JP2019101840A - Ic card and output method of status word - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an IC card which does not return a status word indicating an internal state of the IC card even if a malicious third party makes a round-robin attack on the IC card. And. SOLUTION: An IC card is preset in an IC card that outputs a status word indicating an internal state of the IC card to an external device as a result of arithmetic processing by an IC card 10 that has received a command transmitted from an external device 20. When a special command is received, a true status word is returned, and when a command other than those commands is received, a specific status word that does not represent the internal state of the IC card is output. IC card. [Selection diagram] Fig. 1

Description

The present invention relates to a highly secure IC card. In more detail, even if attacked by an unauthorized user, a personal identification number or PIN (Personal Identification)
It relates to an IC card which is difficult to find out secret information such as a Number) code.

  The IC card has high security and is used as a bank card or a credit card for making electronic payment. As illustrated in FIG. 3A, the IC card 10 is generally a contact consisting of a plurality of electrodes that can communicate with a terminal device for an IC card such as an automatic teller machine (hereinafter also referred to as an external device). An interface circuit 6 enabling communication between the electrode 7 and an external device, an EEPROM (Electrically Erasable Read-Only Memory, also called data memory), a RAM (Random Access Memory, also called working memory), a ROM (Read- Storage unit 8 such as “Only Memory” (also referred to as “program memory”) and a control unit 9 for writing data to them and reading them from them. All exchange of data with the external device is performed via the control unit 9. Although the control unit 9 includes the CPU 4, the control unit 9 is called the control unit 9 including the cryptographic co-processor 5 which is a dedicated processor for executing the operation of RSA (Rivest-Shamir-Adleman cryptosystem, one of public key encryption) at high speed. .

  To withdraw or deposit cash from an external device installed in a bank or convenience store using a bank card or the like, first insert the IC card into the reader / writer 25 of the external device 20 (see FIG. 3B). ). The external device 20 includes a keyboard 24, a printer 23, a display device 22, and a control unit 21 of an external device that controls the entire device, in addition to a reader / writer 25 that reads and writes information on the IC card 10. Usually, the external device 20 can communicate with the server of the bank, and uses the IC card 10 inserted in the reader / writer 25 of the external device 20 and the unique information of the user input from the keyboard 24. After authenticating whether the user is the correct user, perform processing such as paying cash according to the input information, or the PIN code recorded on the IC card 10 and the user input from the keyboard 24 It determines whether the information matches and performs authentication.

  If confidential information such as such a PIN code is known to an unauthorized user, cash can be illegally withdrawn. Therefore, an unauthorized user attacks a smart card to seek out a PIN code or the like.

  In general, when receiving a command, the IC card internally performs arithmetic processing in response to the received command, and outputs a status word as the processing result. In this manner, the unauthorized user gives the IC card a series of command codes for finding out the secret information such as the PIN code recorded in the IC card, and the status word returned thereto is Make an attack to get secret information by examining.

  Even if such an attack by an unauthorized user is performed on an IC card, high security is required that can not find out secret information.

For example, Patent Document 1 provides a portable electronic device such as an IC card that can obtain high security even against random attack of a command as a technology that can not find out secret information even if an attack is performed on the IC card. In order to solve the problem, when a command input from the outside is received, processing is performed on the received command, and the portable electronic device that outputs the status word to the outside as the processing result performs processing on the received command, An identification means for identifying whether to output a normal status word indicating the processing content or a specific status word different from the normal status word, and the normal status word based on the identification result of the identification means Or a specific status word different from the regular status word Portable electronic device that includes a status output means for selectively outputting the status word is disclosed.

  Further, according to Patent Document 2, a plurality of applications can be registered for the same problem, and each registered application receives a command input from the outside, performs processing on the received command, and processes the same. In an electronic device that outputs information indicating the result to the outside, the first information indicating the processing result for the command received according to the application is output, or the second information indicating the content different from the processing result is output To output the first information based on the storage content of the storage unit storing the determination information for determining whether or not to perform the processing for the received command, or Determining means for determining whether to output the second information, and the first information or the first information based on the determination result of the determining means. Electronic device that an output means for outputting information selectively, characterized by comprising is disclosed.

  These technologies have a plurality of criteria for status words output at the time of command processing, and based on those criteria, output a true status word or specify no information indicating the internal state of the IC card. It is determined whether or not to output the status word, and the status word corresponding to the determination result is output, which is a technology with excellent security.

  However, since these techniques do not change the return of the status word indicating the internal status of the IC card in response to a command given by the malicious third party to the IC card, the command is executed round-round, There was a problem that a malicious third party knew the status word for it, and it could be analyzed.

Patent No. 4542766 Patent No. 3688971

  In order to solve the above problems, the present invention is to return a status word indicating the internal state of the IC card even if a malicious third party performs an attack command to execute the IC card in a round-robin manner. The challenge is to provide an IC card with no

As means for solving the above problems, according to a first aspect of the present invention, a status word representing an internal state of an IC card is output to an external device as a result of the IC card receiving a command transmitted from the external device performing arithmetic processing. In the IC card that outputs
If the IC card receives a true status command acquisition command in advance, it returns a true status word, and if a command other than those commands is received, a specific status word not representing the internal state of the IC card It is an IC card characterized by outputting.

  It is necessary to collate the key data that only a proper user knows before execution of the command as the execution condition of this true status word acquisition command. As described above, unless the special command for acquiring the true status word from the IC card is input to the IC card, the true status word indicating the internal state of the IC card is not output, and the internal state of the IC card is irrelevant. By outputting a certain status word, an unauthorized user who does not know the key data can not obtain any internal information of the IC card.

In the second aspect, the external device outputs a normal command to the IC card, and the IC card receives the command in step 1;
Step 2 of performing internal processing on the command received by the IC card;
Step 3 of recording the true status word in the non-volatile memory of the IC card
Step 4 which determines whether Step 1 to Step 3 ended normally
If the process ends normally in step 4, the IC card outputs a status word corresponding to the normal completion to the external apparatus, and the external apparatus receives the status word.
In the case of abnormal termination in step 4, the IC card outputs a specific status word corresponding to the abnormal termination to the external device, and the external device receives in step 6;
And a method of outputting a status word.

  According to the above method of outputting the status word, when a normal command is input, the status word unrelated to the internal state of the IC card is output from the IC card to the external device, and the external device is abnormally terminated. The message will be displayed.

In the third aspect, the external device outputs a command for verifying the key to the IC card, and
A step B of collating key data received by the IC card and outputting a collation result to an external device;
Step C: determining the matching result received by the external device;
If the determination in the check result in step C is a match (Yes), the external device outputs a true status word acquisition command to the IC card, and the IC card receives the true status word acquisition command,
If the determination of the matching result in step C is not a match (No), step D, returning to step A;
Step E where the IC card gets the true status word from the non-volatile memory;
Step F determining whether or not the true status word has been successfully acquired in step E;
If the true status word is successfully acquired in step F, step G: the external device receives the status word for true status and the status word for normal termination for the status word acquisition command from the IC card;
If the true status word can not be acquired normally in step F, the external device receives the status word for error in response to the status word acquisition command from the IC card, and the step H is provided. It is the output method of the word.

  With the above status word output method, when a true status word acquisition command is input, a true status word can be acquired, and the status word for normal completion for the true status word and the true status word acquisition command is IC. Output from card to external device.

As long as a normal command is input from the external device to the IC card, it does not output a true status word, but outputs only a specific status word unrelated to the internal state of the IC card, which is malicious. It is possible to prevent the analysis of IC card internal processing due to the brute force command execution by a third party. Also, a legitimate user can obtain a true status word by executing a true status word obtaining command.

Explanatory drawing which illustrates the system flow regarding the status word output in cases other than a true status word acquisition command in the IC card of this invention. Explanatory drawing which illustrates the system flow regarding the true status word output when the true status word acquisition command is input in the IC card of this invention. (A) is explanatory drawing which illustrated the structure of IC card, (b) shows the structure of the terminal device for IC cards.

<IC card>
The IC card according to the present invention is an IC card that outputs a status word representing the internal state of the IC card to an external device as a result of the IC card receiving a command transmitted from the external device performing arithmetic processing.
If the IC card receives a true status word acquisition command for the IC card set in advance, it returns a true status word, and if it receives a command other than those commands, it does not represent the internal state of the IC card. Output a specific status word.

  For example, a malicious third party who has obtained an IC card such as a bank card of another person executes an brute force command using a computer in order to search out secret information such as a PIN code of the IC card. Do. In the conventional IC card, response information reflecting the internal state of the IC card is returned to such an attack. Therefore, by analyzing the response information, the confidential information was acquired by a malicious third party and suffered damage.

  In the IC card of the present invention, even if a brute force command is executed using a computer, it will only return a specific response unless it is a true status word acquisition command, and a malicious third party is an IC. It is impossible to obtain information about the card.

  On the other hand, the owner of the IC card or the person on the bank side returns a true status word to those commands by inputting the IC card true status word acquisition command into the IC card. In this way, unauthorized use of the IC card by a malicious third party can be prevented.

  Hereinafter, a method of outputting a status word when the IC card of the present invention is inserted into a terminal device such as a bank will be described.

<Method of Outputting Status Word: First Embodiment>
The first embodiment of the method for outputting the status word of the present invention will be described below.
In the first embodiment of the method for outputting status word according to the present invention, the external command outputs a normal command to the IC card, and the IC card receives the command in step 1; Step 2 in which internal processing is performed, step 3 in which the true status word is recorded in the non-volatile memory of the IC card, step 4 in which it is determined whether step 1 to step 3 ended normally, and step 4 If the IC card outputs a status word corresponding to normal termination to the external device in step 5 and if the external device receives an abnormal termination in step 4, it corresponds to abnormal termination. The IC card outputs a specific status word to the external device, and the external device receives step 6). Which is the output method of the status word to butterflies.

  A workflow for outputting the status word when a malicious third party or a person who does not know the special command that is the IC card key data inputs an inappropriate command or inputs a command in a round-robin manner It illustrated in FIG. 1 as a figure.

Hereinafter, a first embodiment of the method for outputting status word of the present invention will be described using FIG.
(Step 1)
When the user inputs a command into the keyboard of the external device, the reader / writer of the external device transmits a normal command to the IC card, and the IC card receives the command.

(Step 2)
The IC card performs internal processing for the command received by the IC card.

(Step 3)
The IC card determines whether step 1 to step 2 have ended normally.

(Step 4)
If the process is normally ended in step 3 (Yes), the IC card transmits a status sum corresponding to the normally ended to the external apparatus, and the external apparatus receives it.

(Step 5)
If the process ends abnormally in step 3 (No), the IC card records a true status word in the system area of the NMV (nonvolatile memory) of the IC card.

(Step 6)
The IC card sends a specific status word for error to the external device.

(Step 7)
The external device receives a specific status word for an error from the IC card.

  Since the specific status word transmitted by the IC card to the external device in step 7 does not include information reflecting the internal state of the IC card, it is not possible to search out the internal information of the IC card.

<Method of Outputting Status Word: Second Embodiment>
Next, a second embodiment of the status word output method of the present invention will be described.
In the second embodiment of the method for outputting status word according to the present invention, step A in which a true status word acquisition command is output from the external device to the IC card and key data received by the IC card are compared, and the comparison result is If the determination of the verification result in step B for outputting to the external device, step C for determining the verification result received by the external device, and the verification result in step C is coincident (Yes), the external device acquires a true status word acquisition command. If the IC card receives a true status word acquisition command and the judgment of the collation result in step C is not coincident (No), the IC card returns from step A, and the IC card receives the command from the nonvolatile memory Step E for obtaining a true status word, and whether or not the true status word was successfully obtained in step E And if the true status word is successfully obtained in step F, the external device receives the status word for true status and the status word for normal completion from the status word obtaining command from the IC card. G and step H in which the external device receives an error status word for the status word acquisition command from the IC card when the true status word can not be acquired normally in step F.

  A method of outputting a status word when a user who can send a correct collation command inputs a true status command acquisition command is illustrated in FIG. 2 as a work flow diagram. The second embodiment of the method for outputting the status word of the present invention will be described below with reference to FIG. Here, the key data means data used for matching PIN, RSA (registered trademark), or DES private key.

(Step A)
First, a valid user inputs a verification command, which is an execution condition, from a keyboard of an external device such as a cash dispenser installed in a bank etc., to collate the execution condition from the reader / writer of the external device to the IC card. When key data which is a command is transmitted, the IC card receives the key data and collates the received key data.

(Step B)
The IC card transmits the verification result obtained by collating the key data to the external device.

(Step C)
The external device determines the received matching result.
If it is determined that the collation result in step C is not correct key data (No), the process returns to step A.

(Step D)
If it is determined that the collation result in step C is correct key data (Yes), the external device transmits a true status word acquisition command to the IC card. The IC card receives a true status word acquisition command.

(Step E)
The IC card that has received the true status word acquisition command acquires the true status word from the non-volatile memory.

(Step F)
The IC card determines in step E whether or not the true status word has been successfully acquired.
If the true status word is successfully acquired in step F, the IC card transmits the status word for normal completion and the status word for normal completion to the status word acquisition command to the external device.
If the true status word can not be acquired normally in step F, the IC card transmits the error status word for the status word acquisition command to the external device.

(Step G)
If the true status word can not be acquired normally in step F, the external device receives the error status word for the status word acquisition command from the IC card.

(Step H)
If the true status word can be acquired normally in step F, the external device receives the status word for true status and the status word for normal completion for the status word acquisition command from the IC card.

  Through the above steps A to H, a legitimate user can obtain a true status word.

1 ... RAM (working memory)
2 ... ROM (program memory)
3 ... EEPROM (data memory)
4 · · · CPU (control element)
5: Cryptographic coprocessor 6: Interface circuit 7: Contact electrode 8: Storage unit 9: Control unit 10: IC card 20: External device (terminal device)
21: Control unit 22 of external device: Display unit 23: Printer 24: Keyboard 25: Reader / writer

Claims (3)

In an IC card which outputs a status word representing the internal state of the IC card to an external device as a result of the IC card having received a command transmitted from the external device performing arithmetic processing,
If the IC card receives a special command set in advance, it returns a true status word, and if it receives a command other than those commands, it outputs a specific status word that does not represent the internal state of the IC card. IC card characterized by having. A normal command is output from the external device to the IC card, and the IC card receives the command in step 1;
Step 2 of performing internal processing on the command received by the IC card;
Step 3 of recording the true status word in the non-volatile memory of the IC card
Step 4 which determines whether Step 1 to Step 3 ended normally
If the process ends normally in step 4, the IC card outputs a specific status word corresponding to the normal end to the external apparatus, and the external apparatus receives
In the case of abnormal termination in step 4, the IC card outputs a specific status word corresponding to the abnormal termination to the external device, and the external device receives step 6; Word output method. Step A in which a command for collating a key with an IC card is output from an external device;
A step B of collating key data received by the IC card and outputting a collation result to an external device;
Step C: determining the matching result received by the external device;
If the determination in the check result in step C is a match (Yes), the external device outputs a true status word acquisition command to the IC card, and the IC card receives the true status word acquisition command,
If the determination of the matching result in step C is not a match (No), step D, returning to step A;
Step E where the IC card gets the true status word from the non-volatile memory;
Step F determining whether or not the true status word has been successfully acquired in step E;
If the true status word is successfully acquired in step F, step G: the external device receives the status word for true status and the status word for normal termination for the status word acquisition command from the IC card;
If the true status word can not be acquired normally in step F, the external device receives the status word for error in response to the status word acquisition command from the IC card, and the step H is provided. Word output method.