JP7397402B2 - Electronic information storage medium, data transmission method, and program - Google Patents

Description

The present invention relates to a technical field such as a command transmission/reception method using an electronic information storage medium such as a secure element.

In recent years, with the spread of IoT (Internet of Things), secure elements are being used in embedded IC modules to ensure security. In addition to the interface defined by the international standard ISO/IECISO7816-2, interfaces such as SPI (Serial Peripheral Interface) and I ² C (Inter-Integrated Circuit) are often used for secure element communication. For example, the length of a command APDU (Application Protocol Data Unit) sent and received over these interfaces is often specified in the header (first field) of the block containing the command APDU, but the length that can be specified in the header is In order to transmit/receive a command APDU with a longer length, it is necessary to extend the header length or to divide the command APDU and transmit/receive it. Patent Document 1 describes that when encrypting plaintext with a large amount of data, the plaintext is divided into block sizes that can be included in one command APDU, and only the plaintext is encoded without generating a command APDU for each divided plaintext. An invention is disclosed that can shorten processing time by transmitting and receiving information.

Patent No. 4840012

However, since the technique disclosed in Patent Document 1 requires a special mode, there is a possibility that the data format already determined by international standards or the like may be changed. When using a protocol whose data format has already been determined, it is not easy to change the data format, such as by expanding the header length, due to compatibility with existing products.

Therefore, the present invention has been made in view of the above points, and provides electronic information that allows specifying a data length exceeding the length that can be specified in the header without changing the existing data format. The objective is to provide a storage medium, a data transmission method, and a program.

In order to solve the above problem, the invention according to claim 1 provides a first receiving means for receiving a first block including length data indicating the length of transmission data to be transmitted from an external device; Holding means for holding the length data included in the block; and determining means for determining whether the transmission data of the length indicated by the length data included in the first block can be received at one time. and when the determination means determines that the transmission data cannot be received at one time, length designation data indicating the length of the transmission data that can be received at one time is sent as a response to the first block. a third block transmitted from the external device in response to the second block, the third block having the length indicated by the held length data; The apparatus is characterized by comprising: a second receiving means for receiving a third block including the transmission data from an external device; and an execution means for executing processing based on the transmission data included in the third block.

According to a second aspect of the invention, in the electronic information storage medium according to the first aspect, the second receiving means divides the transmitted data of the length indicated by the held length data. A third block including transmission data is received from an external device multiple times, and the execution means executes the transmission of the length indicated by the length data by concatenating the divided transmission data received multiple times. It is characterized in that when data is obtained, processing is executed based on the transmitted data.

The invention according to claim 3 provides a first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device; a holding means for holding a second block; a sending means for sending a second block to the external device as a response to the first block; and a third block sent from the external device in response to the second block; a second receiving means for receiving from an external device a third block including the transmission data having the length indicated by the length data; and execution for executing processing based on the transmission data included in the third block. means , wherein the first block and the third block each include an information field for storing data used in an application layer by a predetermined application, and a means for specifying a length of the information field. The information field of the first block stores the length data of the length specified by the LEN, The transmission data having the length indicated by the length data is stored in the information field of the third block, and the execution means ignores the LEN included in the first field of the third block and stores the transmission data in the information field of the third block. The present invention is characterized in that processing is executed based on the transmission data included in three blocks.

The invention according to claim 4 is a data receiving method executed by a computer included in an electronic information storage medium, wherein the first block including length data indicating the length of transmission data to be transmitted is sent from an external device. a step of receiving, a step of holding the length data included in the first block, and whether it is possible to receive the transmission data of the length indicated by the length data included in the first block at one time. a step of determining whether or not the transmission data can be received at one time; and when it is determined that the transmission data cannot be received at one time, a length specification indicating a length in which the transmission data can be received at one time as a response to the first block; transmitting a second block containing data to the external device; and a third block transmitted from the external device in response to the second block, the length of which is indicated by the retained length data. The method is characterized by comprising the steps of: receiving a third block including the transmission data from an external device; and executing processing based on the transmission data included in the third block. The invention according to claim 5 is a data receiving method executed by a computer included in an electronic information storage medium, in which a first block including length data indicating the length of transmission data to be transmitted is sent from an external device. receiving the length data; retaining the length data included in the first block; transmitting a second block to the external device as a response to the first block; receiving from an external device a third block transmitted from the device, the third block including the transmitted data having the length indicated by the held length data; an execution step of performing processing based on the transmitted data, wherein the first block and the third block each include an information field for storing data used in an application layer by a predetermined application; The information field is configured of a predetermined data format having a first field including a LEN (Length byte) consisting of a predetermined byte for specifying the length of the information field, and the information field of the first block has a length byte specified by the LEN. The length data of the length indicated by the length data is stored in the information field of the third block, and the transmission data of the length indicated by the length data is stored in the information field of the third block. The present invention is characterized in that processing is executed based on the transmission data contained in the third block, ignoring the LEN contained in the first field.

The invention according to claim 6 provides a first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device; and a first receiving means for receiving the length data included in the first block. a holding means for holding, a determining means for determining whether or not the transmission data of the length indicated by the length data included in the first block can be received at one time; When it is determined that the data cannot be received at one time, the external device sends a second block including length designation data indicating the length of the transmission data that can be received at one time as a response to the first block. a third block transmitted from the external device in response to the second block, the third block including the transmission data having the length indicated by the held length data; The present invention is characterized in that the computer functions as a second receiving means for receiving data from an external device, and an execution means for executing processing based on the transmitted data included in the third block. The invention according to claim 7 provides a first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device; a holding means for holding a second block; a sending means for sending a second block to the external device as a response to the first block; and a third block sent from the external device in response to the second block; a second receiving means for receiving from an external device a third block including the transmission data having the length indicated by the length data; and execution for executing processing based on the transmission data included in the third block. A program that causes a computer to function as a means, wherein the first block and the third block each include an information field for storing data used in an application layer by a predetermined application, and a length of the information field. The information field of the first block includes the length specified by the LEN. data is stored, the transmission data having the length indicated by the length data is stored in the information field of the third block, and the execution means stores the LEN included in the first field of the third block. The present invention is characterized in that processing is executed based on the transmission data included in the third block while being ignored .

According to the present invention, a data length that exceeds the length that can be specified in a header can be specified without changing the existing data format.

It is a figure showing an example of a outline composition of SE1. 3 is a diagram showing a data format (structure) of a block BLn transmitted and received between SE1 and an external device 2. FIG. 3 is a diagram showing a specific example of a data format of a block BLn transmitted and received between SE1 and an external device 2. FIG. 7 is a flowchart illustrating an example of the processing of the CPU 10 when the block BLn from the external device 2 is received by the SE 1 in the first embodiment. 7 is a flowchart illustrating an example of the processing of the CPU 10 when the block BLn from the external device 2 is received by the SE 1 in the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described below is an embodiment in which the present invention is applied to a secure element (hereinafter referred to as "SE").

[1. SE1 configuration and functions]
First, with reference to FIG. 1, the configuration and functions of SE1 according to the present embodiment will be described. FIG. 1 is a diagram showing an example of a schematic configuration of SE1. SE1 is an example of the electronic information storage medium of the present invention. As shown in FIG. 1, the SE1 includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 11, a ROM (Read Only Memory) 12, an NVM (Nonvolatile Memory) 13 (nonvolatile memory), and an I/O It is configured to include a circuit 14, etc. (ROM 12 may not be included). SE1 is used by being installed in, for example, IoT products and terminals such as smartphones. Note that the SE1 may be installed in the terminal as a removable IC card, or it may be installed on the embedded board as an eUICC (Embedded Universal Integrated Circuit Card) so that it cannot be easily removed or replaced from the terminal (in other words, it is not connected to the terminal). integrally formed).

The CPU 10 is a processor (computer) that executes various programs stored in the ROM 12 or NVM 13. The CPU 10 functions as a first receiving means, a holding means, a transmitting means, a second receiving means, a determining means, and an executing means in the present invention. RAM 11 is used as a working memory. For example, a flash memory is applied to the NVM 13. The NVM 13 may be an "Electrically Erasable Programmable Read-Only Memory". The NVM 13 stores various programs (including the program of the present invention) and data. The various programs include an operating system (OS), applications, and the like. Note that some of the various programs and data stored in the NVM 13 may be stored in the ROM 12.

The I/O circuit 14 serves as an interface with the external device 2. The external device 2 is, for example, a controller of a terminal in which SE1 is installed. However, the external device 2 may be a server connected to a network or a reader/writer capable of contact (or non-contact) communication. Examples of the interface include SPI (Serial Peripheral Interface), I ² C (Inter-Integrated Circuit), and ISO/IEC7816 interface.

When the I/O circuit 14 is responsible for SPI, the I/O circuit 14 is equipped with a shift register, four signal lines, and the like. The four signal lines are SCLK (Serial Clock), MOSI (Master-Out Slave-In), MISO (Master-In Slave-Out), and SLS (SLave Select). For example, communication is started when the external device 2 as a master makes SLS low active. Further, when the I/O circuit 14 serves as an ISO/IEC7816 interface, the I/O circuit 14 is provided with eight known terminals C1 to C8.

In this embodiment, SPI is used in the lower layer (physical layer) in communication between the SE 1 and the external device 2, the TPDU (Transmission Protocol Data Unit) protocol (for example, T=1) is used in the middle layer, and the upper layer (application layer) is used in the middle layer. ), it is assumed that the APDU (Application Protocol Data Unit) protocol is used. However, it is not limited to this. Note that SPI can have multiple slaves, and in this embodiment, a case where communication is performed with one SE1 as a slave is taken as an example, but the external device 2 may also communicate with multiple slaves. .

The APDU protocol is a protocol for transmitting and receiving command APDUs and response APDUs defined in ISO/IEC7816-3. Here, the command APDU is composed of, for example, CLA, INS, P1, and P2 (consisted only of a header) (Case 1). CLA indicates a command class, INS indicates a command code, and P1 and P2 indicate command parameters. Alternatively, the command APDU is composed of CLA, INS, P1 and P2, and Le (composed of a header and a body) (Case 2). Le indicates the maximum length of the response APDU. Alternatively, the command APDU is composed of CLA, INS, P1 and P2, and Lc and Data (Case 3). Lc indicates the length of Data. Alternatively, the command APDU is composed of CLA, INS, P1 and P2, and Lc, Data and Le (Case 4). On the other hand, the response APDU is composed of, for example, SW1 and SW2 (Case1, Case3). SW1 and SW2 are status words and indicate the results of command processing executed based on the command APDU (in other words, processing according to the command APDU). For example, when SW1 and SW2 are "0009(h)", it indicates a normal end, and when SW1 and SW2 are "6???(h)", it indicates an error corresponding to the numerical value of "?". Alternatively, the response APDU is composed of, for example, DATA, SW1, and SW2 (Case 2, Case 4).

Further, in communication according to the TPDU protocol, an I (Information) block, an R (Receive Ready) block, or an S (Supervisory) block (management block) is used. Here, the I block is used to convey data (eg, command APDU and response APDU) used in the application layer by a predetermined application. The R block is used, for example, to convey an acknowledgment (ACK) or a negative acknowledgment (NAK). S blocks are used to convey control information. ISO/IEC7816-3 stipulates WTX request, WTX response, IFS change request, IFS change response, ABORT request, ABORT response, etc. as control information, but in this embodiment, new control information , a LEN request that specifies the length (data length) of transmission data (eg, command APDU and response APDU) to be transmitted by the I block, and a LEN response to the LEN request.

FIG. 2 is a diagram showing the data format (structure) of block BLn exchanged between SE1 and external device 2. As shown in FIG. As shown in FIG. 2, the block BLn is configured with a predetermined data format having a first field (Prologue field), an information field (Information field), and a last field (Epilogue field). Here, the information field is a field for storing data used in the application layer by a predetermined application. The final field is a field for storing a check code (for example, an error detection code such as LRC or CRC).

The first field is a field corresponding to the header of block BLn, and includes a NAD (Node Address Byte) indicating the destination address of block BLn, and a PCB (Protocol Control Byte) indicating the data format type (that is, the type of block BLn). ), and LEN (Length Byte) for specifying the length of the information field. NAD, PCB, and LEN each consist of, for example, 1 byte (ie, 256 bits). Note that when the external device 2 communicates with multiple slaves via SPI, the block BLn is broadcast from the external device 2, but if the transmission destination (destination) of the block BLn is only SE1, the block BLn is broadcast to the NAD of the block BLn. contains an address (for example, identification information) unique to SE1.

The first two bits (b8b7) of the PCB indicate whether the block BLn is an I block, R block, or S block, and the remaining six bits (b6 to b1) indicate control information. For example, b8b7=00 on the PCB indicates an I block, and b8b7=10 on the PCB indicates an R block. In addition, when b8b7=00 in the PCB (that is, in the case of an I block), b6 is a block chaining bit (chaining bit), and when b1=1, the I block is chained to the next I block. On the other hand, an I block in the case of b1=0 is not chained to the next I block. On the other hand, b8b7=11 in the PCB indicates an S block, in this case, b6 to b1=000011 indicates a WTX request, b6 to b1=100011 indicates a WTX response, b6 to b1=0000001 indicates an IFS change request, b6-b1=100001 indicates an IFS change response, b6-b1=000010 indicates an ABORT request, and b6-b1=100010 indicates an ABORT response. In this embodiment, b6 to b1 on the PCB are newly defined to indicate a LEN request and a LEN response. For example, the LEN request is assigned to b6~b1=000101 (bit string not used in ISO/IEC7816-3) on the PCB, and the LEN request is assigned to b6~b1=100101 (bit string not used in ISO/IEC7816-3) on the PCB. A LEN response is assigned.

FIG. 3 is a diagram showing a specific example of the data format of block BLn transmitted and received between SE1 and external device 2. As shown in FIG. 3(A) shows the data format of block BL1 (an example of the first block) that is first transmitted from the external device 2 to SE1, and FIG. 3(B) shows the data format from SE1 to the external device 2 as a response to block BL1. A block BL2 (an example of a second block) is shown. FIG. 3(C) shows the data format of block BL3 (an example of the third block) that is next transmitted from the external device 2 to SE1 in response to block BL2, and FIG. 3(D) shows the data format of block BL3 (an example of the third block) as a response to block BL3. It shows block BL4 transmitted from SE1 to external device 2.

In the block BL1 that is first transmitted from the external device 2 to the SE1, as shown in FIG. 3(A), the PCB is set to indicate the S block and LEN request, and the information field of the block BL1 contains Length data of the length specified by LEN of BL1 is stored. This length data indicates the length of transmission data (for example, command APDU) to be transmitted later. Note that the NAD of block BL1 includes an address (for example, identification information) unique to SE1. In block BL2 transmitted from SE1 to external device 2 as a response to block BL1, as shown in FIG. Fields do not need to store meaningful data. Note that the NAD of block BL2 includes an address (for example, identification information) unique to the external device 2.

On the other hand, in the block BL3 that is next transmitted from the external device 2 to the SE1, the PCB is set to indicate the I block, as shown in FIG. Transmission data (for example, command APDU) of the length indicated by the length data stored in the information field of block BL1 is stored. Note that the NAD of block BL3 includes an address (for example, identification information) unique to SE1. In block BL4 sent from SE1 to external device 2 as a response to block BL3, the PCB is set to indicate the I block, as shown in FIG. 3(D), and the information field of block BL4 is For example, a response APDU is stored. Note that the NAD of block BL4 includes an address (for example, identification information) unique to the external device 2.

By configuring as shown in FIG. 3, it becomes possible to specify a length using length data that exceeds the length that can be specified by, for example, a 1-byte LEN (maximum 255 bytes). For example, if the length specified by the 1-byte LEN (i.e. length data length) is 2 bytes (i.e. 65536 bits), the 2-byte length data can be used to transmit data (e.g. command APDU). You can specify the length. This makes it possible to specify a data length that exceeds the length that can be specified by the LEN of the first field, without changing the existing data format. Note that since LEN of block BBL2 is not used (ignored by SE1), it may be set to, for example, "00(h)" or "FF(h)".

[2. SE1 operation]
Next, the operation of SE1 will be explained separately in Example 1 and Example 2.

(Example 1)
First, with reference to FIG. 4, the operation of SE1 according to the first embodiment will be described. FIG. 4 is a flowchart showing an example of the processing of the CPU 10 (for example, the OS) when the block BLn from the external device 2 is received by the SE 1 in the first embodiment.

When the process shown in FIG. 4 is started, the CPU 10 determines whether a block BL1 including a LEN request has been received immediately before the received block BLn (step S1). If the CPU 10 determines that the block BL1 has not been received (step S1: NO), the process proceeds to step S2. On the other hand, if the CPU 10 determines that block BL1 has been received (step S1: YES), that is, if the received block BLn is block BL3 transmitted from the external device 2 in response to block BL2, then step Proceed to S7.

In step S2, the CPU 10 determines whether the received block BLn is the block BL1 including the LEN request by referring to the PCB. When the CPU 10 determines that the received block BLn is the block BL1 including the LEN request (step S2: YES), the CPU 10 retains the length data included in the block BL1 (step S3). For example, length data for the length specified by LEN included in the first field of block BL1 is acquired from the information field of block BL1, and the acquired length data is stored in the retention area of RAM and retained. be done. Next, the CPU 10 transmits the block BL2 including the LEN response to the external device 2 as a response to the block BL1 (step S4).

On the other hand, in step S2, if the CPU 10 determines that the received block BLn is not the block BL1 including the LEN request (step S2: NO), that is, if it is a normal block BL5, the CPU 10 determines that the received block BLn is not included in the information field of the block BL5. For example, normal command processing is executed based on the command APDU (the OS causes the application to execute processing according to the command APDU) (step S5), and as a response to block BL5, block BL6 (response indicating the result of command processing) is executed. (including APDU) to the external device 2 (step S6).

In step S7, the CPU 10 executes processing (for example, command processing) based on the transmission data (for example, command APDU) included in the received block BL3. For example, a command APDU with a length indicated by the length data held in step S3 is obtained from the information field of block BL3 (LEN included in the first field of block BL3 is ignored), and the obtained command Command processing is executed based on the APDU (the OS causes the application to execute processing according to the command APDU). Next, the CPU 10 transmits a block BL4 (including, for example, a response APDU indicating the result of command processing) to the external device 2 as a response to the block BL3 (step S8).

As a modification of the first embodiment, when the CPU 10 determines in step S2 of FIG. 4 that the received block BLn is the block BL1 including the LEN request (step S2: YES), the CPU 10 moves to step S3. Beforehand, it may be determined whether transmission data (for example, command APDU) of the length indicated by the length data included in block BL1 can be received at one time. For example, if the length indicated by the length data included in block BL1 is less than or equal to the storage capacity of the buffer area for temporarily storing the transmitted data, it is determined that the transmitted data can be received at once, and the corresponding The length data is held (step S3), and the process advances to step S4. On the other hand, if it is determined that the transmission data cannot be received at one time, block BL2 containing length specification data indicating the length of the transmission data that can be received at one time (for example, the length specification data is written in the information field). stored) is transmitted to the external device 2. Then, the external device 2 changes the length of the transmission data to be less than or equal to the length indicated by the length specification data included in the block BL2, and the block BL1 including the length data indicating the changed length is again set to SE1. The process shown in FIG. 4 is executed.

(Example 2)
Next, with reference to FIG. 5, the operation of SE1 according to the second embodiment will be described. In the modified example of the first embodiment, it is necessary to change the length of the transmission data, but there are cases where the length of the transmission data cannot be changed. In view of this, the second embodiment is configured such that the external device 2 divides the transmission data into lengths that can be received at one time and transmits the divided data to the SE1. FIG. 5 is a flowchart showing an example of the processing of the CPU 10 when the block BLn from the external device 2 is received by the SE 1 in the second embodiment.

When the process shown in FIG. 5 is started, the CPU 10 receives a block BL1 including a LEN request before the received block BLn (in this case, it does not have to be immediately before, and may be within a predetermined time in the past). It is determined whether it has been completed (step S11). If the CPU 10 determines that the block BL1 has not been received (step S11: NO), the process proceeds to step S12. On the other hand, if the CPU 10 determines that the block BL1 has been received (step S11: YES), that is, if the received block BLn is the block BL3 transmitted from the external device 2 in accordance with the block BL2, the CPU 10 Proceed to S19.

In step S12, the CPU 10 determines whether the received block BLn is a block BL1 including a LEN request. When the CPU 10 determines that the received block BLn is the block BL1 including the LEN request (step S12: YES), the CPU 10 retains the length data included in the block BL1 (step S13). Next, the CPU 10 determines whether transmission data of the length indicated by the length data held in step S13 can be received at one time (step S14).

If the CPU 10 determines that the transmission data can be received at one time (step S14: YES), the CPU 10 transmits the block BL2 including the LEN response to the external device 2 as a response to the block BL1 (step S15). On the other hand, if the CPU 10 determines that the transmission data cannot be received at one time (step S14: NO), the CPU 10 includes length specification data indicating the length of the transmission data that can be received at one time as a response to the block BL1. Block BL2 is transmitted to external device 2 (step S16).

Thereby, the external device 2 divides the transmission data into two or more pieces so that the length is less than or equal to the length indicated by the length specification data included in the block BL2, and blocks BL3 containing the divided transmission data divided from the transmission data. will be sequentially transmitted to SE1. For example, when transmission data is divided into n (n>2) pieces, each block BL3 containing the divided transmission data to be transmitted first to the block BL3 containing the divided transmission data to be transmitted at the (n-1)th The block chain bit b6 in the PCB is set to "1". On the other hand, the block chain bit b6 in the PCB of the block BL3 containing the n-th (that is, the last) transmitted divided transmission data is set to "0".

On the other hand, in step S12, if the CPU 10 determines that the received block BLn is not the block BL1 including the LEN request (step S12: NO), that is, if it is a normal block BL5, the information field of the block BL5 is For example, normal command processing is executed based on the command APDU included (the OS causes the application to execute processing according to the command APDU) (step S17), and as a response to the block BL5, the block BL6 (the result of the command processing is including the response APDU shown) to the external device 2 (step S18).

In step S19, the CPU 10 determines whether the transmission data of the length indicated by the length data held in step S13 has been completed (if the transmission data is divided and transmitted, all divided transmission data have been completed). Determine. Here, when the transmission data is divided and transmitted by block BL3, each time the divided transmission data included in each block BL3 is stored in the buffer area, it is transferred from the buffer area to the transmission data reproduction area on the RAM, for example. The divided transmission data is migrated (written) and concatenated. Then, the lengths of the concatenated divided transmission data in the transmission data reproduction area are accumulated, and when the accumulated length matches the length indicated by the length data held in step S13 (that is, the length is If the transmission data of the length indicated by the length data is obtained by concatenating the divided transmission data received over the period of time), it is determined that all the divided transmission data have been completed.

If the CPU 10 determines that the transmission data of the length indicated by the length data held in step S13 is not complete (step S19: NO), the CPU 10 sends the block BL4 (for example, the next divided transmission data) as a response to the block BL3. (including the request) to the external device 2 (step S20). On the other hand, if the CPU 10 determines that the transmission data of the length indicated by the length data held in step S13 is complete (step S19: YES), the CPU 10 performs processing (for example, command processing) (the OS causes the application to execute processing according to the command APDU) (step S21), and as a response to block BL3, block BL4 (including, for example, a response APDU indicating the result of the command processing) is executed. It is transmitted to the external device 2 (step S22).

As explained above, according to the above embodiment, when SE1 receives block BL1 including length data indicating the length of transmission data to be transmitted from external device 2, SE1 retains the length data included in block BL1. Then, when block BL2 is transmitted to external device 2 as a response to block BL1, and block BL3 containing transmission data of the length indicated by the above length data is received from external device 2 in response to block BL2, block BL3 is Since the configuration is configured to execute processing based on the included transmission data, it is possible to specify a data length that exceeds the length that can be specified in the header without changing the existing data format.

1 SE
2 External device 10 CPU
11 RAM
12 ROM
13 NVM
14 I/O circuit

Claims (7)

first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device;
holding means for holding the length data included in the first block;
determining means for determining whether the transmission data of the length indicated by the length data included in the first block can be received at one time;
When the determination means determines that the transmission data cannot be received at one time, as a response to the first block , the first block includes length designation data indicating the length of the transmission data that can be received at one time. transmitting means for transmitting two blocks to the external device;
A third block that is transmitted from the external device in response to the second block and that includes the transmission data of the length indicated by the held length data from the external device. 2 receiving means;
Executing means for executing processing based on the transmission data included in the third block;
An electronic information storage medium comprising: The second receiving means receives a third block including divided transmission data divided from the transmission data of the length indicated by the held length data from an external device multiple times,
The execution means executes processing based on the transmission data when the transmission data having the length indicated by the length data is obtained by concatenating the divided transmission data received a plurality of times. The electronic information storage medium according to claim 1 , characterized in that: first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device;
holding means for holding the length data included in the first block;
Transmitting means for transmitting a second block to the external device as a response to the first block;
A third block that is transmitted from the external device in response to the second block and that includes the transmission data of the length indicated by the held length data from the external device. 2 receiving means;
Executing means for executing processing based on the transmission data included in the third block;
Equipped with
The first block and the third block each include an information field for storing data used in the application layer by a predetermined application, and a LEN (LEN) consisting of a predetermined byte for specifying the length of the information field. It consists of a predetermined data format with a first field including (Length byte),
The information field of the first block stores the length data specified by the LEN, and the information field of the third block stores the transmission data of the length indicated by the length data. stored,
The electronic information storage medium is characterized in that the execution means executes the process based on the transmission data included in the third block, ignoring LEN included in the first field of the third block. A data receiving method performed by a computer included in an electronic information storage medium, the method comprising:
receiving from an external device a first block including length data indicating the length of the transmission data to be transmitted;
retaining the length data included in the first block;
determining whether the transmission data of the length indicated by the length data included in the first block can be received at one time;
If it is determined that the transmission data cannot be received at one time, the second block including length designation data indicating the length of the transmission data that can be received at one time is sent as a response to the first block. transmitting to an external device;
receiving from an external device a third block that is transmitted from the external device in response to the second block and includes the transmitted data having the length indicated by the held length data; and,
performing processing based on the transmission data included in the third block;
A data receiving method characterized by comprising: A data receiving method performed by a computer included in an electronic information storage medium, the method comprising:
receiving from an external device a first block including length data indicating the length of the transmission data to be transmitted;
retaining the length data included in the first block;
transmitting a second block to the external device as a response to the first block;
receiving from an external device a third block transmitted from the external device in response to the second block, the third block including the transmitted data having the length indicated by the held length data; and,
an execution step of executing processing based on the transmission data included in the third block;
including;
The first block and the third block each include an information field for storing data used in the application layer by a predetermined application, and a LEN (LEN) consisting of a predetermined byte for specifying the length of the information field. It consists of a predetermined data format with a first field including (Length byte),
The information field of the first block stores the length data specified by the LEN, and the information field of the third block stores the transmission data of the length indicated by the length data. stored,
The data receiving method is characterized in that, in the execution step, processing is executed based on the transmission data included in the third block, ignoring LEN included in the first field of the third block. first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device;
holding means for holding the length data included in the first block;
determining means for determining whether the transmission data of the length indicated by the length data included in the first block can be received at one time;
When the determination means determines that the transmission data cannot be received at one time, as a response to the first block , the first block includes length designation data indicating the length of the transmission data that can be received at one time. transmitting means for transmitting two blocks to the external device;
A third block that is transmitted from the external device in response to the second block and that includes the transmission data of the length indicated by the held length data from the external device. 2 receiving means;
A program that causes a computer to function as an execution means for executing processing based on the transmission data included in the third block. first receiving means for receiving a first block including length data indicating a length of transmission data to be transmitted from an external device;
holding means for holding the length data included in the first block;
Transmitting means for transmitting a second block to the external device as a response to the first block;
A third block that is transmitted from the external device in response to the second block and that includes the transmission data of the length indicated by the held length data from the external device. 2 receiving means;
A program that causes a computer to function as an execution means for executing processing based on the transmission data included in the third block,
The first block and the third block each include an information field for storing data used in the application layer by a predetermined application, and a LEN (LEN) consisting of a predetermined byte for specifying the length of the information field. It consists of a predetermined data format with a first field including (Length byte),
The information field of the first block stores the length data specified by the LEN, and the information field of the third block stores the transmission data of the length indicated by the length data. stored,
The program is characterized in that the execution means executes the process based on the transmission data included in the third block, ignoring LEN included in the first field of the third block .

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