JP4529156B2 - Method for confirming data writing to portable storage medium, portable storage medium, server, and system, - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for confirming data writing between a portable storage medium in an information processing terminal having a communication function and a remote server via a communication network.
[0002]
[Prior art]
Various proposals have been made to establish secure communication with a server connected via a network via a portable terminal such as a cellular phone in which an IC card is set so that electronic payment can be performed (patents). Reference 1).
If the processing is interrupted due to the power failure of the mobile device or the failure of the communication network, the same processing can be started again from the beginning, It will cancel itself.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-324202
[Problems to be solved by the invention]
As described above, it is sufficiently possible that processing between entities (substances) via the communication network is interrupted. However, if the process of writing highly confidential data such as an encryption key is interrupted, it cannot be confirmed whether the data has been correctly written in the card. . For example, when data writing fails and a processing request instruction (command) is lost, the data writing command is lost before reaching the IC card, or the response to the data writing command is lost before reaching the server It is unknown. In such a case, in order to confirm the data writing, there may be a method of reading the data that would have been written. However, it is not appropriate in terms of security to easily output confidential data outside the tamper-resistant device. Absent. Similarly, it may be used by external attackers to allow attempts to write highly confidential data such as encryption keys multiple times in succession. Such a point is not disclosed in Patent Document 1.
[0005]
[Means for Solving the Problems]
The present invention is intended to solve the above-mentioned problem, and when writing data from a remote server to an IC card in a portable terminal, it is confirmed whether or not the writing is normally performed without reading the written data. The purpose is to make it possible.
For this purpose, the present invention provides that the portable storage medium and the server have the same master key and the same session key set generated from the master key, generate these session key sets for each communication session, and use the response authentication code. In a secure communication environment, when the portable storage medium receives a data write command from the server and writes the data, the response authentication code generated by encrypting the command and response data with the session key is used as a check value. The server stores the check value by sending a response message, and when the response message disappears, the server sends an acquisition command to acquire the check value, and compares it with the stored check value. It ’s a highly sensitive day Is a method for confirming whether or not correctly written,
When establishing a secure channel, data that does not require confidentiality is sent from the server to the portable storage medium as a check value, and after the stored check value is stored in the memory, a response message is returned and received by the server. Initialize the check value by storing it as a check value,
When a data write command is sent from the server, on the portable storage medium side, when the processing is completed normally, the stored check value is updated to the newly generated check value. Or check value at the time of initialization,
When the response message from the portable storage medium disappears, the secure channel is closed, a new secure channel is opened, a check value acquisition command is sent from the server to the portable storage medium, and the server receives the response from the portable storage medium The secure channel is blocked, a new secure channel is opened, and a check value acquisition command is sent until the check value is acquired. When the check value is acquired, the server compares it with the check value that has already been acquired and holds the data based on the comparison result. It is characterized by confirming whether or not can be written correctly.
In addition, the present invention is characterized by a portable storage medium that stores a plurality of applications, stores a check value for each application, and is used in the confirmation method.
In addition, the present invention is characterized by a server used in the confirmation method for storing a plurality of applications, storing a check value for each application, and performing secure communication using a response authentication code. .
Further, the present invention is characterized by a system including the portable storage medium and the server.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. In the following embodiments, an IC card will be described as an example. However, the present invention is not limited to this, and a portable information processing storage medium having an arithmetic processing / storage function (hereinafter, The portable terminal in the following embodiments is not limited to a cellular phone, and can be applied to any information processing terminal having a communication function such as a personal computer.
FIG. 1 is a conceptual diagram illustrating the system of this embodiment.
The IC card 1 is set in a portable terminal 2 such as a cellular phone, and is connected to a remote server 3 via a network such as the Internet by wireless or wired. Communication between the IC card 1 and the server 3 via the portable terminal is made up of a pair of a processing request command (command) and a response (response) to the command, and is established by establishing a secure communication channel. For this purpose, the IC card and the server side have the same master key, and when starting communication, mutual authentication is performed by performing an authentication operation using a random number and a master key that are generated mutually. Have the same session key set for C-MAC generation, command data encryption, and R-MAC generation, and these session key sets are generated for each communication session.
[0007]
The MAC (Message Authenticate Code) is a message authentication code obtained by encrypting transmission data to check whether or not the data has been tampered with, and is sent together with the transmission data. C-MAC is a command message authentication code generated by encrypting a command with a session key on the server side, and R-MAC is a response message authentication generated by encrypting a command and response data decrypted on the IC card side with a session key. Code.
[0008]
As shown in FIG. 2, the command transmitted from the server side to the IC card is composed of a header indicating the content of the command, the length of data to be transmitted, and the command data. C-MAC is generated by encryption with a key, command data is encrypted using a session key for command data encryption, and (header + encrypted command data + C-MAC) is transmitted as a command message to the IC card.
On the IC card side, the received command is decrypted and processed, and the decrypted command and response data are encrypted with the R-MAC generation session key to generate the R-MAC and store it in the nonvolatile memory. At the same time, (response data + R-MAC) is returned to the server as a response message.
[0009]
FIG. 3 is a diagram for explaining a MAC generation algorithm used in this embodiment.
In this example, the DES encryption is generated in a CBC (Cypher Block Chaining) mode. On the server side, the command (header + command data) is divided into 8-byte units, DES encrypted with the session key for C-MAC generation, and exclusive OR with the previous 8-byte encrypted data is generated sequentially. To generate a C-MAC. The partner of the first 8-byte exclusive OR is ICV (Initial Chaining Vector), which is an initial value for generating a MAC.
On the IC card side, the decrypted command and response data are generated using the session key for R-MAC generation, and the R-MAC is generated in the CBC mode of DES encryption in the same manner as the C-MAC generation. In this example, DES encryption is used for MAC generation, but it goes without saying that other encryption methods may be used.
[0010]
In this embodiment, when data is written to the IC card, the IC card side generates an R-MAC each time the received write command is executed in order to confirm that the data has been written without reading the written data. The value is stored as a check value, and the server uses a command to obtain this check value. When the IC card receives this command, it returns the stored check value to the server side. This R-MAC can be used to guarantee a command or response sequence.
[0011]
To further explain this point, for example, the following sequence:
(1) The IC card receives a command for writing highly confidential data.
(2) The IC card executes a writing process.
(3) In the IC card, R-MAC is generated and stored in the card, and response data + R-MAC is transmitted to the server.
(4) The response message disappears in the communication path for some reason.
(5) Since the response does not return, the server determines that the server is abnormal and closes the secure channel. At this point, the IC card is still in a state of opening a secure channel.
(6) The server issues a command to open a secure channel again to the IC card in order to know the writing result.
(7) When the IC card receives a secure channel opening command (this command is different from the command being opened and does not include command data encryption or C-MAC), the IC card determines that the command does not meet the conditions, Once the current secure channel session is closed (the session is already closed on the server side), a process for establishing a secure channel is performed again.
When the session established between the server and the IC card becomes invalid, the session key becomes invalid.
[0012]
In addition, the loss of the response message
・ When the power of the IC card itself drops during communication ・ When a failure occurs in the communication path, the secure channel is blocked.
・ When a command to end a session is sent from the server side. ・ An illegal command or a data encryption promise has not been fulfilled. ・ A command that does not meet the conditions is received.
[0013]
When the response message is lost as described above, the secure channel session at that time is blocked, and the server obtains an R-MAC value as a check value in the next secure channel session in order to confirm the execution result of the command. Issue to card. Since the server side already holds the acquired R-MAC value and R-MAC generation session key, the acquired R-MAC is verified, and writing is performed depending on whether or not the R-MAC is the previous secure channel session. Whether it is normal can be confirmed. That is, if the acquired R-MAC is the initial value or the confirmed R-MAC value for the result of the previous response disappearing (not the R-MAC value of the previous secure channel session), the writing was not performed normally. Therefore, if the acquired R-MAC is not the initial value or the confirmed R-MAC value for the result of the previous response disappearing (the R-MAC value of the previous secure channel session), the writing was performed normally. However, it can be seen that the response is lost in the communication process.
[0014]
A write confirmation processing sequence when such a response message is lost will be described with reference to FIG.
When writing highly confidential data from the server to the IC card, mutual authentication is performed, a session key set is generated, a secure channel is opened, and a check value is initialized. The initialization of the check value sends 8-byte data that does not require confidentiality to the IC card as the check value. The IC card stores the check value in the non-volatile memory, returns a response, and receives it at the server for storage. It is done by doing. This process is performed until a response is returned normally.
[0015]
When the check value is initialized and the secret data write command is sent from the server, the IC card side updates the stored check value to the generated R-MAC when processing is completed normally. Update the check value to another value, or retain the check value at the time of initialization. If the response message disappears for some reason at this time, a new secure channel is established as described above. Then, when a command for obtaining a check value is sent from the server side and a response cannot be received, this secure channel is closed, a secure channel is opened again, and a command for obtaining the check value is sent. When the response can be acquired in this way, the server holds the session key, the transmitted command, and the check value. Therefore, the R-MAC is acquired and the R-MAC value created from the initialized check value is obtained. When it is found that writing has been performed normally for the first time and writing has not been performed normally, 8-byte data that has been initialized as a check value is acquired.
[0016]
Furthermore, in subsequent secure channel sessions, a command to write confidential data is sent, and if a response is not obtained for some reason, the secure channel is blocked, and the command to open the next secure channel and acquire the check value is again executed. Send. Then, when the check value is acquired in this secure channel session, it is confirmed whether or not the writing is normally performed based on the R-MAC value of the previous secure channel session or the R-MAC value of the previous secure channel session. Can do.
[0017]
In the above description, there is one application that performs secure communication with the server on the IC card side, and an example in which one R-MAC is generated and held is described. However, a plurality of applications are stored in the IC card, When the application performs secure communication with the server, it is possible to confirm data writing for each application by generating and holding the R-MAC for each application.
〔Example〕
As a premise, the Secure Channel Protocol 02 defined in Global Platform Gard Specification 2.1.1 established by Global Platform is used between the IC card in the mobile terminal and the remote server, and the required Security Level is -Encryption of command data-Message authentication code C-MAC for transmission messages (generated by DES encryption CBC mode)
・ With message authentication code R-MAC for response message (generated by CBC mode of DES encryption)
And The message authentication code of the previous session is used for the ICV in the CBC mode.
[0018]
When a command for writing highly confidential data arrives from the server to the application, processing is normally performed and an R-MAC is generated, the command is stored in the card. If the response of this command disappears in the middle of being sent to the server, the server sends and obtains a command for obtaining the R-MAC value. Since the server side can predict the response when the command is completed normally, the acquired R-MAC can be verified, and data can be read or overwritten to determine whether the writing has been completed normally or failed. It can be judged without doing.
[0019]
【The invention's effect】
As described above, according to the present invention, when writing data that cannot be read with high confidentiality from a remote server to a portable storage medium, writing is performed by acquiring the check value without reading the written data. It is possible to check whether the process has been completed normally or has failed.
It is also possible to clarify whether the data write command has disappeared before reaching the portable storage medium or whether the response to the data write command has disappeared before reaching the server.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating a system according to an embodiment.
FIG. 2 is a diagram illustrating a command.
FIG. 3 is a diagram illustrating a MAC generation algorithm.
FIG. 4 is a diagram for explaining a write confirmation processing sequence;
[Explanation of symbols]
1 ... IC card, 2 ... mobile terminal, 3 ... server.

Claims (4)

The portable storage medium and the server have the same master key and the same session key set generated from the master key. These session key sets are generated for each communication session, and secure communication is performed using the response authentication code. In the environment where the portable storage medium receives the data write command from the server and writes the data , the portable storage medium stores the response authentication code generated by encrypting the command and the response data with the session key as a check value , and the response message When the server stores the check value and the response message is lost, the server sends an acquisition command to acquire the check value, and compares it with the stored check value for high confidentiality. Data was written correctly A method for confirming whether or not,
When establishing a secure channel, data that does not require confidentiality is sent from the server to the portable storage medium as a check value, and after the stored check value is stored in the memory, a response message is returned and received by the server. It initializes the check value by saving as a check value,
When a data write command is sent from the server, on the portable storage medium side, when the processing is completed normally, the stored check value is updated to the newly generated check value. Or check value at the time of initialization,
When the response message from the portable storage medium disappears, the secure channel is closed, a new secure channel is opened, a check value acquisition command is sent from the server to the portable storage medium, and the server receives the response from the portable storage medium The secure channel is blocked, a new secure channel is opened, and a check value acquisition command is sent until the check value is acquired. When the check value is acquired, the server compares it with the check value that has already been acquired and holds the data based on the comparison result. A method for confirming data writing to a portable storage medium, comprising: confirming whether or not the data has been correctly written.   The portable storage medium used in the confirmation method according to claim 1, wherein a plurality of applications are stored and a check value is stored for each application.   2. The server used in the confirmation method according to claim 1, wherein a secure communication is performed using a response authentication code and a portable storage medium storing a plurality of applications and storing a check value for each application.   A system comprising the portable storage medium according to claim 2 and the server according to claim 3.

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