JP7275963B2 - Communication system and communication method - Google Patents

Description

The present invention relates to a technical field of electronic information storage media such as a secure element (SE) having an application (sometimes referred to as “Application”) that encrypts communication data between communication terminals.

Among IC (Integrated Circuit) cards such as SEs that load Applications, products conforming to the Java (registered trademark) Card specifications and GlobalPlatform (registered trademark) specifications have become de facto standards. An IC card always has one or more security domains (SD), which are applications for managing the IC card itself and applications in the IC card. SD includes ISD (Issuer Security Domain) and SSD (Supplementary Security Domains). Such SD mainly supports the following functions (1) to (9).

(1) IC card life cycle management
(2) Application program lifecycle management
(3) Application instance lifecycle management
(4) Loading application programs
(5) Generation of application instance (installation)
(6) deletion of application programs or application instances;
(7) Write issue data for application
(8) Read data
(9) Securing a secure communication path according to the Secure Channel Protocol (SCP)

By supporting the above functions (1) to (9), the ISD realizes the management and security policies of the IC card issuer for the card content (application programs, application instances, etc.) in the IC card. . On the other hand, by supporting the above functions (1) to (9), the SSD realizes the management and security policy of the third party who provides the service on the IC card for the card content in the IC card. . Here, a third party who provides services on an IC card means a person other than the issuer of the IC card and the holder of the IC card (the user to whom the IC card is issued). In function (9) above, the SCP ensures the confidentiality of command data, command integrity (and security), providing additional confidentiality of sensitive data (e.g. keys and PIN codes) within the command data (plaintext). According to the GlobalPlatform specifications, when executing functions (1) to (7) above, it is mandatory to execute them on an SCP. Therefore, the SD and the external device hold a secure channel key so that secure communication can be performed between the IC card and the external device.

In Patent Document 1, regarding the key version of the secure channel key used for secure processing to secure a communication channel (secure channel) that has already been established between an external device and an application, the key version is explicitly specified on the external device side. A technique is disclosed that allows multiple default key versions to be used properly without specifying the default key version.

JP 2018-82246 A

As shown in FIG. 1, a secure channel is used when an SE-using device (external device) and an application in the SE communicate with each other. For the secure channel, the secure channel key KA held by each of the SSD and SE using devices corresponding to the Application is used. In other words, secure communication is ensured by encrypting communication data between the SE-using device and Application using the secure channel key KA. Also, when the SE-using device communicates with a server (not shown), the SE-using device requests Application to perform encryption/decryption processing of communication data between the SE-using device and the server (encryption/decryption processing using encryption key KB). ), and a secure channel is also used for sending and receiving plaintext and ciphertext (encrypted plaintext) at that time.

On the other hand, the encryption key KB held by Application has an upper limit of the number of times of use for ensuring security, and when the number of times of use reaches the upper limit, it is necessary to update the encryption key KB. Specifically, the SE key management device 3 updates the encryption key KB held by Application. Here, when using/updating the encryption key KB, a secure channel is used. However, according to the GlobalPlatform specifications, one Application cannot use multiple secure channels simultaneously, A secure channel opened by an application cannot be used by multiple devices. Therefore, the SE key management device 3 cannot update the encryption key KB held by the Application while the Application is communicating with the SE using device. Therefore, in order to update the encryption key KB, once the communication between the Application and the SE-using device is terminated, a secure channel is opened between the SE key management device 3 and the Application to update the encryption key KB. It is necessary to go through the procedure of terminating the communication between the device 3 and the application and then opening a secure channel between the device using the SE and the application again, which takes time to update the key. In particular, when the SE-using device needs to update the key while communicating with the server, it may be necessary to interrupt the communication with the server as well.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a communication system or the like capable of updating a key held by an Application even while the Application is communicating with a communication terminal such as an SE-using device.

In order to solve the above problems, the invention according to claim 1 provides an electronic information storage having storage means for storing a first security management application, a second security management application, a first application, and a second application. a medium, a communication terminal that communicates with the first application via a first secure channel that uses a first secure channel key held by the first security management application, and the second security management a key updating device that communicates with the second application via a second secure channel that uses a second secure channel key held by the application, and updates encryption key information held by the first application; wherein the key update device includes update key information transmission means for transmitting update encryption key information for updating the encryption key information to the electronic information storage medium, The information storage medium comprises: holding means for causing the second application to hold the update encryption key information when the update encryption key information is received from the key update device; a passing means for passing the encryption key information for the update to the first application; and updating for updating the encryption key information held by the first application with the encryption key information for updating passed from the second application. and means.

The invention according to claim 2 is the communication system according to claim 1, wherein the electronic information storage medium comprises key information using means for performing predetermined processing using the encryption key information, and counting the number of times the information has been used, and when the number reaches a predetermined number of times, transmitting arrival information indicating that the number of times the encryption key information has been used has reached the predetermined number of times to the communication terminal; and information transmission means, wherein the communication terminal transmits warning information indicating that the number of uses of the encryption key information has reached the predetermined number of times when the arrival information is received from the electronic information storage medium. warning information transmission means for transmitting to the key update device, wherein the update key information transmission means of the key update device transmits the update encryption key information to the electronic information when the warning information is received from the communication terminal. It is characterized by transmitting to a storage medium.

The invention according to claim 3 is the communication system according to claim 2, wherein the predetermined number of times is less than an upper limit of the number of times the encryption key information is used.

The invention according to claim 4 is the communication system according to claim 2 or 3, wherein the second secure channel is opened after receiving the warning information from the communication terminal. .

The invention according to claim 5 is the communication system according to any one of claims 2 to 4, wherein the execution unit of the electronic information storage medium executes the first application to perform the It functions as key information using means, arrival information transmitting means, and updating means, and functions as holding means and delivery means by executing the second application.

According to a sixth aspect of the invention, there is provided an electronic information storage medium having storage means for storing a first security management application, a second security management application, a first application, and a second application; a communication terminal that communicates with the first application via a first secure channel that uses a first secure channel key held by a management application; and a second secure held by the second security management application. A communication method in a communication system comprising: a key update device that communicates with the second application via a second secure channel that uses a channel key, and updates encryption key information held by the first application an update key information transmission step in which the key update device transmits update encryption key information for updating the encryption key information to the electronic information storage medium; a holding step of causing the second application to hold the update encryption key information when the update encryption key information is received from an update device; a delivery step of delivering the encryption key information for the update to the first application, and the electronic information storage medium transmits the encryption key information held by the first application to the updating and an updating step of updating with the encryption key information.

According to the present invention, even when the first application is communicating with the communication terminal via the first secure channel, the second application receives the update key information from the key update device via the second secure channel. is received and passed to the first application, the key held by the first application can be updated.

FIG. 11 is a block diagram showing a conventional update example of a cryptographic key KB; It is a block diagram which shows the update example of encryption key KB1 by this embodiment. FIG. 2 is a block diagram showing a schematic configuration example of an SE-using device 1 and an SE 2 according to this embodiment; FIG. 3 is a diagram showing an example of a hierarchical structure formed between multiple SDs and multiple Applications; 3 is a block diagram showing a schematic configuration example of an SE key management device 3 according to this embodiment; FIG. FIG. 4 is a sequence diagram showing the flow of encryption processing using an encryption key KB1 in this embodiment; FIG. 4 is a sequence diagram showing the flow of key update processing for updating the encryption key KB1 with the encryption key KB2 in this embodiment;

Embodiments of the present invention will be described below with reference to the drawings. The embodiment described below is an embodiment in which the present invention is applied to a key update system having SE using device 1, SE 2, and SE key management device 3. FIG.

[1. Overview of key update system S]
First, an overview of the key update system S according to the present embodiment will be described with reference to FIG. 2 and the like. A secure channel is used when SE-using device 1 and Application-1 in SE communicate with each other. The secure channel uses the secure channel key KA held by the SSD-1 corresponding to Application-1 and the SE-using device 1, respectively. In other words, secure communication is ensured by encrypting communication data between SE-using device 1 and Application-1 using secure channel key KA (a secure channel between SE-using device 1 and Application-1 is defined as " may be referred to as a "first secure channel"). Also, when the SE-using device 1 communicates with a server (not shown), the SE-using device 1 requests Application-1 to encrypt the communication data (plaintext) between the SE-using device 1 and the server (encryption key KB1 is encryption processing). The encryption key KB1 held by Application-1 has an upper limit on the number of times it can be used. When the number of times of use reaches the upper limit, the encryption key KB1 must be updated. Specifically, the SE key management device 3 performs processing for updating the encryption key KB1 held by Application-1.

Here, as described above using FIG. 1, when using/updating the encryption key KB1, a secure channel is used. According to the GlobalPlatform specifications, Application-1 uses multiple secure channels simultaneously. you can't. In other words, while Application-1 is communicating with SE-using device 1, SE-key management device 3 cannot directly update encryption key KB1 held by Application-1.

Therefore, in the key update system S of this embodiment, as a mechanism for updating the encryption key KB1 held by Application-1, Application-2 for key update and SSD-2 for managing this are provided in SE2. do. When the SE key management device 3 attempts to update the encryption key KB1, first, the secure channel between Application-2 and Application-2 (the secure channel between the SE key management device 3 and Application-2 is sometimes referred to as the "second secure channel"). exist). That is, secure communication is ensured by encrypting communication data between the SE key management device 3 and Application-2 using the secure channel key KC. Next, the SE key management device 3 transmits the encryption key KB2 for updating the encryption key KB1 to Application-2 via the second secure channel. Application-2 transfers the encryption key KB2 to Application-1, and Application-1 updates the encryption key KB1 with the received encryption key KB2.

[2. Configuration of SE-using device 1 and SE 2]
The configurations of the SE-using device 1 and the SE 2 capable of communicating with the SE-using device 1 will be described with reference to FIG. The SE-using device 1 has a control unit 11 , a communication unit 12 , an input unit 13 and an output unit 14 .

The control unit 11 includes a CPU (Central Processing Unit) 111, a RAM (Random Access Memory) 112, a ROM (Read Only Memory) 113, an I/O circuit 114, and a non-volatile memory 115. to control. For example, the control unit 11 performs processing based on input data and input information input to the input unit 13 and outputs output data and output information to the output unit 14 . The communication unit 12 performs processing for communicating with an external device such as a server (not shown). The input unit 13 inputs input data and input information to the control unit 11 . The output unit 14 performs output based on output data and output information output from the control unit 11 .

The RAM 112 stores, for example, data temporarily required for the functioning of an OS (Operating System) and various applications. The ROM 113 stores an OS, various applications, and the like. The I/O circuit 114 serves as a communication interface with SE2. A flash memory or an "electrically erasable programmable read-only memory" can be applied to the nonvolatile memory 115, for example. The nonvolatile memory 115 stores programs and the like for executing processes described later.

The SE2 comprises a CPU 21, a RAM 22, a nonvolatile memory 23 and an I/O circuit 24. SE2 has high tamper resistance. High tamper resistance means that confidential information such as keys for encryption, decryption, and signature verification, as well as the mechanism for processing confidential information, can be illegally observed or altered from the outside. It means that it is extremely difficult to modify to Note that in this embodiment, the SE2 has higher tamper resistance than the control unit 11, which is a non-secure element.

The RAM 22 stores, for example, data temporarily required for the OS and various applications to function.

Flash memory or "Electrically Erasable Programmable Read-Only Memory" can be applied to the nonvolatile memory 23, for example. The non-volatile memory 23 stores an OS, various applications, programs for executing processes to be described later, keys, and the like.

The I/O circuit 24 serves as a communication interface with the controller 11 .

FIG. 4 is a diagram showing an example of the functional configuration of SE2. In the example of FIG. 4, ISD, SSD-1, SSD-2, Application-1, Application-2, and Application-3 operate on the OS of SE2. SSD-1, SSD-2, and Application-3 exist under ISD, Application-1 exists under SSD-1, and Application-2 exists under SSD-2. SSD-1, SSD-2, and Application-3 under ISD operate according to ISD's security policy. SSD-1 holds a secure channel key KA used for a secure channel between Application-1 and SE-using device 1 . Similarly, SSD-2 holds a secure channel key KC used for a secure channel between Application-2 and SE key management device 3 . Application-1 also holds an encryption key KB1 for encrypting/decrypting communication between the SE-using device 1 and a server (not shown). The secure channel key KA, secure channel key KC, and encryption key KB1 are managed in the key storage. The key storage is provided in a secure storage area in the non-volatile memory 23, for example.

[3. Configuration of SE Key Management Device 3]
Next, the configuration of the SE key management device S will be described using FIG. As shown in FIG. 5, the SE key management device S includes a control section 31, a storage section 32, a communication section 33, a display section 34 and an operation section 35. FIG.

The storage unit 32 is composed of, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores an OS, a program for executing processing described later, various other data, and Application-1. The encryption key KB1 key and the like for updating the encryption key KB1 to be used are stored.

The communication unit 33 controls communication with SE2 (especially Application-2).

The display unit 34 is composed of, for example, a liquid crystal display or the like, and displays information such as characters and images.

The operation unit 35 is composed of, for example, a keyboard, a mouse, etc., receives an operation instruction from an operator, and outputs the content of the instruction to the control unit 31 as an instruction signal.

The control unit 31 includes a CPU that controls the entire control unit 31, a ROM in which control programs for controlling the control unit 31 are stored in advance, and a RAM that temporarily stores various data. Various functions are realized by the CPU reading and executing various programs stored in the ROM and storage unit 32 .

[4. Encryption processing using encryption key KB1]
Next, the flow of cryptographic processing using the cryptographic key KB1 in the key update system S will be described with reference to FIG. Specifically, the cryptographic processing is as follows: SE-using device 1 sends plaintext to Application-1, Application-1 encrypts the plaintext using encryption key KB1, and encrypts the encrypted ciphertext. Refers to the process of receiving. Before starting the process of FIG. 6, a secure channel key for establishing a first secure channel between the SE using device 1 and the SSD-1 is required between the SE using device 1 and the SSD-1. It is assumed that KA is shared. Similarly, the secure channel key KC for opening the second secure channel between the SE key management device 3 and Application-2 should be shared between the SE key management device 3 and SSD-2. do. Also, in Application-1, the upper limit of the number of times the encryption key KB1 held by Application-1 is used is set in advance.

First, the SE using device 1, Application-1 and SSD-1 use the secure channel key KA to establish a first secure channel between the SE using device 1 and Application-1. Specifically, the control unit 11 of the SE-using device 1 transmits an INITIALIZE UPDATE command to Application-1 (step S1). Communication between the SE using device 1 and Application-1 and between the SE key management device 3 and Application-2 is performed by APDU (Application Protocol Data Unit).

When Application-1 (the CPU 21 of SE2 that executes Application-1; the same applies hereinafter) receives the INITIALIZE UPDATE command from SE-using device 1, it transmits the INITIALIZE UPDATE command to SSD-1 (step S2). Specifically, the INITIALIZE UPDATE command is sent by processSecrutiy() of GPAPI (GlobalPlatform API).

When SSD-1 (the CPU 21 of SE2 that executes SSD-1; hereinafter the same) receives the INITIALIZE UPDATE command, it executes processing according to the command, and responds with response data and SW (Status Word) "9000h" ( SW indicating normal termination) is returned to Application-1 (step S3).

When Application-1 receives the response data and SW "9000h" from SSD-1, it transmits them to SE-using device 1 (step S4).

After receiving the response data and SW "9000h" from Application-1, the control unit 11 of the SE-using device 1 then transmits an EXTERNAL AUTHENTICATE command to Application-1 (step S5).

When Application-1 receives the EXTERNAL AUTHENTICATE command from SE-using device 1, Application-1 transmits the EXTERNAL AUTHENTICATE command to SSD-1 (step S6). Specifically, an EXTERNAL AUTHENTICATE command is sent by processSecrutiy() of GPAPI (GlobalPlatform API).

Upon receiving the EXTERNAL AUTHENTICATE command, SSD-1 executes processing according to the command and returns SW "9000h" to Application-1 (step S7).

When Application-1 receives SW "9000h" from SSD-1, it transmits it to SE-using device 1 (step S8). As described above, a secure channel is established between the SE-using device 1 and Application-1 by the processing of steps S1 to S8, and communication is performed via the secure channel thereafter.

When the secure channel is opened, the SE-using device 1 requests Application-1 to encrypt the plaintext, and Application-1 encrypts the plaintext using the encryption key KC1.

Specifically, the control unit 11 of the SE-using device 1 uses the PSO ENCIPHER to send a command APDU including MAC (Message Authentication Code) and data obtained by encrypting the plaintext to be encrypted using the secure channel key KA. -1 (step S9). The command APDU is composed of, for example, CLA, INS, P1, P2, Lc, a data field, MAC, and Le, and the data field stores data obtained by encrypting plaintext with the secure channel key KA. In addition, SM (Secure Messaging) is performed between Application-1 and SSD-1, and if it is before SM processing (step S11) described later, the SM bit of CLA in the command APDU (command defined in Global Platform and ISO7816 A bit indicating the presence or absence of SM in the APDU) is set to "ON", and after SM processing, the SM bit is set to "OFF" in the command APDU (hereinafter, a command APDU with the SM bit set to "ON") is set to "ON". A command APDU whose SM bit is "OFF" may be called a "command APDU after SM processing"). There are three types of SM, and which one to use is specified by the EXTERNAL AUTHENTICATE command.

When Application-1 receives the pre-SM processing command APDU from the SE-using device 1, first, Application-1 transmits a request for SM processing to SSD-1 (step S10). Specifically, the command APDU before SM processing is transmitted by unwrap( ) of GPAPI.

Upon receiving the request for SM processing (pre-SM processing command APDU), SSD-1 executes SM processing (step S11). Specifically, MAC authentication processing and processing for decrypting the data stored in the data field with the secure channel key KA are performed. If there is no problem with these processes, SSD-1 sends the post-SM processing command APDU edited in the following (1) and (2) to the pre-SM processing command APDU received from Application-1 to Application -1 (step S12).
(1) SM bit is "OFF"
(2) Store the plaintext decrypted with the secure channel key KA in the data field.

When Application-1 receives the SM-processed command APDU, Application-1 encrypts the plaintext stored in the data field using the encryption key KB1 (step S13). Application-1 then counts up the number of uses of the encryption key KB1 (step S14). Next, Application-1 transmits a response APDU including a ciphertext (encrypted plaintext) and SW "9000h" to SE-using device 1 (step S15).

After that, the SE-using device 1, Application-1 and SSD-1 repeat the processing of steps S9 to S15 until a predetermined condition is satisfied. The predetermined conditions are, for example, (1) that the SE-using device 1 no longer needs to encrypt the plaintext, and (2) that the number of times the encryption key KB1 is used reaches its upper limit.

[5. Key update process for updating encryption key KB1 with encryption key KB2]
Next, with reference to FIG. 7, the flow of key update processing for updating the encryption key KB1 with the encryption key KB2 in the key update system S will be described. Specifically, the key update process is a process in which the SE key management device 3 updates the encryption key KB1 to the encryption key KB2 when the number of uses of the encryption key KB1 of Application-1 reaches the upper limit. Before starting the processing in FIG. 7, a secure channel key for establishing the first secure channel between the SE using device 1 and the SSD-1 is required between the SE using device 1 and the SSD-1. It is assumed that KA is shared. Similarly, the secure channel key KC for opening the second secure channel between the SE key management device 3 and Application-2 should be shared between the SE key management device 3 and SSD-2. do. Also, in Application-1, the upper limit of the number of times the encryption key KB1 held by Application-1 is used is set in advance.

A specific process of the key update process is performed when the number of uses of the encryption key reaches the upper limit. That is, Application-1 (the CPU 21 of SE2 that executes Application-1; the same shall apply hereinafter) repeats steps S9 to S15 in FIG. If it is determined that the number has reached, the ciphertext encrypted in step S13 and the SW "62XXh" (or "63XXh") are transmitted to the SE-using device 1. FIG. SW "62XXh" (or "63XXh") is SW indicating that the number of uses of the encryption key has reached the upper limit.

Upon receiving the ciphertext and SW "62XXh" (or "63XXh") from Application-1, the control unit 11 of the SE-using device 1 outputs warning information indicating that the number of uses of the encryption key KB1 has reached the upper limit. It is transmitted to the management device 3 (step S17). Then, the controller 11 of the SE-using device 1 interrupts the encryption processing (steps S9 to S15 in FIG. 6).

When the controller 31 of the SE key management device 3 receives the warning information from the SE using device 1, the SE key management device 3, Application-2 and SSD-2 use the secure channel key KC to perform SE key management. Open a second secure channel between device 3 and Application-2. Since the specific processing is the same as the processing of steps S1 to S8 in FIG. 6, description thereof is omitted.

When the second secure channel is opened, the control unit 31 of the SE key management device 3 then includes data obtained by encrypting the encryption key KB2 for updating the encryption key KB1 with the secure channel key KC and the MAC. A command APDU before SM processing is sent to Application-2 by CHANGE REFERENCE DATA (step S18).

When Application-2 receives the pre-SM processing command APDU from the SE key management device 3, first, Application-2 transmits a request for SM processing to SSD-2 (step S19). Specifically, the command APDU before SM processing is transmitted by unwrap( ) of GPAPI.

Upon receiving the request for SM processing (pre-SM processing command APDU), SSD-2 executes SM processing (step S20). Specifically, MAC authentication processing and processing for decrypting the data stored in the data field with the secure channel key KC are performed. If there is no problem with these processes, SSD-2 sends the post-SM processing command APDU edited in the following (1) and (2) to the pre-SM processing command APDU received from Application-1 to Application -2 (step S21).
(1) SM bit is "OFF"
(2) Store the encryption key KB2 decrypted with the secure channel key KC in the data field.

When Application-2 receives the SM-processed command APDU, Application-2 transmits the encryption key KB2 stored in the data field to Application-1 (step S22). For example, if Application-1 and Application-2 comply with Java (registered trademark) specifications, they are transmitted using a Java inter-application data transfer method.

When Application-1 receives the encryption key KB2 from Application-2, Application-1 updates the encryption key held by itself from encryption key KB1 to encryption key KB2 (step S23). Application-1 then initializes the number of times the encryption key has been used (step S24). Next, Application-1 notifies Application-2 that the key update process has been completed normally (step S25).

Application-2, upon receiving the notification, sends a response APDU including SW "9000h" to the SE key management device 3 (step S26).

When the control unit 31 of the SE key management device 3 receives SW "9000h" from Application-2, it notifies the SE utilization device 1 that the key update has ended (step S27).

Upon receiving the notification, the control unit 11 of the SE using device 1 resumes the interrupted encryption processing (steps S9 to S15 in FIG. 6) and repeats it until a predetermined condition is satisfied. However, in the process of step S13, encryption is performed using the updated encryption key KB2.

6 and 7, the case of encrypting plaintext has been described, but the same processing can be performed in the case of decrypting ciphertext into plaintext.

As described above, the key update system S according to this embodiment includes SSD-1 (an example of a “first security management application”), SSD-2 (an example of a “second security management application”), Application -1 (an example of a "first application") and SE2 (an example of a "second application") having a nonvolatile memory 23 (an example of a "storage means") that stores Application-2 (an example of a "second application") (an "electronic information storage medium ”) and SE use that communicates with Application-1 via the first secure channel using the secure channel key KA (an example of “first secure channel key”) held by SSD-1 Device 1 (an example of a "communication terminal") and Application-2 via a second secure channel using a secure channel key KC (an example of a "second secure channel key") held by SSD-2 and an SE key management device 3 (an example of a “key update device”) that communicates with and updates the encryption key KB1 (an example of “encryption key information”) held by Application-1. The control unit 31 (an example of "updating key information transmitting means") of the SE key management device 3 transmits the encryption key KB2 (an example of "updating encryption key information") for updating the encryption key KB1 to the SE2. . When the CPU 21 of SE2 (an example of "holding means", "delivery means", and "update means") receives the encryption key KB2 from the SE key management device 3, it causes Application-2 to hold the encryption key KB2, and Application- The encryption key KB2 held by Application-2 is transferred to Application-1, and the encryption key KB1 held by Application-1 is updated with the encryption key KB2 transferred from Application-2.

Therefore, according to the key update system S of this embodiment, even if Application-1 is communicating with the SE using device 1 via the first secure channel, Application-2 is By receiving the encryption key KB2 from the SE key management device 3 and passing it to Application-1, the encryption key KB1 held by Application-1 can be updated.

Also, when the first secure channel between Application-1 and SE-using device 1 is terminated once for key update and a new secure channel is opened after the key update, data is stored in the nonvolatile memory 23 for opening the secure channel. Although many times of writing are required, according to the present embodiment, since this is not required, the life of the nonvolatile memory 23 can be extended.

Furthermore, conventionally, since the SE using device 1 holds the secure channel key KA, there was a problem that a malicious person could use the SE using device 1 to update the encryption key KB1. According to the key update system S of the embodiment, since the encryption key KB1 can be updated only through Application-2, it is possible to prevent such a problem from occurring.

Further, in the key update system S according to the present embodiment, the CPU 21 (an example of "key information using means" and "arrival information transmitting means") of SE2 performs encryption processing ( an example of a "predetermined process"), counts the number of times the encryption key KB1 has been used, and when the number reaches the predetermined number of times, it indicates that the number of uses of the encryption key KB1 has reached the predetermined number of times. SW “62XXh” (or “63XXh”) indicated (an example of “arrival information”) is sent to the SE-using device 1 . When the control unit 11 (an example of the “warning information transmitting means”) of the SE using device 1 receives the SW “62XXh” (or “63XXh”) from the SE2, the number of uses of the encryption key KB1 reaches a predetermined number. It sends warning information indicating that it has been done to the SE key management device 3 . When the controller 31 of the SE key management device 3 receives the warning information from the SE using device 1, it transmits the encryption key KB2 to the SE2. Therefore, according to the key update system S according to the present embodiment, when the number of uses of the encryption key KB1 reaches a predetermined number, the encryption key KB2 can be updated. decline can be prevented.

In this embodiment, the number of uses of the encryption key KB1 is counted, and when the upper limit of the predetermined number of times is reached, the fact is sent to the SE key management apparatus 3 via Application-1 and the SE using apparatus 1. However, in this case, it takes time to update the key after the number of uses of the encryption key KB1 reaches the upper limit. In some cases, the process has to be interrupted. Therefore, a modified example of the present embodiment described below may be adopted.

First, Application-1 counts the number of times the encryption key KB1 has been used, and when it reaches a value smaller than the upper limit value (an example of the "predetermined number of times" of the present invention), Application-1 and SE-using device 1 (steps S16 and S17 in FIG. 7), and the encryption key KB2 is transmitted from the SE key management device 3 to Application-1 through steps S18 to S22. and When Application-1 receives the encryption key KB2, it temporarily holds it, and when the number of uses of the encryption key KB1 reaches the upper limit, Application-1 updates the encryption key KB1 with the once held encryption key KB2. As a result, the time from when the number of uses of the encryption key KB1 reaches the upper limit to when the key is updated can be greatly shortened. The value less than the upper limit is a value obtained by subtracting a value greater than the number of encryption processes (steps S9 to S15) executed within the time required for the processes of steps S16 to S22. For example, if the processing from step S16 to step S22 takes s seconds, and the encryption processing can be performed n times in s seconds, the number of times larger than n is subtracted (a larger number of times with a margin good).

In this modification, Application-1 may update the encryption key KB1 immediately after receiving the encryption key KB2 even if the number of uses of the encryption key KB1 has not reached the upper limit. In this case, Application-1 does not use the encryption key KB2 up to the upper limit. Since it is no longer necessary to determine the , the processing load can be reduced.

1 SE using device 11 Control unit 111 CPU
112 RAM
113 ROMs
114 I/O circuit 115 nonvolatile memory 12 communication unit 13 input unit 14 output unit 2 SE
21 CPUs
22 RAM
23 Nonvolatile memory 24 I/O circuit 3 SE key management device 31 Control unit 32 Storage unit 33 Communication unit 34 Display unit 35 Operation unit KA, KC Secure channel key KB, KB1, KB2 Encryption key

Claims (6)

an electronic information storage medium having storage means for storing a first security management application, a second security management application, the first application and the second application;
a communication terminal that communicates with the first application via a first secure channel that uses a first secure channel key held by the first security management application;
communicating with the second application via a second secure channel using a second secure channel key held by the second security management application, and transmitting encryption key information held by the first application; a key update device for updating;
A communication system comprising:
The key update device
update key information transmission means for transmitting update encryption key information for updating the encryption key information to the electronic information storage medium;
with
The electronic information storage medium is
holding means for causing the second application to hold the update encryption key information when the update encryption key information is received from the key update device;
a delivery means for delivering the update encryption key information held by the second application to the first application;
updating means for updating the cryptographic key information held by the first application with the update cryptographic key information passed from the second application;
A communication system comprising: A communication system according to claim 1,
The electronic information storage medium is
a key information using means for performing a predetermined process using the encryption key information;
counting the number of times the encryption key information has been used, and when the number reaches a predetermined number of times, sending arrival information indicating that the number of times the encryption key information has been used has reached the predetermined number of times to the communication terminal; arrival information transmission means for transmission;
with
The communication terminal is
warning information transmission means for transmitting warning information indicating that the number of uses of the encryption key information has reached the predetermined number of times to the key update device when the arrival information is received from the electronic information storage medium;
with
The update key information transmission means of the key update device is
A communication system, wherein the update encryption key information is transmitted to the electronic information storage medium when the warning information is received from the communication terminal. A communication system according to claim 2,
The communication system, wherein the predetermined number of times is less than an upper limit of the number of times the encryption key information is used. A communication system according to claim 2 or 3,
The communication system, wherein the second secure channel is opened after receiving the warning information from the communication terminal. The communication system according to any one of claims 2 to 4,
The execution unit of the electronic information storage medium,
By executing the first application, functioning as the key information using means, the arrival information transmitting means, and the updating means,
A communication system that functions as the holding means and the delivery means by executing the second application. an electronic information storage medium having storage means for storing a first security management application, a second security management application, the first application and the second application;
a communication terminal that communicates with the first application via a first secure channel that uses a first secure channel key held by the first security management application;
communicating with the second application via a second secure channel using a second secure channel key held by the second security management application, and transmitting encryption key information held by the first application; a key update device for updating;
A communication method in a communication system having
an update key information transmission step in which the key update device transmits update encryption key information for updating the encryption key information to the electronic information storage medium;
a holding step of causing the second application to hold the update encryption key information when the electronic information storage medium receives the update encryption key information from the key update device;
a delivery step in which the electronic information storage medium delivers the update encryption key information held by the second application to the first application;
an update step in which the electronic information storage medium updates the encryption key information held by the first application with the update encryption key information received from the second application;
A communication method comprising:

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