JP7409335B2 - IC cards, data transmission methods, and IC chips - Google Patents

Description

The present invention relates to an IC card that transmits and receives data to and from a connecting device such as a terminal.

In recent years, the uses of IC cards mounted with IC chips, which are semiconductor integrated circuits, have been expanding, and the size of data transmitted and received by IC cards has been increasing. Furthermore, IC cards are increasingly being used in physically harsh environments.

For example, SAM (Secure Application Module), which is an IC card installed in IoT devices, contains encryption keys and digital certificates used for mutual authentication of TLS (Transport Layer Security), which is a standard protocol used on the Internet. Stored. Although it depends on the length of the encryption key (public key), if the key length is 1024 bits, the size of the digital certificate will be approximately 1K bytes. Furthermore, IoT devices that implement SAM are often installed in physically harsh environments such as outdoors.

Unless the IC card is a special IC card, the IC card performs serial communication with a connecting device using a half-duplex communication method. For IC cards that support half-duplex serial communication, in order to avoid collisions between the IC card and the connected device (the IC card and the connected device transmit data almost simultaneously), the transmission mode and reception Switching modes. According to Non-Patent Document 1, which is an international standard related to IC cards, an IC card and a connecting device switch to a reception mode when data transmission is completed, and switch to a transmission mode when data reception is completed.

ISO/IEC 7816 Part3

When IC cards are used in physically harsh environments, they become susceptible to noise. If noise occurs while the IC card is transmitting data, collisions between the IC card and the connecting device are likely to occur due to the influence of the noise. This is considered to be because the connected device or IC card malfunctions due to noise. Naturally, as the size of data transmitted by an IC card increases, noise is more likely to occur while the IC card is transmitting and receiving data, and collisions between the IC card and the connected device are more likely to occur. .

Therefore, the present invention provides an IC that can prevent collisions between an IC card and a connecting device even when the size of data transmitted and received by an IC card is large and the IC card is used in a physically harsh environment. The present invention aims to provide a card, a data transmission method, and an IC chip for an IC card.

A first invention for solving the above-mentioned problems is an IC card that serially communicates with a connected device using a half-duplex communication method that switches to a reception mode when data transmission is completed, and switches to a transmission mode when data reception is completed, When starting data transmission, set the function of the input/output port to input port to confirm that data is not being transmitted from the connected device and that noise is not occurring. a transmission processing unit that measures the time during which the level of the input/output port is at a High level, and when the time reaches a determination time, sets the function of the input/output port to an output port and starts data transmission processing. This is an IC card that is characterized by: In the first invention, it is preferable to use "Block Guard Time" defined in ISO/IEC 7816 Part 3 as the determination time.

A second invention for solving the above-mentioned problem is that when data transmission is started using a half-duplex communication method, which switches to reception mode when data transmission is completed and switches to transmission mode when data reception is completed, data is sent from the connecting device. In order to confirm that the input/output port is not being transmitted and that noise is not occurring, set the input/output port function to input port and measure the time that the input/output port level is high. This data transmission method is characterized by comprising the steps of: setting the function of the input/output port to an output port and starting data transmission processing when the time reaches a determination time. Note that in the second invention, it is preferable to use "Block Guard Time" defined in ISO/IEC 7816 Part 3 as the determination time.

A third invention that solves the above-mentioned problem is that when starting data transmission using a half-duplex communication method, which switches to reception mode when data transmission is completed and switches to transmission mode when data reception is completed, data is sent from the connecting device. In order to confirm that the input/output port is not being transmitted and that noise is not occurring, set the input/output port function to input port and measure the time that the input/output port level is high. However, when the time reaches a determination time, the IC chip includes a transmission processing unit that sets the function of the input/output port to an output port and starts processing to transmit data. In the third invention, it is preferable to use "Block Guard Time" defined in ISO/IEC 7816 Part 3 as the determination time.

According to the present invention described above, the IC card can confirm that data is not being transmitted from the connected device and that noise is not occurring before starting data transmission. Therefore, according to the present invention, even if the size of data transmitted and received by the IC card is large and the IC card is used in a physically harsh environment, collisions between the IC card and the connecting device can be prevented. can

FIG. 3 is a diagram illustrating a connection between an IC card and a connecting device according to the present embodiment. FIG. 3 is a diagram illustrating an IC chip mounted on an IC card. FIG. 3 is a diagram illustrating the operation of a transmission processing section included in the IC card.

From here, embodiments according to the present invention will be described. This embodiment is provided to facilitate understanding of the present invention. The present invention is not limited to this embodiment. Unless otherwise specified, each component may be singular or plural. Further, unless otherwise specified, the drawings are schematic diagrams drawn to facilitate understanding of the present invention.

FIG. 1 is a diagram illustrating the connection between the IC card 1 and the connection device 2 according to the present embodiment. The connecting device 2 becomes a terminal that electrically connects to the IC card 1. The connection device 2 includes a communication device or various devices (for example, IoT devices). The IC card 1 is connected to the connecting device 2 through a signal line 20. For this reason, the surface of the IC card 1 is provided with an external terminal 11 on which a resin-molded IC chip 12 is mounted.

The shape of the IC card 1 shown in FIG. 1 is an ID-000 type defined by ISO7810. The ID-000 type specified by ISO7810 is a SIM shape that is installed in smartphones, IoT devices, etc. The shape of the IC card 1 is not limited to the shape illustrated in FIG. For example, the shape of the IC card 1 may be the ID-1 type used in credit cards and cash cards. Furthermore, the IC card 1 may be an eSIM (Embedded SIM).

The external terminal 11 shown in FIG. 1 complies with ISO7816-3. Although the number of terminals provided in the external terminal 11 is eight, the number of terminals used by the IC card 1 according to this embodiment is five. In the external terminal 11 provided on the IC card 1, a supply voltage terminal C1, a reset terminal C2, a clock terminal C3, a ground terminal C5, and an input/output terminal C7 are arranged according to ISO7816-3. Although the IC card 1 of this embodiment does not use the terminals C4, C6, and C8, it is possible to envisage a configuration in which at least one of these terminals is used. Moreover, the shape of the external terminal 11 is also arbitrary.

Five terminals used for connection with the connection device 2 are connected to the connection device 2 through signal lines 20, respectively. The supply voltage terminal C1 of the external terminal 11 is connected to the supply voltage terminal T1 of the connecting device 2. The reset terminal C2 of the external terminal 11 is connected to the reset terminal T2 of the connection device 2. A clock terminal C3 of the external terminal 11 is connected to a clock terminal T3 of the connecting device 2. The ground terminal C5 of the external terminal 11 is connected to the ground terminal T5 of the connection device 2. The input/output terminal C7 of the external terminal 11 is connected to the input/output terminal T7 of the connecting device 2.

FIG. 2 is a diagram illustrating the IC chip 12 mounted on the IC card 1. The IC chip 12 mounted on the IC card 1 includes a CPU 120 (Central Processing Unit), an input/output port 121, a clock pulse generator 123 (CPG: Clock Pulse Generator in FIG. 2), a ROM 124 (Read Only Memory), and a RAM 125 (Random Access). memory), NVM 126 (Non-volatile memory), timer 122, and a bus 127 to which these are connected. Further, the IC chip 12 includes a supply voltage pad P1, a ground pad P5, a reset pad P2, a clock pad P3, and an input/output pad P7 as pads connected to the external terminals 11 of the IC card 1.

The CPU 120 is a circuit that processes data and instructions. ROM 124 is a nonvolatile memory that cannot be electrically rewritten. RAM 125 is volatile memory. NVM 126 is an electrically rewritable nonvolatile memory. The timer 122 is a circuit that measures time.

The ground terminal C5 of the external terminal 11 is connected to the ground pad P5 of the IC chip 12, and the reference voltages in the IC card 1 and the connecting device 2 become the same. A supply voltage terminal C1 of the external terminal 11 is connected to a supply voltage pad P1 of the IC chip 12. The supply voltage supplied from the connection device 2 to the supply voltage pad P1 via the supply voltage terminal C1 becomes the operating voltage of the IC chip 12.

A reset terminal C2 of the external terminal 11 is connected to a reset pad P2 of the IC chip 12. Reset pad P2 is connected to CPU 120. The reset signal input by the connection device 2 to the reset terminal C2 of the external terminal 11 is input to at least the CPU 120 via the reset pad P2.

A clock terminal C3 of the external terminal 11 is connected to a clock pad P3 of the IC chip 12. Clock pad P3 is connected to clock pulse generator 123. The clock signal input by the connecting device 2 to the clock terminal C3 of the external terminal 11 is input to the clock pulse generator 123 via the clock pad P3. Clock pulse generator 123 generates an internal clock used by CPU 120 from the clock signal input to clock pad P3.

The input/output terminal C7 of the external terminal 11 connected to the connection device 2 is connected to the input/output pad P7 of the IC chip 12. The input/output pad P7 is connected to an input/output port 121, which is a circuit that serves as an external interface for the CPU 120.

The input/output port 121 is configured to perform serial half-duplex communication with the connecting device 2 connected to the external terminal 11. Depending on the settings of the register related to the input/output port 121, the input/output port 121 functions as either an input port or an output port.

The input/output port 121 has two logical levels: Low level and High level. Generally, a maximum low-level voltage value and a minimum high-level voltage value are determined according to the operating voltage of the CPU 120. When functioning as an output port, the input/output port 121 can control the output level of the input/output port 121 by controlling the voltage applied to the input/output pad P7. When functioning as an input port, the input/output port 121 can determine the level of the input/output port 121 by reading the voltage applied to the input/output pad P7.

The IC card 1 includes a transmission processing section 10 that controls an input/output port 121 and transmits data. The transmission processing unit 10 is realized by a computer program that causes the CPU 120 to operate. This computer program is stored in the ROM 124, NVM 126, or the like. When the CPU 120 executes this computer program, the CPU 120 functions as the transmission processing section 10. Note that the functions related to the transmission processing section 10 are generally provided by the operating system of the IC card 1.

In order to achieve the object of the present invention, the transmission processing unit 10 included in the IC card 1 monitors the level of the input/output port 121 before starting the process of controlling the input/output port 121 to transmit data. Confirm that no data is being sent from the connected device 2 and that no noise is occurring.

When data is not transmitted or received between the connecting device 2 and the IC card 1, the level of the input/output port 121 is High level. When the connecting device 2 transmits data, the level of the input/output port 121 becomes Low level by the connecting device 2. Further, noise may be added to the signal line 20 that electrically connects the connecting device 2 and the IC card 1, so that the level of the input/output port 121 may change from a high level to a low level. Therefore, before starting the process of controlling the input/output port 121 to transmit data, if it is confirmed that the level of the input/output port 121 is not Low level, the transmission processing unit 10 of the IC card 1 can control the input/output port 121. 121 to transmit data, it can be confirmed that no data is being transmitted from the connecting device 2 and that no noise is occurring.

Specifically, when the transmission processing unit 10 of the IC card 1 starts the process of controlling the input/output port 121 to transmit data, it measures the time that the high level continues. Then, when this time reaches the determination time, the transmission processing unit 10 included in the IC card 1 determines that the level of the input/output port 121 did not become Low level during the determination time, and starts processing to transmit data. do.

FIG. 3 is a diagram illustrating the operation of the transmission processing section 10 included in the IC card 1. The explanation of FIG. 3 also serves as an explanation of the data transmission method according to the present invention.

When starting data transmission, the transmission processing unit 10 according to the present embodiment first sets the function of the input/output port 121 as an input port as a first step S1.

In the next step S2, the transmission processing unit 10 of the IC card 1 initializes the measurement time of the timer 122 in order to measure the time period during which the level of the input/output port 121 is at the High level. Activate.

In the next step S3, the transmission processing unit 10 of the IC card 1 checks the level of the input/output port 121. If the level of the input/output port 121 is Low, the transmission processing unit 10 of the IC card 1 stops the timer 122 in step 4, and returns the process to step S2. If the level of the input/output port 121 is High level, the transmission processing unit 10 of the IC card 1 checks the time measured by the timer 122 in step S5. If the time measured by the timer 122 has not reached the determination time, the transmission processing unit 10 of the IC card 1 returns the process to step S3. If the time measured by the timer 122 has reached the determination time, the transmission processing unit 10 of the IC card 1 sets the function of the input/output port 121 to an output port in step S6. Then, the transmission processing unit 10 of the IC card 1 starts the process of transmitting data in step S7, and the procedure of FIG. 3 ends. In the process of transmitting data, the transmission processing unit 10 of the IC card 1 controls the input/output port 121 to transmit data bit by bit in bit order.

As the determination time, it is desirable to use, for example, "Block Guard Time" specified in ISO/IEC 7816 Part 3. "Block Guard Time" is the minimum interval between the leading edges of consecutive characters in the opposite direction between the connecting device 2 and the IC card 1. In ISO/IEC 7816 Part 3, after receiving a character from the connecting device 2, the IC card 1 must wait at least until the "Block Guard Time" elapses before transmitting data. It can be said that it is desirable to use "Guard Time".

1 IC card 10 Transmission processing section 11 External terminal C7 Input/output terminal 12 IC chip 120 CPU
121 Input/output port 122 Timer P7 Input/output pad 2 Connection device

Claims (6)

An IC card that performs serial communication with a connected device using a half-duplex communication method that switches to a reception mode when data transmission is completed, and switches to a transmission mode when data reception is completed,
When starting data transmission, set the function of the input/output port to input port to confirm that data is not being transmitted from the connected device and that noise is not occurring. a transmission processing unit that measures the time during which the level of the input/output port is at a High level, and when the time reaches a determination time, sets the function of the input/output port to an output port and starts data transmission processing. An IC card that is characterized by The IC card according to claim 1, characterized in that the determination time is "Block Guard Time" specified in ISO/IEC 7816 Part 3. When starting data transmission using the half-duplex communication method, which switches to reception mode when data transmission is completed and switches to transmission mode when data reception is completed, make sure that no data is being transmitted from the connected device and that there is no noise. In order to confirm that this has not occurred, a step of setting the function of the input/output port to an input port and measuring the time that the level of the input/output port is at High level, and when the time reaches the judgment time, , a method for transmitting data comprising the step of setting the function of an input/output port to an output port and starting processing to transmit data. 4. The data transmission method according to claim 3, wherein the determination time is "Block Guard Time" defined in ISO/IEC 7816 Part 3. When starting data transmission using the half-duplex communication method, which switches to reception mode when data transmission is completed and switches to transmission mode when data reception is completed, make sure that no data is being transmitted from the connected device and that there is no noise. In order to confirm that this has not occurred, set the function of the input/output port to input port, measure the time that the level of the input/output port is at High level, and when the time reaches the judgment time, An IC chip equipped with a transmission processing unit that sets the function of an input/output port to an output port and starts processing to transmit data. 6. The IC chip according to claim 5, wherein the determination time is "Block Guard Time" defined in ISO/IEC 7816 Part 3.

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