JP2001227217A - Keyless entry system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure safety by varying a code every time it is sent; and determine whether a door is open or closed through one-way communications alone. SOLUTION: In a transmitter 11, the number of requests to open or close the door is counted by a transmission counter 112. A seed value in a seed storage part 111 is renewed at each transmission and encoded by an encoding part 113, with this encoded value being transmitted by a transmitting part 114, together with the data of the transmission counter. In a receiver 12, the number of times of transmission during the previous proper process and data for checking are retained respectively in a transmission counter 121 and a seed storage part 122. The seed value is anticipated based on the data renewed by the transmission counter 121. A verifying part 126 compares the encoded seed value anticipated with the encoded seed value transmitted thereto to determine whether the door is locked or unlocked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a keyless entry system for locking and unlocking a door by remote control.

[0002]

2. Description of the Related Art In recent years, electronic circuits have also been used in automobile security devices, and keyless entry systems that can remotely open and close a door without inserting a key into the door have become widespread. This keyless entry system receives a signal transmitted from the transmitter, which transmits a door opening / closing signal, and determines whether or not the signal is from a legitimate device. And an output receiver.

[0003] The transmitter has a configuration in which, for example, an antenna, a modulation circuit, a storage circuit, an arithmetic unit and the like are integrated with a key. Further, the transmitter is provided with a transmission button, and when this transmission button is pressed, a radio wave is transmitted from a remote place to a receiver installed in the automobile. The receiver determines the transmitted code and controls the opening and closing of the door.

In a conventional keyless entry system, a fixed code is used. For example, the same specific code is recorded in a storage unit or the like between a transmitter that issues a lock opening / closing request and a receiver that performs opening / closing determination. When opening and closing the lock, a specific code is transmitted from the transmitter,
The receiver compares whether the received specific code is the same as the specific code held. Since the transmitter and the receiver that form a pair must share the same code, if the code is the same, it is determined that the code is transmitted from a valid device, and the door is unlocked or locked.

Another example is to use a disposable code each time. In this example, a different code is transmitted from the transmitter every time, and the receiver determines whether the transmitted code is correct by performing arithmetic processing. FIG.
FIG. 2 is a configuration diagram of a keyless entry system using a disposable code every time. The keyless entry system includes a receiver 40 and a transmitter 41 that perform bidirectional communication.
The receiver 40 includes a numerical information generation unit 42 and an encryption processing unit 43, and the transmitter 41 includes an encryption processing unit 44.

The numerical information generating section 42 generates different numerical information every time. The encryption processing unit 44 of the transmitter 41 uses the numerical information transmitted from the receiver 40
This is to generate an encryption code. The encryption processing unit 43 of the receiver 40 performs the same encryption processing as the encryption processing unit 44 of the transmitter 41, and generates an encryption code based on the numerical information output from the numerical information generation unit 42.

The operation of the keyless entry system having such a configuration will be described. When a door opening / closing request is issued, a start signal is transmitted from the transmitter 41. When the receiver 40 receives the activation signal, the numerical information generation unit 42 generates numerical information different from the last time, and transmits the numerical information to the transmitter 41. Upon receiving the numerical information, the transmitter 41 supplies the numerical information to the encryption processing unit 43, generates an encryption code, and
Send the encryption code to 0.

[0008] Also in the receiver 40, an encryption code is generated by an encryption processing unit 43 based on the numerical information generated by the numerical information generation unit 42. At this time, the transmitter 41
In addition, the encrypted code generated by the receiver 40 has a different value each time because the numerical information that is the basis of the encrypted code is different each time. Further, since the same encryption processing is performed in the encryption processing units 43 and 44, the encryption codes generated from the same numerical information should be the same on the transmitter 41 side and the receiver 40 side.

Therefore, the receiver 40 checks the received encrypted code against the encrypted code generated by the encryption processing unit 43, and if the codes are the same, determines that the code is transmitted from a legitimate device. Perform the locking operation. Different from the example of the keyless entry system using the fixed code described above, a different code is used for communication each time. For this reason,
Even if the transmitted code is eavesdropped, the receiver 40 performs collation using a different code when the next door opening / closing request is issued. Therefore, it is impossible to open or close the door again using the wiretapped code. Further, since the encrypted code is used, it is difficult to analyze the code generation processing method from the transmitted code.

[0010]

However, in the case of a keyless entry system using a code fixed for each user, the unlocking or locking operation can be performed only by one-way communication from the transmitter to the receiver. Since communication is performed using the same code every time, wiretapping of the code to be communicated is easy. Eavesdropping on a communicating code can forge a similar device. Even if the communication code is encrypted, if the original code is the same, the same encryption code will be generated, so as an eavesdropper, the eavesdropping encrypted code without knowing the encryption method Can be unlocked and unlocked by transmitting
Not safe.

In the case of a keyless entry system using a disposable code, it is necessary to synchronize a value (numerical information) shared between a receiver and a transmitter every time in order to generate an encrypted code. For example, a process for performing bidirectional communication between the receiver 40 and the transmitter 41 and exchanging a code serving as a seed for encryption processing is required. For this reason, a circuit for transmitting a code serving as a seed for encryption processing in the receiver 40 and a circuit for receiving a code serving as a seed for encryption processing in the transmitter 41 are required, and there is a limit to reduction in manufacturing cost and miniaturization of the apparatus.

The present invention has been made in view of such a conventional problem.
A keyless entry system that does not require a receiver circuit to synchronize data, and does not require a transmitter circuit to synchronize data at the receiver, and cannot easily predict the code for opening and closing the door from the transmission code. The purpose is to realize.

[0013]

According to a first aspect of the present invention, there is provided a keyless entry system for performing communication between a transmitter and a receiver and unlocking and locking a key by remote control. A transmission counter that counts the number of times of transmission, a seed storage unit that updates a seed value each time the opening / closing signal is transmitted, and an encryption that encrypts a seed value held in the seed storage unit and outputs an encrypted seed value. And a processing unit.

According to a second aspect of the present invention, there is provided a keyless entry system for performing communication between a transmitter and a receiver to unlock and lock a key by remote control, wherein the transmitter counts the number of times of opening and closing signals. A first transmission counter, a first seed storage unit that updates a seed value each time the open / close signal is transmitted, and an encrypted seed value that is encrypted by encrypting the seed value held in the first seed storage unit. A first cryptographic processing unit for outputting, wherein the receiver has a second transmission counter that holds at least the number of transmissions from the transmitter when the open / close determination is successful,
A count update value is obtained from a difference value between the number of transmissions received from the transmitter and the number of transmissions held in the second transmission counter, and a seed of the same series as the first seed storage unit is obtained from the count update value. Calculating a new seed value by calculating the value, and outputting the same as collation data; and a second arithmetic processing unit calculating the seed value when the open / close determination is successful. A second seed storage unit that holds the data as data, a second encryption processing unit that encrypts the collation data obtained by the second arithmetic processing unit and outputs a collation opening / closing code, and a second encryption unit. A verification unit configured to perform an open / close determination by comparing a check opening / closing code of a processing unit with the encrypted seed value received from the transmitter.

According to such a configuration, since a different encrypted seed value is transmitted from the transmitter each time, there is no need to worry about opening and closing the door from a transmission code once eavesdropped. In addition, since open / close determination is performed by predicting data transmitted by the receiver, a receiving circuit for synchronizing data with the transmitter and a transmitting circuit for synchronizing data with the receiver are not required.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a keyless entry system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a keyless entry system according to the present embodiment. The keyless entry system includes a transmitter 11, a receiver 12, and a door opening / closing control unit 13. Transmitter 11
Is a device for transmitting a door opening / closing code, and is provided, for example, inside a key. The transmitter 11 has a first
, A first transmission counter 112, a first encryption processing unit 113, and a transmission unit 114.

The seed storage unit 111 stores the transmitter 11
Is a storage unit that issues a seed value for each open / close signal (open / close code) based on a predetermined rule and stores the data. The transmission counter 112 is a counter that counts the number of times that the open / close code is transmitted from the transmitter 11 and stores the count value. The encryption processing unit 113 includes the seed storage unit 11
This is a processing unit that encrypts the seed value read from 1 and generates an encrypted seed value. The transmission unit 114 transmits the count value of the transmission counter 112 and the encrypted seed value as an opening / closing code.

The receiver 12 receives the opening / closing code transmitted from the transmitter 11, performs a determination process, and outputs a door locking or unlocking signal based on the determination result. As shown in FIG. 1, the receiver 12 includes a second transmission counter 121, a second seed storage unit 122, an arithmetic processing unit 123, a receiving unit 124, a second encryption processing unit 125, and a verification unit 125. .

The transmission counter 121 includes a transmitter 1
This counter counts the number of times the opening / closing code transmitted from 1 is transmitted, including the number of times the opening / closing code is successfully transmitted and the number of times the opening / closing code is not accepted, and stores the count value. The seed storage unit 122 is a storage unit that stores the seed value calculated by the calculation processing unit 123 based on the count value of the transmission counter 121. The arithmetic processing unit 123 includes the transmission counter 12
A new seed value is stored in the seed storage unit 1 based on the count value of
This is a processing unit that issues in the same series as 11 and generates the seed value as collation data. The receiving unit 124 is a circuit that receives the opening / closing code transmitted from the transmitter 11. The encryption processing unit 125 is a processing unit that performs encryption processing on the collation data (update seed value) generated by the arithmetic processing unit 123 and generates a collation opening / closing code. Verification unit 126
Is the collation opening / closing code generated by the encryption processing unit 125,
The collation with the received opening / closing code (encrypted seed value) is performed, and the collation result is notified to the arithmetic processing unit 123 and the door opening / closing control unit 13. The door opening / closing control unit 13 is a verification unit 12
A control unit that controls the opening and closing of the door based on the result of the comparison in step 6.

The operation of the keyless entry system configured as described above will be described. First, the transmitter 11 and the receiver 12 shown in FIG. 1 are a pair of devices, and the encryption processing unit 113 of the transmitter 11 and the encryption processing unit 125 of the receiver 12 perform the same encryption processing. As an example, if it is realized by a common key cryptosystem using a public algorithm such as DES cryptography, it is only necessary to set the same key value in a transmitter and a receiver that are paired with the same key after mass production of the device . In the setting stage, the seed storage unit 111 of the transmitter 11
And the seed storage unit 122 of the receiver 12 sets the same value as the initial seed value.

First, a user sets an open / close request with the transmitter 11. When the open / close request is set, the transmitter 11 updates the contents of the seed storage unit 111 and the transmission counter 112. Regarding the update method, the same update content is set between the transmitter 11 and the receiver 12 forming a pair. As an example of the updating method, there is a method of increasing the content of the data currently held, that is, the data of the seed storage unit 111 and the data of the transmission counter 112 one by one. Assuming that the count value of the transmission counter 112 is n and the seed value that is data in the seed storage unit 111 is f (n), the seed value f (n) preferably has a non-linear relationship with the count value n.

The seed storage unit 111 issues and holds a different seed value every time based on a predetermined algorithm, and supplies the updated seed value to the encryption processing unit 113. The encryption processing unit 113 encrypts the seed value f (n) according to a predetermined rule,
Generate an encrypted seed F (n). The transmitting unit 114 calculates the encrypted seed F (n) and the count n of the transmission counter 112.
Is transmitted to the receiver 12 as an open / close code.

Next, when the receiver 12 receives the transmitted opening / closing code, the arithmetic processing unit 123 updates the count based on the received count value of the transmission counter 112 and the count value stored in the transmission counter 121. Generate a value. Next, the arithmetic processing unit 123 calculates a new seed value using the obtained count update value, and outputs the result as collation data. The cryptographic processing unit 125 performs cryptographic processing on the input collation data and generates a collation opening / closing code. The verification unit 126 compares the generated collation opening / closing code with the received encrypted seed value. If the collation results are the same value, the verification unit 1
26 notifies the arithmetic processing unit 123 of the fact,
A control signal is sent to the door opening / closing control unit 13 to perform a locking operation when the door is unlocked, and perform an unlocking operation when the door is closed. Then, the arithmetic processing unit 123 causes the seed storage unit 122 to store the updated seed value.

The above operation will be described in further detail with reference to the flowcharts of FIGS. 2 and 3. First, FIG.
The transmission process in the transmitter 11 will be described with reference to FIG. At the start of transmission, in step S21, the data of the seed storage unit 111 and the transmission counter 112 are updated. In the present embodiment, the data value is increased by one. Specifically, if the previous count value of the transmission counter 112 is n, the count value is n + 1, and if the data in the seed storage unit 111 is f (n), the seed value is f
(N) +1 (= f (n + 1)). Next step S
At 22, the seed value f (n + 1) held in the seed storage unit 111 is encrypted, and the encrypted seed F (n + 1) is encrypted.
Generate In step S23, the generated encrypted seed F (n + 1) and the data of the number of transmissions (n + 1) held in the transmission counter 112 are transmitted as an open / close code.

Next, the receiving process in the receiver 12 will be described with reference to FIG. It is assumed that the receiving unit 124 has received the opening / closing code transmitted from the transmitter 11 in step S31. In the next step S32, the data (n + 1) of the transmission counter 112 of the transmitter 11 and the data n ′ (= n) of the transmission counter 121 of the receiver 12 are compared based on the received opening / closing code. If the devices are valid, the following relationship is established. The value of the transmission counter 112> the value of the transmission counter 121 If the above condition is satisfied, the process proceeds to step S33;
Judge that the data is invalid, and suspend or end the process.

In step S33, the next count update value is calculated from the transmitted data of the transmission counter 112 and the data of the transmission counter 121. Value of transmission counter 112-value of transmission counter 121 = count update value

In the next step S34, the seed value is updated using the calculated count update value to generate collation data. As the collation data, the seed value of the receiver 12 may be updated so as to correspond to the count value transmitted by the transmitter 11. The collation data is obtained by the following equation. Seed value stored in seed storage unit 122 + seed update value = collation data

In step S35, the obtained collation data is supplied to the encryption processing unit 125 to be encrypted. Then, the encrypted verification data is used as a verification opening / closing code.
In the next step S36, the verification unit 126 collates the encryption seed included in the opening / closing code transmitted from the transmitter 11 with the collation opening / closing code generated by the receiver 12. If the code is correct, the transmitter 11
The seed value and matching data sent from are the same,
Since the encryption processing is the same, the following relationship is established. If this condition is satisfied, the process proceeds to step S37, where the data is determined to be valid by the door opening / closing control unit 13, and the unlocking or locking operation of the lock is performed. Do. Here, each time a valid opening / closing code is received, the unlocking operation and the locking operation are alternately repeated. In addition, it notifies the arithmetic processing unit 123 of a signal indicating the successful opening and closing as a successful opening and closing signal. If the above conditions are not satisfied, it is determined that the data is invalid, and the processing is interrupted or terminated. In this case, the closed door cannot be opened.

In the next step S38, the arithmetic processing unit 123 predicts an open / close code to be used for the next transmission.
Updates the data of the transmission counter 121 and the data of the seed storage unit 122. That is, the data in the seed storage unit 122 is updated to the collation data f (n + 1), and the transmission counter 1 is updated.
The data of 21 is updated to the count value (n + 1) transmitted from the transmitter 11. If valid processing has been performed, the collation data should be the same as the seed value stored in the seed storage unit 111 of the transmitter 11. Therefore, the transmitter 11 and the receiver 12 have a common seed value f.

Here, the verification operation will be described in more detail. The receiver 12 estimates the seed value of the encrypted data transmitted from the transmitter 11 based on the seed value change rule and the valid collation data of the previous reception held in the seed storage unit 122. That is, by calculating the difference value from the data of the transmission counters of the transmitter 11 and the receiver 12, it is possible to determine the number of times the transmitter 11 has updated the seed value by counting from the time when the previous open / close determination was successful. .

Since the receiver 12 holds the collation data at the time of the previous successful open / close determination, that is, the seed value in the transmitter 11, the seed value is updated by the same number of times as the number of times that the transmitter 11 updates. If the updating is performed based on the desired regularity, the same value as the seed value transmitted from the transmitter 11 should be obtained on the receiver 12 side. However, except for legitimate data,
Since the seed value cannot be determined, the security of the communication is compensated.

Here, the security of communication will be further described. In the reception process, the transmission counter 112 of the transmitter counts the number of times that the opening / closing request has been transmitted. Further, the transmission counter 121 of the receiver holds at least the number of transmissions when the last valid open / close signal (successful open / close signal) is received. As long as the value of the transmission counter is set to up-count, between normal devices,
As described above, the following relationship always holds. If the value of the transmission counter 112> the value of the transmission counter 121 does not hold in step S32, the process is interrupted as invalid data. Therefore, even if the data transmitted last time is wiretapped and used, the condition of the transmission counter is not satisfied, and thus the data is not recognized as a valid code. In this case, when the driver having the proper key manually opens the door using the key, the transmission counter 121 of the receiver 12 counts down, and the current value of the transmission counter 121 is counted by the transmission counter 112. What is necessary is just to control so that it may correspond to a numerical value.

The seed value initially set in each seed storage unit at the time of manufacturing the device is unknown to the eavesdropper. In addition, since the seed value changes every time, the data obtained by encrypting the seed value changes every time and becomes unpredictable. Furthermore,
The transmitted data is encrypted, and the seed value itself held during communication is not transmitted. Therefore, it is impossible to decipher the seed values held by each other from the data used for communication. Therefore, it is difficult to guess the data to be used for opening and closing from the eavesdropped communication data, and the security at the time of communication is sufficiently ensured.

As described above, according to the keyless entry system of the present embodiment, since the seed value to be shared is estimated from the data of the transmission counter held by the transmitter 11 and the receiver 12, the code which changes every time is used. , Security can be enhanced, and one-way communication from the transmitter 11 to the receiver 12 can be realized. Further, even when the transmitted code is not directly received by the receiver 12 and only the seed value of the transmitter 11 is updated, the seed value is accurately predicted on the receiver 12 side. For this reason, opening / closing can be determined only by determining once whether or not the seed values are equal.

The method of updating the seed value in the present embodiment only needs to have a regularity capable of estimating the seed value from the updated value. Randomness may be provided using a table or the like. Further, stronger security can be realized by encrypting the seed value for each update or changing the update pattern.

In the above embodiment, each time a valid opening / closing code is received, the opening operation and the closing operation are alternately repeated. This assumes that the transmitter 11 is provided with one push button. The key may be provided with two pressing buttons, one of which is a lock button (locking), the other is an unlock button (unlocking), and the above unlocking operation may be performed only when the unlock button is pressed.

[0037]

As described above, according to the present invention, by encrypting a different seed value each time in the transmitter, the security of the transmitted code can be maintained. In addition, since the transmission counter of the receiver holds the number of transmissions when the last valid processing was performed, and the seed storage unit holds the seed value at that time, the data stored in the receiver and the open / close code are used. , The seed value to be transmitted next time can be predicted. In this case, the door can be unlocked and locked only by one-way communication from the transmitter to the receiver.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a keyless entry system according to an embodiment of the present invention.

FIG. 2 is a flowchart of a transmission process in the transmitter according to the present embodiment.

FIG. 3 is a flowchart of a receiving process in the receiver of the present embodiment.

FIG. 4 is a configuration diagram of a keyless entry system in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Transmitter 12 Receiver 13 Door opening / closing control part 111,122 Seed storage part 112,121 Transmission counter 113,125 Encryption processing part 114 Transmission part 123 Operation processing part 124 Receiving part 126 Verification part

Claims (2)

[Claims] 1. A keyless entry system that performs communication between a transmitter and a receiver and unlocks and locks a key by remote control, wherein the transmitter includes: a transmission counter that counts the number of times of opening and closing signals; A seed storage unit that updates a seed value every time a transmission is performed, and an encryption processing unit that encrypts a seed value held in the seed storage unit and outputs an encrypted seed value. Keyless entry system to do. 2. A keyless entry system that performs communication between a transmitter and a receiver and unlocks and locks a key by remote control, wherein the transmitter includes a first transmission counter that counts the number of times an open / close signal is transmitted, A first seed storage unit that updates a seed value each time the opening / closing signal is transmitted, and a first encryption process that encrypts a seed value held in the first seed storage unit and outputs an encrypted seed value A second transmission counter that holds at least a number of transmissions from the transmitter when the open / close determination is successful; a number of transmissions received from the transmitter and the second transmission counter. A count update value is obtained from a difference value from the number of transmissions held in the storage unit, and a seed value of the same series as the first seed storage unit is obtained from the count update value. Calculating a new seed value and outputting the same as collation data; and a second arithmetic processing unit that calculates the seed value when the open / close determination is successful as collation data. A second seed storage unit to hold; a second encryption processing unit that encrypts the collation data obtained by the second arithmetic processing unit and outputs a collation opening / closing code; and a second encryption processing unit. And a verification unit for performing an open / close determination by comparing the open / close code for verification with the encrypted seed value received from the transmitter.