Method and device for generating and distributing symmetric keys for secure communication in in-vehicle network

Abstract

The present disclosure relates to a method and a device for generating and distributing symmetric keys for secure communication in an in-vehicle network. This communication control device generates a random number when a vehicle is started, and transmits the random number to a plurality of electronic control units, and the communication control device and each of the electronic control units generate a mutually corresponding symmetric key on the basis of the random number and a master key corresponding to each of the electronic control units. The communication control device configures a symmetric key set which includes the symmetric keys corresponding to the respective plurality of electronic control units, encrypts the symmetric key set by using the respective symmetric keys corresponding to the electronic control units, and transmits the symmetric key set. The electronic control units each decrypt the received encrypted symmetric key set so as to acquire the symmetric keys corresponding to the other electronic control units, and thus direct secure communication between the electronic control units is possible. Accordingly, security enhancement and efficient symmetric key management in an in-vehicle communication environment are possible.

Description

Method and device for generating and distributing symmetric keys for secure communication in an internal vehicle network

[0001] The present disclosure relates to a secure communication technology performed in an internal vehicle network, and more specifically, to a method and apparatus for generating and distributing symmetric keys for secure communication between internal vehicle components.

[0002] The following description merely provides background information related to the present embodiment and does not constitute prior art.

[0003] Recently, as vehicle functions such as autonomous driving, advanced driver assistance systems, and V2X communication have become more sophisticated, the number of various sensors and Electronic Control Units (ECUs) installed in vehicles is increasing. Communication between internal vehicle components takes place in real time through the In-Vehicle Network (IVN), and consequently, security threats are also on the rise.

[0004] Unlike general information and communications (IT) networks, in-vehicle networks are characterized by an embedded environment featuring real-time control capabilities, limited data transmission capacity, and restricted computational resources. For example, vehicle control systems may require responsiveness in the millisecond range; accordingly, encryption and authentication processing must also be performed with low latency.

[0005] In general information and communications environments, a hybrid security method is widely used in which a session key is exchanged through a public key-based key exchange procedure, followed by symmetric key encryption.

[0006] However, in an in-vehicle network environment, the computational capabilities and memory resources of the ECU are limited, and the size of communication frames may also be restricted; therefore, methods that repeatedly perform public key-based operations may find it difficult to meet real-time communication requirements.

[0007] Therefore, there is a need for a lightweight key management method and an efficient secure communication structure suitable for in-vehicle network environments.

[0008] The present disclosure aims to improve the security of communication between electronic control units performed in an internal vehicle network environment by providing a symmetric key management structure that enables secure communication between internal vehicle components while reducing the risk of long-term key exposure, by having a plurality of electronic control units and a communication control unit cooperatively generate a symmetric key according to the vehicle ignition status or security events, and efficiently distribute it.

[0009] The present disclosure aims to provide a method for generating and sharing symmetric keys that enables the dynamic establishment of secure communication channels between each device in an in-vehicle network environment where direct communication is performed between a plurality of electronic control units.

[0010] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0011] According to one aspect of the present disclosure, a method for performing secure communication in an internal vehicle network is provided.

[0012] The above method may include the steps of: a communication control device communicating with a plurality of electronic control devices connected to a vehicle internal network generating a cryptographically secure random number; the communication control device transmitting the generated random number to each of the plurality of electronic control devices through the vehicle internal network; the communication control device generating symmetric keys corresponding to each of the plurality of electronic control devices based on the random number and master keys pre-set for each electronic control device; each of the plurality of electronic control devices generating a symmetric key for each electronic control device based on the random number and a master key stored in the electronic control device; the communication control device configuring a symmetric key set to include the symmetric keys corresponding to each of the plurality of electronic control devices; the communication control device generating an encrypted symmetric key set for each electronic control device by encrypting the symmetric key set for each electronic control device using the symmetric key corresponding to each electronic control device; and the communication control device transmitting the encrypted symmetric key set for each electronic control device to the corresponding electronic control device.

[0013] Each of the above plurality of electronic control units can obtain symmetric keys corresponding to other electronic control units connected to the vehicle internal network by decrypting the encrypted symmetric key set using a symmetric key corresponding to itself, and can perform secure communication with the other electronic control units using the obtained symmetric keys.

[0014] According to another aspect of the present disclosure, a communication control device for supporting secure communication in an internal vehicle network is provided.

[0015] The above communication control device includes a communication interface, at least one processor, and a memory for storing instructions executed by the processor. The processor may be configured to generate a random number, transmit the random number to a plurality of electronic control devices, generate symmetric keys based on the random number and a master key for each electronic control device, form a set of symmetric keys, and encrypt and transmit the set of symmetric keys for each electronic control device.

[0016] According to another aspect of the present disclosure, an electronic control unit for supporting secure communication in an internal vehicle network is provided.

[0017] The above electronic control unit may be configured to include a communication interface, at least one processor, and memory, wherein the processor receives a random number from a communication control unit, generates a symmetric key based on the random number and a stored master key, decrypts an encrypted set of symmetric keys to obtain symmetric keys corresponding to other electronic control units, and performs secure communication using the symmetric keys.

[0018] According to another aspect of the present disclosure, a system for performing secure communication in an internal vehicle network is provided.

[0019] The above system includes a communication control device and a plurality of electronic control devices interconnected through an internal vehicle network, and the communication control device and the plurality of electronic control devices may be configured to generate corresponding symmetric keys based on a random number and a master key, and to perform secure communication between internal vehicle components using the generated symmetric keys.

[0020] According to the present disclosure, since a symmetric key is generated based on a new random number every time the vehicle is started, the security of subsequent communication can be maintained even if the previously used symmetric key is exposed.

[0021] In addition, by configuring and distributing a symmetric key set based on a symmetric key corresponding to each of the multiple electronic control units, secure communication becomes possible during direct communication between electronic control units without a separate key exchange procedure.

[0022] In addition, the security level of the in-vehicle network can be continuously maintained through event-based or policy-based key update structures, and service-unit security isolation can be implemented by generating and applying different symmetric keys for multiple functions or services.

[0023] Accordingly, this has the effect of simultaneously improving security, scalability, and operational efficiency in the in-vehicle communication environment.

[0024] The effects of the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0025] Figure 1 is a diagram showing the schematic structure of an overall communication environment that can be applied to a vehicle.

[0026] FIG. 2 is a diagram schematically showing entities participating in performing secure communication in an in-vehicle network according to one embodiment of the present disclosure and the connection relationships between them.

[0027] FIG. 3 is a diagram showing a schematic sequence of a procedure for generating and distributing a symmetric key to perform secure communication in an in-vehicle network according to one embodiment of the present disclosure.

[0028] FIG. 4 is a diagram schematically showing the data structure of a symmetric key set (SK_SET) according to one embodiment of the present disclosure.

[0029] FIG. 5 is a block diagram showing an example of the configuration of a device for performing secure communication in an internal vehicle network according to one embodiment of the present disclosure.

[0030] Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present disclosure, if it is determined that a detailed description of related known components or functions could obscure the essence of the present disclosure, such detailed description is omitted.

[0031] In describing the components of the embodiments according to the present disclosure, symbols such as first, second, i), ii), a), b), etc., may be used. These symbols are intended only to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the symbols. When a part in the specification is described as 'comprising' or 'having' a component, this means that, unless explicitly stated otherwise, it does not exclude other components but may include additional components.

[0032] The detailed description set forth below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure may be practiced.

[0033] Today, communication technology plays a crucial role in performing vehicle control functions and various service functions.

[0034] Figure 1 is a diagram showing the schematic structure of an overall communication environment that can be applied to a vehicle.

[0035] As illustrated in FIG. 1, the in-vehicle communication environment can be divided into an external communication area for communication with an external network or external device and an internal communication area for communication between in-vehicle components.

[0036] The external communication area may include an external gateway and one or more external communication interfaces.

[0037] The external gateway is connected to an external communication interface and can operate as a communication node that relays or manages data transfer between the vehicle's internal network and the external network.

[0038] The external communication interface may include a telematics module, a Bluetooth interface, a Wi-Fi interface, a storage media interface (SD or USB), an On-Board Diagnostics (OBD) interface, a Power Line Communication (PLC) interface, or a mobile communication-based wireless interface.

[0039] The vehicle internal communication area is an area where data exchange takes place between multiple electronic control units that perform vehicle function control, and may be configured with a structure including at least one internal gateway and multiple functional domain networks.

[0040] The internal gateway can perform the function of relaying or routing data transmission between multiple networks using different communication protocols within the vehicle's internal network, and can operate as a pivotal communication node for internal vehicle communication.

[0041] The vehicle internal communication area may include multiple functional domain networks separated by vehicle function, such as a chassis control domain, a body control domain, a powertrain control domain, an Advanced Driver Assistance System (ADAS) domain, or a vehicle infotainment domain.

[0042] Multiple electronic control units (ECUs) can be connected to each functional domain network, and these ECUs can communicate with ECUs in other functional domain networks through an internal gateway.

[0043] Meanwhile, an in-vehicle network (IVN) can have a special communication environment distinct from general information and communication networks.

[0044] For example, since vehicle control systems may require responsiveness at the millisecond (ms) level, communication delays need to be minimized, and security processing such as encryption or authentication also needs to be designed to meet these real-time requirements.

[0045] Vehicle communication protocols may have limitations on the size of data that can be transmitted per frame, and accordingly, the exchange of security-related messages also needs to be configured to minimize the communication burden.

[0046] Since electronic control units installed in vehicles can be implemented as embedded systems with limited computational capabilities and memory resources, methods that repeatedly perform computationally intensive public-key based cryptographic operations may not be suitable for the in-vehicle communication environment.

[0047] Considering the characteristics of such in-vehicle networks, a lightweight, secure communication structure is required that can satisfy real-time communication requirements while ensuring secure communication between in-vehicle components.

[0048] In particular, since direct data exchange between multiple electronic control units can be performed in in-vehicle networks as well as through relay nodes, a key management method that can be efficiently applied in such communication environments is required.

[0049] The present disclosure relates to a symmetric key-based secure communication structure applicable in such an in-vehicle communication domain, and provides a symmetric key management technology for ensuring confidentiality, integrity, and authentication of communication between in-vehicle components.

[0050] A symmetric key generated and managed according to an embodiment of the present disclosure can be applied not only to encryption processing for data confidentiality protection but also to Message Authentication Code (MAC) generation or communication authentication procedures.

[0051] FIG. 2 is a diagram schematically showing entities participating in performing secure communication in an in-vehicle network according to one embodiment of the present disclosure and the connection relationships between them.

[0052] Referring to FIG. 2, a symmetric key management system according to one embodiment of the present disclosure may include a plurality of electronic control units (ECUs, 220-1 to 220-n) connected through a communication control unit (210) and an in-vehicle network (230) as a configuration for performing a symmetric key generation and distribution procedure in an in-vehicle network.

[0053] The communication control device (210) can operate as a central control node that controls secure communication procedures in the vehicle internal network or performs symmetric key management functions.

[0054] For example, the communication control device (210) can perform network control functions such as relaying, routing, or monitoring the communication status of a data transmission path on a vehicle internal network, and at the same time, perform security management functions related to the generation, management, and distribution of cryptographic keys to be applied to vehicle internal communication.

[0055] The communication control unit (210) can be implemented in the form of a central gateway, a connectivity control unit, a domain gateway, or an integrated vehicle computing node.

[0056] A plurality of electronic control units (220-1 to 220-n) are embedded devices that perform various function controls of a vehicle, and can perform, for example, powertrain control, chassis control, body function control, driver assistance function control or vehicle infotainment function control.

[0057] Multiple electronic control units (220-1 to 220-n) can generate or set a symmetric key to be applied to vehicle internal communication through a cooperation procedure with a communication control unit (210).

[0058] The vehicle internal network (230) can provide a communication path that enables communication between a communication control unit (210) and a plurality of electronic control units (220-1 to 220-n). For example, the vehicle internal network (230) can be configured based on various vehicle communication protocols such as CAN (Controller Area Network), CAN FD (CAN with Flexible Data Rate), LIN (Local Interconnect Network), MOST (Media-Oriented Systems Transport), FlexRay, or vehicle Ethernet.

[0059] In a symmetric key management system according to an embodiment of the present disclosure, a communication control device (210) and a plurality of electronic control devices (220-1 to 220-n) can cooperatively perform a procedure for generating or setting a symmetric key to be applied to internal vehicle communication.

[0060] The symmetric key generated or established through this cooperation procedure can be used to ensure the confidentiality, integrity, and authentication of communication not only during communication between the communication control unit and the ECU, but also during the direct data exchange process between multiple ECUs.

[0061] A symmetric key management system according to an embodiment of the present disclosure can operate under the following preconditions.

[0062] First, the communication control device (210) and the plurality of electronic control devices (220-1 to 220-n) may each include a hardware security module (HSM).

[0063] An HSM can be implemented as dedicated hardware designed to securely store encryption keys and perform cryptographic operations (e.g., encryption, decryption, signature generation, or authentication processing) at high speed, and in automotive environments, it can be implemented in lightweight forms such as automotive HSMs, SHEs (security hardware extensions), or HSEs (hardware security engines).

[0064] Second, each ECU has a unique master key (MK i Can save ).

[0065] A master key is a type of long-term key that can be individually injected into each ECU during the vehicle manufacturing phase and can be used as a base key for subsequent symmetric key generation or authentication procedures.

[0066] Third, the communication control device (210) can generate a random value each time the vehicle is started, and the random value can be generated to have a different value each time the vehicle is started.

[0067] Fourth, the communication control device (210) can store or manage master keys corresponding to each of the multiple ECUs, and thereby identify each ECU connected to the vehicle internal network or perform a symmetric key management procedure.

[0068] At the point when the vehicle is first started (e.g., the final stage of the vehicle manufacturing process or the initial operation stage before the vehicle is delivered to a customer), the master key injected into each ECU can be safely transmitted to and stored in the communication control unit (210). For example, the communication control unit (210) can generate its own public key and private key pair and transmit the generated public key to each ECU. Each ECU can encrypt its own master key using the received public key and then transmit it to the communication control unit (210), and the communication control unit (210) can safely store the master key of each ECU by decrypting it using its own private key. This process can be performed once at the point when the vehicle is first started.

[0069] Meanwhile, the configuration illustrated in FIG. 2 is an example for illustrative purposes, and in an actual vehicle internal network structure, it may be extended to include additional domain gateways, sub-networks, or functional domain-based ECU group structures.

[0070] The symmetric key management technology of the present disclosure can be applied to these various internal vehicle network structures based on the same principles.

[0071] FIG. 3 is a diagram showing a schematic sequence of a procedure for generating and distributing a symmetric key to perform secure communication in an in-vehicle network according to one embodiment of the present disclosure.

[0072] The procedure for generating and distributing symmetric keys according to one embodiment of the present disclosure is performed whenever a vehicle is started or when the initialization of a secure communication session is required, and the generated symmetric keys are maintained only while the vehicle is in operation. That is, when the vehicle is turned off, these symmetric keys are discarded.

[0073] Referring to FIG. 3, a communication control device (210) and a plurality of electronic control devices (220-1 to 220-n) can perform a procedure to cooperatively generate and share a symmetric key to be applied to internal vehicle security communication.

[0074] The communication control device (210) generates a cryptographically secure random number (S310). The random number can be generated to have a different value at each vehicle start time and can be used as an input parameter for a symmetric key generation procedure performed thereafter.

[0075] The communication control device (210) can generate cryptographically secure random numbers by utilizing a secure random number generator. For example, a CSPRNG (Cryptographically Secure Pseudo-Random Number Generator) can be used as the secure random number generator, but is not limited thereto. A CSPRNG can generate an unpredictable random number sequence by receiving a seed as input.

[0076] The communication control device (210) transmits the generated random number to each of the plurality of electronic control devices (220-1 to 220-n) through the vehicle internal network (230) (S320). The transmission of the random number may be performed in a broadcast manner to minimize the communication load of the vehicle internal network. All electronic control devices receive the same value of the random number.

[0077] Random numbers generated by the communication control unit and unique master keys for each electronic control unit (MK1, MK2, ..., MK n Symmetric keys (SK1, SK2, ..., SK) corresponding to each of the multiple electronic control units based on )n Generates )(S330-1).

[0078] Each electronic control unit (220-i) receives a random number and its own master key (master key, MK i Based on ), symmetric key (SK i ) generates (S330-2). For example, the first electronic control unit (220-1) generates a symmetric key (SK1) based on a random number and a master key (MK1), the second electronic control unit (220-2) generates a symmetric key (SK2) based on a random number and a master key (MK2), and the nth electronic control unit (220-n) generates a symmetric key based on a random number and a master key (MK n Based on ), symmetric key (SK n Can generate ).

[0079] The communication control device (210) and each electronic control device (220-i) can independently generate identical symmetric keys corresponding to each other by using the same key generation algorithm. As a key generation algorithm, a key derivation function (KDF), a block encryption algorithm (e.g., AES-128, AES-192, AES-256, etc.), a hash function (e.g., SHA-256, etc.), an XOR operation, etc., may be used, but are not limited thereto.

[0080] The communication control unit (210) and each electronic control unit (220-i) can generate symmetric keys and store master keys using a hardware security module (HSM).

[0081] At the point when the aforementioned process (S330-1 and S330-2) is completed, the communication control device (210) possesses symmetric keys corresponding to all electronic control devices, and each electronic control device (220-i) possesses only the symmetric key corresponding to itself. Subsequently, through subsequent processes (S340 to S370), each electronic control device can additionally acquire symmetric keys corresponding to other electronic control devices.

[0082] It is also necessary to share a symmetric key for secure communication among multiple electronic control units (220-1 to 220-n).

[0083] The communication control device (210) configures a symmetric key set (SK_SET) to include a plurality of generated symmetric keys (S340). The communication control device (210) configures a symmetric key set (SK_SET) to include symmetric keys of all electronic control devices (220-1 to 220-n). The communication control device (210) may configure a symmetric key set (SK_SET) to include a plurality of entries in which identification information of each electronic control device (220-i) and a symmetric key corresponding to each electronic control device are mapped as pairs.

[0084] The communication control device (210) may configure a symmetric key set (SK_SET) including identification information of each electronic control device (220-i) and a symmetric key corresponding to each electronic control device in the format shown in FIG. 4, but is not limited thereto. For example, the symmetric key of the first electronic control device (220-1) may be SK1, the symmetric key of the second electronic control device (220-2) may be SK2, and the symmetric key of the nth electronic control device (220-n) may be SK n If referred to as such, the communication control device (210) refers to the symmetric key set (SK_SET) as " 1||SK1||2||SK2||...||n||SK n It can be configured as follows. In addition, depending on various implementations, header information such as the identification number of each electronic control unit (220-i), the number of symmetric key pairs, and the total payload length may be added to the format of the symmetric key set.

[0085] The communication control device (210) encrypts the configured symmetric key set for each electronic control device (220-i) using a symmetric key corresponding to each electronic control device, thereby producing a plurality of encrypted symmetric key sets (ESK_SET1, ESK_SET2, ..., ESK_SET). n) generates (S350). For example, an encrypted symmetric key set to be transmitted to a specific electronic control unit can be encrypted using a symmetric key corresponding to that electronic control unit. That is, the communication control unit (210) generates an encrypted symmetric key set for each of the multiple electronic control units (220-1 to 220-n).

[0086] The communication control unit (210) transmits an encrypted symmetric key set generated for each electronic control unit to the corresponding electronic control unit via the vehicle internal network (S360). For example, a symmetric key set (ESK_SET1) encrypted using the symmetric key of the first electronic control unit (220-1) is transmitted to the first electronic control unit (220-1), a symmetric key set (ESK_SET2) encrypted using the symmetric key of the second electronic control unit (220-2) is transmitted to the second electronic control unit (220-2), and a symmetric key set (ESK_SET2) encrypted using the symmetric key of the nth electronic control unit (220-n) is transmitted to the second electronic control unit (220-2). n ) can be transmitted to the nth electronic control unit (220-n).

[0087] Each electronic control unit (220-i) receives an encrypted symmetric key set (ESK_SET). i A symmetric key set (SK_SET) is obtained by decrypting the ) using a symmetric key generated by itself (S370). For example, the first electronic control unit (220-1) decrypts the encrypted symmetric key set (ESK_SET1) using its own symmetric key (SK1), the second electronic control unit (220-2) decrypts the encrypted symmetric key set (ESK_SET2) using its own symmetric key (SK2), and the nth electronic control unit (220-n) decrypts the encrypted symmetric key set (ESK_SET n ) its own symmetric key (SK nDecrypted using ) to obtain a symmetric key set (SK_SET). Each electronic control unit (220-i) can obtain the symmetric keys of other electronic control units based on the decrypted symmetric key set (SK_SET). Through this, each electronic control unit obtains not only its own symmetric key but also all symmetric keys corresponding to other electronic control units.

[0088] Subsequently, secure communication using symmetric keys can be performed during direct data communication between electronic control units. For example, a specific electronic control unit can encrypt transmitted data using a symmetric key corresponding to itself, and another electronic control unit receiving the data can decrypt the data using a symmetric key corresponding to the transmitting electronic control unit.

[0089] Symmetric keys generated by the aforementioned procedure can be discarded upon vehicle shutdown, and new symmetric keys can be generated based on new random numbers upon the next vehicle startup. This reduces the risk of long-term key exposure and enhances security within the vehicle's internal communication environment.

[0090] FIG. 4 is a diagram schematically showing the data structure of a symmetric key set (SK_SET) according to one embodiment of the present disclosure.

[0091] Referring to FIG. 4, the symmetric key set (SK_SET) may be configured to include a structure comprising multiple entries in which identification information of each of the multiple electronic control units and corresponding symmetric keys are mapped in a pair form.

[0092] For example, identification information and a symmetric key (SK1) of the first electronic control unit (220-1), identification information and a symmetric key (SK2) of the second electronic control unit (220-2), ..., identification information and a symmetric key (SK) of the nth electronic control unit (220-n). n ) can be configured in a sequentially arranged form.

[0093] Additionally, depending on the implementation example, a header field containing the number of entries, total data length, or version information may be added to the symmetric key set.

[0094] According to another embodiment of the present disclosure, when a single electronic control unit supports multiple functions or multiple services, different symmetric keys can be generated for each function or service and distributed.

[0095] Specifically, when the communication control device (210) and each electronic control device (220-i) generate a symmetric key, additional parameters for distinguishing functions or services are used in addition to the random number and master key, thereby allowing different symmetric keys to be generated for each function or service even for the same electronic control device. At this time, it is assumed that the communication control device (210) shares the additional parameters with each electronic control device (220-i) in advance.

[0096] Additional parameters may include information capable of identifying the function or service to which the generated symmetric key is to be applied, such as a function identifier, a service identifier, a security level identifier, or application identification information.

[0097] For example, if an electronic control unit supports over-the-air (OTA) software update, Feature on Demand (FOD) function, and general vehicle control function together, multiple symmetric keys different for each function may be generated for the electronic control unit.

[0098] For example, a symmetric key of the following form can be generated for the first electronic control unit (220-1) by function or service.

[0099] (i) SK 1_OTA = KDF(MK1, R, Service_ID_OTA)

[0100] (ii) SK 1_FoD= KDF(MK1, R, Service_ID_FoD)

[0101] (iii) SK 1_GEN = KDF(MK1, R, Service_ID_GEN)

[0102] Here, the master key (MK1) refers to a long-term key uniquely set in the first electronic control unit (220-1), and the random number (R) refers to a value newly generated by the communication control unit (210) at each vehicle start time and transmitted to each electronic control unit. KDF is a key derivation function that generates a symmetric key by receiving the master key, the random number, and additional parameters for identifying a function or service as inputs. Service_ID_OTA is an additional parameter for identifying an OTA service, Service_ID_FoD is an additional parameter for identifying a FoD service, and Service_ID_GEN is an additional parameter for identifying a general vehicle control function. The additional parameters may consist of, for example, a Service Identifier, a Function Code, a Security Context Identifier, etc.

[0103] That is, each of the communication control device (210) and the first electronic control device (220-1) is a symmetric key (SK) used when performing an OTA service. 1_OTA ), symmetric key used when performing FoD service (SK 1_FoD ) and symmetric keys (SK) used for general vehicle control message processing 1_GEN Can generate ).

[0104] Multiple symmetric keys can be generated for other electronic control units based on the same principle for each function or service.

[0105] As described above, by generating different symmetric keys for each function or service, it is possible to prevent the simultaneous exposure of symmetric keys used for other functions or services even if the symmetric key used for one function or service is exposed. In other words, by separating cryptographic keys by function or service, the key usage area can be logically divided, and the spread of a security breach in a specific function or service area to the entire vehicle internal network can be suppressed.

[0106] The communication control device (210) can configure a symmetric key set including symmetric keys for each function or service in the same manner as the above-described basic embodiment, and can encrypt it using a symmetric key for each electronic control device or a symmetric key for each function / service and then transmit it to the corresponding electronic control device.

[0107] Accordingly, each electronic control unit can selectively acquire symmetric keys corresponding to the functions or services it supports and perform secure communication procedures suitable for the corresponding functions or services.

[0108] Furthermore, the function or service-specific symmetric key generation structure can be effectively applied even when multiple communication sessions with different security requirements coexist in an internal vehicle network. For example, since vehicle control messages and infotainment data may have different required security levels or communication characteristics, according to an embodiment of the present disclosure, a separate symmetric key can be generated and applied for each of them.

[0109] According to the symmetric key generation and distribution method according to the embodiments of the present disclosure, communication safety can be effectively improved against various security threats in an internal vehicle network environment.

[0110] Whenever the vehicle is started, a new random number (R) is generated by the communication control unit (210), and a symmetric key is generated based on the random number and the master key (MKi) uniquely set for each electronic control unit (220-i). Therefore, even if an attacker steals the symmetric key used during past vehicle operation, it is virtually impossible to decrypt or falsify the communication using the new symmetric key generated when the vehicle is started. In other words, according to the embodiment of the present disclosure, a session-based dynamic key generation structure is implemented, thereby significantly reducing security vulnerabilities caused by long-term key exposure.

[0111] Security can be enhanced even in attack scenarios where an unauthorized device is connected to the vehicle's internal network. Since the communication control unit (210) can store and manage a master key set corresponding to normal electronic control units in advance during the vehicle manufacturing stage or the initial provisioning process, even if an unauthorized device is physically connected to the vehicle's internal network, the device cannot participate in the normal symmetric key generation procedure because it does not possess a valid master key. Consequently, the symmetric key set configured by the communication control unit does not include a symmetric key corresponding to an unauthorized device, and the unauthorized device may be restricted from participating in secure communication within the vehicle or generating valid cryptographic data.

[0112] Furthermore, an attacker can eavesdrop on the vehicle's internal network and the encrypted symmetric key set (ESK_SET) for each electronic control unit i Even if the attacker obtains ), since the attacker does not possess the corresponding symmetric key, the encrypted symmetric key set (ESK_SET) i ...cannot be decrypted. In other words, since the symmetric key set is individually encrypted using the unique symmetric key of each electronic control unit, the possibility of key leakage can be effectively blocked even if the encrypted symmetric key set is exposed on the communication path.

[0113] Furthermore, according to an embodiment in which different symmetric keys are generated for each function or service, even if a security breach occurs in a specific service area, it is possible to prevent the communication security of other service areas from deteriorating sequentially. For example, even if the symmetric key used for OTA services is exposed, the symmetric key used for vehicle control message communication can be maintained separately, thereby improving the resilience of the entire vehicle security system.

[0114] According to another embodiment of the present disclosure, a symmetric key used in an internal vehicle network is not limited to being generated at the time of vehicle startup, but can be dynamically updated in response to various security events or changes in system state.

[0115] For example, the communication control device (210) may be configured to generate a new random number (R') when the following event occurs and to perform a symmetric key update or regeneration procedure based thereon.

[0116] (a) Change in vehicle ignition status (e.g., the point at which ignition switches from OFF to ON)

[0117] (b) When performing vehicle software updates or OTA (Over-the-Air) updates

[0118] (c) The point in time when a specific security threat event is detected (e.g., detection of unauthorized messages, detection of abnormal communication patterns, ECU authentication failure, etc.)

[0119] (d) Timing of changes in vehicle internal network topology (e.g., addition of new ECU, replacement of ECU, reconfiguration of function modules, etc.)

[0120] (e) When a certain amount of time has elapsed or a data transfer threshold is reached (e.g., expiration of a predefined key validity period)

[0121] When a key update trigger event as described above occurs, the communication control device (210) can generate a new random number (R') and transmit it to a plurality of electronic control devices (220-1 to 220-n) through the vehicle internal network (230).

[0122] Each electronic control unit (220-i) can generate a new symmetric key using the same key generation algorithm as before based on a newly received random number (R') and a previously stored master key, and the communication control unit (210) can redistribute a new set of symmetric keys by configuring them to include new symmetric keys corresponding to each of the multiple electronic control units.

[0123] In addition, during the key renewal process, the previously used symmetric key may be immediately discarded, and depending on the implementation method, a grace period may be established during which the previous session key and the new session key can be used concurrently for a certain period. This allows for the simultaneous assurance of continuity and security in-vehicle communication while minimizing communication interruptions that may occur during the key renewal process.

[0124] According to another embodiment of the present disclosure, a high level of security can be continuously maintained even in a long-term operation environment of an in-vehicle network through an event-based or policy-based symmetric key update structure.

[0125] FIG. 5 is a block diagram showing an example of the configuration of a device for performing secure communication in an internal vehicle network according to one embodiment of the present disclosure.

[0126] Referring to FIG. 5, the device (50) may include a processor (510), memory (520), a security module (530), and a communication interface (540).

[0127] The device (50) may be implemented as a communication control device or electronic control device that performs a secure communication procedure in a vehicle internal network, and may be configured to perform all or part of the symmetric key generation and distribution procedure described in FIG. 3.

[0128] The processor (510) can perform various secure communication operations according to the present disclosure by executing instructions stored in memory (520). For example, the processor (510) may be configured to perform functions such as random number generation control, symmetric key generation operation control, symmetric key set configuration control, encrypted symmetric key set generation control, and secure communication control.

[0129] The processor (510) may be implemented as a single processor or as a structure including multiple processing cores.

[0130] The memory (520) can store program code executed by the processor (510), parameters related to symmetric key management, electronic control unit identification information, key generation algorithm information, and communication control information.

[0131] The memory (520) may include at least one of volatile memory and non-volatile memory. For example, the volatile memory may include SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory), and the non-volatile memory may include flash memory or EEPROM (Electrically Erasable Programmable Read-Only Memory).

[0132] The security module (530) can be implemented as a security hardware block that performs secure storage of cryptographic keys and cryptographic operation processing.

[0133] The security module (530) may include a key storage unit (532) and a cryptographic operation unit (534).

[0134] The key storage unit (532) may be configured to store a master key, a symmetric key, or other security parameters in a protected state from the outside.

[0135] The cryptographic operation unit (534) may be configured to perform symmetric key generation operations, encryption operations, decryption operations, message authentication code generation or verification operations, etc.

[0136] The security module (530) can be implemented in the form of a vehicle hardware security module (HSM), a security hardware extension (SHE), or a hardware security engine (HSE).

[0137] The communication interface (540) can provide a communication function for transmitting and receiving data with the vehicle's internal network.

[0138] The communication interface (540) can be configured to support automotive communication protocols such as CAN (Controller Area Network), CAN FD, LIN (Local Interconnect Network), FlexRay, or automotive Ethernet.

[0139] Additionally, the communication interface (540) may be configured to perform random number transmission, encrypted symmetric key set transmission, and secure data exchange between the communication control device and a plurality of electronic control devices.

[0140] The device (50) according to an embodiment of the present disclosure represents an example of a functional configuration for performing a secure communication method in an internal vehicle network, and depending on the actual implementation form, some components may be integrated, omitted, or added. For example, when implemented as a communication control device, the function of generating and managing symmetric keys corresponding to a plurality of electronic control devices may be emphasized, and when implemented as an electronic control device, the function of generating a symmetric key based on its own master key and decrypting an encrypted set of symmetric keys may be emphasized.

[0141] Each component of the device or method according to the present invention may be implemented in hardware or software, or in a combination of hardware and software. Additionally, the function of each component may be implemented in software, and a microprocessor may be implemented to execute the function of the software corresponding to each component.

[0142] Various embodiments of the systems and techniques described herein may be realized as digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include being implemented as one or more computer programs executable on a programmable system. A programmable system comprises a storage system, at least one input device, and at least one programmable processor (which may be a special-purpose processor or a general-purpose processor) coupled to receive data and instructions from and transmit data and instructions to at least one output device. Computer programs (which are also known as programs, software, software applications, or code) include instructions for the programmable processor and are stored on a "computer-readable recording medium."

[0143] Computer-readable recording media include all types of recording devices in which data that can be read by a computer system is stored. Such computer-readable recording media may be non-volatile or non-transitory media such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device, and may also include transitory media such as data transmission media. Additionally, computer-readable recording media may be distributed across networked computer systems, and computer-readable code may be stored and executed in a distributed manner.

[0144] Although the flowcharts and timing diagrams in this specification describe each process as being executed sequentially, this is merely an illustrative explanation of the technical concept of one embodiment of the present disclosure. In other words, a person skilled in the art to which one embodiment of the present disclosure belongs may modify and adapt the flowcharts and timing diagrams in various ways, such as changing the order described in the flowcharts and timing diagrams or executing one or more of the processes in parallel, without departing from the essential characteristics of one embodiment of the present disclosure; therefore, the flowcharts and timing diagrams are not limited to a chronological order.

[0145] The above description is merely an illustrative explanation of the technical concept of the present embodiment, and a person skilled in the art to which the present embodiment belongs would be able to make various modifications and variations within the scope of the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain, not limit, the technical concept of the present embodiment, and the scope of the technical concept of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present embodiment.

[0146] CROSS-REFERENCE TO RELATED APPLICATION

[0147] This patent application claims priority to Korean patent application No. 10-2025-0040693 filed on March 28, 2025, the entire contents of which are incorporated into this patent application by reference.

Claims

1. A method for performing secure communication in an internal vehicle network, The process of a communication control device generating cryptographically secure random numbers; The process of the above communication control device transmitting the above random number to each of a plurality of electronic control devices connected to the vehicle internal network; The communication control device generates symmetric keys corresponding to each of the plurality of electronic control devices based on the random number and master keys pre-set for each electronic control device; A process in which each of the plurality of electronic control units generates a symmetric key for each electronic control unit based on the random number and the master key stored in the electronic control unit; and The process of configuring a symmetric key set such that the communication control device includes symmetric keys corresponding to each of the plurality of electronic control devices; A process in which the communication control device generates an encrypted symmetric key set for each electronic control device by encrypting the symmetric key set for each electronic control device using a symmetric key corresponding to each electronic control device; and The process of the above communication control device transmitting an encrypted symmetric key set for each electronic control device to a corresponding electronic control device; A process in which each of the plurality of electronic control devices decrypts a received set of encrypted symmetric keys using a symmetric key corresponding to itself and obtains symmetric keys corresponding to other electronic control devices; and Each of the above plurality of electronic control devices performs secure communication using a symmetric key corresponding to itself and symmetric keys corresponding to other electronic control devices, wherein A method in which the communication control device and the plurality of electronic control devices use the same key generation algorithm so that corresponding symmetric keys are generated.

2. In Paragraph 1, Each electronic control unit is, Encrypts transmitted data using a symmetric key corresponding to itself, and A method for decoding data received from another electronic control unit using a symmetric key corresponding to the other electronic control unit.

3. In Paragraph 1, The process of generating the above random number is performed every time the vehicle is started, and A method in which the above random number is generated to have a different value each time the vehicle is started.

4. In Paragraph 1, A method in which the master key stored in each electronic control unit is a long-term key set for each electronic control unit during the vehicle manufacturing stage.

5. In Paragraph 1, At the time the above communication control device first starts the vehicle, The public key of the above communication control device is constantly transmitted to multiple electronic control devices, and A master key encrypted using the public key is received from each of the plurality of electronic control devices, and A method further comprising the process of decrypting and storing a received encrypted master key using the private key of the communication control device.

6. In Paragraph 1, A method in which the process of each of the above communication control device and the above plurality of electronic control devices generating a symmetric key is performed every time the vehicle is started.

7. In Paragraph 1, A method in which symmetric keys generated by each of the communication control device and the plurality of electronic control devices are used to encrypt data transmitted and received in a vehicle internal network or to generate a Message Authentication Code.

8. In Paragraph 1, A method in which symmetric keys generated by each of the above communication control device and the above plurality of electronic control devices are discarded when the vehicle is started.

9. In Paragraph 1, The above-mentioned identical key generation algorithm is a method that operates deterministically to generate the same symmetric key for the same input value.

10. In Paragraph 1, The symmetric key set configured by the above communication control device is A method comprising a data structure including multiple entries in which identification information of each electronic control unit and a symmetric key corresponding to each electronic control unit are mapped as pairs.

11. In Paragraph 1, The above encrypted symmetric key set for each electronic control unit is A method in which each electronic control unit is generated to be decryptable using only its own symmetric key.

12. A communication control device for supporting secure communication in an internal vehicle network, Communication interface; At least one processor; and It includes memory for storing instructions executed by the above processor, and The above at least one processor Generate cryptographically secure random numbers, and The above random number is transmitted to each of the plurality of electronic control units connected to the vehicle internal network, and Based on the above random number and master keys pre-set for each electronic control unit, symmetric keys corresponding to each of the plurality of electronic control units are generated, and A symmetric key set is configured to include symmetric keys corresponding to each of the plurality of electronic control devices, and The above symmetric key set is encrypted for each electronic control unit using a symmetric key corresponding to each electronic control unit to generate an encrypted symmetric key set for each electronic control unit, and A communication control device configured to transmit a generated set of encrypted symmetric keys for each electronic control unit to a corresponding electronic control unit.

13. In Paragraph 12, It further includes a Hardware Security Module (HSM), and The above hardware security module is a communication control device configured to perform encryption key storage and encryption operations in an internal, independent execution environment.

14. An electronic control unit for supporting secure communication in an internal vehicle network, Communication interface; At least one processor; and It includes memory for storing instructions executed by the above processor, and The above at least one processor Receive a random number from the communication control device, and A symmetric key is generated based on the above random number and the stored master key, and Receive an encrypted symmetric key set from the above communication control device, and By decrypting the encrypted set of symmetric keys using the above symmetric key, symmetric keys corresponding to other electronic control units connected to the vehicle internal network are obtained, and An electronic control device configured to perform secure communication with other electronic control devices using a generated symmetric key and an acquired symmetric key.

15. In Paragraph 14, It further includes a Hardware Security Module (HSM), and The above hardware security module is an electronic control unit configured to store cryptographic keys and perform cryptographic operations in an internal, independent execution environment.

16. In a system for performing secure communication in an internal vehicle network, It includes a communication control unit and a plurality of electronic control units interconnected through an internal vehicle network, and The above communication control device is Generate cryptographically secure random numbers, and The above random number is transmitted to each of the plurality of electronic control devices, and Based on the above random number and master keys pre-set for each electronic control unit, symmetric keys corresponding to each of the plurality of electronic control units are generated, and A symmetric key set is configured to include symmetric keys corresponding to each of the plurality of electronic control devices, and The above symmetric key set is encrypted for each electronic control unit using a symmetric key corresponding to each electronic control unit to generate an encrypted symmetric key set for each electronic control unit, and It is configured to transmit the generated encrypted symmetric key set for each electronic control unit to the corresponding electronic control unit, and Each of the above plurality of electronic control devices is Receive the random number from the above communication control device, and A symmetric key is generated based on the above random number and the stored master key, and By decrypting the encrypted symmetric key set received from the communication control device using the generated symmetric key, symmetric keys corresponding to other electronic control devices are obtained, and A system configured to perform secure communication with other electronic control devices using a generated symmetric key and an acquired symmetric key.

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