Abstract: An in-vehicle communication device on a transmitting side of a message includes: a delay time measuring unit measuring a delay time from when transmission of a message is first attempted to when the transmission of the message is started; and an assigning unit assigning the delay time measured by the delay time measuring unit to the message. An in-vehicle communication device on a receiving side of a message includes: a reception point acquisition unit acquiring a point in time when a message from the in-vehicle communication device on the transmitting side is received; a delay time acquisition unit acquiring a delay time assigned to the received message; and a calculation unit calculating a transmission cycle of each message based on a point in time acquired by the reception point acquisition unit and a delay time acquired by the delay time acquisition unit for each of two received messages.

Abstract: A communication device that can prevent the transmission of a message from being continuously hindered over a long period of time, a communication system and a message arbitration method are provided. The communication device transmits and receives a message to and from another device connected to a common communication line which comprises a calculation unit that calculates as to a message to be transmitted a margin time before a time when a transmission of the message is completed; a transmission unit that transmits the message to which information related to the margin time calculated by the calculation unit is attached; and an arbitration unit that performs arbitration based on the information attached to the message when simultaneous message transmissions to the communication line occur, and as to multiple of messages simultaneously transmitted to the communication line, the arbitration unit performs arbitration in such a manner as to prioritize a message with a shorter margin time.

Abstract: A communication device stores a first secret key and a first public key, and the on-vehicle authentication device stores a second secret key, a second public key and a signature verification key. The on-vehicle authentication device acquires the first public key, verifies the authenticity of the electronic signature using a signature verification key, encrypts the second public key using the authentic first public key and transmits the encrypted second public key. The communication device receives the encrypted second public key, decrypts the encrypted second public key using the first secret key, encrypts the first public key using the decrypted second public key. The on-vehicle authentication device receives the encrypted first public key, decrypts the encrypted first public key using the second secret key, and authenticates that the communication device is an authentic device when the decrypted first public key has been determined to be authentic.

Abstract: An in-vehicle communication device on a transmitting side of a message includes: a delay time measuring unit measuring a delay time from when transmission of a message is first attempted to when the transmission of the message is started; and an assigning unit assigning the delay time measured by the delay time measuring unit to the message. An in-vehicle communication device on a receiving side of a message includes: a reception point acquisition unit acquiring a point in time when a message from the in-vehicle communication device on the transmitting side is received; a delay time acquisition unit acquiring a delay time assigned to the received message; and a calculation unit calculating a transmission cycle of each message based on a point in time acquired by the reception point acquisition unit and a delay time acquired by the delay time acquisition unit for each of two received messages.

Abstract: A communication device that can prevent the transmission of a message from being continuously hindered over a long period of time, a communication system and a message arbitration method are provided. The communication device transmits and receives a message to and from another device connected to a common communication line which comprises a calculation unit that calculates as to a message to be transmitted a margin time before a time when a transmission of the message is completed; a transmission unit that transmits the message to which information related to the margin time calculated by the calculation unit is attached; and an arbitration unit that performs arbitration based on the information attached to the message when simultaneous message transmissions to the communication line occur, and as to multiple of messages simultaneously transmitted to the communication line, the arbitration unit performs arbitration in such a manner as to prioritize a message with a shorter margin time.

Abstract: In the on-vehicle communication system according to the present embodiment, a plurality of on-vehicle communication devices are classified by a plurality of security levels, and a common key is specified for each of the security levels. Each of the on-vehicle communication devices stores a common key according to a security level of itself, adds an authentication code generated by using the common key to a message to be transmitted and determines whether or not an authentication code added to a received message is authorized by using the common key. The on-vehicle communication control device stores common keys of respective security levels, determines whether or not a authentication code added to a received message is authorized by using the corresponding common key and, if determining that the authentication code is not authorized, makes a report to the on-vehicle communication device that does not store the common key used for this determination.

Abstract: An in-vehicle communication device, an in-vehicle communication system and in-vehicle communication method which make it possible to detect a high-risk message transmitted into the in-vehicle communication system by a simple configuration is provided. This in-vehicle communication device is provided with a communication unit bus-connected to an in-vehicle communication bus, and is provides with a communication control unit that controls transmission and reception of messages including object messages to be counted by the communication unit, and causes a specified message including authentication information to be intermittently transmitted from the communication unit, wherein the communication control unit includes, in the specified message to be transmitted at a first time point, the number of times of transmission of the object messages transmitted between the transmission of the most recent specified message transmitted before the first time point and the first time point.

Abstract: A communication device stores a first secret key and a first public key, and the on-vehicle authentication device stores a second secret key, a second public key and a signature verification key. The on-vehicle authentication device acquires the first public key, verifies the authenticity of the electronic signature using a signature verification key, encrypts the second public key using the authentic first public key and transmits the encrypted second public key. The communication device receives the encrypted second public key, decrypts the encrypted second public key using the first secret key, encrypts the first public key using the decrypted second public key. The on-vehicle authentication device receives the encrypted first public key, decrypts the encrypted first public key using the second secret key, and authenticates that the communication device is an authentic device when the decrypted first public key has been determined to be authentic.

Abstract: Provided are a communication system and a communication device that allow a reception node to estimate delay time, a generation time point or the like of a message. A delay time estimation part in an ECU determines whether a message received by itself is transmitted in sequence with another message without being provided with time information by a transmission node. If the received message is transmitted in sequence with another message, the received message may be delayed due to arbitrary processing. Thus, the delay time estimation part checks the priority of one or more sequential messages preceding the received message, and estimates delay time of the received message occurring due to the arbitrary processing in accordance with the priority of each message. A generation time point estimation part estimates the time point when the received message is generated by an ECU, based on the delay time estimated.

Abstract: Provided are a CAN communication system and an error information recording device that may be expected to facilitate identification of the cause of any error occurring in communication. The monitoring device is connected to a CAN bus and determines whether or not an error is included in a message transmitted by an ECU. In the case where an error is included in the transmitted message, the monitoring device records, in the recording unit, information concerning the error in the message as error information. Furthermore, the monitoring device comprises the CAN controller performing communication in accordance with the CAN protocol and the processor performing various types of information processing. The CAN controller may determine whether or not an error is included in message transmission, and if determined that an error is included, may notify the processor of the CAN-ID attached to the message by an interrupt.

Abstract: A relay device capable of preventing transmission of an improper message to one or more networks even if improper falsification is made to a program for executing relay processing. If one CAN controller receives a message, a gateway stores the received message in the message storage unit and also sends the message to the processing unit. The processing unit that received the message performs processing necessary for relay of the message by executing a relay program, and sends the message to be relayed to the CAN controller. The gateway compares the message before being sent from the CAN controller to the processing unit with the message sent from the processing unit to the CAN controller, to determine the properness of the message.

Abstract: Provided are a communication control device and a communication system capable of detecting message transmission in the case where an invalid device transmits a message to a common communication line. A monitoring device decides a reference time point t0 for periodical message transmission by an ECU, decides multiple scheduled transmission time points t1, t2, . . . obtained by adding a period corresponding to an integer multiple of a transmission cycle T of a message to the reference time point t0, and decides that a predetermined period including each of the scheduled transmission time points is a permission period for message transmission. The monitoring device determines whether or not a detected message on a CAN bus has been transmitted during the permission period. If determined that transmission of an invalid message is not permitted, the monitoring device performs processing of causing the ECU which receives the message to discard the message.

Abstract: A communication device capable of detecting transmission of an improper message to a network. A CAN controller in the gateway transmits and receives a message attached with a priority level (ID) to/from an ECU through a communication line, and counts, by the consecutive block number counter, the number of transmitted messages that are consecutively blocked as a result of arbitration processing as the number of consecutive blocks and stores the number as the number of allowed blocks into an allowed block number table in the storage unit in association with a priority level attached to the message received at the communication line. Every time a message is received, the controller compares the number of consecutive blocks with the number of allowed blocks for this message, and detects abnormality if the number of consecutive blocks is larger than the number of allowed blocks.

Abstract: Provided are a communication device and a communication restriction program capable of suppressing invalid message transmission to a network by injecting an invalid program. The ECU includes a CAN controller having a register group storing a value concerning communication with a different ECU and a processing unit processing a value for the register group. The ECU switches the mode between the full control mode in which writing and reading are allowed for the register group in the CAN controller and the restriction mode wherein writing and reading are restricted for a part of the registers in the register group. The ECU sets a predetermined period from activation corresponding to the full control mode, and switches the full control mode to the restriction mode after the predetermined period elapses. After switching to the restriction mode, the ECU will not switch the mode to the full control mode.

Abstract: Provided are a communication system, an abnormality detection device and an abnormality detection method that detects abnormality concerning communication such as information forged by utilizing a difference in timings of sampling between multiple communication devices. For the system configuration where ECUs transmit and receive information through a common communication line, abnormality detection related to communication is performed by a monitoring device connected to the communication line. Each ECU receives information by sampling once at a predetermined timing during a transmission period of one-bit information. The ECUs may also be allowed to perform sampling at different timings.

Abstract: A relay device capable of preventing transmission of an improper message to one or more networks even if improper falsification is made to a program for executing relay processing. If one CAN controller receives a message, a gateway stores the received message in the message storage unit and also sends the message to the processing unit. The processing unit that received the message performs processing necessary for relay of the message by executing a relay program, and sends the message to be relayed to the CAN controller. The gateway compares the message before being sent from the CAN controller to the processing unit with the message sent from the processing unit to the CAN controller, to determine the properness of the message.

Abstract: A communication system and key information sharing method which allows first and second communication devices to share key information and perform cryptograph processing. The monitoring device calculates hash value based on copy data of storage content of an ECU, and transmits a part to the ECU as confirmation information. The ECU further extracts a part from a value, obtained by removing confirmation information from hash value calculated by the ECU, and transmits part to the monitoring device as response information when the received confirmation information is included in the hash value calculated by the ECU. The monitoring device determines whether the received response information is included in hash value of the monitoring device or not. The ECU and monitoring device each use residual value, obtained by removing confirmation information and response information from hash value calculated by the ECU or monitoring device, for following cryptograph processing as a shared key.

Abstract: A communication device capable of detecting transmission of an improper message to a network. A CAN controller in the gateway transmits and receives a message attached with a priority level (ID) to/from an ECU through a communication line, and counts, by the consecutive block number counter, the number of transmitted messages that are consecutively blocked as a result of arbitration processing as the number of consecutive blocks and stores the number as the number of allowed blocks into an allowed block number table in the storage unit in association with a priority level attached to the message received at the communication line. Every time a message is received, the controller compares the number of consecutive blocks with the number of allowed blocks for this message, and detects abnormality if the number of consecutive blocks is larger than the number of allowed blocks.

Abstract: Provided are a communication device and a communication restriction program capable of suppressing invalid message transmission to a network by injecting an invalid program. The ECU includes a CAN controller having a register group storing a value concerning communication with a different ECU and a processing unit processing a value for the register group. The ECU switches the mode between the full control mode in which writing and reading are allowed for the register group in the CAN controller and the restriction mode wherein writing and reading are restricted for a part of the registers in the register group. The ECU sets a predetermined period from activation corresponding to the full control mode, and switches the full control mode to the restriction mode after the predetermined period elapses. After switching to the restriction mode, the ECU will not switch the mode to the full control mode.

Abstract: Provided are a CAN communication system and an error information recording device that may be expected to facilitate identification of the cause of any error occurring in communication. The monitoring device is connected to a CAN bus and determines whether or not an error is included in a message transmitted by an ECU. In the case where an error is included in the transmitted message, the monitoring device records, in the recording unit, information concerning the error in the message as error information. Furthermore, the monitoring device comprises the CAN controller performing communication in accordance with the CAN protocol and the processor performing various types of information processing. The CAN controller may determine whether or not an error is included in message transmission, and if determined that an error is included, may notify the processor of the CAN-ID attached to the message by an interrupt.