Communication system

Abstract

To provide a communication system capable of enhancing security.SOLUTION: A communication system 100 transmits and receives data between a head unit 200 and a display 300. The head unit 200 includes a random number generation unit 212 that generates a random number by providing a seed value, a sampling rate setting unit 213 that sets a sampling rate corresponding to the seed value, a seed value transmitting unit 215 that transmits the seed value to the display 300, a random number receiving unit 216 that, when a random number, as a calculation result, generated in the display 300 in response to the transmitted seed value is notified, receives the random number at the set sampling rate, and a communication continuation determination unit 217 that determines to continue communication when the random number generated on its own device side matches the received random number.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a communication system for transmitting and receiving data between two devices.

Background Art

[0002] Generally, in LVDS (Low voltage differential signaling) communication between SerDes (Serializer / Deserializer), communication between SerDes becomes possible when the communication bandwidths of differential lines match at startup.

[0003] In this case, even if one of the SerDes is a non-legitimate product (a counterfeit product), there is a risk that communication will be possible if the communication bandwidths match. To improve this risk, it is conceivable to add a checksum or parity to the transmitted and received data, but since it is determined as a communication format, it is easy to identify its content, and there is a concern that sufficient security cannot be ensured.

[0004] On the other hand, there is known a communication system in which a message ID is attached to a frame transmitted between communication devices and the message ID is updated every time it is transmitted to prevent forgery and the like (see, for example, Patent Document 1). In this communication system, the message ID is updated by performing arithmetic operations according to a predetermined rule every time it is transmitted.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the communication system disclosed in Patent Document 1 described above, when a predetermined rule for updating the ID is inferred, the message ID updated according to the number of transmissions becomes somewhat predictable. Therefore, further measures to enhance security (confidentiality) and prevent impersonation are desired.

[0007] The present invention has been created in view of such points, and its object is to provide a communication system capable of enhancing security.

Means for Solving the Problems

[0008] In order to solve the above-described problems, the communication system of the present invention performs data transmission and reception between a first communication device and a second communication device. The first communication device includes: a first calculation means for performing a predetermined calculation by giving an initial value; a first sampling rate setting means for setting a sampling rate corresponding to the initial value; an initial value transmission means for transmitting the initial value toward the first communication device; a calculation result receiving means for receiving the calculation result sent from the second communication device at the sampling rate set by the first sampling rate setting means; a comparison means for comparing the calculation result received by the calculation result receiving means with the calculation result obtained by the calculation of the first calculation means; and a communication continuation determination means for determining the continuation of communication with the second communication device when a comparison result indicating agreement is obtained by the comparison means. The second communication device includes: an initial value receiving means for receiving the initial value sent from the first communication device; a second calculation means for performing a calculation having the same content as that of the first calculation means by giving the initial value received by the initial value receiving means; a second sampling rate setting means for setting a sampling rate corresponding to the initial value received by the initial value receiving means based on setting information having the same content as that of the first sampling rate setting means; and a calculation result transmission means for transmitting the calculation result obtained by the calculation of the second calculation means toward the first communication device at the sampling rate set by the second sampling rate setting means.

[0009] Communication can be continued only when the result of the operation with the specified initial value is correct and the set sampling rate is correct. Therefore, compared with the case where the communication is performed after confirming the agreement of the operation results, it is possible to enhance the security. For this reason, it is possible to effectively prevent the combination or forgery of non-genuine communication devices.

[0010] Also, it is desirable that the above-described first and second operation means generate a pseudo-random number using an initial value as seed information. By generating a pseudo-random number by specifying seed information, the operation result becomes difficult to predict, and thus it becomes easy to ensure security.

[0011] Also, it is desirable that the setting information used in the above-described first and second sampling rate setting means be correspondence information associating an initial value with a sampling rate corresponding to this initial value. Thereby, it becomes easy to specify an arbitrary sampling rate, and it becomes even more difficult to predict the regularity.

[0012] Also, it is desirable that the above-described first communication device further include a restart instruction means for instructing the second communication device to restart when a comparison result indicating non-agreement is obtained by the comparison means. Thereby, it is possible to avoid a situation where communication becomes impossible due to a malfunction caused by temporary noise or the like.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

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Mode for Carrying Out the Invention

[0014] Hereinafter, a communication system according to an embodiment to which the present invention is applied will be described with reference to the drawings.

[0015] FIG. 1 is a diagram showing the configuration of a communication system according to an embodiment. The communication system 100 shown in FIG. 1 includes a head unit 200 mounted on a vehicle and a display 300 attached to a part thereof. In the present embodiment, by performing LVDS communication between SerDes, data of an image to be displayed is transmitted from the head unit 200 to the display 300.

[0016] The head unit 200 includes an HU (head unit) processing unit 210 that performs processing related to communication security, and a Ser (serializer) 220 that converts parallel data input via a bus interface unit (bus IF) into serial data and outputs it to differential lines. The HU processing unit 210 is configured by, for example, an SoC (System on a chip), and realizes necessary functions by executing a predetermined program with a processor. Note that the head unit 200 is provided with a configuration for realizing its original operations (such as a navigation operation, a TV / radio reception operation, an audio playback operation, etc.), but in FIG. 1, only the configuration focused on security-related operations performed at startup is shown.

[0017] FIG. 2 is a diagram showing the configuration of the head unit 200. As shown in FIG. 2, the HU processing unit 210 includes a seed value setting unit 211, a random number generation unit 212, a sampling rate (SR) setting unit 213, a look-up table (LUT) 214, a seed value transmission unit 215, a random number reception unit 216, and a communication continuation determination unit 217.

[0018] The seed value setting unit 211 sets a seed value (seed information) necessary for random number generation. The random number generation unit 212 generates a random number using the seed value set by the seed value setting unit 211. The sampling rate setting unit 213 sets a sampling rate corresponding to the set seed value by referring to the LUT 214. The LUT 214 records sampling rates corresponding to each of a plurality of seed values. The seed value transmission unit 215 transmits the seed value set by the seed value setting unit 211 from Ser220 toward the display 300. The random number reception unit 216 receives, from the display 300 at the sampling rate set by the sampling rate setting unit 213, the generation result of the random number corresponding to the transmitted seed value. The communication continuation determination unit 217 compares the random number generated by the random number generation unit 212 with the random number sent from the display 300, determines to continue communication when these values match, and determines to cut off communication when they do not match.

[0019] The display 300 includes a D (display) processing unit 310 that performs processing related to communication security, and a Des (deserializer) 320 that converts serial data as display data from the head unit 200 sent via a differential line into parallel data. The D processing unit 310 is configured by, for example, a microcomputer, and realizes necessary functions by executing a predetermined program. Note that the display 300 is provided with a configuration for realizing its original operation (such as a display unit such as a liquid crystal display device and a display driver that converts the received parallel data into a video signal), but in FIG. 1, only the configuration focused on the security-related operation performed at startup is shown.

[0020] Figure 3 is a diagram showing the configuration of the display 300. As shown in Figure 3, the D processing unit 310 includes a seed value receiving unit 311, a random number generating unit 312, a sampling rate setting unit (SR) 313, a look-up table (LUT) 314, and a random number transmitting unit 315.

[0021] The seed value receiving unit 311 receives the seed value sent from the seed value transmitting unit 215 in the HU processing unit 210. The random number generating unit 312 generates a random number using the received seed value. This random number generating unit 312 performs random number generation using the same random number generation algorithm as the random number generating unit 212 provided in the HU processing unit 210 of the head unit 200, and a random number value as the same calculation result can be obtained when the same seed value is used. The sampling rate setting unit 313 sets the sampling rate corresponding to the seed value received by the seed value receiving unit 311 by referring to the LUT 314. The LUT 314 has the same content as the LUT 214 in the HU processing unit 210, and the sampling rates corresponding to each of a plurality of seed values are recorded. The random number transmitting unit 315 samples the generation result of the random number by the random number generating unit 312 at the sampling rate set by the sampling rate setting unit 313 and transmits it from the Des 320 toward the head unit 200.

[0022] Figure 4 is a diagram showing the operating principle of generating and transmitting a random number in the display 300. Using the seed value sent from the head unit 200, random number generation by the random number generating unit 312 and selection (setting) of the sampling rate by the sampling rate setting unit 313 are performed. In the configuration shown in Figure 4, the random number transmitting unit 315 includes a result register and a bus IF. The generated random number is stored in the result register, output from the bus IF at the selected sampling rate, and sent to the Des 320.

[0023] FIG. 5 is a diagram showing the relationship between the seed value, random number generation, and the sampling rate. As shown in FIG. 5, n selectable seed values from 1 to n are prepared, and when one of them is selected, one sampling rate corresponding one-to-one to the selected seed value is selected from among AA [Mbps] to CC [Mbps]. Further, when the seed value is determined, the random number generated by the random number generation unit 312 is also determined one-to-one. However, since the sampling rate when transmitting the generated random number toward the head unit 200 is variably set according to the seed value, if the correct sampling rate corresponding to the seed value is not known, omission or duplicate reading of each bit of the data constituting the transmitted and received random number will occur, and a coincidence determination cannot be obtained in the comparison of the random numbers in the head unit 200.

[0024] The above-described head unit 200 corresponds to the first communication device, and the display 300 corresponds to the second communication device. Further, the random number generation unit 212 corresponds to the first arithmetic means, the sampling rate setting unit 213 corresponds to the first sampling rate setting means, the seed value transmission unit 215 corresponds to the initial value transmission means, the random number reception unit 216 corresponds to the arithmetic result reception means, and the communication continuation determination unit 217 corresponds to the comparison means and the communication continuation determination means. Further, the seed value reception unit 311 corresponds to the initial value reception means, the random number generation unit 312 corresponds to the second arithmetic means, the sampling rate setting unit 313 corresponds to the second sampling rate setting means, and the random number transmission unit 315 corresponds to the arithmetic result transmission means.

[0025] The communication system of this embodiment has such a configuration. Next, the security-related operations performed at startup will be described.

[0026] FIG. 6 is a timing diagram at startup for confirming the coincidence of the random numbers generated in the head unit 200 and the display 300, respectively. FIG. 7 is a flowchart showing the operation procedure of the head unit 200 at startup. FIG. 8 is a flowchart showing the operation procedure of the display 300 at startup.

[0027] When power is supplied to the head unit 200 and the display 300 that are interconnected via a differential line (for example, when a power switch (not shown) provided in the head unit 200 is turned on, or when the accessory switch of the vehicle is turned on), in each of the head unit 200 and the display 300, after the supply of power required for operation is started and reset release for each part is performed, communication rate adjustment (equalization and Eye adjustment) is performed between Ser220 and Des320, and a communication line is established (steps 200, 300).

[0028] In the head unit 200 after the communication line is established, the seed value setting unit 211 in the HU processing unit 210 sets a seed value (step 202), and the seed value transmission unit 215 notifies (transmits) this set seed value to the display 300 (step 204).

[0029] After (or in parallel with) this seed value notification operation, using the set seed value, random number generation by the random number generation unit 212 (step 206) and sampling rate setting by the sampling rate setting unit 213 (step 208) are performed.

[0030] Also, in the display 300 after the communication line is established, when the seed value reception unit 314 receives the seed value sent from the head unit 200 (step 302), using the received seed value, random number generation by the random number generation unit 312 (step 304) and sampling rate setting by the sampling rate setting unit 313 (step 306) are performed. Also, the random number transmission unit 315 transmits the generated random number to the head unit 200 at the set sampling rate (step 308).

[0031] In the head unit 200, when the random number receiving unit 216 in the HU processing unit 210 receives the random number sent from the display 300 at the sampling rate set by the sampling rate setting unit 213 (step 210), the communication continuation determination unit 217 determines whether the random number generated by its own device (random number generation unit 212) matches the random number received from the display 300 (step 212). If they match (positive determination), a decision is made to continue the communication (step 214). If they do not match (negative determination), a decision is made to cut off the communication (step 216).

[0032] As described above, in the communication system of this embodiment, subsequent communication can be continued only when the calculation result of random number generation with the specified seed value is correct and the set sampling rate is correct. Therefore, it is possible to enhance security compared to the case where the communication is performed after confirming the match of the calculation results of random number generation. For this reason, it is possible to effectively prevent the combination or forgery of non-genuine communication devices (displays).

[0033] In addition, by generating a pseudo-random number by specifying a seed value, the random number as the calculation result becomes difficult to predict, so it becomes easy to ensure security.

[0034] Also, by using the look-up tables 214 and 314 as the correspondence information associating the seed value with the sampling rate corresponding to this seed value, it becomes easy to specify an arbitrary sampling rate, and it becomes even more difficult to predict the regularity.

[0035] Note that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. In the above-described embodiment, when the comparison result of the random numbers does not match, the head unit 200 cuts off the communication with the display 300. However, a restart instruction unit as a restart instruction means may be added in the HU processing unit 210 of the head unit 200 to instruct the display 300 to restart. In this case, communication interruption may be performed when the mismatch of the random numbers cannot be resolved even after restarting a certain number of times. Thereby, it is possible to avoid a situation where communication becomes impossible due to a malfunction caused by temporary noise or the like, resulting in a mismatch of random numbers.

[0036] Also, in the above-described embodiment, the match / mismatch is determined on the premise that random numbers are sent from the display 300 (steps 210 and 212 in FIG. 7). However, random numbers are not necessarily sent from the display 300. Therefore, the random number receiving unit 216 may be provided with a WDT (watch dog timer) or the like to monitor the elapse of a certain time, and perform communication interruption or restart instruction when random numbers are not sent from the display 300 within a certain time.

[0037] Also, it is desirable that the above-described first communication device further includes a restart instruction means for instructing the second communication device to restart when a comparison result indicating non-match is obtained by the comparison means. Thereby, it is possible to avoid a situation where communication becomes impossible due to a malfunction caused by temporary noise or the like.

[0038] Also, in the above-described embodiment, the case where each operation for enhancing security is realized by executing a predetermined program by a processor has been described. However, it may be realized by a logic circuit using hardware. For example, the configuration of FIG. 4 corresponding to the D processing unit 310 of the display 300 may be realized by glue logic.

[0039] In the above-described embodiment, the communication performed between the head unit 200 and the display 300 has been described. However, the present invention can also be applied to the communication between other communication devices. Further, the present invention can be applied to communication other than LVDS communication between SerDes.

[0040] In the present embodiment, random number generation is performed using the same seed value in both the head unit 200 and the display 300. However, as long as the initial value of the operation corresponding to the seed value is specified in the head unit 200 and the operation result corresponding to this initial value is obtained, the present invention can be applied to determine the match / mismatch of operation results other than random number generation and to determine whether to continue communication.

Industrial Applicability

[0041] As described above, according to the present invention, subsequent communication can be continued only when the result (random number) of the operation with the specified initial value (seed value) is correct and the set sampling rate is correct. Therefore, it is possible to enhance the security compared to the case where the match of the operation result is confirmed and subsequent communication is performed. For this reason, it is possible to effectively prevent the combination or forgery of non-genuine communication devices.

Explanation of Signs

[0042] 100 Communication system 200 Head unit (HU) 300 Display 210 HU processing unit 220 Ser (Serializer) 211 Seed value setting unit 212, 312 Random number generation unit 213, 313 Sampling rate setting unit 214, 314 Look-up table (LUT) 215 Seed value transmission unit 216 Random number reception unit 217 Communication continuation determination unit 310 D (Display) processing unit 320 Deserializer 311 Seed value receiving section 315 Random number transmitting section

Claims

1. A communication system for transmitting and receiving data between a first communication device and a second communication device, wherein the first communication device includes: a first arithmetic means for performing a predetermined arithmetic operation with an initial value; a first sampling rate setting means for setting a sampling rate corresponding to the initial value; an initial value transmission means for transmitting the initial value toward the first communication device; an arithmetic result receiving means for receiving an arithmetic result sent from the second communication device at a sampling rate set by the first sampling rate setting means; a comparison means for comparing the arithmetic result received by the arithmetic result receiving means with the arithmetic result obtained by the arithmetic operation of the first arithmetic means; a communication continuation determination means for determining to continue communication with the second communication device when a comparison result indicating agreement is obtained by the comparison means; and wherein the second communication device includes: an initial value receiving means for receiving the initial value sent from the first communication device; a second arithmetic means for performing an arithmetic operation having the same content as the first arithmetic means with the initial value received by the initial value receiving means; a second sampling rate setting means for setting a sampling rate corresponding to the initial value received by the initial value receiving means based on setting information having the same content as the first sampling rate setting means; and an arithmetic result transmission means for transmitting the arithmetic result obtained by the arithmetic operation of the second arithmetic means toward the first communication device at a sampling rate set by the second sampling rate setting means.

2. The communication system according to claim 1, wherein the first and second arithmetic means generate pseudo-random numbers using the initial value as seed information.

3. The communication system according to claim 1, wherein the setting information used by the first and second sampling rate setting means is correspondence information associating the initial value with a sampling rate corresponding to the initial value.

4. The communication system according to claim 1, wherein the first communication device further includes a restart instruction means for instructing the second communication device to restart when a comparison result indicating non-agreement is obtained by the comparison means.

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