Abstract: There is provided a technique for improving the accuracy of estimation of a position of a nearby vehicle. A nearby vehicle position estimation system is formed that includes a relative position information obtaining part that obtains relative direction of a nearby vehicle with respect to a host vehicle, the nearby vehicle being present around the host vehicle; a map information obtaining part that obtains map information around a current position of the host vehicle; and a nearby vehicle position estimating part that obtains, based on the map information, a nearby road that overlaps a straight line extending in the relative direction from the host vehicle, and estimates that the nearby vehicle is present on the nearby road.

Abstract: A map updating system that stores map data and a priority sequence table, acquires first update data and second update data of the map data according to the priority sequence table, and updates the map data based on the first update data and second update data according to the priority sequence table.

Abstract: A CPU of a navigation apparatus stores public keys to which priorities are set and which are published by an information distribution center in a public key storage section. The CPU of the navigation apparatus extracts an electronic signature of distribution data which is distributed from the information distribution center and verifies the electronic signature by using only ‘valid’ public keys among the public keys in order of the priorities. The CPU of the navigation apparatus determines that the distribution data is valid information which is distributed from the information distribution center when the electronic signature passes verification.

Abstract: When updating means 24 for performing a differential update on map data M using update data U performs an update on the map data M using update data U stored on a recording medium R, update data U having section identification information that matches the section identification information of the map data M and a later update version than the update version of the map data M are extracted from the plurality of update data U stored on the recording medium R, and a differential update is performed on the map data M using the extracted update data U.

Abstract: When updating means 24 for performing a differential update on map data M using update data U performs an update on the map data M using update data U stored on a recording medium R, update data U having section identification information that matches the section identification information of the map data M and a later update version than the update version of the map data M are extracted from the plurality of update data U stored on the recording medium R, and a differential update is performed on the map data M using the extracted update data U.

Abstract: A CPU of a navigation apparatus stores public keys to which priorities are set and which are published by an information distribution center in a public key storage section. The CPU of the navigation apparatus extracts an electronic signature of distribution data which is distributed from the information distribution center and verifies the electronic signature by using only ‘valid’ public keys among the public keys in order of the priorities. The CPU of the navigation apparatus determines that the distribution data is valid information which is distributed from the information distribution center when the electronic signature passes verification.

Abstract: A map updating system that stores map data and a priority sequence table, acquires first update data and second update data of the map data according to the priority sequence table, and updates the map data based on the first update data and second update data according to the priority sequence table.