In-vehicle system and communication method

An in-vehicle system for communicating with an external tool, the system comprising:

• a communication device;
• a tool key acquisition device;
• and
• a communication controller,
• wherein the in-vehicle system and an external server provide a vehicular communication system,
• wherein the external tool stores a tool secret key,
• wherein the external server stores external tool information,
• wherein the external tool information provides a tool public key and key identification information, which are associated with each other,
• wherein the tool public key provides a public key, which pairs with the tool secret key,
• wherein the key identification information provides identification information about the tool public key,
• wherein the communication device communicates with the external server,
• wherein, when the external tool requests communication connection with the in-vehicle system, the tool key acquisition device transmits the key identification information corresponding to the external tool as a request source to the external server via the communication device, so that the tool key acquisition device acquires the tool public key associated with the key identification information from the external server via the communication device, and
• wherein the communication controller performs cryptographic communication with the external tool as the request source with using the tool public key acquired by the tool key acquisition device.