JP5900184B2 - Random number generation device and in-vehicle electronic control device having the same - Google Patents

Description

  The present invention relates to a random number generation device and an in-vehicle electronic control device having the same.

  Conventionally, a plurality of electronic control units (hereinafter referred to as ECUs) for controlling each device are mounted on a vehicle. As one of the systems realized by the ECU, there is known an electronic key system in which a vehicle receives authentication information from an electronic key by wireless communication and collates it to perform door lock / release control, engine start control, and the like. Yes.

  For example, the keyless entry ECU receives the authentication information transmitted from the electronic key by wireless communication, compares the received authentication information with the authentication information held in advance by the keyless entry ECU, and unlocks or locks the door. Control. Further, the immobilizer ECU receives the electronic key authentication information and checks the authentication information held by the immobilizer ECU to control the engine start.

  A random number may be used as authentication information exchanged between such a vehicle and an electronic key, or as an encryption key for encrypting authentication information during wireless communication. For this random number, a pseudo random number generated by a random number generation circuit such as a linear feedback shift register (hereinafter referred to as LFSR) is usually used.

JP 2004-015305 A JP 2002-244844 A

  However, since pseudorandom numbers have a certain regularity, random numbers can be predicted if the random number generation method leaks to a third party. In particular, since the LFSR operates at a constant period, the pseudorandom numbers generated by the LFSR are not excellent in randomness. As a result, it is easily deciphered by a third party and the vehicle may be stolen.

  Therefore, an object of the present invention is to provide a random number generation device that generates a random number excellent in randomness and an in-vehicle electronic control device having the same.

The first aspect of the random number generator is
A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A random number generator for
A CPU for executing a program for controlling the operation of the random number generator;
A first memory for storing storage data generated by the CPU executing the program;
A calculation specification information acquisition unit that receives the frame transmitted by the plurality of electronic control units via the communication line, and acquires calculation specification information of a predetermined field in the received frame at a predetermined period;
An address generation unit that calculates the obtained operation specification information and generates an access destination address;
The CPU reads stored data at the access destination address from the first memory and generates a random number.

  According to the first aspect of the random number generation device, a random number having excellent randomness can be generated.

It is a figure which shows the structure of the control system of the vehicle in this Embodiment. It is a figure which shows the electronic key system in this Embodiment. It is a flowchart of the address generation process of keyless entry ECU in this Embodiment. It is a flowchart of the authentication process of keyless entry ECU in this Embodiment. It is a timing chart which shows the specific example of the address generation process in this Embodiment, and an authentication information generation process.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, an ECU constituting a vehicle control system is used as a specific example using the random number device of the present invention.

[Configuration of CAN]
FIG. 1 is a diagram showing a configuration of a vehicle control system in the present embodiment. As shown in FIG. 1, a vehicle control system 10 includes a meter ECU 11, a body control ECU 12, a keyless entry ECU 13, an air conditioner ECU 14, and an audio ECU 15, and the ECUs 11 to 15 are connected to each other via a CAN bus 17. Connecting.

  The CAN bus 17 is two communication lines connected via termination resistors 16 at both ends. The ECUs 11 to 15 transmit and receive signals via a CAN bus 17 of a system that propagates differential voltage signals to two communication lines. In this system, a signal level “0”, that is, a dominant state when there is a voltage difference between two communication lines, and a signal level “1”, that is, a recessive state, when there is no voltage difference between the two communication lines. The ECUs 11 to 15 transmit and receive data in units of frames, which are a group of such signals.

  The frame transmitted / received via the CAN bus 17 includes a data frame for transmitting data, a remote frame for requesting data transmission, and the like. For example, the data frame corresponds to the SOF field indicating the start of the frame, the ID field including the identifier indicating the data type and the destination ECU, the Control field indicating the number of bytes in the data field, and the data to be transmitted in order from the top. It consists of a data field, an EOF field indicating the end of the frame, and the like. The remote frame has a configuration in which the data field is removed from the data frame. The identifier of the ID field is assigned to the ECUs 11 to 15 in order to identify the data type such as speed and temperature and the transmission source ECU.

  Each of the ECUs 11 to 15 has a CAN controller that controls transmission and reception of frames. The ECUs 11 to 15 receive all the frames sent to the CAN bus 17 via their CAN controllers, check the identifiers included in the ID fields of the received frames, and acquire the frames addressed to themselves. When frame transmission competes when a plurality of ECUs attempt to transmit a frame at the same time, the frame transmission priority is determined based on the identifier included in the frame ID field.

[Electronic key system]
FIG. 2 is a diagram showing an electronic key system in the present embodiment. The electronic key system 20 includes a keyless entry ECU 13 and an electronic key 41.

  The electronic key 41 transmits the authentication information of the electronic key 41 together with the authentication request signal to the keyless entry ECU 13. When the keyless entry ECU 13 receives authentication information from the electronic key 41 by wireless communication, the keyless entry ECU 13 starts an authentication process described later, and collates the authentication information stored in advance by the keyless entry ECU 13 with the received authentication information.

  When the mutual authentication information matches, the door is unlocked or locked. At the same time, the keyless entry ECU 13 generates new authentication information, updates the authentication information of the keyless entry ECU 13, and transmits the latest authentication information to the electronic key 41. When receiving the latest authentication information from the keyless entry ECU 13, the electronic key 41 updates the stored authentication information to the received latest authentication information. When the keyless entry ECU 13 receives the authentication number from the electronic key 41 again, the keyless entry ECU 13 performs the authentication process in the same manner.

  Thus, in the present embodiment, the keyless entry ECU 13 not only checks the authentication information when authenticating the electronic key 41 but also generates new authentication information. For authentication information, it is necessary to use data that is difficult to predict so that it cannot be easily deciphered by a third party.

  Therefore, in this embodiment, as will be described later, data stored in a predetermined address (hereinafter referred to as an access destination address) of the RAM 29 included in the keyless entry ECU 13 is used as authentication information. This access destination address is randomly generated by an address generation process described later. In addition, when the CPU 28 that controls the operation of the keyless entry ECU 13 executes a program and performs a predetermined operation, data stored in any address of the RAM 29 (hereinafter referred to as stored data) changes. The stored data at each address in the RAM 29 is also a random number that is difficult to predict. Thereby, the keyless entry ECU 13 can generate a random number excellent in randomness, and the security of the vehicle can be improved by using the random number as authentication information.

[Configuration and operation of keyless entry ECU and electronic key]
Next, the configuration of the keyless entry ECU 13 and the electronic key 41, the address generation process, and the authentication process will be described with reference to FIGS. FIG. 3 is a flowchart of the address generation process of the keyless entry ECU in the present embodiment. FIG. 4 is a flowchart of the authentication process of the keyless entry ECU in the present embodiment.

  As shown in FIG. 2, the keyless entry ECU 13 includes a microcomputer 21 that generates and collates authentication information, and an electronic key 41 and a wireless communication unit 31 that transmits and receives the authentication information. The microcomputer 21 includes a CAN controller 22, a free-run timer 23, a latch circuit 24, an arithmetic circuit 25, an overflow detector 26, a CPU 28, a ROM 27, a RAM 29, and a nonvolatile authentication information storage memory 30. And have.

  The CAN controller 22 receives all frames sent to the CAN bus 17. When the timer count value reaches a predetermined value, the free-run timer 23 outputs an activation signal ENB to the latch circuit 24 (S10 YES). The latch circuit 24 latches and outputs the identifier ID from the frame received by the CAN controller 22 in response to the activation signal ENB (S11). That is, the latch circuit 24 acquires the identifier ID from the CAN bus 17 through the CAN controller 22 with a predetermined period ΔTa of the free-run timer 23. The identifier ID is calculation specification information that is a specification of calculation processing in the calculation circuit 25.

  The arithmetic circuit 25 adds the identifier ID output from the latch circuit 24 to the integrated value fed back from the overflow detector 26, and outputs the addition result to the overflow detector 26 (S12). The overflow detector 26 determines whether the addition result output from the arithmetic circuit 25 exceeds the maximum value of the address in the address area assigned to the RAM 29 (S13).

  When the addition result does not exceed the maximum value of the address in the address area assigned to the RAM 29 (S13 NO), the overflow detector 26 outputs the addition result as an integrated value (S14). When the addition result exceeds the maximum value of the address in the address area assigned to the RAM 29 (S13OK), the overflow detector 26 outputs the minimum value of the address in the predetermined address area assigned to the RAM 29 as an integrated value. At the same time, the integrated value is output as an address value to the CPU 28 (S15). That is, the integrated value and the address value are updated at a predetermined cycle of the free-run timer 23.

  The CPU 28 executes various programs for controlling the operation of the keyless entry ECU 13 such as an authentication processing control program and a wireless communication control program stored in the ROM 27. The RAM 29 stores various programs loaded by the CPU 28 from the ROM 27, temporary data, and the like. That is, when the CPU 28 executes a program and performs a predetermined operation, any stored data in the RAM 29 is updated. The authentication information storage memory 30 is a non-volatile memory that stores authentication information for collation with authentication information received from the electronic key.

  When the CPU 28 receives the authentication information of the electronic key 41 together with the authentication request signal from the electronic key 41 via the wireless communication unit 31 (S20 YES), the CPU 28 checks the authentication information stored in the authentication information storage memory 30 in advance (S21). . When the authentication information matches (S22 YES), the CPU 28 reads out the storage data of the access destination address from the RAM 29 using the address value output from the overflow detector 26 as the access destination address. Then, the CPU 28 updates the authentication information storage memory 30 with the read stored data as the latest authentication information (S23), and transmits the latest authentication information to the electronic key 41 via the wireless communication unit 31 (S24).

  The electronic key 41 includes a CPU 42, an authentication information storage memory 43, and a wireless communication unit 44. The authentication information storage memory 43 is a non-volatile memory that stores authentication information received from the keyless entry ECU 13. The CPU 42 transmits the authentication information in the authentication information storage memory 43 together with the authentication request signal to the keyless entry ECU 13 via the wireless communication unit 44. Further, the CPU 42 receives the latest authentication information from the keyless entry ECU 13 and updates the authentication information stored in the authentication information storage memory 43 to the received latest authentication information.

[Address generation processing and authentication information generation processing]
Here, a specific example of the operation of the keyless entry ECU 13 will be described. FIG. 5 is a timing chart showing a specific example of the address generation processing and authentication information generation processing in the present embodiment. In FIG. 5, the waveform of the start signal ENB of the free-run timer 23, the identifier ID included in the data received by the CAN controller 22, the content of the identifier ID output from the latch circuit 24, the addition result of the arithmetic circuit 25, The integrated value output from the overflow detector 26, the waveform and authentication information of the authentication request signal received by the CPU 28 from the electronic key 41, and the authentication information stored in the authentication information storage memory 30 are shown.

  In FIG. 5, a frame is output from any of the ECUs 11 to 15 to the CAN bus 17. The RAM 29 is assigned addresses from “0X7000” to “0X8000”, and when the CPU 28 executes a program and performs a predetermined operation, the stored data at any address changes.

  It is assumed that the predetermined period ΔTa of the free-run timer 23 is longer than the frame transmission interval ΔTb via the CAN bus 17 so that the identifier ID changes as much as possible every latch operation of the latch circuit 24. For example, since the data frame transmission interval in CAN is usually ΔTb = 10 ms, the period of the free-run timer 23 is assumed to be ΔTa = 124 ms.

  Further, the period ΔTa is continuously authenticated from the electronic key 41 based on the operation of the electronic key 41 by the user so that the authentication information newly stored in the electronic key 41 changes as much as possible when the electronic key 41 is received. It is assumed that it is shorter than the reception interval ΔTc of the CPU 29 when the request signal is transmitted. For example, ΔTa = 124 ms with respect to ΔTc = 500 ms.

  At time T1, the timer count value of the free-run timer 23 reaches a predetermined value, and the start signal ENB rises. The latch circuit 24 obtains and outputs, for example, the identifier ID “0X25” of the body control ECU 12 from the frame received by the CAN controller 22 in response thereto. The arithmetic circuit 25 adds the identifier ID “0X25” output from the latch circuit 24 to the integrated value “0X7000”, and outputs the addition result “0X7025”. The overflow detector 26 outputs the integrated value “0X7025” and the address value “0X7025” because the addition result “0X7025” has not reached the maximum address value “0X8000” in the RAM 29. At time T1, since the CPU 28 has not received the authentication request signal from the electronic key 41, the authentication information storage memory 30 maintains the authentication information “random number A”.

  When the CPU 28 receives the authentication request signal and the authentication information “random number A” from the electronic key 41 at time T 2, the CPU 28 compares the received authentication information with the authentication information stored in the authentication information storage memory 30. Since the authentication information matches with “random number A”, the CPU 28 reads the stored data from the RAM 29 using the address value “0X7025” output from the overflow detector 26 as the access destination address. Then, the CPU 28 updates the authentication information in the authentication information storage memory 30 from “random number A” to “random number B”, and transmits the authentication information “random number B” to the electronic key 41.

  When the start signal ENB of the free-run timer 23 rises at times T3 and T4, the latch circuit 24, the arithmetic circuit 25, and the overflow detector 26 output new values, respectively, in the same manner as at time T1.

  When the CPU 28 receives the authentication request signal and the authentication information “random number B” from the electronic key 41 at time T5, the authentication information “random number B” of the electronic key 41 is collated. Since the authentication information in the electronic key 41 matches the authentication information in the authentication information storage memory 30, the authentication information in the authentication information storage memory 30 is updated to “random number C” in the same manner as at time T2. Authentication information “random number C” is transmitted to the electronic key 41.

  When the start signal ENB of the free-run timer 23 rises at time T6, the latch circuit 24 and the arithmetic circuit 25 output new values in the same manner as at time T1. Since the addition result “0X8048” of the arithmetic circuit 25 has reached the maximum value “0X8000” of the address of the RAM 29, the overflow detector 26 resets the integrated value to the minimum value “0X7000” of the address of the RAM 29, and the integrated value “0X7000” and the address value “0X7000” are output.

  As described above, in the present embodiment, the keyless entry ECU 13 reads out the memory of the access destination address generated by the address generation process from the RAM 29 and uses it as authentication information. In particular, the stored data stored in each address of the RAM 29 changes every time the keyless entry ECU 13 operates, and thus is difficult to predict. Furthermore, since it is usually difficult to predict the output timing of the frame output to the CAN bus 17, the transmission source ECU, and the data contents, the access destination address that is an integrated value output from the overflow detector 26 is also random. high. Therefore, the authentication information generated by the key entry ECU 13 is excellent in randomness.

  Further, the key entry ECU 13 stores the authentication information transmitted to the electronic key 41 in the authentication information storage memory 30 and then collates the authentication information received from the electronic key 41 with the authentication information in the authentication information storage memory 30. If the authentication information matches, the stored data is read from the RAM 29 and new authentication information is transmitted to the key entry ECU 13.

  In this way, the key entry ECU 13 improves the security by updating the authentication information with a random number excellent in randomness every time the verification of the authentication information is normally performed.

  In this embodiment, the identifier ID included in the frame received by the CAN controller 22 is used as the operation specification information in order to generate the access destination address. However, even if information in other fields is used. Good. For example, the CAN controller 22 receives a frame output from the meter ECU 11 via the CAN bus 17, and predicts data included in the data field of the received frame, such as vehicle state quantity information such as speed information and temperature information. It is also possible to use data that is difficult to handle.

  In this case, the latch circuit 24 acquires the state quantity information from the frame received by the CAN controller 22 and outputs it. The arithmetic circuit 25 adds the state quantity information output from the latch circuit 24 to the integrated value and outputs the addition result. The overflow detector 26 outputs the integrated value in the same manner as described above.

  In this embodiment, the identifier ID is added to the integrated value in order to generate the access destination address. However, other calculation methods may be used. For example, when the arithmetic circuit 25 subtracts the identifier ID from the integrated value and the subtraction result becomes smaller than the minimum value of the address in the address area assigned to the RAM 29, the overflow detector 26 is assigned to the RAM 29. You may make it reset to the maximum value of the address in an address area | region.

  The stored data read from the access destination address of the RAM 29 may be used as an encryption key for encrypting the authentication information during wireless communication. As a result, not only the authentication information but also the encryption key is random, so that the security of the vehicle is improved.

  The above embodiment is summarized as follows.

(Appendix 1)
A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A random number generator for
A CPU for executing a program for controlling the operation of the random number generator;
A first memory for storing storage data generated by the CPU executing the program;
A calculation specification information acquisition unit that receives the frame transmitted by the plurality of electronic control units via the communication line, and acquires calculation specification information of a predetermined field in the received frame at a predetermined period;
An address generation unit that calculates the obtained operation specification information and generates an access destination address;
The CPU is a random number generation device that reads out stored data of the access destination address from the first memory and generates a random number.

(Appendix 2)
In Appendix 1,
The calculation specification information is a random number generation device that is either the identifier or data.

(Appendix 3)
In Appendix 1,
The address generation unit generates the access destination address by adding the operation specification information to a predetermined initial value at the predetermined cycle, and the integration result is a maximum value of an address area allocated to the first memory. A random number generation device that sets a minimum value of an address area allocated to the first memory as the access destination address and resets the accumulation result when the value exceeds

(Appendix 4)
In Appendix 1,
The address generation unit repeatedly subtracts the operation specification information from a predetermined initial value at the predetermined cycle to generate the access destination address, and the subtraction result is a minimum of the address area allocated to the first memory. A random number generation device that, when smaller than the value, sets the maximum value of the address area allocated to the first memory as the access destination address and resets the subtraction result.

(Appendix 5)
In Appendix 1,
The random number generation device in which the intervals at which the plurality of electronic control devices transmit the frames are shorter than the predetermined period.

(Appendix 6)
In Appendix 1,
The identifier is a random number generation device that determines a priority of transmission of the frame when the transmission of the frame through the communication line by the plurality of electronic control devices competes.

(Appendix 7)
A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A CPU for executing a program for controlling the operation of the random number generator, a first memory for storing storage data generated by the CPU executing the program, and a communication line. Receiving the frame transmitted by the plurality of electronic control units, and obtaining a calculation specification information acquisition unit for acquiring calculation specification information of a predetermined field in the received frame at a predetermined cycle, and the acquired calculation specification An address generation unit that calculates original information and generates an access destination address, and the CPU stores the access destination address from the first memory. Has a random number generator for generating random numbers by reading the stored data,
An electronic control device mounted on a vehicle together with the communication line and the plurality of electronic control devices.

(Appendix 8)
A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A CPU for executing a program for controlling the operation of the random number generator, a first memory for storing storage data generated by the CPU executing the program, and a communication line. Receiving the frame transmitted by the plurality of electronic control units, and obtaining a calculation specification information acquisition unit for acquiring calculation specification information of a predetermined field in the received frame at a predetermined cycle, and the acquired calculation specification An address generation unit that calculates original information and generates an access destination address, and the CPU stores the access destination address from the first memory. A random number generator for generating random numbers by reading the stored data,
A second memory for storing the random number;
A wireless communication unit that performs wireless communication with other wireless communication devices;
The CPU receives authentication information from the other wireless communication device via the wireless communication unit, compares the received authentication information with the random number stored in the second memory, and receives the authentication information. If the authentication information matches the random number stored in the second memory, the latest access destination address is acquired from the address generation unit, and the latest access destination address is stored from the first memory. An electronic control device that reads data to generate a latest random number, stores the latest random number in the second memory, and transmits the latest random number to the other wireless communication device via the wireless communication unit.

(Appendix 9)
In Appendix 8,
An electronic control device mounted on a vehicle together with the communication line and the plurality of electronic control devices.

10: Vehicle control systems 11-15: ECU
16: Terminating resistor 17: CAN bus 21: Microcomputer 41: Electronic key

Claims (7)

A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A random number generator for
A CPU for executing a program for controlling the operation of the random number generator;
A first memory for storing storage data generated by the CPU executing the program;
A calculation specification information acquisition unit that receives the frame transmitted by the plurality of electronic control units via the communication line, and acquires calculation specification information of a predetermined field in the received frame at a predetermined period;
An address generation unit that calculates the obtained operation specification information and generates an access destination address;
The CPU is a random number generation device that reads out stored data of the access destination address from the first memory and generates a random number. In claim 1,
The calculation specification information is a random number generation device that is either the identifier or data. In claim 1,
The address generation unit generates the access destination address by adding the operation specification information to a predetermined initial value at the predetermined cycle, and the integration result is a maximum value of an address area allocated to the first memory. A random number generation device that sets a minimum value of an address area allocated to the first memory as the access destination address and resets the accumulation result when the value exceeds In claim 1,
The address generation unit repeatedly subtracts the operation specification information from a predetermined initial value at the predetermined cycle to generate the access destination address, and the subtraction result is a minimum of the address area allocated to the first memory. A random number generation device that, when smaller than the value, sets the maximum value of the address area allocated to the first memory as the access destination address and resets the subtraction result. In claim 1,
The identifier is a random number generation device that determines a priority of transmission of the frame when the transmission of the frame through the communication line by the plurality of electronic control devices competes. A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A CPU for executing a program for controlling the operation of the random number generator, a first memory for storing storage data generated by the CPU executing the program, and a communication line. Receiving the frame transmitted by the plurality of electronic control units, and obtaining a calculation specification information acquisition unit for acquiring calculation specification information of a predetermined field in the received frame at a predetermined cycle, and the acquired calculation specification An address generation unit that calculates original information and generates an access destination address, and the CPU stores the access destination address from the first memory. Has a random number generator for generating random numbers by reading the stored data,
An electronic control device mounted on a vehicle together with the communication line and the plurality of electronic control devices. A plurality of electronic control devices transmit frames having identifiers assigned to the respective electronic control devices, and the plurality of electronic control devices are connected to communication lines that receive frames addressed to themselves based on the identifiers of the frames. A CPU for executing a program for controlling the operation of the random number generator, a first memory for storing storage data generated by the CPU executing the program, and a communication line. Receiving the frame transmitted by the plurality of electronic control units, and obtaining a calculation specification information acquisition unit for acquiring calculation specification information of a predetermined field in the received frame at a predetermined cycle, and the acquired calculation specification An address generation unit that calculates original information and generates an access destination address, and the CPU stores the access destination address from the first memory. A random number generator for generating random numbers by reading the stored data,
A second memory for storing the random number;
A wireless communication unit that performs wireless communication with other wireless communication devices;
The CPU receives authentication information from the other wireless communication device via the wireless communication unit, compares the received authentication information with the random number stored in the second memory, and receives the received authentication information. When the information matches the random number stored in the second memory, the latest access destination address is acquired from the address generation unit, and the storage data of the latest access destination address is acquired from the first memory. An electronic control unit that generates the latest random number, stores the latest random number in the second memory, and transmits the latest random number to the other wireless communication device via the wireless communication unit.

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