Data communication system, center device, master device, storage medium storing encryption program, and storage medium storing decryption program

Abstract

A data communication system includes a center device that distributes update data to a master device, and a master device that installs the update data downloaded from the center device in an electronic control unit to be reprogrammed. The center device generates a common key for encrypting the update data; encrypts the update data with the common key; encrypts the common key; stores the common key encrypted in a campaign notification; places the update data encrypted with the common key in a content delivery network (CDN); and transmits the campaign notification. The master device acquires the common key from the campaign notification; decrypts the encrypted common key to extract the common key; downloads and acquires encrypted update data from the CDN; performs an exclusive OR operation; and transfers the decrypted update data to the electronic control unit, and installs the update data in the electronic control unit.