| 摘要 |
PROBLEM TO BE SOLVED: To prevent a vehicle door from being unlocked by a relay attack without equipping an electronic key nor a vehicle-side device with equipment for acquiring position information.SOLUTION: A portable machine 20 acquires position information from a position information terminal 30 and saves the position information in itself when a vehicle door is locked. Then when radio communication between the portable machine 20 and a vehicle-side device 10 is performed so as to unlock the vehicle door, the portable machine 20 acquires position information from the position information terminal 30 again. The portable machine 20 determines whether the acquired position information is within an unlocking permission range based upon the position information saved in the portable machine 20. The portable machine 20 continues the radio communication for unlocking the vehicle door when determining that the position information is within the unlocking permission range, and quits the radio communication for unlocking the vehicle door when determining that the position information is not within the unlocking permission range. |
