JP7435577B2 - Proximity IC card, contactless chip, and command execution management method - Google Patents

Description

The present invention relates to a technology for managing the execution of commands installed in a proximity IC card.

When using a proximity IC card, the proximity IC card is held over a proximity coupling device. A proximity coupling device is a device that supplies power to a proximity IC card by inductive coupling and also exchanges data with the proximity IC card. A proximity coupling device is sometimes called a reader/writer.

The power supplied to the proximity type IC card depends not only on the output of the proximity type coupling device but also on the distance from the proximity type IC card to the proximity type coupling device. The strength of the magnetic field generated by the proximity coupling device becomes weaker as the distance from the proximity coupling device, which is the source of the magnetic field, increases. Therefore, the power supplied to the proximity IC card located at a position where the distance to the proximity coupling device is large is reduced. Conversely, the power supplied to a proximity IC card located at a position where the distance to the proximity coupling device is short increases.

When the proximity type IC card begins to be held over the proximity type coupling device, the distance from the proximity type IC card to the proximity type coupling device is large. Therefore, when the proximity type IC card starts to be held over the proximity type coupling device, the power supplied to the proximity type IC card becomes smaller. Therefore, in order to operate the proximity IC card when it begins to be held over the proximity coupling device, it is necessary to operate the proximity IC card with low power consumption.

The power consumption of the proximity IC card depends on the operating clock of the proximity IC card. As the operating clock speed increases, the power consumption of the proximity IC card also increases. Therefore, in the invention disclosed in Patent Document 1, the operating clock is switched depending on the state of power being supplied to the proximity IC card. In the invention disclosed in Patent Document 1, when the power supplied to the proximity IC card is small, the operating clock is set to "low speed".

Furthermore, in the case of a proximity IC card equipped with a coprocessor, which is a dedicated processor for processing cryptographic operations essential for security at high speed, the power consumption of the proximity IC card increases when the coprocessor is operated. Therefore, in the invention disclosed in Patent Document 2, when the power supplied to the proximity IC card is small, the destination of the operation clock is controlled to either the CPU, which is a central processing unit, or a coprocessor. Furthermore, in the invention disclosed in Patent Document 2, when the power supplied to the proximity IC card is small, power consumption is reduced by selecting a security function that consumes less power.

Japanese Patent Application Publication No. 2004-206409 Japanese Patent Application Publication No. 2020-13249

Standards related to proximity type IC cards (for example, ISO/IEC14443) specify various times related to the process (initialization and collision prevention) for establishing a communication path between a proximity type coupling device and a proximity type IC card. There is. For example, this time includes the time from when the proximity IC card enters the operating magnetic field generated by the proximity coupling device until the command can be received. As in the invention disclosed in Patent Document 1, when the operating clock of the proximity IC card is slowed down when the power supplied to the proximity IC card is small, processing can be completed within the time specified by the proximity IC card standard. There are concerns that the project will not be completed. Furthermore, if the security function is changed depending on the power supplied to the proximity IC card as in the invention disclosed in Patent Document 2, the security level of the proximity IC card will be lowered.

If it is possible to limit the processing that can be executed by a PPC card according to the power supplied to the PPC card, the processing required by the PPC card can be done without slowing down the operating clock or reducing the security level. It is believed that this process can be carried out efficiently.

Therefore, it is an object of the present invention to make it possible to limit the processing that can be executed by a proximity IC card depending on the power supplied to the proximity IC card.

A first invention for solving the above-mentioned problems includes: a coil antenna that receives a carrier wave generated by a proximity coupling device; a power supply circuit that generates a DC supply voltage from an AC voltage generated by the coil antenna; A voltage detection circuit that detects the voltage value of the generated supply voltage , a command table that sets a minimum execution voltage value for each command, which is the lowest voltage value at which command execution is permitted, and a command encoded in the carrier wave. Before executing the command corresponding to the message, the command table is referred to, and the voltage value of the supply voltage detected by the voltage detection circuit and the minimum execution voltage value set in the command corresponding to the command message are determined. and if the voltage value of the supply voltage detected by the voltage detection circuit has reached the minimum execution voltage value set in the command corresponding to the command message, the command corresponding to the command message is compared. This is a proximity type IC card characterized by being equipped with a command processing section that executes.

A second invention that solves the above-mentioned problems is a contactless chip mounted on a proximity type IC card, which is connected to a coil antenna that receives a carrier wave generated by a proximity type coupling device, and is connected to an alternating current generated by the coil antenna. A power supply circuit that generates a DC supply voltage from a voltage, a voltage detection circuit that detects the voltage value of the supply voltage generated by the power supply circuit, and a minimum execution voltage value that is the lowest voltage value at which command execution is permitted. A command table in which is set for each command, and the voltage value of the supply voltage detected by the voltage detection circuit and the command corresponding to the command message before executing the command corresponding to the command message encoded in the carrier wave. The voltage value of the supply voltage detected by the voltage detection circuit reaches the minimum execution voltage value set in the command corresponding to the command message. The contactless chip is characterized in that it includes a command processing unit that executes a command corresponding to the command message .

A third invention that solves the above-mentioned problems is a proximity IC that includes a coil antenna that receives a carrier wave generated by a proximity coupling device, and a power supply circuit that generates a DC supply voltage from an AC voltage generated by the coil antenna. A method implemented in a card, the minimum execution voltage being the lowest voltage value at which command execution is permitted before the proximity IC card executes the command corresponding to the command message encoded in the carrier wave. a step of comparing the voltage value of the supply voltage with the lowest execution voltage value set in the command corresponding to the command message using a command table in which voltage values are set for each command; Command execution management comprising the step of causing the proximity IC card to execute the command corresponding to the command message when the minimum execution voltage value set for the command corresponding to the command message has been reached. It's a method.

In order to achieve the object of the present invention, the present invention described above is configured such that the commands that can be executed by the proximity IC card can be restricted depending on the power (voltage) supplied to the proximity IC card. There is.

FIG. 2 is a diagram illustrating a proximity type IC card. FIG. 2 is a diagram illustrating the hardware configuration of a proximity IC card. FIG. 2 is a diagram illustrating a block diagram of a proximity type IC card. A diagram explaining a command message. A diagram explaining a command table. FIG. 3 is a diagram illustrating the operation of a command processing unit included in a proximity IC card. FIG. 7 is a diagram illustrating an example of determining whether or not a command can be executed based on a minimum execution voltage value.

From here, embodiments according to the present invention will be described. This embodiment is provided to facilitate understanding of the present invention, and the present invention is not limited to this embodiment. Further, unless otherwise specified, the drawings are schematic diagrams drawn to facilitate understanding of the present invention.

The proximity IC card 1 according to this embodiment will be explained. FIG. 1 is a diagram illustrating a proximity IC card 1 according to this embodiment. The proximity IC card 1 according to this embodiment is a device compatible with proximity type contactless communication such as ISO/IEC14443_TypeB. The proximity type coupling device 3 is a device that supplies power to the proximity type IC card 1 by inductive coupling and also exchanges data with the proximity type IC card 1. The proximity coupling device 3 is also called a reader/writer.

The proximity IC card 1 includes a coil antenna 1a and a non-contact chip 2 connected to the coil antenna 1a. The proximity type IC card 1 receives the command message transmitted by the proximity type coupling device 3 using the coil antenna 1a, and executes processing corresponding to this command message.

In FIG. 1, a proximity IC card 1 has the shape of a credit card. However, the credit card is only one form of the proximity IC card 1. The proximity type IC card 1 may be any medium in which a coil antenna 1a and a non-contact chip 2 connected thereto are mounted. The proximity IC card 1 may have a stick shape or a coin shape.

FIG. 2 is a diagram illustrating the hardware configuration of the proximity IC card 1. As shown in FIG. As described using FIG. 1, the proximity IC card 1 includes a coil antenna 1a connected to a non-contact chip 2. In order to support close-range non-contact communication, the resonant frequency of the coil antenna 1a is adjusted to around 13.56 MH.

The non-contact chip 2 illustrated in FIG. -volatile Memory) and a coprocessor 26.

An RF circuit 21 included in the non-contact chip 2 is connected to a coil antenna 1a that generates an alternating current voltage from a carrier wave generated by the proximity coupling device 3. The RF circuit 21 included in the non-contact chip 2 includes at least a power supply circuit 210 that generates a DC supply voltage (Vcc) from the AC voltage generated by the coil antenna 1a. The power supply circuit 210 included in the RF circuit 21 is generally configured by a rectifier circuit. The DC supply voltage generated by the power supply circuit 210 is supplied to circuits such as the voltage detection circuit 22, CPU 20, RAM 23, ROM 24, NVM 25, and coprocessor 26.

The RF circuit 21 includes, as circuits not shown in FIG. 2, a modulation circuit that encodes data onto a carrier wave generated by the proximity coupling device 3, and a modulation circuit that encodes data into a carrier wave generated by the proximity coupling device 3. It includes a demodulation circuit that performs data decoding processing, a clock generation circuit that generates an operating clock for the contactless chip 2, and the like.

The CPU 20 is a central arithmetic processing unit of the non-contact chip 2. The RAM 23 is an electrically rewritable volatile memory. ROM24 is a read-only memory. NVM25 is an electrically rewritable nonvolatile memory. The coprocessor 26 is a dedicated processor for processing cryptographic operations essential for security at high speed.

The voltage detection circuit 22 is a circuit that detects the voltage value of the supply voltage generated by the power supply circuit 210 of the RF circuit 21. An AD converter can be used as a circuit that converts the voltage value of the supply voltage generated by the power supply circuit 210 of the RF circuit 21 from an analog signal to a digital signal. When using an AD converter in the voltage detection circuit 22, the output of the AD converter is input to the CPU 20 via a register.

When converting the voltage value of the supply voltage generated by the power supply circuit 210 of the RF circuit 21 from an analog signal to a binary signal, the power supply circuit 210 of the RF circuit 21 serves as a detection circuit that detects the voltage value of the supply voltage. It is also possible to use a circuit that compares the supply voltage and the reference voltage using a comparator. When a comparator is used in the voltage detection circuit 22, the voltage comparison result by the comparator is input to the CPU 20 using a switch or the like.

FIG. 3 is a diagram illustrating a block diagram of the proximity IC card 1. As shown in FIG. According to the block diagram shown in FIG. 3, the proximity IC card 1 includes the RF circuit 21, power supply circuit 210, and voltage detection circuit 22 described using FIG. 2 as hardware. According to the block diagram shown in FIG. 3, the proximity IC card 1 includes a transmission control section 12, a command processing section 10, and a plurality of commands 11 as functions implemented by software.

The transmission control unit 12 included in the proximity type IC card 1 performs processing for establishing a communication path between the proximity type coupling device 3 and the proximity type IC card 1, and communication between the proximity type coupling device 3 and the proximity type IC card 1. This is a function that executes processing related to the transmission control protocol used for. The process of establishing a communication path between the proximity coupling device 3 and the proximity IC card 1 is defined by, for example, ISO14443-3. In ISO14443-3, the process of establishing a communication path between the proximity coupling device 3 and the proximity IC card 1 is called initialization and anticollision. Further, the transmission control protocol used for communication between the proximity coupling device 3 and the proximity IC card 1 is defined by, for example, ISO14443-4.

The messages handled by the transmission control unit 12 included in the proximity IC card 1 are TPDUs (Transmission Protocol Data Units). The TPDU received by the proximity IC card 1 includes a command message (C-APDU: Command Application Protocol Data Unit).

The proximity coupling device 3 transmits a carrier wave in which a TPDU containing a command message is encoded. The proximity IC card 1 receives this carrier wave using a coil antenna 1a. The RF circuit 21 of the proximity IC card 1 decodes the TPDU included in the carrier wave. The transmission control unit 12 verifies the validity of the TPDU decoded by the RF circuit 21. If the validity verification of the TPDU is successful, the command message included in the TPDU is delivered to the command processing unit 10.

FIG. 4 is a diagram illustrating a command message. FIG. 4 illustrates an example of a command message. The command message illustrated in FIG. 4 includes a command identifier serving as information for identifying the command 11, parameters necessary for executing the command 11, and data processed by the command 11. In accordance with ISO/IEC7816-3, the command identifier corresponds to CLA and INS. Furthermore, when complying with ISO/IEC7816-3, the parameters correspond to P1 and P2. Furthermore, when conforming to ISO/IEC7816-3, data corresponds to Lc, data field, and Le.

A command 11 included in the proximity IC card 1 is a function to execute a predetermined process. The proximity IC card 1 includes a plurality of commands 11. The commands 11 provided in the proximity IC card 1 include user commands such as a selection command for selecting a file, a read command for reading a file, a write command for writing data to a file, and an authentication command for performing processing related to authentication. Further, the commands 11 provided in the proximity IC card 1 include system commands such as a lock command for locking the proximity IC card 1. Although the program code for command 11 is generally installed in the ROM 24, the program code for command 11 may also be installed in the NVM 25.

For the command 11, an execution condition indicating a condition for permitting execution of the command 11 is set. In this embodiment, the execution conditions for the command 11 include a minimum execution voltage value that is the lowest voltage value that permits execution of the command 11. The number of execution conditions set for one command 11 is not limited to one. In addition to the minimum execution voltage value, a security condition (success of specified authentication) can be set as an execution condition for one command 11.

The command processing unit 10 included in the proximity IC card 1 has a command processing function to execute a command 11 corresponding to a command message delivered from the transmission control unit 12. The program code of the command processing unit 10 is generally implemented in the ROM 24.

Before executing the command 11, the command processing unit 10 included in the proximity IC card 1 checks whether all the execution conditions set for the command 11 in the proximity IC card 1 are satisfied, and confirms that all the execution conditions are satisfied. Execute command 11 only if the

In addition to the command processing function described above, the command processing unit 10 included in the proximity IC card 1 has a function of verifying the validity of a command message, and a function of transmitting a response message (R-APDU: Response APDU) indicating the processing result of the command 11 to the vicinity. It has a function of responding to the type coupling device 3, etc.

The command processing unit 10 included in the proximity IC card 1 has a command table 100 in order to specify the minimum execution voltage value set in the command 11 corresponding to the command message delivered from the transmission control unit 12. . It is desirable to implement the command table 100 in the NVM 25 so that the contents of the command table 100 can be changed.

FIG. 5 is a diagram illustrating the command table 100. As illustrated in FIG. 5, in the command table 100, for each command 11 provided in the proximity IC card 1, a command identifier, a minimum execution voltage value that is the lowest voltage value at which execution of the command 11 is permitted, and a command 11 is associated with at least one calling address. The command table 100 illustrated in FIG. 5 includes three command identifiers. They are command A, command B, and command C. According to FIG. 5, the lowest execution voltage value corresponding to the command whose command identifier is command A (hereinafter abbreviated as "command A") is voltage value A, and the calling address of command A is calling address A. Further, the lowest execution voltage value corresponding to the command whose command identifier is command B (hereinafter abbreviated as "command B") is voltage value B, and the calling address of command B is calling address B. Further, the lowest execution voltage value corresponding to the command whose command identifier is command C (hereinafter abbreviated as "command C") is voltage value C, and the calling address of command C is calling address C. The order of magnitude of the lowest effective voltage values is voltage value A<voltage value B<voltage value C. The command A with the lowest minimum execution voltage value is the command 11 with low power consumption, for example, the command 11 used in the process of establishing a communication path between the proximity coupling device and the proximity IC card. Further, the command B having the second lowest minimum execution voltage value is a command 11 with relatively large power consumption, for example, a command 11 such as a write command. The command C with the highest minimum execution voltage value is a command 11 that consumes a large amount of power, for example, a command 11 that uses the coprocessor 26, such as an authentication command.

FIG. 6 is a diagram illustrating the operation of the command processing section 10 included in the proximity IC card 1. The explanation of FIG. 6 also serves as an explanation of the method according to the present invention, that is, the command execution management method.

In step S1 illustrated in FIG. 6, the command processing unit 10 included in the proximity type IC card 1 receives a command message from the proximity type coupling device 3.

Next, in step S2 illustrated in FIG. 6, the command processing unit 10 included in the proximity IC card 1 determines whether or not the process corresponding to the command message received in step S1 is supported. The command processing unit 10 uses the command table 100 for this determination. If the command identifier included in the command message is in the command table 100, the command processing unit 10 included in the proximity IC card 1 determines that the process corresponding to the command message received in step S1 is "supported." Further, if the command identifier included in the command message is not in the command table 100, the command processing unit 10 included in the proximity IC card 1 determines that the process corresponding to the command message received in step S1 is not supported. do.

The command processing unit 10 included in the proximity IC card 1 branches the process based on the determination result in step S2. If the determination result in step S2 is "not supported", in step S8 illustrated in FIG. 6, the command processing unit 10 included in the proximity IC card 1 determines that the process corresponding to the command message is not supported. The procedure of FIG. 6 ends with the response message shown in FIG.

If the determination result in step S2 is "supported", in step S3 illustrated in FIG. 6, the command processing unit 10 included in the proximity IC card 1 uses the Specify command 11. The command 11 used in the process corresponding to the command message can be specified by the command identifier included in the command message.

Next, in step S4 illustrated in FIG. 6, the command processing unit 10 included in the proximity IC card 1 specifies the lowest execution voltage value set in the command 11 used in the process corresponding to the command message. The command processing unit 10 included in the proximity IC card 1 uses the command table 100 to specify the minimum execution voltage value. The command processing unit 10 included in the proximity IC card 1 reads the lowest execution voltage value corresponding to the command identifier included in the command message from the command table 100.

Next, in step S5 illustrated in FIG. Determine whether the minimum execution voltage value has been reached. Note that the voltage value of the supply voltage reaching the minimum effective voltage value means that the voltage value of the supply voltage is equal to or exceeds the minimum effective voltage value.

The command processing unit 10 included in the proximity IC card 1 branches the process based on the determination result in step S5 of FIG. If the voltage value of the supply voltage has not reached the minimum execution voltage value of the command 11 in step S5, the command processing unit 10 included in the proximity IC card 1 satisfies the execution condition of the command 11 in step S9 of FIG. The procedure of FIG. 6 ends by executing a process of responding with a response message indicating that the request has not been made.

In step S5 illustrated in FIG. 6, if the voltage value of the supply voltage has reached the lowest execution voltage value of the command 11, the command processing unit 10 included in the proximity IC card 1 responds to the command message in A call address corresponding to the included command identifier is specified from the command table 100, and the command 11 corresponding to the command message is executed using this call address.

Next, in step S7 illustrated in FIG. 6, the command processing unit 10 included in the proximity IC card 1 executes a process of responding with a response message indicating the execution result of the command 11 executed in S6 of FIG. The procedure of FIG. 6 ends.

FIG. 7 is a diagram illustrating an example of determining whether or not a command can be executed based on the lowest execution voltage value. FIG. 7 is based on the command table 100 illustrated in FIG. According to FIG. 5, when the supply voltage of the proximity IC card 1 is a voltage value A, the command 11 that is permitted to be executed is only the command A if the procedure of FIG. 6 is followed. Since voltage value A is the lowest execution voltage value of command A, when the supply voltage is voltage value A, command A can be executed. Voltage value A is smaller than voltage value B, which is the lowest execution voltage value of command B. Further, voltage value A is smaller than voltage value C, which is the lowest execution voltage value of command C. Therefore, when the supply voltage is voltage value A, command B and command C cannot be executed.

According to FIG. 5, when the supply voltage of the proximity IC card 1 is voltage value B, the commands that are permitted to be executed are command A and command B if the procedure of FIG. 6 is followed. Since voltage value B is the lowest execution voltage value of command B, when the supply voltage is voltage value B, command B can be executed. Further, since voltage value B is larger than voltage value A, which is the lowest execution voltage value of command A, when the supply voltage is voltage value B, command A can be executed. Since voltage value B is smaller than voltage value C, which is the lowest execution voltage value of command C, when the supply voltage is voltage value B, command C cannot be executed.

According to FIG. 5, when the supply voltage value of the proximity IC card 1 is voltage value C, the commands that are permitted to be executed are command A, command B, and command C if the procedure of FIG. 6 is followed. Since the voltage value C is the lowest execution voltage value of the command C, when the supply voltage is the voltage value C, the command C can be executed. In addition, since voltage value C is larger than voltage value A, which is the lowest execution voltage value of command A, and voltage value B, which is the lowest execution voltage value of command B, when the supply voltage is voltage value C, command A and Command B is executable.

When the proximity type IC card 1 starts to be held over the proximity type coupling device 3, the power supplied to the proximity type IC card 1 is small, but in the proximity type IC card 1 according to this embodiment, the proximity type coupling device It is possible to execute commands 11 with low power consumption, such as commands 11 used in processing for establishing a communication path between type IC cards. Furthermore, as the distance between the proximity IC card 1 and the proximity coupling device 3 becomes smaller and the power supplied to the proximity IC card 1 increases, the proximity IC card 1 according to the present embodiment uses commands with low power consumption. In addition to command 11, commands 11 that consume large amounts of power, such as command 11 that uses coprocessor 26, can also be executed.

1 Proximity IC card 10 Command processing unit 100 Command table 2 Contactless chip 21 RF circuit 210 Power supply circuit 22 Voltage detection circuit 3 Proximity coupling device

Claims (3)

a coil antenna that receives carrier waves generated by the proximity coupling device;
a power supply circuit that generates a DC supply voltage from the AC voltage generated by the coil antenna;
a voltage detection circuit that detects the voltage value of the supply voltage generated by the power supply circuit;
A command table that sets the minimum execution voltage value for each command, which is the lowest voltage value at which command execution is permitted, and
Before executing the command corresponding to the command message encoded in the carrier wave, the command table is referred to and the voltage value of the supply voltage detected by the voltage detection circuit and the command corresponding to the command message are set. and when the voltage value of the supply voltage detected by the voltage detection circuit has reached the minimum execution voltage value set in the command corresponding to the command message, a command processing unit that executes a command corresponding to the command message ;
A proximity type IC card that is characterized by: A contactless chip mounted on a proximity IC card,
a power supply circuit connected to a coil antenna that receives a carrier wave generated by the proximity coupling device, and that generates a DC supply voltage from the AC voltage generated by the coil antenna;
a voltage detection circuit that detects the voltage value of the supply voltage generated by the power supply circuit;
A command table that sets the minimum execution voltage value for each command, which is the lowest voltage value at which command execution is permitted, and
Before executing the command corresponding to the command message encoded in the carrier wave, the voltage value of the supply voltage detected by the voltage detection circuit and the minimum execution voltage value set for the command corresponding to the command message. and if the voltage value of the supply voltage detected by the voltage detection circuit has reached the minimum execution voltage value set in the command corresponding to the command message , the command corresponding to the command message is compared. The command processing section that executes
A non-contact chip featuring: A method carried out in a proximity IC card comprising a coil antenna for receiving a carrier wave generated by a proximity coupling device and a power supply circuit for generating a DC supply voltage from an AC voltage generated by the coil antenna, the method comprising: Before the proximity IC card executes the command corresponding to the command message encoded in the carrier wave , it creates a command table in which a minimum execution voltage value, which is the lowest voltage value at which execution of the command is permitted, is set for each command. comparing the voltage value of the supply voltage with a minimum execution voltage value set in the command corresponding to the command message , and the voltage value of the supply voltage being set in the command corresponding to the command message; A command execution management method comprising the step of causing the proximity IC card to execute a command corresponding to the command message if the minimum execution voltage value has been reached.

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