IC card, computer program, IC chip, and method of outputting reset response

Abstract

To provide an IC card that enables an operation class with highest nominal supply voltage in a connection device that supports a plurality of operation classes, and enables one operation class in a connection device that supports the one operation class.SOLUTION: An IC card 1 includes a reset response unit 10 configured to: output, in the case of an operation class with the highest nominal supply voltage when receiving a reset signal, a reset response without referring to previous operation class information; refer to the previous operation class information in the case of an operation class which does not correspond to the highest nominal supply voltage; store, when the determined operation class is different from the operation class indicated by the previous operation class information, the previous operation class information indicating the determined operation class without outputting a reset response; and output the reset response when the determined operation class is the same as the operation class indicated by the previous operation class information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This application relates to an IC card that supports multiple operating classes. [Background technology]

[0002] ISO / IEC 7816 Part 3 is an important international standard that defines the electrical interface and transmission protocol of IC cards with external terminals. Most IC cards with external terminals currently in widespread use comply with ISO / IEC 7816 Part 3. IC cards with external terminals are sometimes called contact-type IC cards. Hereinafter, in this application, IC cards with external terminals will be referred to simply as IC cards.

[0003] ISO / IEC 7816 Part 3 has been revised several times since its first edition was created in 1989. One of the main revisions to ISO / IEC 7816 Part 3 is the operating class supported by IC cards. An operating class is a class consisting of a combination of nominal supply voltage and maximum current value.

[0004] The first edition of ISO / IEC 7816 Part 3 defined only one operating class with a nominal supply voltage of 5V. Subsequent revisions added two new operating classes: one with a nominal supply voltage of 3V and one with a nominal supply voltage of 1.8V. In ISO / IEC 7816 Part 3, the operating class with a nominal supply voltage of 5V is called Class A, the operating class with a nominal supply voltage of 3V is called Class B, and the operating class with a nominal supply voltage of 1.8V is called Class C. The nominal supply voltage is the voltage value that serves as a guide for the voltage supplied to the IC card by the connecting device. Each operating class has a minimum and maximum nominal supply voltage. For example, the minimum nominal supply voltage for Class A is 4.5V, and the maximum is 5.5V.

[0005] Also, ISO / IEC 7816 Part 3 allows IC cards to support multiple operation classes, but if an IC card supports two or more operation classes, those operation classes must be consecutive. According to this, there are three types of two or more operation classes that an IC card can support: Class A and B, Class B and C, and Class A, B and C.

[0006] In this way, the current ISO / IEC 7816 Part 3 allows IC cards to support multiple operation classes, and in response, Patent Document 1 discloses an IC card (portable electronic device) that can flexibly accommodate various operation classes.

[0007] As in the invention disclosed in Patent Document 1, making an IC card compatible with each of a variety of operation classes is important in terms of IC card convenience. However, in recent years, in order to improve the security of services that use IC cards, IC cards have increasingly been made to process advanced cryptographic operations (RSA and elliptic curve cryptography). As a result, the processing time from when an IC card receives a command until it sends a response has become an issue. Therefore, in the case of an IC card that is compatible with multiple operation classes, it is also important to determine the operation class of the IC card so as to shorten the IC card's processing time.

[0008] The faster the processing speed of an IC card, the greater the current consumption of the IC card. The higher the nominal supply voltage, the greater the maximum current value of the operating class. Therefore, in order to shorten the processing speed of an IC card, it is desirable to operate the IC card in the operating class with the highest nominal supply voltage of the operating classes supported by the IC card.

[0009] From the perspective of IC card processing speed, it is desirable to operate the IC card in the operating class with the highest nominal supply voltage, but the operating class in which the IC card can operate depends on the operating class supported by the connecting device (card reader) connected to the IC card.

[0010] Some commercially available connection devices support Class A and B. However, if a connection device that supports Class A and B has specifications that prioritize Class B to reduce the IC card's power consumption, the IC card that supports Class A and B will not operate in Class A, which has a faster processing speed, but will operate in Class B, which has a slower processing speed than Class A. Patent Document 2 discloses an IC card that provides information to guide the IC card to an appropriate voltage when a voltage that cannot guarantee normal operation of the IC card is supplied from a connection device.

[0011] It is possible to prioritize the processing speed of an IC card and limit the operating class that the IC card supports to only Class A, which has the highest nominal supply voltage. In this case, the IC card can operate in Class A with connected devices that support Classes A and B, but will not work with connected devices that do not support Class A. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-150246 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-76439 Summary of the Invention [Problem to be solved by the invention]

[0013] The present application provides an IC card that supports multiple operating classes, and operates in the operating class with the highest nominal supply voltage when connected to a connecting device that supports multiple operating classes, and operates in this operating class when connected to a connecting device that supports only one operating class. [Means for solving the problem]

[0014] A first invention for solving the above-mentioned problems relates to an IC card that supports multiple operating classes. The IC card according to the first invention includes a reset response unit that determines an operating class corresponding to the voltage supplied when a reset signal is received, and, if the determined operating class is an operating class with the highest nominal supply voltage, outputs a reset response without referencing previous operating class information indicating the previous operating class and deletes the previous operating class information. If the determined operating class is an operating class with a nominal supply voltage other than the highest, references the previous operating class information, and, if the determined operating class differs from the operating class indicated by the previous operating class information, updates the previous operating class information to information indicating the determined operating class without outputting a reset response. If the determined operating class is the same as the operating class indicated by the previous operating class information, the reset response unit may output a reset response and then delete the previous operating class information.

[0015] A second invention for solving the above-mentioned problem is a computer program for operating a CPU of an IC card as the reset response unit of the IC card described in the first invention.

[0016] A third invention that solves the above-mentioned problems relates to an IC chip to be mounted on an IC card that supports multiple operating classes. The IC chip of the third invention includes a reset response unit that determines an operating class corresponding to the voltage supplied when a reset signal is received, and if the determined operating class is an operating class with the highest nominal supply voltage, outputs a reset response without referencing previous operating class information indicating the previous operating class and deletes the previous operating class information. If the determined operating class is an operating class with a nominal supply voltage other than the highest, the reset response unit refers to the previous operating class information, and if the determined operating class differs from the operating class indicated by the previous operating class information, updates the previous operating class information to information indicating the determined operating class without outputting a reset response. If the determined operating class is the same as the operating class indicated by the previous operating class information, the reset response unit may output a reset response and then delete the previous operating class information.

[0017] A fourth invention that solves the above-mentioned problems relates to a method executed by an IC card that supports multiple operating classes. The reset response output method according to the fourth invention includes a step a in which the IC card determines an operating class corresponding to the voltage supplied when the IC card receives a reset signal, and a step b in which the IC card outputs a reset response without referencing previous operating class information indicating the previous operating class if the determined operating class is an operating class with the highest nominal supply voltage, and refers to the previous operating class information if the determined operating class is an operating class with a lower nominal supply voltage, and stores the previous operating class information indicating the determined operating class without outputting a reset response if the determined operating class is different from the operating class indicated by the previous operating class information, and outputs a reset response if the determined operating class is the same as the operating class indicated by the previous operating class information. Note that in step b, the IC card may output a reset response and then delete the previous operating class information if the determined operating class is the same as the operating class indicated by the previous operating class information. [Effects of the Invention]

[0018] The IC card disclosed in this application is configured to operate in the operating class with the highest nominal supply voltage when connected to a device that supports multiple operating classes, and to operate in this operating class when connected to a device that supports only one operating class. For example, if the IC card disclosed in this application supports Class A and B, the IC card disclosed in this application will operate in Class A with a connection device that supports Class A and B, and will operate in Class B with a connection device that supports only Class B. [Brief explanation of the drawings]

[0019] [Figure 1] 1A and 1B are diagrams illustrating an IC card according to an embodiment of the present invention. [Figure 2] Block diagram of the IC chip mounted on the IC card. [Figure 3] FIG. 2 is a diagram for explaining the operation of a reset response unit included in the IC card. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described. This embodiment is intended to facilitate understanding of the present invention, and the present invention is not limited to this embodiment. Furthermore, unless otherwise specified, the drawings are schematic diagrams drawn to facilitate understanding of the present invention.

[0021] 1 is a diagram illustrating an IC card 1 according to this embodiment. The IC card 1 according to this embodiment includes an external terminal 110 and an IC chip 100, and its electrical interface and transmission protocol comply with ISO / IEC 7816 Part 3.

[0022] The card body of the IC card 1 is made of a material such as plastic. The external terminal 110 is a plate-shaped component that physically comes into contact with a connecting device. The external terminal 110 includes at least a VCC terminal 111 (VCC: Supply Power Contact), an RST terminal 112 (RST: Reset), a CLK terminal 113 (CLK: Clock), an I / O terminal 114, and a GND terminal 115 (GND: Ground). The VCC terminal 111 is a terminal for supplying power to the IC card 1. The RST terminal 112 is a terminal for inputting a reset signal to the IC card 1. The CLK terminal 113 is a terminal for inputting a clock signal to the IC card 1. The I / O terminal 114 is a terminal used for exchanging data with the connecting device. The GND terminal 115 is a terminal for grounding the signal between the connecting device and the external terminal 110. The IC chip 100 that connects to the external terminal 110 is mounted on the back side of the external terminal 110.

[0023] 2 shows a block diagram of the IC chip 100 mounted on the IC card 1. The IC chip 100 generally includes the hardware shown in the diagram. The IC chip 100 also includes other hardware necessary for the operation of the IC chip 100, such as a timer circuit for measuring time and a random number generation circuit for generating random numbers, which are not shown in the diagram.

[0024] ROM 101 (Read Only Memory), RAM 102 (Random Access Memory), and NVM 103 (Non-volatile memory) are memories. ROM 101 is a non-rewritable memory that can permanently store data. ROM 101 stores program code for the operating system of the IC card 1 and program code for applications. RAM 102 is a memory that cannot permanently store data but can be rewritten at high speed. Data is temporarily stored in RAM 102 when CPU 107 executes a computer program. NVM 103 is a rewritable memory that can permanently store data. In the field of IC cards 1, an EEPROM of several kilobytes to several tens of kilobytes is mainly used as NVM 103. In this embodiment, NVM 103 is used to store previous operation class information that indicates the previous operation class.

[0025] The cryptographic operation circuit 104 is a circuit specialized for a specific cryptographic operation. When high security is required for the IC card 1, the cryptographic operation circuit 104 supports a public key cryptosystem such as RSA.

[0026] The URAT 109 (Universal Asynchronous Receiver-Transmitter) is a circuit for communicating with an external connected device using the I / O terminal 114. In the case of the IC card 1 according to this embodiment, the UART 109 is a serial interface that complies with the transmission protocol of ISO / IEC 7816 Part 3.

[0027] The clock generator 108 is a circuit that uses the clock signal supplied to the CLK terminal 113 to generate a clock signal that operates the IC chip.

[0028] Voltage detection circuit 105 is a circuit that detects the voltage input to VCC terminal 111 and reflects the voltage detection result in voltage detection register 106. Voltage detection circuit 105 is configured using known technology such as a comparator. Specifically, voltage detection circuit 105 according to this embodiment includes a circuit that determines, for each operation class supported by IC card 1, whether the voltage input to VCC terminal 111 is the nominal supply voltage of the operation class. For example, the circuit that determines whether the voltage input to VCC terminal 111 is the nominal supply voltage of Class A is a circuit that determines whether the voltage input to VCC terminal 111 is within the range of the nominal supply voltage for Class A (the range determined by a lower limit and an upper limit).

[0029] Voltage detection register 106 is a register into which voltage detection circuit 105 writes a value indicating the result of determining the operation class corresponding to the voltage input to VCC terminal 111. A portion of the area of ​​a general-purpose register included in CPU 107 can be used as voltage detection register 106. If CPU 107 has a dedicated register that reflects the voltage detection result, this dedicated register can be used as voltage detection register 106.

[0030] In this embodiment, the voltage detection result written by the voltage detection circuit 105 to the voltage detection register 106 becomes information indicating the operation class corresponding to the voltage detected by the voltage detection circuit 105. The information indicating the operation class is a different value for each operation class, such as "0" for class A, "1" for class B, "2" for class C, and "3" for none of the above.

[0031] The CPU 107 is an integrated circuit that performs complex calculations and data processing. A computer program that causes the CPU 107 to function as the reset response unit 10 according to the present application is stored in the ROM 101 or the NVM 103. The CPU 107 functions as the reset response unit 10 according to the present application by executing this computer program.

[0032] The reset response unit 10 included in the IC card 1 has a function of controlling the output of a reset response in the IC card 1, which supports multiple operation classes. The reset response is information that the IC card 1 outputs to the connecting device when the connecting device performs a reset operation by inputting a reset signal to the RST terminal 112. The reset response is also called an ATR (Answer To Reset) or initial response information.

[0033] As described in paragraph 0003 of Patent Document 2, a connection device that supports multiple operating classes applies the operating classes in ascending order of nominal supply voltage. For example, in the case of a connection device that supports Classes A and B, the connection device applies the operating classes in the order of Class B → Class A. When a conventional IC card with an external terminal that supports Classes A and B is used with this connection device, the IC card operates in Class B, which is the first class applied by the connection device. Therefore, in this case, the conventional IC card with an external terminal cannot operate in Class A, which has a faster processing speed than Class B. Furthermore, if an IC card with an external terminal is configured to support only Class A, the IC card cannot be used in a connection device that supports only Class B.

[0034] In consideration of the above-mentioned problems, the reset response unit 10 of the IC card 1 disclosed in this application executes the following processes: determining an operating class corresponding to the voltage supplied when the reset signal is received; if the determined operating class is an operating class with the maximum nominal supply voltage, outputting a reset response without referencing previous operating class information, which is information indicating the previous operating class, and deleting the previous class information; if the determined operating class is an operating class with a nominal supply voltage other than the maximum, referencing the previous operating class information; if the determined operating class and the previous operating class information differ, updating the previous operating class information to information indicating the determined operating class without outputting a reset response; and if the determined operating class and the previous operating class information are the same, outputting a reset response. By performing these operations by the reset response unit 10 of the IC card 1, the IC card 1 operates in the operating class with the maximum nominal supply voltage when connected to a connected device that supports multiple operating classes, and operates in the operating class supported by the connected device when connected to a connected device that supports only one operating class.

[0035] 3 is a diagram illustrating the operation of the reset response unit 10 included in the IC card 1. The operation of the reset response unit 10 included in the IC card 1 will be described with reference to FIG. 3, while also explaining the reset response output method according to the present invention.

[0036] Fig. 3 explains the operation of the reset response unit 10 included in the IC card 1 disclosed in the present application. The first step S1 in Fig. 3 is a step of activating the IC card 1. According to ISO / IEC 7816 Part 3, the connecting device activates the IC card 1 by sequentially setting the RST terminal 112 to state L, supplying power to the VCC terminal 111, setting the connecting device to the receive mode, and supplying a clock signal to the CLK terminal 113. Once activated, the IC card 1 enters a state of waiting for a reset signal.

[0037] The next step S2 is step S2 in which the IC card 1 receives a reset signal. In ISO / IEC 7816 Part 3, the first reset operation executed after the IC card 1 is activated is called a cold reset.

[0038] The next step S3 is a step of starting up the reset response unit 10 of the IC card 1. When the IC card 1 receives the reset signal, the CPU 107 executes a computer program that functions as the reset response unit 10 that controls the output of the reset response, and the CPU 107 functions as the reset response unit 10 according to the present application.

[0039] The next step S4 is a step in which the reset response unit 10 of the IC card 1 determines the operation class corresponding to the voltage being supplied when the reset signal is received. In this embodiment, the reset response unit 10 of the IC card 1 refers to the value stored in the voltage detection register 106 to determine the operation class corresponding to the voltage being supplied when the reset signal is received.

[0040] If the operation class determined in step S4 is the operation class with the maximum nominal supply voltage, the reset response unit 10 of the IC card 1 executes step S8. Step S8 is a step in which the reset response unit 10 of the IC card 1 outputs a reset response. Information to be output as a reset response is stored in the NVM 103 or ROM 101 of the IC card 1. The reset response unit 10 of the IC card 1 reads the information to be used as the reset response from a predetermined memory and outputs the reset response. Note that the reset response unit 10 of the IC card 1 may read the information to be used as the reset response from the predetermined memory immediately after the reset response unit 10 is started in step S3, rather than when executing step S8.

[0041] After executing step S8, the reset response unit 10 of the IC card 1 executes step S9. In step S9, the reset response unit 10 of the IC card 1 erases the previous operation class information stored in NVM 103. The previous operation class information is information indicating the previous operation class applied to the IC card 1 by the connection device. Naturally, if the previous operation class information is not stored in NVM 103, the reset response unit 10 of the IC card 1 does not erase the previous operation class information. Note that the reason for erasing the previous operation class information after outputting the reset response is that the time from receiving a reset signal to outputting a reset response is specified in ISO / IEC 7816 Part 3, and the previous operation class information cannot be erased from NVM 103 during this time. Note that when the reset response unit 10 of the IC card 1 executes step S9, the procedure of FIG. 3 ends.

[0042] If the operation class determined in step S4 is an operation class in which the nominal supply voltage is not maximum, reset response unit 10 of IC card 1 executes step S5. Step S5 is a step in which reset response unit 10 of IC card 1 compares the operation class determined in step S4 with the operation class indicated by the previous operation class information stored in NVM 103. If, in step S5, the operation class determined in step S4 is the same as the operation class indicated by the previous operation class information stored in NVM 103, reset response unit 10 of IC card 1 executes step S7 to output a reset response, and the procedure of FIG. 3 ends.

[0043] In step S5, if the operation class determined in step S4 is different from the operation class indicated by the previous operation class information stored in NVM 103, the reset response unit 10 of the IC card 1 proceeds to step S6. In step S6, the reset response unit 10 of the IC card 1 updates the previous operation class information stored in NVM 103 to information indicating the operation class determined in step S4, and the procedure of Fig. 3 ends. Note that the case in which the operation class determined in step S4 is different from the operation class indicated by the previous operation class information stored in NVM 103 also includes a case in which no previous operation class information is stored in NVM 103. Furthermore, updating the previous operation class information stored in NVM 103 means writing new previous operation class information to NVM 103 when no previous operation class information is stored in NVM 103, and rewriting the previous operation class information stored in NVM 103 with the new previous operation class information when previous operation class information is stored in NVM 103.

[0044] 3, reset response unit 10 of IC card 1 unconditionally outputs a reset response when an operation class with the highest nominal supply voltage is applied among the operation classes supported by IC card 1. Furthermore, when an operation class with a nominal supply voltage other than the highest among the operation classes supported by IC card 1 is applied, reset response unit 10 of IC card 1 outputs a reset response on the condition that the same operation class is applied consecutively.

[0045] The following describes the case of an IC card 1 that supports Classes A and B. As described above, a connection device that supports multiple operating classes applies the operating class in ascending order of nominal supply voltage. Therefore, the operating class that a connection device that supports Classes A and B first applies is Class B. Because Class B is not the operating class with the highest nominal supply voltage, according to FIG. 3, the reset response unit 10 of the IC card 1 executes step S5. If Class B is applied first, the previous operating class information is not stored in NVM 103, so the reset response unit 10 of the IC card 1 executes step S6 to update the previous operating class information to information indicating Class B. If step S6 is executed, the IC card 1 does not output a reset response, so the connection device deactivates the IC card 1. The operating class that a connection device that supports Classes A and B next applies is Class A. Because Class A is the operating class with the highest nominal supply voltage, according to FIG. 3, the reset response unit 10 of the IC card 1 outputs a reset response in step S8 and erases the previous operating class information from NVM 103 in step S9. In this way, when the IC card 1 that supports classes A and B is used with a connection device that supports classes A and B, the IC card 1 operates in class A.

[0046] A connection device that supports only Class B applies only Class B to the IC card 1. According to FIG. 3, when Class B is applied, the reset response unit 10 of the IC card 1 executes step S5. When Class B is applied initially, the previous operating class information is not stored in NVM 103, so the reset response unit 10 of the IC card 1 executes step S6 to update the previous operating class information to information indicating Class B. When step S6 is executed, the IC card 1 does not output a reset response, so the connection device deactivates the IC card 1. When a connection device that supports Class B attempts to connect to the IC card 1 again, the previous operating class information indicating Class B is stored in NVM 103 in step S5, so the reset response unit 10 of the IC card 1 outputs a reset response in step S7. In this way, when an IC card 1 that supports Classes A and B is used with a connection device that supports only Class B, the IC card 1 can operate in Class B.

[0047] Similarly, when an IC card 1 that supports classes B and C is used with a connection device that also supports classes B and C, the IC card 1 that supports classes B and C operates in class B. Also, when an IC card 1 that supports classes B and C is used with a connection device that only supports class C, the IC card 1 that supports classes B and C can operate in class C.

[0048] When IC card 1 supporting classes A, B, and C is used with a connecting device supporting classes A, B, and C, the operating class initially applied is class C. If class C is applied to this IC card 1, in step S6, reset response unit 10 of IC card 1 stores previous operating class information indicating class C in NVM 103. The next operating class applied to this IC card 1 is class B. In this case, class B is applied to IC card 1, but previous operating class information indicating class C is stored in NVM 103. Therefore, in step S6, reset response unit 10 of IC card 1 changes the previous operating class information stored in NVM 103 from previous operating class information indicating class C to previous operating class information indicating class B. The next operating class applied to this IC card 1 is class A. In this case, class A is the operating class with the highest nominal supply voltage, so reset response unit 10 of IC card 1 outputs a reset response in step S8 and erases the previous operating class information stored in NVM 103 in step S9. Therefore, when an IC card 1 that supports classes A, B, and C is used with a connection device that supports classes A, B, and C, the IC card 1 will operate in class A. In the case of a connection device that supports only class C, when a second reset signal is input, an IC card 1 that supports classes A, B, and C will operate in class C. In the case of a connection device that supports only class B, when a second reset signal is input, an IC card 1 that supports classes A, B, and C will operate in class B.

[0049] In the above-described embodiment, if the determined operation class is the same as the operation class indicated by the previous operation class information stored in NVM 103, the reset response unit 10 of the IC card 1 executes step S7 and outputs a reset response without erasing the previous operation class information stored in NVM 103. However, the reset response unit 10 can also be configured to delete the previous operation class information stored in NVM 103 when it executes step S7 and outputs the reset response.

[0050] In this case, for example, if an IC card 1 that supports classes A and B is used consecutively with a connection device that only supports class B, the IC card will become unresponsive on odd-numbered uses. However, if an IC card 1 that supports classes A and B is used alternately with a connection device that supports classes A and B and a connection device that only supports class B, the IC card 1 that supports classes A and B can operate in class A with the connection device that supports classes A and B. [Explanation of symbols]

[0051] 1 IC card 10 Reset response part 105 Voltage detection circuit 106 Voltage detection register

Claims

1. An IC card that supports multiple operation classes, a reset response unit that determines an operation class corresponding to a voltage being supplied when a reset signal is received, and if the determined operation class is an operation class having a maximum nominal supply voltage, outputs a reset response without referring to previous operation class information indicating the previous operation class and deletes the previous operation class information, and if the determined operation class is an operation class having a nominal supply voltage other than the maximum, refers to the previous operation class information, and if the determined operation class differs from the operation class indicated by the previous operation class information, updates the previous operation class information to information indicating the determined operation class without outputting a reset response, and if the determined operation class is the same as the operation class indicated by the previous operation class information, outputs a reset response. An IC card characterized by:

2. 2. The IC card according to claim 1, wherein the reset response unit, when the determined operation class is the same as the operation class indicated by the previous operation class information, outputs a reset response and then deletes the previous operation class information.

3. 3. A computer program for causing a CPU of an IC card to operate as the reset response unit of the IC card according to claim 1.

4. An IC chip to be mounted on an IC card that supports multiple operation classes, a reset response unit that determines an operation class corresponding to a voltage being supplied when a reset signal is received, and if the determined operation class is an operation class having a maximum nominal supply voltage, outputs a reset response without referring to previous operation class information indicating the previous operation class and deletes the previous operation class information, and if the determined operation class is an operation class having a nominal supply voltage other than the maximum, refers to the previous operation class information, and if the determined operation class differs from the operation class indicated by the previous operation class information, updates the previous operation class information to information indicating the determined operation class without outputting a reset response, and if the determined operation class is the same as the operation class indicated by the previous operation class information, outputs a reset response. An IC chip characterized by:

5. 5. The IC chip according to claim 4, wherein the reset response unit, when the determined operation class is the same as the operation class indicated by the previous operation class information, outputs a reset response and then deletes the previous operation class information.

6. 1. A method performed by an IC card that supports multiple operating classes, comprising: a step a) of determining an operation class corresponding to a voltage being supplied when the IC card receives a reset signal; a step b in which, when the determined operation class is an operation class with the maximum nominal supply voltage, the IC card outputs a reset response without referring to previous operation class information indicating the previous operation class and deletes the previous operation class information, and when the determined operation class is an operation class with a nominal supply voltage that is not the maximum, the IC card refers to the previous operation class information, and when the determined operation class differs from the operation class indicated by the previous operation class information, the IC card updates the previous operation class information to information indicating the determined operation class without outputting a reset response, and when the determined operation class is the same as the operation class indicated by the previous operation class information, the IC card outputs a reset response; A method for outputting a reset response, comprising:

7. 7. The reset response output method according to claim 6, wherein, in step b, when the determined operation class is the same as the operation class indicated by the previous operation class information, the IC card outputs a reset response and then deletes the previous operation class information.

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