Patent ID: 8713700

Claim:
An access control method for accessing information at a place, to which a user will move, using a portable information display device, the access control method comprising the steps of: identifying identifiers of planned waypoints during a move to a destination and an identifier of the destination, the destination being a place where the information will be accessed; creating a planned route of the information display device, the planned route represented as a sequence of the identifiers of the planned waypoints and the identifier of the destination; generating an encryption key based on the created planned route; encrypting the information, which will be accessed, using the generated encryption key; repeatedly acquiring position information on the information display device during the move; identifying an actual route of the information display device by identifying identifiers of waypoints and an identifier of a current position based on the acquired position information; generating a decryption key based on the identified actual route; and decrypting the encrypted information using the generated decryption key and, if the decryption is successful, permitting the information display device to access the information within an area corresponding to the destination; wherein the planned route is created in such a way that the identifiers, which constitute the planned route, are different and wherein if duplicated identifiers are included in the actual route, an identifier between the duplicated identifiers and one of the duplicated identifiers are deleted from the sequence of the identifiers.