Patent ID: 7577520

Claim:
A navigation apparatus for use in a map data update system including an authentication key generation apparatus, comprising: an obtaining unit that obtains the authentication key generated by the authentication key generation apparatus based upon an apparatus-inherent ID assigned each of the navigation apparatus, a version of an update map data and a specified map area; a calculation unit that calculates a reference key to be referenced against the authentication key based upon information indicating the apparatus ID, which is held at the navigation apparatus, and update map data version information and map area information recorded in the update map data that has been installed in the navigation apparatus; a decision-making unit that makes a decision as to whether or not the authentication key is correct by comparing the authentication key having been obtained with the reference key; and an enabling/disabling unit that enables the use of the update map data over the specified map area if the authentication key is judged to be correct or disables the use of the update map data if the authentication key is judged to be incorrect.