Portable device, communication device, and communication system

Abstract

The invention provides a portable device, a communication device, and a communication system with high prevention and capable of determining whether relay attack is performed. The communication system (100) includes: a vehicle (1)-mounted communication device (20) and a portable device (10). The communication device (20) includes: a vehicle transmission unit (22) which transmits a plurality of first signals to the portable device, and a vehicle reception unit (21) which receives a second signal transmitted from the portable device. The portable device (10) includes: a portable device reception unit (11) which receives the first signals, a portable device controller (15) which detects signal intensities of the received first signals, and which compares the signal intensities of the first signals, and a portable device transmission unit (12) which transmits the second signal according to control of the portable device controller. The portable device controller (15) sets an output value of the second signal to a predetermined value when a difference between the compared signal intensities of the first signals is equal to or less than a threshold.

Description

technical field [0001] The present invention relates to a portable device, a communication device, and a vehicle communication system using the portable device and the communication device. Background technique [0002] Conventionally, it is widely known that a signal for a passive function is transmitted and received between an on-vehicle communication device included in a vehicle and a portable device held by a user. Here, the passive function refers to a function of locking and unlocking a door or the like (opening and closing body) when the user operates a door handle or a door handle switch without operating the portable device. In this function, when the user performs a predetermined operation on the door handle, etc., the vehicle-mounted communication device transmits a response request signal to reach a predetermined area, and the portable device that receives the response request signal returns a response signal including authentication information. When the authen...

AI Technical Summary

Problems solved by technology

[0008] However, in the countermeasure described in Patent Document 1, if the positional relationship between the portable device and the plurality of antennas is such that the strengths of the compared signals are substantially the same, it is misjudged that a relay attack is in progress, and the portable device The machine does not send a response signal, the passive function does not work

For example, in the case of having a transmitting antenna located in the front of the vehicle and a transmitting antenna located in the rear outside of the vehicle, when the portable device is located near the door at the rear of the vehicle, since the signal strength from the transmitting antenna in the front of the vehicle differs from that from the outside of the vehicle The signal strength of the transmitting antenna at the rear is about the same, so it is misjudged as a relay attack, the passive function does not work, the door cannot be locked and unlocked, etc.

[0009] In addition, in the countermeasure described in Patent Document 2, when it is determined that the regular user is not near the vehicle, the output value of the response signal returned by the portable device is decreased so that the reach distance becomes the arrival distance of the response request signal output from the vehicle. The reach distance of the distance degree, so that it cannot be unlocked

However, since it is impossible to tell whether the signal is received directly from the vehicle or via a repeater, it is still difficult to determine whether a relay attack is in progress

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