KR100387141B1 - Transceiver system - Google Patents

Abstract

It is an object of the present invention to realize, with a simple configuration, a significant improvement in non-performance of a response signal from a responder.

In the transmission / reception unit 2 embedded in the key grip of the ignition key, the microcomputer 3 receives the question signal transmitted together with the random number data from the transmission / reception ECU on the automobile side through the resonance circuit unit EEPROM (4). The bit length of the identification code stored in < Desc / Clms Page number 5 > is changed by using the received random number data and a predetermined function, and the n channel FET 6a in the modulation circuit 6 is turned on in a mode corresponding to the identification code after the bit length change. By controlling the on / off, control is performed to return the encrypted response signal to the transmission / reception ECU.

Description

Transceiver system

(Technical field to which the invention belongs)

The present invention relates to a transmission / reception system for receiving a question signal and a response signal between the interrogator and the answering machine, and more particularly to a transmission / reception system for scrambling the response signal returned from the answering machine.

(Conventional technology)

For example, in an automobile, there is a function of adding an electronic key that uses an electrical identification code to an ignition key in order to improve the security performance against theft. In this case, it is common to embed a transmission / reception unit in the key grip of the ignition key, and the transmission / reception unit has a transponder function (responder) that returns a response signal including a pre-stored identification code when a power signal and a question signal are given from outside As a function).

In this case, a transmitting / receiving electronic control unit (ECU) serving as an interrogator is installed on the automobile side for the electronic key function, and the ignition ECU configured as described above is plugged into the key hole for starting the engine and turned ON. In the state operated in the position or ACC position, the power signal and the question signal are transmitted and the response signal is received from the transmitting / receiving unit on the ignition key side, and only when the identification code in the response signal matches a predetermined identification code. It is a configuration with an immobilizer function which allows the engine to be started by a key.

(Tasks to be solved by the invention)

The transponder function of the conventional transmission / reception unit is generally composed of hardware logic. For this reason, there is a problem that the identification code is usually fixed and its copying is relatively easy, and as a result, the security performance against car theft can not be sufficiently increased.

In order to cope with such a problem, conventionally, as shown in Japanese Patent Laid-Open No. Hei 7-184280, for example, a rolling code that sequentially changes the identification code every time a response signal is transmitted from the transmission / reception unit. It has been considered to employ a rolling code scheme to encrypt a response signal including an identification code. However, in such a means, since a response signal containing the same identification code periodically appears and there is a limit on the number of identification codes that are set, the response signal is decrypted by a third party and copied. In this case, there is a high possibility that the engine can be started by using the decryption response signal, and thus there is a problem that a sufficient improvement in security performance against theft of the vehicle cannot be achieved.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a transmission / reception system capable of realizing a significant improvement in non-fire performance with a simple configuration.

(Means to solve the task)

In order to achieve the above object, the transmission / reception system of the present invention, when receiving a question signal from an interrogator, transmits / receives a transponder having a responder that returns a response signal including an identification code stored in advance in response to the question signal to the interrogator. A system comprising: a function of transmitting random number data to the interrogator side together with the question signal, and calculation of the appropriateness of the received response signal based on the random number data and the identification code stored by the interrogator. A response including a function of changing a bit length of the storage identification code on the responder side based on the received random number data and a predetermined operation, and setting the identification function; It is the configuration which sets the function which returns a signal.

1 is an electrical configuration diagram of a transmission / reception unit showing a first embodiment of the present invention;

2 is a flowchart showing the control contents on the transmission / reception unit side;

3 is a functional block diagram showing the configuration of the entire system;

4 is a flowchart showing the control contents of the transmission / reception unit side as showing the second embodiment of the present invention;

5 is a flowchart showing the control contents of the transmission / reception unit side as showing the third embodiment of the present invention;

Fig. 6 is a flowchart showing the control contents of the transmission / reception unit side as showing the fourth embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: ignition key

2: transmitting and receiving unit (送 受 信)

3: micro-computer

4: EEPROM (Electrically-erasable programmable Read Only Memory)

6 modulation circuit 7 resonant circuit section

8: coil for transponder

9: resonant capacitor

10: transmit and receive ECU (Electronic Control Unit)

12 power supply circuit 13 detection circuit

15: ignition key cylinder

16 antenna coil 23 engine control ECU

According to this configuration, when the answering machine receives the question signal transmitted together with the random number data from the interrogator side, it changes the bit length of the previously stored identification code based on the random number data and the predetermined operation, Return the response signal containing the identification code. The interrogator receiving the response signal thus returned determines whether the response signal is appropriate or not based on the random number data transmitted as described above and an operation based on the identification code stored therein.

In this case, the determination of the acknowledgment of the received response signal on the interrogator side is made based on both the bit length of the identification code in the response signal and the contents of the identification code. In comparison, the deactivation performance of the response signal from the responder is greatly improved (claim 1).

In this case, the transponder encrypts the memory identification code with a predetermined encryption method, changes the received identification code based on the random number data and a predetermined operation received the bit length of the identification code after encryption, and changes the identification code after the change. It may be configured to return a response signal included. According to this configuration, since the encryption of the identification code is doubled, the secretion performance for the response signal from the answering machine is dramatically improved (claim 2).

The transponder is changed based on the random number data receiving the bit length of the storage identification code and the predetermined operation, and then the encrypted identification code is encrypted by a predetermined encryption method and a response signal including the encrypted identification code is returned. A configuration may be made. This configuration also doubles the encryption of the identification code, which greatly improves the performance of the secretion of the response signal from the answering machine (claim 3).

Embodiment of the Invention

A first embodiment to which the present invention is applied to an automobile load control system will be described below with reference to FIGS.

Fig. 1 shows the electrical configuration of the transmission / reception unit 2 (corresponding to the transponder according to the present invention) incorporated in the key grip of the ignition key of the automobile (denoted by reference numeral 1 in Fig. 3).

The transmission / reception unit 2 is configured around the microcomputer 3, and when a power signal and a question signal are received from the outside, a transponder function for returning a response signal as described later in response to the question signal is set. The specific structure thereof is described below.

That is, the microcomputer 3 has an internal structure in which the EEPROM 4, the resistor 5a for the Paeon reset circuit 5 described later, and the n channel FET 6a for the modulation circuit 6 described later are incorporated. In particular, the EEPROM 4 stores an identification code ΔB unique to the corresponding ignition key 1, and a functional formula g described later for changing the bit length of the identification code ΔB. , h is remembered.

In addition, the bit length of the said identification code (DELTA) B is set to a suitable value in the range of 40-48 bits, for example. The functional formulas (g, h) may be written in the program ROM (Read Only Memory) in the microcomputer 3.

The resonant circuit portion 7 is configured by connecting the transponder coil 8 and the resonant capacitor 9 in parallel between the signal line SL and the ground terminal, and the resonant frequency is transmitted / received on the vehicle side. It is set to be equal to the frequency band of the carrier signal transmitted from the ECU (denoted by 10 in FIG. 3).

The power supply circuit 12 connected to the signal line SL through the resistor 11 outputs the rectified and smoothed output of the carrier signal received by the resonant circuit unit 7 to the power supply terminal V of the microcomputer 3. _DD ), the rectifying diode 12a, the smoothing capacitor 12b, the constant voltage diode 12c, and the resistor 12d are connected and configured as shown.

The detection circuit 13 connected to the signal line SL through the resistor 11 determines the interrogation signal supplied with the carrier signal through the resonant circuit unit 7 to determine the input port PI of the microcomputer 3. ) Is configured as a filter circuit for connecting the detection diode 13a, the capacitor 13b, the resistor 13c and the resistor 13d as shown in the figure.

In this case, the time constant of the detection circuit 13 is set to a value sufficiently smaller than the charging time constant of the smoothing function portion by the power supply circuit 12, so that the discrimination of the question signal It is possible.

The modulation circuit 6 including the n-channel FET 6a is in parallel with the resonant capacitor 9 of the resonant circuit unit 7, and the source / drain of the modulation capacitor 6b and the n-channel FET 6a. The direct connection circuit is connected to each other, and the impedance of the resonant circuit portion 7 can be changed in accordance with the ON / OFF state of the n-channel FET 6a.

The reset circuit 5 has a period until the voltage level (output voltage level of the power supply circuit 12) supplied to the power supply terminal V _DD of the microcomputer 3 rises above a predetermined level. For the power-on reset function for keeping the microcomputer 3 in a reset state, the diode 5b, the capacitor 5c and the resistor 5a are connected as shown. Configure. In addition, an oscillation circuit 14 composed of a resistor 14a and a capacitor 14b is provided to determine the clock frequency of the microcomputer 3.

The function of the transmission / reception unit 2 configured as described above will be described together with the control contents by the microcomputer 3.

That is, when receiving the question signal including the carrier signal (power signal) transmitted from the transmitting and receiving ECU 10 side and the predetermined random number data ΔA through the resonance circuit unit 7, the carrier wave received by the power supply circuit 12 The reset holding state is reset by the reset circuit 5 when the signal is rectified / smooth output is supplied to the power supply terminal V _DD of the microcomputer 3 and its output voltage rises above a predetermined level. The microcomputer 3 is converted into an active state. Further, the question signal received by the detection circuit 13 is discriminated and supplied to the input port PI of the microcomputer 3.

The microcomputer 3 in the active state reads the identification code ΔB stored in the EEPROM 4 in response to the question signal being supplied through the detection circuit 13, and the bit length thereof will be described later. By operating the modulating circuit 6, the modulator 6 functions as a transponder for transmitting (replying) an encrypted response signal including the modified identification code ΔB 'through the resonant circuit section 7 as follows. The control contents will be described with reference to the flowchart of FIG.

That is, when the microcomputer 3 receives the question signal including the random number data ΔA (S1 to YES), the microcomputer 3 reads the identification code ΔB and the function equations g and h from the EEPROM 4 (S2), Subsequently, in S3 to S5, the bit length of the identification code ΔB is changed based on the functional formulas g and h and the received random number data ΔA, and the operation is performed to obtain the identification code ΔB '. It goes without saying that in the configuration in which (g, h) is stored in the program ROM, reading of the above functions (g, h) is unnecessary.

In this case, the function equation (g) indicates that the first bit (LSB; Least Significant Bit) of the identification code (ΔB ') after the bit length is changed is the number of bits of the identification code (ΔB) before the change (hereinafter referred to as X-th bit). In S3, a function operation in which both the random number data ΔA and the identification code ΔB are variables or a function operation in which only the random number data ΔA is a variable The value of X is calculated by In other words,

X = g (ΔA, ΔB) or

X = g (ΔA)

The function formula (h) indicates that the last bit (MSB; Most Significant Bit) of the identification code (ΔB ') after the bit length change is referred to as the Yth bit (hereinafter, referred to as the Yth bit) of the identification code (ΔB) before the change. In S4, the value of Y is calculated by a function operation using both random number data ΔA and an identification code ΔB as a variable or a function operation using only random data ΔA as a variable. do. In other words,

Y = h (ΔA, ΔB) or

V = h (ΔA)

In S5, (AXY) from the X th bit to the Y th bit of the identification code ΔB is extracted based on the values of X and Y calculated as described above, and the (AXY) is the identification code after the bit length is changed. Let (ΔB ') be.

After obtaining the identification code ΔB 'in this manner, the microcomputer 3 operates to transmit a response signal including the identification code ΔB' (S6), and then returns to S1.

Specifically, in S6, the carrier wave received by changing the impedance of the resonant circuit section 7 by turning on / off the n channel FET 6a in the modulation circuit 6 in a mode corresponding to the identification code ΔB '. Amplitude modulation of the signal in a mode corresponding to the identification code ΔB ', which transmits and receives an impedance change state of the resonant circuit portion 7 by the modulation circuit 6 to the transmitting and receiving ECU 10 side. The response signal (including the identification code ΔB ') encrypted by the detection is returned to the transmission / reception ECU 10 side.

3, the structure of the whole system is shown typically by the combination of functional blocks. In FIG. 3, the antenna coil 16 is provided around the ignition key cylinder 15 for a vehicle. In the state where the ignition key 1 is inserted into the ignition key cylinder 15, the antenna coil 16 and The transponder coil 8 (refer to FIG. 1) incorporated in the ignition key 1 is configured to be electromagnetically coupled.

The transmission / reception ECU 10 provided on the automobile side corresponds to the interrogator in the present invention, and is configured around the microcomputer 17. The microcomputer 17 corresponds to the ignition key cylinder 15. The on signal from the IG switch 18 and the key mind switch 19 of the well-known structure provided are input through the switch interface 20. As shown in FIG. In this case, the microcomputer 17 has a configuration in which a reception signal by the antenna coil 16 is input through the reception circuit 21.

The microcomputer 17 is configured to control transmission through the antenna coil 16 by the output of the power amplifier 22, and the details of the control will be described later. In addition, the microcomputer 17 is configured to receive a signal between the engine control ECU 23 and the serial interface 24, and the engine starts by the engine control ECU 23 as described later. An immobilizer function is set that can selectively inhibit operation.

In addition, the microcomputer 17 is configured to receive data between the EEPROM 25 and the random number data ΔA generated each time a new question signal is transmitted to the transmission / reception unit 2 side. ) Is sequentially updated and recorded, and the same identification as the identification code (ΔB) stored in the EEPROM (4) on the side of the ignition key 1 prepared for the vehicle and the function expressions (g, h) for changing the bit length, respectively. The code ΔB and the functional formulas g and h are stored in advance. The functional formulas (g, h) may be configured to be written in the program ROM in the microcomputer 17.

Hereinafter, the control contents of the microcomputer 17 of the transmission / reception ECU 10 will be described together with the operation of the relevant parts.

That is, when the microcomputer 17 receives the ON signal from the key mind switch 19 and the IG switch 18, that is, the ignition key 1 is inserted into the ignition key cylinder 15 and operated in the on position. At this time (in this state, the antenna coil 16 and the transponder coil 8 on the side of the ignition key 1 are electromagnetically coupled), and the new random number data ΔA is generated by a predetermined random number generation calculation. ), The random number data ΔA is stored in the EEPROM 25, while a pulse train shape question signal including the random number data ΔA is generated, and the power amplifier 22 is generated. By operating, the antenna coil 16 transmits a question signal including a carrier signal of a predetermined frequency and the random number data ΔA in a state of being superimposed thereon.

In this way, the carrier signal and the question signal are transmitted to the transmission / reception unit 2 (see FIG. 1) side of the ignition key 1 through the antenna coil 16. In the transmission / reception unit 2, as described above, The microcomputer 3 is converted into an active state by the carrier signal and accordingly the function using the random number data ΔA in the question signal, the identification code ΔB stored in the EEPROM 4 and the function equations g and h The transponder function of obtaining the identification code? B 'whose bit length is changed by the operation and returning an encrypted response signal including the identification code? B' is exhibited.

The microcomputer 17 operates similarly to the microcomputer 3 on the transmission / reception unit 2 side based on the random number data ΔA, the identification code ΔB, and the function equations g and h read from the EEPROM 25. (Corresponding to the calculation of S3 to S5 shown in Fig. 2), the identification code? B 'is obtained, and the identification code included in the identification code? B' and the response signal returned from the transmission / reception unit 2 side ( A decode operation for comparing [Delta] B ') is performed to prevent starting of the vehicle engine by the engine control ECU 23 when the two do not match, that is, when the received response signal is not appropriate. Of course, in the configuration in which the functional formulas (g, h) are stored in the program ROM, the reading (reading) of the functional formulas (g, h) is of course unnecessary.

Therefore, when the IG switch 18 is turned on by the inadequate ignition key 1 in which the identification codes do not match, the engine for the vehicle is not started and the security against theft is improved.

On the other hand, when the identification code ΔB 'obtained by the operation of decoding is identical to the identification code ΔB' included in the response signal returned from the transmission / reception unit 2 side, that is, the received response signal is appropriate. In this case, starting of the engine for automobiles by the engine control ECU 23 is permitted.

Therefore, when the appropriate ignition key 1 is inserted into the ignition key cylinder 15 in which the appropriate ignition key ΔB 'coincides with the generated bit length change based on the identification code ΔB or the like, the vehicle is controlled by the engine control ECU 23. Since the engine is allowed to be started, it is configured to exhibit an immobilizer function as described above.

That is, the structure of this embodiment mentioned above has the effect demonstrated below.

In the transmission / reception unit 2, the response signal for the question signal transmitted from the transmission / reception ECU 10 is returned in an encrypted state. Therefore, the security performance against theft of the vehicle is improved according to the non-performance. In particular, in this case, the transmission / reception unit 2 changes the bit length of the identification code ΔB previously stored using random number data ΔA included in the question signal and predetermined function equations g and h. Since the encrypted response signal including the identification code ΔB 'after the change is returned, the encryption of the response signal can be realized with a simple configuration.

Further, the determination of whether the received response signal is performed on the transmitting and receiving ECU 10 side is made based on both the bit length of the identification code ΔB 'and the contents of the identification code ΔB' of the response signal. Compared with the conventional method of rolling the identification code sequentially, the deactivation performance for the response signal returned from the transmission / reception unit 2 is greatly improved.

4 shows a second embodiment of the present invention which exhibits the same effects as the first embodiment. Only parts different from those of the first embodiment will be described below.

That is, in the second embodiment, the content of the bit length change control of the identification code ΔB by the microcomputer 3 on the transmission / reception unit 2 side is different from that in the first embodiment. Is shown.

In FIG. 4, when the microcomputer 3 receives the question signal including the random number data ΔA (Y1 to S1), the microcomputer 3 reads the identification code ΔB and the function equation (i) from the EEPROM 4 (S2 '). In S3 'and S5' thereafter, the bit length of the identification code ΔB is changed based on the function formula i and the received random number data ΔA, and an operation for obtaining the identification code ΔB 'is performed. do.

In this case, the function formula (i) is for calculating the bit length Z of the identification code ΔB 'after the bit length is changed. In S3', both the random number data ΔA and the identification code ΔB are used as variables. The value of the bit length Z is calculated by a function operation having only a function operation or random number data ΔA as a variable. In other words,

Z = i (ΔA, ΔB) or

Z = i (ΔA)

In S5 ', the code A _1Z from the first bit LSB of the identification code ΔB to the Zth bit is extracted based on the value of the bit length Z calculated as described above, and the code A _1Z ) is obtained as an identification code ΔB 'after the bit length is changed.

In this case, the identification code? B 'may be obtained by extracting up to the Z-th bit from the MSB of the identification code? B toward the lower bit.

After the microcomputer 3 obtains the identification code? B 'in this manner, the microcomputer 3 operates to transmit a response signal including the identification code? B' (S6), and then returns to S1.

5 shows a third embodiment of the present invention in which the configuration of the first embodiment is changed. Only parts different from those of the first embodiment will be described below.

In other words, the third embodiment encrypts the identification code? B by a predetermined encryption method in the previous step of the bit length change control of the identification code? B by the microcomputer 3 on the transmission / reception unit 2 side. A characteristic feature is that the bit length change control is performed on the following identification code, and the control content is shown in the flowchart of FIG.

In Fig. 5, when the microcomputer 3 receives a question signal containing random number data ΔA (Yes from R1), the microcomputer 3 receives the identification code ΔB and the function expressions (f, g, h) from the EEPROM 4; After reading (R2), the bit length of the identification code (ΔB) in R3 to R6 thereafter is changed based on the function expressions (f, g, h) and the received random number data (ΔA), and the identification code (ΔB '). Calculate to find

In this case, the function (f) is for encrypting the identification code (ΔB). For example, it is also possible to employ a conventional rolling code method as the function (f). In the present embodiment, an encryption code having a predetermined bit length (for example, 40 to 48 bits) is obtained by converting the identification code (ΔB) into a cryptographic ring by a function operation in which both the random data (ΔA) and the identification code (ΔB) are variables in R3. Calculate (A _max ). In other words,

A _max = f (ΔA, ΔB)

The function equation (g) is for calculating whether the initial bit LSB of the identification code ΔB 'after the bit length change corresponds to the bit of the encryption code A _max and the bit of the X (bit X). The value of X is calculated at R4 by a function operation using both the random number data ΔA and the identification code ΔB as a variable or a function operation using only the random number data ΔA as a variable. In other words,

X = g (ΔA, ΔB) or

X = g (ΔA)

The function (h) is for calculating whether the last bit MSB of the identification code ΔB 'after the bit length change corresponds to the bit (Y-th bit) of the encryption code A _max and In R5, the value of Y is calculated by a function operation using both the random number data ΔA and the identification code ΔB as a variable or a function operation using only the random number data ΔA as a variable. In other words,

Y = h (ΔA, ΔB) or

V = h (ΔA)

In R6, the code A _XY is extracted from the X th bit to the Y th bit of the encryption code Amax based on the values of X and Y calculated as described above, and the code A _XY is the bit length. Obtained as the identification code ΔB 'after the change.

After the microcomputer 3 obtains the identification code ΔB 'in this manner, the microcomputer 3 operates to transmit a response signal including the identification code ΔB' (R7), and then returns to S1.

Therefore, in this embodiment configured as described above, the same effect as in the first embodiment is obtained, and in particular, according to the present embodiment, since the identification code ΔB 'included in the response signal is encrypted twice, the response from the transmission / reception unit 2 is obtained. The sparking performance with respect to a signal is remarkably improved.

Fig. 6 shows a fourth embodiment of the invention which has the same effect as the third embodiment. In the following, only portions different from those in the third embodiment will be described.

In other words, in the fourth embodiment, the content of the bit length change control of the identification code? B by the microcomputer 3 on the side of the transmission / reception unit 2 is different from the transmission / reception system. Is shown.

In Fig. 6, when the microcomputer 3 receives a question signal containing random number data ΔA (Yes in R1), the microcomputer 3 reads the identification code ΔB and the function equations (f, i) from the EEPROM 4 ( R2 ') and subsequent bit lengths of the identification code ΔB in R3, R4' and R6 'are changed based on the function formula f and i and the received random number data ΔA and the identification code ΔB'. Calculate to find It goes without saying that in the configuration in which the function expressions (f, i) are stored in the program ROM, the reading (reading) of the function expressions (f, i) as described above is unnecessary.

In this case, the function equation (f) is for encrypting the identification code ΔB as in the third embodiment. An encryption code Amax of a predetermined bit length (for example, 40 to 48 bits) encrypted with ΔB) is calculated. In other words,

The function formula (i) is for calculating the bit length Z of the identification code ΔB 'after the bit length is changed, and in R4', a function operation using both the random number data ΔA and the identification code ΔB as variables. Alternatively, the value of the bit length Z is calculated by a function operation having only random data ΔA as a variable. In other words,

Z = i (ΔA, ΔB) or

Z = i (ΔA)

In R6 ', the code A _1Z from the first bit LSB of the encryption code Amax to the Z-th bit is extracted based on the value of the bit length Z calculated as described above. (A _1Z ) is obtained as the identification code ΔB 'after the bit length change. In this case, the identification code? B 'may be obtained by extracting the Z-th bit from the MSB of the encryption code A _max toward the lower bit.

After the microcomputer 3 obtains the identification code ΔB 'in this manner, the microcomputer 3 operates to transmit a response signal including the identification code ΔB' (R7), and then returns to S1.

In addition, this invention is not limited to an Example mentioned above, The expansion or a deformation | transformation which are demonstrated below are possible.

In each embodiment of the third and fourth embodiments, the bit length of the encryption code A _max is changed after encrypting the identification code ΔB using the function f in the transmission / reception unit 2 side. However, the configuration may be such that after changing the bit length of the identification code (DELTA) B, the identification code after the change is encrypted using the function (f).

The decoding operation on the transmission / reception ECU 70 side is performed by the microcomputer 3 on the transmission / reception unit 2 side based on the random number data ΔA, the identification code ΔB and the function equations g and h stored in the EEPROM 25. The identification code ΔB 'is calculated by performing the same operation as described above, and the identification code ΔB' is compared with the identification code ΔB 'included in the response signal returned from the transmission / reception unit 2 side. And calculating the identification code ΔB from the identification code ΔB ′ included in the response signal, and performing the decoding operation by comparing the operation result with the random number data ΔA stored in the EEPROM 25. Various decode operations are possible, such as a configuration. Although a transmission / reception unit 2 having a transponder function for returning a response signal in response to a power signal (carrier signal) and a question signal has been exemplified, it may be applied to a general transmission / reception unit having a separate power source. The encryption method of the response signal is not limited to the above embodiment.

According to the present invention, as apparent from the above description, when the answering machine is provided with a response device for returning a response signal including an identification code stored in advance in response to the question signal from the interrogator, By changing the bit length using the received random number data and a predetermined function, and returning a response signal including the identification code after the change, a significant improvement in the deactivation performance of the response signal can be realized. It can have a beneficial effect.

Claims (3)

A transmitting / receiving system having a transponder for returning a response signal including an identification code stored in advance in response to the interrogation signal to the interrogator when the interrogation signal from the interrogator is received, A function of transmitting random number data together with the question signal to the interrogator side and a function of determining whether or not the received response signal is arithmetic based on the random number data and the identification code stored therein; and, And a function of changing the bit length of the storage identification code based on the received random number data and a predetermined operation, and returning a response signal including the identification code after the change to the answering machine side. Transceiver system. The method of claim 1, The answering machine encrypts the storage identification code by a predetermined encryption method, changes the bit length of the identification code after the encryption based on the received random number data and a predetermined operation, and includes a response including the identification code after the change. Transmitting and receiving system, characterized in that the configuration for returning a signal. The method of claim 1, The responder changes the bit length of the storage identification code based on the received random number data and a predetermined operation, and then encrypts the changed identification code by a predetermined encryption method and outputs a response signal including the encrypted identification code. Transmitting and receiving system, characterized in that the configuration to return.