An authentication server may obtain information about a plurality of nodes or information about a replacement node in an in-vehicle system, and perform authentication on the nodes based on the information about the nodes or perform authentication on the replacement node based on the information about the replacement node. After the authentication succeeds, the authentication server may further send an identifier of a subnode of a node, key information of the subnode of the node, an identifier of a parent node of the node, and key information of the parent node of the node to the node in the in-vehicle system. Therefore, when the in-vehicle system is started, the node performs authentication on another node in the in-vehicle system.