK2 in accordance with the transmission prohibition request PD. After that, the security device 30 waits.

[0028] Then, the target device 20 performs the processing in step S21 in response to a request from the in-vehicle network or the like. In step S21, the execution device 21 executes a specific application APS. The specific application APS is one of several applications stored in the target device 20. In this embodiment, the specific application APS is either the first application AP1 or the second application AP2. As the execution device 21 executes the specific application APS, it generates target information TA, which is information for security management. After that, the target device 20 proceeds to step S22.

[0029] In step S22, the execution device 21 performs authentication information generation processing. In the authentication information generation processing, the execution device 21 generates a digital signature DS for access as authentication information AT using the private key SK associated with the specific area AS, which is the area where the specific application APS is stored. Authentication information AT is information that can be authenticated using the public key PK associated with the specific area AS.

[0030] Subsequently, the execution device 21 performs authentication request processing. In the authentication request processing, the execution device 21 requests security management for the target information TA from the security device 30. When requesting security management in the authentication request processing, the execution device 21 sends the target information TA, the digital signature DS generated in the authentication information generation processing, and information indicating the specific area AS to the security device 30.

[0031] When security device 30 requests security management, execution device 31 performs the process in step S23. In step S23, execution device 31 performs identification processing. In identification processing, execution device 31 identifies the public key PK to be used for authentication based on information indicating a specific area AS. After that, execution device 31 proceeds to step S24.

[0032] In step S24, the execution device 31 authenticates the authentication information AT. If the execution device 31 fails to authenticate the authentication information AT, it does not perform security management for the target information TA. On the other hand, if the execution device 31 succeeds in authenticating the authentication information AT, it performs security management for the target information TA.

[0033] Specifically, the execution device 31 authenticates by verifying the digital signature DS for access using the identified public key PK. If the execution device 31 fails to authenticate, it does not perform security management for the target information TA. On the other hand, if the execution device 31 succeeds in authentication, it performs security management for the target information TA.

[0034] Subsequently, if the execution device 31 performs security management on the target information TA, the execution device 31 sends the security-managed target information TA to the target device 20 as an authentication result RE. On the other hand, if the execution device 31 does not perform security management on the target information TA, the execution device 31 sends information indicating that authentication failed to the target device 20 as an authentication result RE. With this, the security system 10 terminates this series of processes related to access restriction.

[0035] <Operation of the First Embodiment> The target device 20 generates authentication information AT using a secret key SK corresponding to a specific area AS in order to request security management for the target information TA when executing a specific application APS. Then, when the target device 20 requests security management for the target information TA, it transmits the authentication information AT to the security device 30.

[0036] Therefore, when the target device 20 requests security management for information associated with the execution of the first application AP1, it can access the first area AR1 when executing the first application AP1. Therefore, when the target device 20 legitimately accesses the first area AR1 by executing the first application AP1, it generates authentication information AT using the first secret key SK1.

[0037] On the other hand, when the target device 20 executes the second application AP2, it cannot access the first area AR1, which is an internal area, and therefore does not generate authentication information AT using the first secret key SK1.

[0038] <Effects of the First Embodiment> (1-1) According to the first embodiment described above, the security device 30 authenticates authentication information AT using one of the key pairs for each area, using the other key pair for each area. If the security device 30 fails to authenticate the authentication information AT received from the target device 20, it does not perform security management. Therefore, the security device 30 can prevent information that has been security-managed by the management key MK of a specific area AS from being acquired in conjunction with the execution of an application stored in another area.

[0039] (1-2) When the target device 20 is started up, the security device 30 performs a new key pair generation process. Therefore, even if the target device 20 is accessed once by the execution of an application stored in a different area AS than the specific area AS of the target device 20, a new key pair is generated each time the target device 20 is started up. After startup, the one key pair that was previously obtained will no longer be used to authenticate with the security device 30. This prevents the target device 20 from accessing the security device 30 again.

[0040] (1-3) After receiving one of the key pairs for each region, the target device 20 sends a transmission prohibition request PD to the security device 30. The security device 30 then prohibits the transmission of one of the key pairs in response to the transmission prohibition request PD. This prevents an excessive number of opportunities for the secret key SK to be leaked during communication between the security device 30 and the target device 20 due to excessive communication of one of the key pairs.

[0041] (1-4) The execution device 21 stores one of the key pairs for each region in the storage device 23 so that it is only available when executing an application stored in that region. Therefore, it is possible to prevent the use of one of the key pairs when an application stored in another region is executed.

[0042] (1-5) According to the first embodiment, the security system 10 can restrict access from the target device 20 to the security device 30 by utilizing the digital signature DS.

[0043] <Second Embodiment> The second embodiment of the security system will be described below with reference to the drawings. The same configuration as in the first embodiment will be simplified or omitted from the description. The second embodiment differs from the first embodiment in that it uses a symmetric key pair as the key pair. That is, the security system 10 in the second embodiment uses a symmetric key cryptography scheme to restrict access.

[0044] As shown in Figure 3, the security system 10 performs a series of processes related to access restrictions for security management. Specifically, when the target device 20 is started up, the security system 10 starts the series of processes. Once the security system 10 starts the series of processes, the execution device 31 first performs the process in step S31.

[0045] In step S31, the execution device 31 performs the first key pair generation process. In the first key pair generation process, the execution device 31 generates a pair of first common keys CK1 as the key pair for the first region AR1. After that, the execution device 31 proceeds to step S32.

[0046] In step S32, the execution device 31 performs the second key pair generation process. In the second key pair generation process, the execution device 31 generates a pair of second common keys CK2 as the key pair for the second region AR2. After that, the execution device 31 proceeds to step S33.

[0047] In step S33, the execution device 31 performs the other-side storage process. In this embodiment, one and the other of the key pair are the same common key CK. In the other-side storage process, the execution device 31 stores the first common key CK1 in the storage device 33, associated with the first area AR1. The execution device 31 also stores the second common key CK2 in the storage device 33, associated with the second area AR2.

[0048] Subsequently, the execution device 31 performs a transmission process. In the transmission process, the execution device 31 sends the first common key CK1 to the target device 20, linked to the first area AR1. The execution device 31 also sends the second common key CK2 to the target device 20, linked to the second area AR2.

[0049] When the target device 20 receives the first common key CK1 and the second common key CK2, the execution device 21 performs the process in step S34. In the process in step S34, the execution device 21 performs a one-way storage process. In the one-way storage process, the execution device 21 stores the first common key CK1 in the storage device 23 so that the first common key CK1 of the first area AR1 can be used only when executing the first application AP1 stored in the first area AR1. The execution device 21 also stores the second common key CK2 in the storage device 23 so that the second common key CK2 of the second area AR2 can be used only when executing the second application AP2 stored in the second area AR2.

[0050] Subsequently, the execution device 21 performs a prohibition request process. In the prohibition request process, the execution device 21 sends a transmission prohibition request PD to the security device 30, which is a request to prohibit the transmission of the first common key CK1 and the second common key CK2.

[0051] When the security device 30 receives a transmission prohibition request PD, the execution device 31 performs the process in step S35. In step S35, the execution device 31 prohibits further transmission of the first common key CK1 and the second common key CK2 in accordance with the transmission prohibition request PD. After that, the security device 30 waits.

[0052] Then, the target device 20 performs the processing in step S41 in response to a request from the in-vehicle network or the like. In step S41, the execution device 21 executes the specific application APS. The execution device 21 generates target information TA in conjunction with executing the specific application APS. After that, the target device 20 proceeds to step S42.

[0053] In step S42, the execution device 21 performs authentication information generation processing. In the authentication information generation processing, the execution device 21 generates a message authentication code MAC as authentication information AT using a common key CK associated with a specific area AS. Authentication information AT is information that can be authenticated using the common key CK associated with a specific area AS.

[0054] Subsequently, the execution device 21 performs authentication request processing. In the authentication request processing, the execution device 21 requests security management for the target information TA from the security device 30. When requesting security management in the authentication request processing, the execution device 21 sends the target information TA, the message authentication code MAC as authentication information AT, and information indicating the specific area AS to the security device 30.

[0055] When security device 30 requests security management, execution device 31 performs the process in step S43. In step S43, execution device 31 performs identification processing. In identification processing, execution device 31 identifies the common key CK to be used for authentication based on information indicating a specific area AS. After that, execution device 31 proceeds to step S44.

[0056] In step S44, the execution device 31 authenticates the authentication information AT. If the execution device 31 fails to authenticate the authentication information AT, it does not perform security management for the target information TA. On the other hand, if the execution device 31 successfully authenticates the authentication information AT, it performs security management for the target information TA.

[0057] Specifically, the execution device 31 authenticates the message authentication code MAC using the identified common key CK. If the execution device 31 fails to authenticate, it does not perform security management for the target information TA. On the other hand, if the execution device 31 succeeds in authentication, it performs security management for the target information TA. After that, the execution device 31 sends the authentication result RE to the target device 20. With this, the security system 10 terminates this series of processes related to access restriction.

[0058] <Effects of the second embodiment> According to the second embodiment described above, in addition to the effects (1-1) to (1-4) in the first embodiment, the following effects can be achieved.

[0059] (2-1) According to the second embodiment, the security system 10 can restrict access from the target device 20 to the security device 30 by utilizing the message authentication code MAC.

[0060] <Third Embodiment> The third embodiment of the security system will be described below with reference to the drawings. The same configuration as in the first embodiment will be simplified or omitted from the description. The third embodiment differs from the first embodiment mainly in that it uses encrypted data of the target information TA as the authentication information AT.

[0061] As shown in Figure 4, the security system 10 performs a series of processes related to access restrictions for security management. Specifically, when the target device 20 is started up, the security system 10 starts the series of processes. Once the security system 10 starts the series of processes, the execution device 31 first performs the process in step S51.

[0062] In step S51, the execution device 31 performs the first key pair generation process. In the first key pair generation process, the execution device 31 generates a pair of the first private key SK1 and the first public key PK1 as the key pair for the first area AR1. After that, the execution device 31 proceeds to step S52.

[0063] In step S52, the execution device 31 performs the second key pair generation process. In the second key pair generation process, the execution device 31 generates a pair of the second private key SK2 and the second public key PK2 as the key pair for the second area AR2. After that, the execution device 31 proceeds to step S53.

[0064] In step S53, the execution device 31 performs the other-key storage process. In this embodiment, the other key of the key pair is the secret key SK. In the other-key storage process, the execution device 31 stores the first secret key SK1 in the storage device 33, associated with the first area AR1. The execution device 31 also stores the second secret key SK2 in the storage device 33, associated with the second area AR2.

[0065] Subsequently, the execution device 31 performs a transmission process. In this embodiment, one of the key pairs is the public key PK. During the transmission process, the execution device 31 sends the first public key PK1 to the target device 20, linked to the first area AR1. The execution device 31 also sends the second public key PK2 to the target device 20, linked to the second area AR2.

[0066] When the target device 20 receives the first public key PK1 and the second public key PK2, the execution device 21 performs the process in step S54. In the process in step S54, the execution device 21 performs a one-way storage process. In the one-way storage process, the execution device 21 stores the first public key PK1 in the storage device 23. The execution device 21 also stores the second public key PK2 in the storage device 23.

[0067] Subsequently, the execution device 21 performs a prohibition request process. In the prohibition request process, the execution device 21 sends a transmission prohibition request PD to the security device 30, which is a request to prohibit the transmission of the first public key PK1 and the second public key PK2.

[0068] When the security device 30 receives a transmission prohibition request PD, the execution device 31 performs the process in step S55. In the process in step S55, the execution device 31 prohibits further transmission of the first public key PK1 and the second public key PK2 in accordance with the transmission prohibition request PD. After that, the security device 30 waits.

[0069] Then, the target device 20 performs the processing in step S61 in response to a request from the in-vehicle network or the like. In step S61, the execution device 21 executes a specific application APS. The execution device 21 generates target information TA in conjunction with the execution of the specific application APS. After that, the target device 20 proceeds to step S62.

[0070] In step S62, the execution device 21 performs authentication information generation processing. In the authentication information generation processing, the execution device 21 generates encrypted data as authentication information AT by encrypting the target information TA using the public key PK associated with the specific area AS. Authentication information AT is information that can be authenticated using the private key SK associated with the specific area AS.

[0071] Subsequently, the execution device 21 performs authentication request processing. In the authentication request processing, the execution device 21 requests security management for the target information TA from the security device 30. When requesting security management in the authentication request processing, the execution device 21 sends encrypted data of the target information TA and information indicating a specific area AS to the security device 30.

[0072] When security device 30 requests security management, execution device 31 performs the process in step S63. In step S63, execution device 31 performs identification processing. In identification processing, execution device 31 identifies the secret key SK to be used for authentication based on information indicating a specific area AS. After that, execution device 31 proceeds to step S64.

[0073] In step S64, the execution device 31 authenticates the authentication information AT. If the execution device 31 fails to authenticate the authentication information AT, it does not perform security management for the target information TA. On the other hand, if the execution device 31 succeeds in authenticating the authentication information AT, it performs security management for the target information TA.

[0074] Specifically, the execution device 31 authenticates by decrypting the encrypted data of the target information TA using the identified secret key SK. If the execution device 31 fails to authenticate, it does not perform security management for the target information TA. On the other hand, if the execution device 31 succeeds in authentication, it performs security management for the target information TA. After that, the execution device 31 sends the authentication result RE to the target device 20. With this, the security system 10 terminates this series of processes related to access restriction.

[0075] <Effects of the Third Embodiment> According to the third embodiment described above, in addition to the effects (1-1) to (1-3) in the first embodiment, the following effects can be achieved.

[0076] (3-1) According to the third embodiment, the security system 10 can restrict access from the target device 20 to the security device 30 by utilizing encrypted data as authentication information AT.

[0077] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0078] The security device 30 does not need to perform the key pair generation process every time the target device 20 is started up. The timing of the key pair generation process may be at predetermined intervals.

[0079] The target device 20 does not have to perform one-way storage processing. Also, the security device 30 does not have to perform key pair generation processing, other-way storage processing, and transmission processing. For example, the target device 20 may have one of the key pairs stored in advance, and the security device 30 may have the other of the key pairs stored in advance.

[0080] The execution device 21 does not need to perform transmission prohibition request processing. The security device 30 may, in its one-way storage process, store one of the key pairs in a way that makes it available when executing an application stored in a different area than the corresponding area. [Explanation of symbols]

[0081] 10…Security system 20…Target device 21…Execution device 23…Storage device 30…Security device 31…Execution device 33…Storage device APS...Specific Application AS…specific area AT... Authentication information MK…Management key TA…Target Information

Claims

1. A target device having a storage device that stores applications in each of multiple areas, and an execution device that executes the said applications, A security device that performs security management using different management keys for each area regarding information associated with the execution of the aforementioned application, A security system equipped with, The execution device is A key pair for authenticating the security management of information associated with the execution of the aforementioned application, comprising an authentication information generation process that generates authentication information that can be authenticated by the other key pair for a specific area, using one of the key pairs for a specific area where one of the multiple aforementioned applications is stored, and When requesting security management from the security device regarding target information associated with the execution of the specified application, the following authentication request process is performed: sending information indicating the specified area and the authentication information generated in the authentication information generation process to the security device. When security management is requested, the security device performs a specific process to identify the other key in the key pair used for authentication based on information indicating the specific area. If the security device fails to authenticate the authentication information using the other key of the key pair identified in the specified process, it will not perform the security management for the information of the target device. If it succeeds in authenticating the authentication information using the other key of the key pair identified in the specified process, it will perform the security management. Security system.

2. The security device is When the target device is started, a key pair generation process is performed to generate the key pair for each region, A transmission process that transmits one of the multiple key pairs generated in the key pair generation process to the target device, The other key pair generated in the key pair generation process is stored in association with the area in a storage process. The execution device performs a one-way storage operation, which involves storing one of the multiple key pairs received by the transmission process in the storage device. The security system according to claim 1.

3. After the execution device receives one of the key pairs for each region, it performs a prohibition request process that requests the security device to prohibit the transmission of the other key pair. The security device prohibits the transmission of one of the key pairs in accordance with the prohibition request processing. The security system according to claim 2.

4. In the aforementioned one-way storage process, the security device stores one of the multiple key pairs received by the transmission process in the storage device, making it available only when executing the application stored in the corresponding area. The security system according to claim 2.

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