KR20130117093A - Method to protect relay-attack of smartkey system - Google Patents

Abstract

PURPOSE: A relay attack prevention method of a smart key system is provided to prevent the robbery possibility of articles stored in a vehicle in advance by determining a normal user. CONSTITUTION: An information transceiving step (S10) transmits a response signal including two or more kind information to a smart key (SMK) unit by receiving a signal applied by the SMK unit through a FOB key. A decoding step decodes the response signal received by the SMK unit (S20). A normal user determination step (S30) determines the state of a passive operation signal by using a distance between the vehicle and the FOB key. [Reference numerals] (AA) Start; (BB) Decoding step; (CC) Normal user determination step; (DD) Yes; (EE) Encoding code identical ?; (FF) No; (GG) SMK unit operation signal applying; (HH) End; (S10) Information transception step

Description

[0001] The present invention relates to a smart key system,

The present invention relates to a method for preventing a relay attack of a smart key system, and more particularly, a LF signal (LF signal) from a vehicle even when a user carrying a fob key is separated from the vehicle by a predetermined distance or more. ) Is transmitted to the fob key (hereinafter referred to as a relay attack), and a method for preventing a relay attack of a smart key system capable of overcoming a problem that a vehicle can be stolen by a third party.

In general, a smart key system in a vehicle means that a driver (or user) carries a fob key and a smart key unit (hereinafter referred to as SMK unit) interprets an encryption code applied from the fob key. It is a system that prevents and prevents theft accident of a vehicle by operating various functional operation parts of the vehicle only when authenticating that the user is a normal user.

That is, when a user approaches the vehicle within a predetermined distance while carrying the fob key, the SMK UNIT wakes up the fob key and then communicates encrypted data of a transponder embedded in the fob key. After the process of authenticating the normal user ID, if it is determined that the user is a normal user, various functions such as starting the engine of the vehicle, opening / closing the trunk door, opening / closing the side door, and the like are operated.

However, when the side door is opened, the signal transmission system may be classified into the following two situations. That is, first, after authenticating the normal user ID, a user directly inputs a switch related to the operation of the side door among operating switches of various function operating units provided in the PODK key, and sends a predetermined signal to the SMK UNIT And the second is a case of transmitting a triggering signal generated from the handle of the side door to the SMK UNIT after authenticating the normal user ID.

The triggering signal generated from the handle of the side door may be generated by the user directly pulling the handle of the side door or may be caused by pressing a triggering button provided on the handle of the side door.

Hereinafter, a normal user ID authentication process performed between the SMK UNIT and the Pov key in the smart key system according to the related art will be briefly described.

First, when the fob key approaches the vehicle within a predetermined distance or pulls the handle of the side door directly, a challenge signal is generated, and the generated signal is modulated and demodulated by the SMK UNIT. Received by the LF receiver of the fob key.

When the Pawkey receives the challenge signal, a response signal including an ID code and an encryption code is transmitted using the RF transmitter of the Pawkey, and the RF receiver of the SMK unit receives the response signal and stores it in advance It is determined whether or not the ID code and the encryption code coincide with each other, and then the operation of the function operation section is enabled only when the code matches.

However, the smart key system according to the prior art is normally operated from the vehicle even when the user carrying the fob key is far away from the vehicle for a predetermined distance (for example, the maximum viewing distance that the driver can observe the vehicle). When a signal is transmitted to the fob key (called "Relay Attack"), the possibility of theft of the vehicle and the equipment stored in the vehicle is raised by maintaining the state in which the various functional operation parts can be operated by a third party. There is a problem.

The present invention has been made to solve the above technical problem, the response signal having at least two types of information after receiving the signal applied from the smart key unit (SMK UNIT) of the vehicle (FOB key) (Response) information) for transmitting a signal) to the SMK UNIT, a decoding step for decoding the response signal received by the SMK UNIT, and a result interpreted by the decoding step, wherein the current between the vehicle and the fobkey And a normal user determination step of determining whether the passive operation signal applied from the door of the vehicle is normal in addition to the fob key after calculating the separation distance, thereby substantially eliminating the distance between the vehicle and the fob key. Therefore, the relay of the smart key system can determine the passive operation and prevent the theft of the vehicle and the equipment stored in the vehicle in advance. To provide a prevention method for that purpose.

In a preferred embodiment of the method for preventing a relay attack of the smart key system according to the present invention, a fob key for carrying a signal applied from a smart key unit (hereinafter referred to as “SMK UNIT”) installed in a vehicle is provided. An information transmitting / receiving step of transmitting a response signal having at least two kinds of information to the SMK UNIT after receiving, a decoding step of decoding the response signal received by the SMK UNIT after the information transmitting / receiving step; Using the result analyzed by the decoding step, after calculating the current separation distance between the vehicle and the fob key, it is normal to determine whether the passive operation signal applied from the door of the vehicle other than the fob key is normal. And a user determination step, wherein the response signal includes a received electric field sensitivity (hereinafter referred to as RSSI) and a current voltage level of the fob key (VL). LA can be a signal with a box) information.

Here, the response signal may further include an encryption code transmitted by the fob key for normal user authentication in the normal user determination step.

In the normal user determination step, the VL may include information when the setting voltage is higher than or equal to the setting voltage, and the RSSI may include information when the setting sensitivity is higher than or equal to the setting sensitivity.

Further, in the normal user determination step, the set sensitivity of the RSSI when the VL is equal to or greater than the set voltage (hereinafter referred to as “first set sensitivity”) is the set sensitivity of the RSSI when the VL is less than the set voltage. (Hereinafter referred to as “second set sensitivity”).

The current separation distance may be near if the RSSI is equal to or greater than the first or second set sensitivity, and far if the RSSI is less than the first or second set sensitivity. In the normal user determination step, the passive operation signal is determined to be normal only when it is calculated as the near, and when it is calculated as the far, the passive operation signal is determined to be abnormal. can do.

The set voltage may be linearly varied, and the first set sensitivity and the second set sensitivity may be stored in the SMK UNIT as map data as a variable that is changed in proportion to the set voltage.

The relay attack prevention method of the smart key system according to the present invention, by accurately calculating the separation distance between the actual vehicle and the fob key using the RSSI and the current voltage level of the fob key to determine whether the passive operation signal is normally applied. Since the determination is performed accurately, it has the effect of blocking the possibility of theft of the vehicle and the items stored in the vehicle in advance.

1 is a schematic diagram showing a state in which a passive entry between a poby key and a smart key unit is possible in a door handle triggering operation,
2 is a block diagram illustrating a procedure of a method for preventing a relay attack of the smart key system according to the present invention.
3 is a schematic view showing an operating state of FIG.
4 is an exemplary table of map data stored in a smart key unit.

Hereinafter, a preferred embodiment of the relay attack prevention method of the smart key system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram showing a passive entry between a fob key and a smart key unit when a door handle triggering operation is enabled, and FIG. 2 is a block diagram illustrating a method of preventing a relay attack of the smart key system according to the present invention. 2 is a schematic diagram showing an operating state of FIG. 2, and FIG. 4 is an exemplary table of map data stored in a smart key unit.

In the vehicle to which the relay attack prevention method of the smart key system according to the present invention is applied, a smart key for controlling the operation of various functional operation units installed in the vehicle body according to various electrical signals applied due to a switch operation installed in the vehicle body or an operation of the portable terminal. The unit (hereinafter referred to as "SMK UNIT") is installed.

The SMK unit controls the operation of various functional units such as an engine, a transmission, and an air-conditioning unit installed in the vehicle body.

A preferred embodiment of the relay attack prevention method of the smart key system according to the present invention is characterized in that the SMK unit is installed in a small size such that it can be carried by a driver (or a user) And a method of communicating with a FOB key communicating with each other in a method. The Pov key is a kind of the portable terminal described above.

That is, the outline of the communication method of the smart key system, the user pulls the handle of the side door installed in the vehicle body (hereinafter referred to as "Door Handle Triggering"), or the plurality of keys provided in the fob key An LF signal is generated by operating two switches, and the generated LF signal is modulated and demodulated and transmitted to the fob key. The fob key responds to the LF signal in response to the LF signal. Signal) to the SMK UNIT, the SMK UNIT decodes the encryption code and various information included in the response signal, and then determines whether the data related to the previously stored encryption code is coincident with each other. It is determined whether the user carrying the normal user.

When the communication method outline of the smart key system is directly applied to the vehicle body, the distance between the SMK UNIT and the Povkey is within a range of a limit distance for authenticating the normal user by wireless communication with each other. Generally, if only the separation distance within the limit distance range is maintained, the SMK unit can be determined to be a normal user, and various functions of the vehicle can be operated by a third party who does not carry the Pov key will be. At this time, it is preferable that the limit distance is set to be within a visible range in which the mobile phone of the pod key can normally observe the vehicle, but it is problematic that the limit distance is preset in the SMK UNIT, It can be extended to the extent that the user can not observe the vehicle.

That is, as shown in Figure 1, the LF signal generated by the triggering of the door handle is transmitted to the fob key through two or more repeaters (Repeater 1, 2) located between the SMK UNIT and the fob key, Accordingly, the passive key and the passive start caused by the door handle triggering of a third party may be generated even when the fob key is separated from the vehicle by a visible distance by allowing the fob key to transmit the response signal. (This is commonly referred to as a “relay attack in a smart key system.”) For example, Repeater 1 receives the LF signal generated by the triggering of the door handle and receives it as an RF1 signal. The distance that can be modulated is short within 2 m, and the distance that the fob key can receive the LF signal demodulated by the repeater 2 Although short within 8m, the distance that the modulated RF1 signal can communicate through the two repeaters (Repeater1,2) is relatively large, and the distance that the SMK UNIT can receive the response signal transmitted by the fob key is also relatively large ( When the triggering of the door handle occurs, the mobile device of the fob key may be out of the range of the visible distance that the vehicle can observe.

The present invention solves the problems as described above, the vehicle stolen from a third party by allowing the user of the fob key to go through the normal user authentication process only within the visible distance that can directly observe the vehicle as possible. It is designed to proactively block the theft of equipment.

That is, in the method of preventing a relay attack of the smart key system according to the present invention, as shown in FIG. 2, the fob key receives a signal applied from the SMK UNIT installed in a vehicle and has at least two kinds of information. An information transmission / reception step (S10) of transmitting a signal to the SMK UNIT, a decoding step (S20) of decoding the reaction signal received by the SMK UNIT after the information transmission / reception step (S10), and the decoding step The normal user who uses the result analyzed by S20, calculates a current distance between the vehicle and the fob key, and then determines whether the passive operation signal applied from the door of the vehicle other than the fob key is normal. A determination step S30 is included.

Here, the response signal transmitted by the fob key in response to the LF signal has at least two kinds of information, and the information includes a received electric field sensitivity (hereinafter referred to as “RSSI”) and the fob key. Information on the current voltage level (hereinafter referred to as "VL") may be included.

The response signal may further include an encryption code transmitted by the fob key for normal user authentication in the normal user determination step (S30) as well as the RSSI and the VL.

The encryption code is data received by the SMK UNIT and compared with an encryption code pre-stored in the SMK UNIT so as to know whether the portable person carrying the fob key is a normal user.

On the other hand, the VL includes two pieces of information, one of more than the set voltage and less than the set voltage, and the RSSI includes two pieces of information of more than the set sensitivity and less than the set sensitivity, so that in the normal user determination step Apply to calculate the current separation distance between the vehicle and the fob key.

In more detail, when the RSSI is equal to or greater than the set sensitivity, it is determined that the current separation distance between the vehicle and the fob key is close (Near), indicating that it is a passive operation signal by a normal user and the RSSI is set sensitivity. If less, it may be determined that the current separation distance between the vehicle and the fob key is far and thus a passive operation signal by an abnormal user.

However, even when the RSSI is the same, the calculated current separation distance and the actual separation distance may be different. For example, when the VL is greater than or equal to the set voltage (where the set voltage is set to “3 V”), when the RSSI is greater than or equal to the set sensitivity, the current separation distance may be regarded as near (Near). Is less than the set sensitivity, the current separation distance can be regarded as Far even if the VL is greater than or equal to the set voltage. On the contrary, even when the VL is less than the set voltage, the current separation distance is greater than or equal to the set sensitivity. This is because the separation distance can be seen as near, but even when the VL is greater than or equal to the set voltage, when the RSSI is less than the set sensitivity, the current separation distance can be regarded as far.

According to the present invention, the RSSI and the VL information are set to a sensitivity higher than or equal to a set voltage for more accurate calculation of the reaction signal transmitted from the fob key in response to the LF signal. The case is divided into the case and the case less than that to transmit to the SMK UNIT.

Here, the set sensitivity of the RSSI when the VL is greater than or equal to the set voltage (hereinafter referred to as "first set sensitivity") and the set sensitivity of the RSSI when the VL is less than the set voltage (hereinafter referred to as "second set" Sensitivity ”) will have different values.

Preferably, the first set sensitivity may be set to a value greater than the second set sensitivity. Then, when the VL is greater than or equal to the set voltage, the vehicle and the fob at least when the RSSI has a value of the first set sensitivity having a value greater than the second set sensitivity compared to the case where the VL is less than the set voltage. This is because the current separation distance between keys can be determined to be close. On the contrary, when the VL is less than the set voltage, the RSSI has the value of the second set sensitivity having a value smaller than the first set sensitivity when the VL is less than the set voltage. Since it is determined that the current separation distance between the fob keys is close, it is possible to prevent malfunctions when the battery remaining amount of the fob keys is small.

The set voltage is linearly varied based on the RSSI, and the first set sensitivity and the second set sensitivity are also stored in the SMK UNIT as map data as a variable that is proportionally variable with the set voltage. do.

Therefore, the current separation distance between the vehicle and the fob key calculated in the normal user determination step S30 is near when the RSSI is equal to or greater than the first setting sensitivity or the second setting sensitivity, and the RSSI. Is less than the first set sensitivity or the second set sensitivity, it is calculated as far Far, and the normal user determination step S30 sets the passive operation signal to normal only when it is calculated to be near. If it is determined that the distance Far is calculated, the passive operation signal is determined to be abnormal.

Referring to the application process of the preferred embodiment of the relay attack prevention method of the smart key system according to the present invention configured as described above are as follows.

First, as shown in FIG. 2, when the door handle triggering is generated by a person carrying a fob key or a third person not carrying the fob key, the SMK UNIT of the vehicle generates an LF signal. The LF signal is modulated and demodulated and transmitted to the fob key.

The fob key receiving the LF signal transmits a response signal to the SMK UNIT as part of a response form, and the SMK UNIT receiving the response signal decodes information included in the response signal. After comparing the previously stored encryption code and the received encryption code data, the side door is unlocked only when they match.

Here, the response signal includes a reception field sensitivity (RSSI) and a battery level (VL) indicating a current battery level, thereby accurately calculating a current separation distance between the vehicle and the fob key, thereby allowing the fob key holder to see the actual distance of the vehicle. If it is out of range, the relay attack can be prevented.

A preferred embodiment of the relay attack prevention method of the smart key system according to the present invention has been described in detail with reference to the accompanying drawings. However, the embodiment of the present invention is not necessarily limited to the above-described preferred embodiment, and it is natural that various modifications and equivalents can be made by those skilled in the art to which the present invention pertains. something to do. For example, in the preferred embodiment of the present invention, the relay attack prevention method of the smart key system for normal user authentication regarding the passive entry operation signal among the various function operation parts of the vehicle has been exemplified and explained, It should be noted that the scope of right of the present invention can be applied not only to the passive start but also to the relay attack of the smart key system involved in the operation of the various function operating units provided in the vehicle such as the opening and closing operations of the trunk door. Therefore, the true scope of the present invention should be determined by the following claims.

S10: transmitting and receiving information S20: decoding step
S30: normal user determination step

Claims (6)

The SMK receives a response signal having at least two types of information after receiving a signal received from a smart key unit installed in a vehicle (hereinafter referred to as “SMK UNIT”) by a fob key that a user carries. Transmitting and receiving information to the UNIT;
A decoding step of decoding the response signal received by the SMK UNIT after the information transmission and reception step;
Using the result analyzed by the decoding step, after calculating the current separation distance between the vehicle and the fob key, it is normal to determine whether the passive operation signal applied from the door of the vehicle other than the fob key is normal. A user determination step,
The response signal is a signal having a received electric field sensitivity (hereinafter referred to as RSSI ") and information about the current voltage level (hereinafter referred to as" VL ") of the fob key. .
The method according to claim 1,
The reaction signal is,
And an encryption code transmitted by the fob key for normal user authentication in the normal user determination step.
The method according to claim 1,
In the normal user determination step,
And the VL includes information when the setting voltage is higher than or equal to the setting voltage, and the RSSI includes information when the setting sensitivity is higher than or equal to the setting sensitivity.
The method according to claim 3,
In the normal user determination step,
The set sensitivity of the RSSI when the VL is greater than or equal to the set voltage (hereinafter referred to as "first set sensitivity") is the set sensitivity of the RSSI when the VL is less than the set voltage (hereinafter referred to as "second set sensitivity"). How to prevent relay attack of smart key system.
The method of claim 4,
The current separation distance,
Near is calculated when the RSSI is equal to or greater than the first set sensitivity or the second set sensitivity, and when the RSSI is less than the first set sensitivity or the second set sensitivity, it is calculated as far.
The normal user determination step,
And determining the passive operation signal as normal only when it is calculated as the near, and determining the passive operation signal as abnormal when it is calculated as the far.
The method according to claim 5,
The set voltage is linearly variable, and the first set sensitivity and the second set sensitivity are variables which are proportionally variable with the set voltage and are stored in the SMK UNIT as map data. How to prevent attack.

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