JP3015680U - Cordless telephone with anti-theft function - Google Patents

Abstract

(57) [Summary] [Purpose] An identification code that identifies each other between a parent device and a child device of a cordless telephone prior to a call can be randomly set every time the child device is on-hook to the parent device. Provided is a cordless telephone having an anti-theft function that makes it difficult to analyze the identification code and prevents the external line of the parent device from being stolen. [Configuration] Each time the slave unit is on-hook by the master unit, a random number for the ID code used at the next off-hook and a random number for the decryption key for decrypting the encrypted ID code transferred from the slave unit are provided. The acquired data is stored in the buffer (S21 to S24). After that, when going off-hook, the encrypted ID code is transmitted from the slave unit, and the master unit decrypts it using the decryption key and confirms the ID code.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cordless telephone that is composed of a base unit and a handset that communicate wirelessly, and in particular, an external code of the base unit is obtained by decoding an identification code for identifying each other before communication, by a device other than the handset. The present invention relates to a cordless telephone having an anti-theft function that prevents the stolen mobile phone from being stolen.

[0002]

[Prior art]

 Conventionally, in cordless telephones, an identification code (ID code) for identifying each other is communicated between the base unit and the handset prior to communication, and the identification code of the base unit and the handset match. After confirming, the communication channel is established. This prevents the external line of the parent device from being stolen by devices other than the child device.

[0003]

[Problems to be solved by the device]

 However, in the conventional cordless telephone as described above, the identification code is set when the power is first turned on, and thereafter, unless the power is turned off, the fixed identification code set when the power is turned on is used. If the device is left off-hook, the identification code is identified by analyzing the radio frequency between the master and slave, and the external line connected to the master is easily stolen by a device other than the slave. There is such a problem. In addition, even if the identification code is encrypted (scrambled) before being sent, the fixed identification code is scrambled to the fixed encryption, so the problem that the identification code can be easily identified is the same as above. is there. The present invention has been made to solve the above-mentioned problems, and makes it possible to randomly set the identification code with a simple configuration, making the identification code difficult to analyze and connecting it to the master unit. It is an object of the present invention to provide a cordless telephone having an anti-theft function that can reliably prevent the stolen external line from being stolen.

[0004]

[Means for Solving the Problems]

 In order to achieve the above object, the cordless telephone having the anti-theft function of the invention of claim 1 comprises a master unit connected to an external line and a slave unit wirelessly communicating with the master unit. , By communicating an identification code for identifying each other prior to communication between the base unit and the handset, and establishing a communication channel when the identification codes match each other. A cordless telephone having an anti-theft function that prevents the external line of the base unit from being stolen from the device, and an on-hook determination means for determining that the handset is on-hook by the base unit and an on-hook by the on-hook determination means. And an identification code setting means for receiving the determination signal and setting a new identification code. Further, in the cordless telephone having the anti-theft function of the invention of claim 2, in the configuration of claim 1, the identification code setting means includes a random number generator for generating a random number, and the identification code setting means It uses a random number to set a new identification code. Also, in the cordless telephone having the anti-theft function of the invention of claim 3, in the configuration of claim 1 or 2, the identification code transmitted from the slave unit or the master unit is generated by a random number generator. It is scrambled using the obtained random number, and the master unit or the slave unit that receives the scrambled identification code signal decrypts the signal using the decryption key, and the decryption key is set using the random number. It is what

[0005]

[Action]

 In the cordless telephone having the anti-theft function according to claim 1 having the above-mentioned structure, the identification code setting means receives a new identification code from the on-hook determination means when the child machine is on-hooked by the parent machine. Set. This new identification code is wirelessly communicated between the master unit and the slave unit, a communication channel is established when the identification codes match, and communication is performed from the slave unit through an external line connected to the master unit. When the communication is completed and the slave unit is on-hook with the master unit, the following new identification code is set. Therefore, at the time of the next off-hook, the master unit and the slave unit can be specified by the new identification code set at the time of the previous on-hook. Therefore, it is almost impossible to analyze the identification code for the purpose of plagiarism.

In the cordless telephone having the anti-theft function according to claim 2, when the handset is hooked on the base unit, the identification code setting means randomly generates a new identification code by using the random number from the random number generator. Set.

Further, in the cordless telephone having the anti-theft function according to claim 3, the identification code transmitted from the slave unit (or the master unit) is scrambled by using the random number obtained by the random number generator, and the scramble is performed. The master unit (or slave unit) receiving the generated identification code signal descrambles the identification code using the above random number as a decryption key. The random number generated by the random number generator each time the slave is on-hook by the master is a random value, and the identification code communicated between the master and slave is scrambled using this random number. As a result, the identification code is rarely analyzed for wire theft.

[0008]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a base unit and a handset of a cordless telephone having a theft prevention function. In the cordless telephone according to the present embodiment, an example is shown in which only one slave unit 2 corresponds to the master unit 1, and the master unit 1 sets a new identification code (ID code) when on-hook and the slave unit. 2, the slave unit 2 inquires of the master unit 1 about the ID code when it is off-hook, and the master unit 1 confirms the ID code in response to this inquiry. The base unit 1 stores an NCU 4 (network control unit) that controls connection with an external line 3, a transmission / reception circuit 5 including a synthesizer for transmitting / receiving signals to / from the handset unit 2, and a system program of the base unit 1. ROM 6 stored therein, RAM 7 for storing ID code and the like, CPU 8 for controlling them as a whole, a new ID code is set for each on-hook, and an encryption key for encrypting the same and an encrypted ID code are decrypted. Random number generator 8a such as a counter for setting a decryption key, an on-hook / off-hook detector 9 for detecting that the slave unit 2 is on-hook by the master unit 1, and a signal sending / receiving unit And the antenna 10 of.

In the ROM 6 of the base unit 1, an ID code / decoding for acquiring a decryption key for acquiring a new ID code and for decrypting the encrypted ID code transmitted from the slave unit 2. The key acquisition program 6a, the decryption program 6b for decrypting the encrypted ID code transmitted from the slave unit 2 using the decryption key, the decrypted ID code from the slave unit 2 and the master unit 1 An ID code confirmation program 6c for collating and confirming with the registered ID code is stored.

The RAM 7 also stores an ID code storage buffer 7a for storing an ID code verified by the ID code confirmation program 6c and a decryption key acquired by the ID code / decryption key acquisition program 6a. The decryption key storage buffer 7b and the encrypted ID code storage buffer 7c for storing the encrypted ID code transmitted from the handset 2 have an area for the buffer 7c, and the areas for the buffers 7a and 7b are newly set code keys. , And an old buffer in which the previously used code key is stored.

On the other hand, the handset 2 has a key input unit 11 for various inputs such as dial keys, a transmitter / receiver circuit 15 including a synthesizer for transmitting / receiving signals to / from the base unit 1, and a system program for the handset 2. Is provided with a ROM 16 in which is stored, a RAM 17 for storing an ID code and the like, a CPU 18 for controlling them as a whole, and an antenna 19 for transmitting and receiving signals.

A code generation program for encrypting the ID code using the ID code transferred from the base unit 1 and the decryption key (this is called an encryption key in the handset 2) is stored in the ROM 16 of the handset 2. 16a is stored. In addition, the RAM 17 of the child device 2 includes an ID code storage buffer 17a that stores the ID code transferred from the parent device 1, an encryption key storage buffer 17b that stores the encryption key transferred from the parent device 1, and an encryption key. It has an area of an encrypted ID code storage buffer 17c for storing the ID code encrypted by the generation program 16a, and areas of the buffers 17a and 17b have a temporary buffer and an old buffer.

Next, the operation of the cordless telephone configured as described above will be described with reference to FIG. FIG. 2 is a flow chart showing an operation procedure of the base unit 1 of the cordless telephone. In FIG. 2, the CPU 8 of the base unit 1 determines whether or not the handset 2 is on-hook from the off-hook state by the on-hook / off-hook detector 9 (S 1), and if it is on-hook (S 1 YES), the ID code. And a decryption key acquisition process is executed (S2). This acquisition processing is performed by the ID code / decryption key acquisition program 6a in the ROM 6. The processing procedure is shown in FIG. The CPU 8 acquires a random number for the ID code from the random number generator 8a (S21), and stores it as a new ID code in the temporary buffer of the ID code storage buffer 7a of the RAM 7 (S22).

Next, the CPU 8 acquires a random number for a decryption key for decrypting the encrypted ID code transmitted from the slave unit 2 from the random number generator 8a (S23). This random number for decryption key is stored in the temporary buffer of the decryption key storage buffer 7b of the RAM 7 as a new decryption key (S24). The new ID code acquired in S21 and the new decryption key acquired in S23 are transferred to the handset 2 (S25), and the transferred new ID code is the temporary buffer of the ID code storage buffer 17a of the handset 2. The new decryption key stored and stored in is stored in the temporary buffer of the encryption key storage buffer 17b as an encryption key. Then, in the master device 2, the ID code and the decryption key stored in each temporary buffer of the ID code storage buffer 7a and the decryption key storage buffer 7b are made valid, and the data of the old buffer used last time is made invalid. (S25). It should be noted that the decryption key and the encryption key in the handset 2 have the same code.

It takes about 100 ms to complete the processing of the subroutine shown in FIG. 3. Therefore, if the processing is off-hook before the completion of the processing, on-hook detection is interrupted. , The above process is not completed. Therefore, when the subroutine processing of FIG. 3 is completed, although not shown, a bit indicating the effective status is set at the head address of the temporary buffer, and this status is set in the determination of S4 of FIG. 2 described later. By checking, it is decided whether or not to set a new ID code / decryption key.

Returning to the flowchart of FIG. 2, the description will be continued. The CPU 8 of the main unit 1 determines whether or not it is sequentially off-hooked (S3), and when it is off-hooked (S3YES), a new ID code / decryption key is obtained by checking the above-mentioned valid status. It is determined (S4). If a new ID code / decryption key has been acquired (S4 YES), the new ID code / decryption key is set as the code and key to be used for the off-hook this time (S5). If a new ID code / decryption key has not been acquired (S4 NO), the new ID code / decryption key acquired in S2 is discarded, and the previous ID code / decryption key is the code and key used during this off-hook operation, respectively. (S6).

After off-hook, the CPU 18 of the child device 2 encrypts (scrambles) the ID code by using the encryption key by the encryption generation program 16a. This encryption is performed by, for example, encrypting the ID code by an exclusive OR operation of the ID code and the encryption key (hereinafter, referred to as Ex-OR operation) as shown in FIG. Scramble to machine 1. The CPU 8 of the parent device 1 determines whether or not the encrypted ID code from the child device 2 is received after the off-hook (S7), and when it is received (S7 YES), the received signal is used by the decryption program 6b as the decryption key. And decode it (S8). In this decryption processing, for example, an ID code is obtained by an Ex-OR operation of a scrambled ID code and a decryption key as shown in FIG. 4 (b). Thereafter, the ID code confirmation program 6c is used to determine whether or not the decrypted ID code is the same as that stored in the ID code storage buffer 7a of the RAM 7 of the parent device 1 (S9). If so (YES in S9), it is determined that the handset 2 is correct, the call channel is established (S10), and the call is enabled (S11). An available channel is appropriately selected as the call channel.

In S9, if the ID code transmitted from the handset 2 is different from the ID code stored in the base unit 1 or is not transmitted correctly (NO in S9), the call channel is cut off (S12). , The process ends. Incidentally, when the communication is completed and the hook is put on again, the ID code and the decryption key (encryption key) are stored in the old buffers of the ID code storage buffer 7a and the decryption key storage buffer 7b, respectively.

As described above, according to the cordless telephone having the theft prevention function of the present embodiment, when it is determined that the handset 2 is on-hook by the base unit 1 based on the signal from the on-hook / off-hook detector 9, the CPU 8 Uses the random number generator 8a based on the ID code / decryption key acquisition program 6a to obtain and set the ID code and decryption key to be used at the next off-hook, and transfer them to the handset 2 However, at the time of off-hook, the ID code is encrypted in the handset 2 using the encryption key, and the ID code is inquired prior to the communication with the base unit 1. The ID code set when the power is turned on is not used as it is. Therefore, even if the cordless handset 2 is in the off-hook state, the cordless handset It is difficult for the ID code to be identified by the analysis of the radio frequency between them, and the external line 3 connected to the master device 1 is not stolen by a device other than the slave device 2. Moreover, since the decryption key (encryption key) is also changed during on-hook, scrambling is performed reliably, and it becomes difficult to identify the ID code as in the above case.

Further, the ID code transmitted from the slave unit 1 is scrambled by using the encryption key, and the master unit 1 receiving the transmission signal of the scrambled ID code is used to descramble the ID code. Since the encryption key is used as the decryption key, it is not necessary to individually set the scrambling key number, and the process of setting the ID code encryption key and the decryption key can be simplified.

The present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, in the configuration of the master unit 1 and the slave unit 2, the master unit 1 determines an ID code and the like when it is on-hook and transfers it to the slave unit 2, and when the off-hook, the slave unit 2 sends an ID to the master unit 1. A code inquiry is made, and the master unit 1 confirms the ID code in response to this query. However, both the master unit 1 and the slave unit 2 can set the ID code, and either can make an inquiry. You may do it. Further, although the example in which the ID code is encrypted by performing the Ex-OR operation with the encryption key has been described above, the present invention is not limited to this, and various operations may be used. Further, although the cordless telephone has shown the example in which only one child device 2 corresponds to the parent device 1, it is not limited to this, and may be applied to a cordless telephone in which the child device can be added. Further, the number of times of confirming the correct ID code (connection or rejection) may be determined not only once but also multiple times.

[0022]

[Effect of device]

 As described above, according to the cordless telephone having the anti-theft function of the invention of claim 1, the master unit and the slave unit confirm the identification code for identifying each other prior to the communication. The identification code setting means sets the setting every time the slave unit is on-hook with the master unit.Therefore, when the off-hook, the new identification code is used to identify the master unit and the slave unit. It is difficult for devices other than the slave unit paired with the master unit to analyze, and it is possible to prevent an external line connected to the master unit from being stolen by devices other than the slave unit.

According to the cordless telephone having the anti-theft function according to the invention of claim 2, the identification code setting means includes a random number generator for generating a random number, and when the slave unit is on-hook with the master unit, Since the new identification code is set using the random number of the random number generator, the identification code can be changed with a simple configuration.

Further, according to the cordless telephone having the anti-theft function of the invention of claim 3, the identification code for identifying the slave unit and the master unit is a random number generated by the random number generator each time it is on-hook. The master unit or the slave unit that has been scrambled by using the received scrambled identification code transmission signal uses the above random number as a decryption key to descramble the identification code, so the identification number is analyzed. This makes it possible to prevent the circuit from being stolen, and to simplify the process of setting these numbers without the need to separately set a random number for scrambling and a decryption key. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a master unit and a slave unit of a cordless telephone having an anti-theft function according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a communication procedure of a master unit of the cordless telephone.

FIG. 3 is a flowchart showing a procedure for acquiring an ID code and a decryption key in the master unit of the cordless telephone.

FIG. 4 (a) is a diagram showing an example of encryption calculation in a child device of the cordless telephone, and FIG. 4 (b) is a diagram showing an example of decryption operation in a parent device.

[Explanation of symbols]

1 Master Unit 2 Slave Unit 3 External Line 6a ID Code / Decryption Key Acquisition Program (Identification Code Setting Means) 6b Decryption Program 6c ID Code Confirmation Program 7a ID Code Storage Buffer 7b Decryption Key Storage Buffer 8 CPU 8a Random Number Generator 9 On-hook Off-hook detector (on-hook determination means) 16a encryption generation program 17a ID code storage buffer 17b encryption key storage buffer 18 CPU

Claims (3)

[Scope of utility model registration request] 1. A master unit connected to an external line, and a slave unit wirelessly communicating with the master unit. The master unit and the slave unit identify each other prior to communication. By communicating the identification code to establish a communication channel when the identification codes match, there is a theft prevention function that prevents the external line of the parent device from being stolen from devices other than the child device. In the cordless telephone set, an on-hook determination unit that determines that the slave unit is on-hook with the master unit, and an identification code setting unit that receives a determination signal of on-hook by the on-hook determination unit and sets a new identification code are provided. A cordless telephone with an anti-theft function. 2. The plagiarism according to claim 1, wherein the identification code setting means includes a random number generator for generating a random number, and a new identification code is set by using the random number from the random number generator. Cordless telephone with a prevention function. 3. The identification code transmitted from the slave unit or the master unit is scrambled by using a random number obtained by a random number generator, and the master unit or the slave unit that has received the scrambled identification code signal. The decryption key is decrypted by using a decryption key, and the decryption key is set by using the random number.