KR20000014730A - Preservation apparatus for communication system - Google Patents

Abstract

PURPOSE: A preservation apparatus for a communication system capable of preventing private career information from being discharged by a third person wherein the private career information is inputted through a communication terminal such as a telephone by a user's provided. CONSTITUTION: A preservation apparatus for a communication system, the apparatus comprising: a key input section(102) for outputting a code data corresponding to an operation of a key pad; a password code generator(103) for producing and outputting a password code based on an input password code, and changing and outputting the password code each time a clock signal is inputted; a logic arithmetic section(104) for exclusive-ORing the code data from the key input section(102) and the password data from the password code generator(103); an MFC generator(106) for producing a DRMF signal based on the code data from the logic arithmetic section(104); a decoding data storage section(106) for non-volatile storing the decoded data; and a controller(111) for inputting the decoded data stored in the decoding data storage section(106) to the password code generator(103), and supplying a clock signal to the password code generator(103).

Description

Security device for communication system

The present invention relates to a communication system for, for example, a tele-banking service, and more particularly, to securely prevent personal identification information, etc. that a user inputs through a terminal such as a telephone, from leaking to the outside. A security device for a communication system.

Recently, with the rapid development of communication technology, a so-called telebanking service, which enables a user to receive a financial service or a securities service using a phone connected to a public switched telephone network (PSTN network), for example, has been developed and activated.

In the case of the above-mentioned telebanking service, the user usually makes a phone call to a bank or a stock exchange where he / she is trading, and then, according to an automatic response message provided by the computer system of the corresponding destination, enters his / her account number or password and the desired transaction number. By inputting, you can receive financial services such as checking the balance of accounts, remittance and deposit.

However, in the above-described telebanking system, there is a problem that a third party may leak out his or her account number or password input by the user. That is, in general, input of an account number using a telephone or the like is performed by the user by using a dial key provided in the telephone, a so-called 10-key, and the telephone is selected when the user selects a predetermined dial key. The DTMF (Dual Tone Multi-Frequency) corresponding to the dial key is output through a telephone line, and in the case of a computer system installed in a bank, the account number or password entered by the user is detected by detecting the DTMF transmitted from the user's telephone. Etc. can be recognized. In addition, since such a decoder for DTMF detection is generalized, a person with some technical knowledge can easily find out a password inputted by a user using the decoder. That is, by connecting the DTMF decoder to a telephone line of a specific user, a password or an account number input by the user can be recognized.

Therefore, the above-described financial service system has an advantage that the user's convenience can be greatly improved, while there is a problem that a large financial accident may occur.

In addition, such a risk is not limited to the financial service system only, and there is a possibility that it may be generated in a wide range, including the leakage of personal information such as a subscriber account required for computer communication.

Accordingly, the present invention has been made in view of the above-described circumstances, and a security system for a communication system that can reliably prevent leakage of personally identifiable information input by a user through a communication terminal such as a telephone by a third party. The purpose is to provide.

1 is a block diagram showing the configuration of a communication terminal 100 in the security device for a communication system according to the present invention.

Figure 2 is a block diagram showing the main configuration of the main device 200 in the security device for a communication system according to the present invention.

3 is a timing diagram for explaining the operation of the apparatus according to the present invention;

4 is an operation flowchart for explaining the operation of the security system for a communication system according to an embodiment of the present invention.

5 is a configuration diagram showing the configuration of a security system for a communication system according to another embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

100: communication terminal 200: main device

101: keypad 102: key input unit

103, 203: encryption code generation unit 104, 204: logical operation unit

105: decoder 106: MFC generating unit

107, 201: Network control unit (NCU) 108, 202, 53, 207: DTMF receiver

109, 208: DTMF generator 111, 210: microprocessor

205: tri-state buffer 206: main system

209: subscriber code storage unit 51: first access port

52: second connection port

Security device for a communication system according to the present invention for realizing the above object is provided with a keypad to output a DTMF signal corresponding to the operation of the keypad, and using the personal identification information input from the terminal A communication system having a claim value for providing a predetermined service to a user,

The terminal comprises a key input means for outputting code data corresponding to an operation of the keypad, and a first generation of generating and outputting an encryption code based on the input encryption data and changing and outputting the encryption code every time the clock signal is input. A first logical operation means for outputting an exclusively OR of the encryption code generating means, the code data output from the key input means and the encryption data output from the first encryption code generating means, and output from the first logical operation means. MFC generating means for generating and outputting a DTMF signal based on code data, a unique number storing means for storing the unique number of the device and non-volatile storage of the encrypted data, and storing in the first encrypted data storing means Input control of the encrypted data to the first encryption code generating means, and the first encryption code Comprising: a first control means for supplying a clock signal to the play means,

The claim value is a DTMF receiving means for inputting a DTMF signal input through the trunk line and outputting code data corresponding thereto, and generating and outputting an encryption code based on the input encryption data, and changing the encryption code every time the clock signal is input. Second logic operation means for outputting the second encryption code generating means, the code data output from the DTMF receiving means and the encryption data output from the second encryption code generating means, respectively, exclusively and outputting the second logic code; Data output means for inputting code data outputted from the calculation means into the main system, subscriber information storage means for non-volatile storage of unique numbers and encrypted data for each subscriber, and subscribers connected to the communication device for the main device. Encrypting the encrypted data to the second encrypted data storing means. Read out to claim characterized in that configured by a second control means for supplying a clock signal to the second password input control code generating means, and the second encrypted code generating means.

According to the present invention having the above-described configuration, data transmission and reception between the terminal and the main device is executed through a predetermined encryption operation, and in particular, an encryption device and data used for such an encryption operation are provided internally in the terminal and the main device and are not externally provided. Since the data is not exposed and the encrypted data is continuously changed every time data is transmitted and received, the user can securely secure personal credit information with respect to an external third party.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

Figure 1 is a configuration diagram showing the configuration of the communication terminal 100 in the security device for a communication system according to the present invention, which shows the case in which the present invention is applied to the most generalized telephone of the communication terminal.

In Fig. 1, reference numeral 101 denotes a keypad provided with a plurality of key buttons, and 102 denotes a four-bit corresponding to an operation key detected by the kisscan operation in addition to executing a kisscan operation on the keypad 101. As a key input unit for outputting data, the key input unit 102 is configured of, for example, PAL (Programmable Array Logic).

In the drawing, reference numeral 103 denotes an encryption code generator that generates and outputs, for example, 4-bit encryption codes P0 to P3 under the control of the microprocessor 111 to be described later. The encryption code generator 103 outputs 4-bit data of "0" in the initial state, and then inputs a clock signal after the microprocessor 111 sets predetermined initial data to the encryption code generator 103. Each time the clock signal is input, different encryption codes are sequentially generated and output. The encryption code generator 103 may use, for example, a PN code, Walsh code, Gold code, etc. as the encryption code, but the present invention is not limited to a specific encryption code. Instead, an encryption code according to any algorithm can be used. Since the encryption code generating unit 103 is not a specific one and is generally known, its detailed configuration and description will be omitted.

In the drawing, reference numeral 104 denotes an exclusive logical OR of 4-bit data output from the key input unit 102 and 4-bit encryption codes P0 to P3 output from the encryption code generator 103, respectively. Is a logical operation unit having four exclusive logical sum circuits (EX-OR1 to EX-OR4), and 105 decodes the 4-bit data output from the logical operation unit 104 and outputs predetermined 8-bit data corresponding thereto. It is a decoder. The decoder 105 is configured of, for example, PAL (Programmable Arry Logig).

Further, reference numeral 106 generates a predetermined DTMF signal based on 8-bit data output from the decoder 105, that is, data input through the first input terminals C1 to C4 and the second input terminals R1 to R4. MFC (Multi Friquency Code) generation unit, and 107 is a Network Control Unit (NCU) for processing the voice signal and tone signal transmitted and received. The network controller 107 is coupled to the output terminal of the MFC generator 106 through a coupling capacitor C to output a frequency signal output from the MFC generator 106 through the trunk line.

The network control unit 107 couples the handset (not shown) to the trunk line to transmit the voice signal input from the handset to the trunk line and output the voice signal input from the trunk line to the handset. In addition, the network controller 107 inputs a signal (voice signal and frequency signal) transmitted and received through the trunk line to the DTMF receiver 108 and outputs a frequency signal output from the DTMF generator 109 through the trunk line. Done.

The DTMF receiver 108 outputs code data corresponding to the DTMF signal, that is, control data composed of a series of numbers, to the microprocessor 111 based on the input DTMF signal, and the DTMF generator 109 outputs the microprocessor. Based on the control data output from the 111 to generate a frequency signal corresponding to the output to the network control unit 107.

In addition, reference numeral 110 is a unique code number storage unit for storing the unique code number corresponding to the unique equipment number of the communication terminal, that is, the phone as data, this unique code number storage unit generates a code with a unique code number Reference encrypted data for the data, that is, data to be supplied to the encryption code generator 103 is stored.

Reference numeral 111 denotes a microprocessor for controlling the entire apparatus, which is set every time an arbitrary DTMF signal is received through the DTMF receiving unit 108, particularly after setting encryption data for the encryption code generating unit 103. By applying the clock signal to the encryption code generator 103, the encryption code output from the encryption code generator 103 is changed.

In addition, the microprocessor 111 is coupled to the selection node (SW) for the user to send the unique code number of the device to the host device, that is, for example, the main device 200 installed in the bank, etc., and coupled to the coupling node The power supply voltage Vcc is coupled through a predetermined pull-up resistor. When the user selects the selection switch SW, the microprocessor 111 reads out the unique code number from the unique code number storage unit 110 and transmits the unique code number through the DTMF generator 109. Then, the encrypted data stored in correspondence with the unique code number is registered and controlled in the encryption code generator 103.

On the other hand, Figure 2 is a block diagram showing the main configuration of the main device 200, for example, providing a telebanking service in the security system for a communication system according to the present invention.

In FIG. 2, reference numeral 201 denotes a network controller (NCU) for processing voice signals and tone signals transmitted and received, and 202 denotes a DTMF receiver for outputting DTMF signals received through trunk lines as 4-bit data corresponding thereto. Here, the 4-bit data output from the DTMF receiver 202 has the same data value as the 4-bit data output from the logical operation unit 104 of FIG.

In the drawing, reference numeral 203 denotes an encryption code generator for generating and outputting, for example, 4-bit encryption codes P0 to P3 under the control of the controller 000 to be described later. The structure is substantially the same as that of the part 103. That is, the encryption code generator 203 generates and outputs the same encryption code according to the input of the clock signal when the same encryption data as the encryption code generator 103 of FIG. 1 is set.

Reference numeral 204 denotes an exclusive OR of four bits of data output from the DTMF receiver 202 and four bits of encryption codes P0 to P3 output from the encryption code generator 203, respectively. A logic operation unit including four exclusive logic sum circuits EX-OR5 to EX-OR8, and 205 denotes a clock signal that is input from the microprocessor 210 to 4-bit data applied from the logic operation unit 204, that is, a latch signal. The tri-state buffer 206 latches and outputs the voice guidance message for the tele-banking service through the voice transmission / reception line L1, and also based on the data applied from the tri-state buffer 205. It is the main system that executes tasks.

In FIG. 2, reference numeral 207 denotes a DTMF receiver which detects a DTMF signal among signals (voice signals and frequency signals) input from a trunk line and outputs corresponding number data, and 208 denotes a microprocessor 210 which will be described later. The DTMF generator generates a DTMF signal based on the control data applied from the controller and outputs the DTMF signal to the network controller 201.

In the drawing, reference numeral 209 is stored along with the encryption data required for generation of the encryption code corresponding to the reference code data, that is, the encryption code generator 203 corresponding to the plurality of subscriber customer communication terminals As the subscriber code number storage unit, the encrypted data stored in the subscriber code number storage unit 209 is encrypted stored in the unique code number storage unit (110 of FIG. 1) of the communication terminal corresponding to the corresponding subscriber code number. It has the same data value as the data.

In addition, reference numeral 210 denotes a microprocessor for controlling the encryption operation of the main apparatus. When the unique code number is received from the terminal illustrated in FIG. 1 through the DTMF receiver 207, the subscriber code is based on the received unique code number. After reading the reference encrypted data from the number storage unit 209, it is registered in the encryption code generation unit 203. After that, when it is detected that an arbitrary DTMF signal is input through the DTMF receiving unit 207, the predetermined code signal is output to the encryption code generator 203 to control the generation of the encryption code. In addition, the microprocessor 210 outputs a latch signal LA to the tri-state buffer 205 when it detects that an arbitrary DTMF signal has been input through the DTMF receiver 207. The output data is input to the main system 206.

In particular, the microprocessor 210 outputs a clock signal to the encryption code generator 203 after a predetermined time t1 after the DTMF signal is received, as shown in FIG. 3, and also to the encryption code generator 203. By outputting the latch signal LA after a predetermined delay time t2 after outputting the clock signal, the decoded data is stably applied to the main system 206.

Next, the operation of the security device of the communication terminal having the above configuration will be described with reference to the operation flowchart shown in FIG.

First, in the initial operation state, the terminal (FIG. 1) side encryption code generating unit 103 and the main apparatus (FIG. 2) side encryption code generating unit 203 are reset to output encryption code data of "0", respectively. Accordingly, the data output from the key input unit 102 in FIG. 1 and the DTMF receiving unit 202 in FIG. 2 passes through the logic operation units 104 and 204, respectively, and is input to the decoder 105 and the tri-state buffer 205, respectively. Will be.

On the other hand, when the user makes a call to the main apparatus 200 using the terminal 100 shown in FIG. 1 in order to receive the financial service, the main system 206 at the main apparatus side executes an automatic answering function. The user is prompted to enter the unique number of the device. And, such a guide message is output to the trunk line through the line (L1) and the network control unit 201 in Figure 2, the output message thus output to the handset through the network control device 107 of the terminal 100 again To be authorized.

Subsequently, when the user hears the above guide message and turns on the selection switch SW of the terminal 100 (step ST11), the microprocessor 111 of the terminal 100 is unique from the unique code number storage unit 110. The code number is read and inputted to the DTMF generator 109 (step ST12), and the DTMF generator 109 generates a DTMF signal corresponding to the number data based on the input number data, through the network controller 107. Will output

On the other hand, in the main device 200, when a unique code number is input from the trunk line to the network control unit 201, which is input to the microprocessor 210 through the DTMF receiving unit 207, the logic and the DTMF receiving unit 202 The main system 206 is input to the main system through the operation unit 204 and the three-state buffer 206, and when the input unique code number is determined to be normal, the main system 206 sends a guide message again to input an account number or a password. Will be required. When the unique code number is input through the DTMF receiver 207 (step ST21), the microprocessor 210 reads the subscriber code storage unit 209 based on the inputted unique code number, and the corresponding subscriber. When the code is read out, the corresponding standard encrypted data is read out from the subscriber code storage unit 209 and set in the encryption code generator 203 (step ST22), and predetermined control data indicating that a unique code number has been received. The DTMF generation unit 208 outputs the trunk line (ST23 step).

In addition, in the above operation state, if the unique code number received from the terminal 100 is not the normal subscriber code number, the main system outputs a guide message for inputting the unique code number again, and at this time, the microprocessor 210 In the case where the unique code number is not registered in the subscriber code storage unit 209, the encryption code generator 203 is kept in an inoperative state.

Subsequently, in the terminal 100, the microprocessor 111 generates an encryption code from the unique code number storage unit 110 when acknowledgment data is input from the main apparatus 200 through the DTMF receiver 108 (step ST13). Reads the encrypted data for the encryption code generator 103 and sets it to the encryption code generator 103 and applies one clock signal to the encryption code generator 103 so that the first encryption code is output from the encryption code generator 103. Control (ST14 step).

Thereafter, the microprocessor 111 outputs a clock signal to the encryption code generator 103 whenever the user manipulates the keypad 101 once and the corresponding DTMF signal is output. By changing the encryption code output from the) is securely secured personal information such as account number or password output from the terminal (100 steps ST15, ST16).

That is, for example, when the account number input by the user is "3452 1431" and the clock signal is output from the microprocessor 111, for example, "1", "10", "11" from the encryption code generator 103; ",… Assuming that the encryption code of the output is, first, when the user inputs "3" by operating the keypad 101, the "11" data corresponding to "3" and the encryption code of "1" are logical operation unit 104. In this case, code data corresponding to " 10 ", that is, " 2 " of the keypad 101 are inputted to the MFC generator 106 through the decoder 104 from the logical operator 104. 106 outputs a DTMF signal corresponding to "2".

Subsequently, when the above-described DTMF signal output is detected through the DTMF receiving unit 108, the microprocessor 111 outputs a clock signal to the encryption code generating unit 103 so that the encryption code generating unit 103 performs the next encryption. The code "10" is outputted, and when the user inputs "4" by operating the keypad 101, the "100" data corresponding to "4" and the password of "10" in the logic operation unit 104. Since the codes are exclusively ORed, code data corresponding to “110”, that is, “6” are output from the logic operation unit 104 and input to the MFC generation unit 106 through the decoder 105. That is, the MFC generation unit 106 generates and outputs a DTMF signal corresponding to "6". In addition, if it is detected through the DTMF receiving unit 108 that the frequency signal is output from the MFC generation unit 106 in this manner, the microprocessor 111 outputs the clock signal to the encryption code generating unit 103 again, thereby encrypting the next cipher. Output control of the code.

By repeatedly executing the above-described operation, the personal image information input by the user is reliably encrypted and transmitted.

On the other hand, in the main apparatus 200, when an arbitrary DTMF signal is received through the DTMF receiver 207 (step ST24), the microprocessor 210 clocks the encryption code generator 203 as described in FIG. Will output a signal. Of course, at this time, the DTMF signal input through the network control unit 201, that is, the DTMF signal for "2" first transmitted from the terminal 100, is decoded by the DTMF receiving unit 202, and the logical operation unit 204 receives the decode. Although code data of "10" corresponding to "2" is outputted, in this case, the latch signal (3) is inputted to the tri-state buffer 205 before the clock signal is input to the encryption code generator 203 as described in FIG. Since LA) is not outputted, code data outputted from the logical operation unit 204 is not inputted to the main system 206.

Subsequently, as described above, when the clock signal is input from the microprocessor 210 to the encryption code generation unit 203 and the first encryption code, that is, "1" is output from the encryption code generation unit 203, the encryption code. The data is exclusively OR'd by the " 10 " data outputted from the DTMF receiver 202 and the logical operator 204, and " 11 " from the logical operator 204, i.e., originally input by the user through the terminal 100. Code data corresponding to 3 "is output and input to the tri-state buffer 205.

Subsequently, when the latch signal LA is output from the microprocessor 210 as described with reference to FIG. 3, the data of “11” is input to the main system 206 through the tri-state buffer 205.

When the next DTMF signal reception is detected through the DTMF receiving unit 207, the clock signal is output to the encryption code generating unit 203 again as described above, and the encryption code output from the encryption code generating unit 203 is next. Change to the encryption code, and then repeatedly execute the operation of supplying the clock signal to the tri-state buffer 205 to input the original data input by the user through the terminal 100 to the main system 206. (ST25 step).

On the other hand, if the user terminates the telephone call while repeatedly performing the above-described operation, the microprocessors 111 and 210 of the terminal 100 and the main apparatus 200 reset the encryption code generators 103 and 203, respectively. Thus, the initial state, that is, the output data of the encryption code generators 103 and 203 are all set to "0", and then the encryption process is terminated (steps ST17, ST18, ST26, ST27).

In this case, the determination of the end of the call can be easily detected by the on-hook / off-hook detection means or the trunk line voltage level detection means, which is usually employed in a telephone or an exchanger, although it is not shown in the drawing.

As described above, according to the embodiment, data transmission and reception between the terminal 100 and the main device 200 is executed through a predetermined encryption operation, and in particular, an encryption device and data used for the encryption operation are connected to the terminal 100. Since it is provided internally to the main device 200 and is not exposed to the outside at all, and encrypted data is continuously changed each time one data is transmitted and received, the user can securely secure personal credit information to an external third party. You can do it.

On the other hand, in the above-described embodiment, since the encryption device is provided in the terminal 100, there is an unreasonable point in that a separate telephone must be purchased in order to use the encryption device.

Figure 5 shows the configuration of a terminal of a security device for a communication system according to another embodiment of the present invention in view of the above circumstances, which allows a user to connect to the terminal and use the security device as needed.

That is, in Fig. 5, the first connection port 51 is provided to couple terminals such as a telephone, and the second connection port 52 is provided to couple the security device to the trunk line. And a DTMF receiver 53 for converting the DTMF signal received through the 51, that is, the DTMF signal output from the terminal to the trunk line into code data corresponding thereto. In addition, the first connection port 51 and the network control device 107 is coupled through a separate line (L2) is configured to transmit and receive a general voice signal, not a DTMF signal through the line (L2), The line L2 is provided with a predetermined switching section 54 to block DTMF signals input from the telephone, i.e., personal identification information, from being transmitted to the trunk line through the line L2. The microprocessor 111 generates an encryption code generator when predetermined control data is received from the microprocessor 210 of the main apparatus 200 shown in FIG. 2, that is, when confirmation data is received in step ST13 of FIG. 4A. In addition to driving 103, the switching unit 54 is turned off to block personal image information output from the telephone from being output through the trunk line. In addition, the microprocessor 111, although not shown in detail in the drawing, after checking the voltage level of the trunk line through the network control device 107 to determine the on-hook state of the terminal (telephone), when the user on-hook the terminal In addition to resetting the code generator 103, the switching unit 54 is set to the on state.

Since other operations are substantially the same as those of the above-described embodiment, detailed description thereof will be omitted.

Since the security device shown in Figure 5 is configured separately from the existing terminal, the problem that the user has to purchase a separate terminal is solved, and the user can carry the security device combined with the desired terminal to use The user's convenience is greatly improved.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical scope of the present invention. For example, in the embodiment shown in Figs. 1 and 5, the unique code number of the device is stored in the memory device, but this can be configured to set the unique code number using a conventional dip switch. It may be. That is, the present invention may be limited only by the claims described herein.

As described above, according to the present invention, it is possible to realize a security system for a communication system that can reliably prevent leakage of personal image information input by a user through a communication terminal such as a telephone by a third party.

Claims (8)

And a terminal configured to output a DTMF signal corresponding to the keypad when the keypad is operated, and a claim value for providing a predetermined service to a user using personal identification information inputted from the terminal. In The terminal comprises a key input means for outputting code data corresponding to the operation of the keypad; An encryption code generating means configured to generate and output an encryption code based on the input encryption data, and to change the encryption code for each clock signal input; Logical operation means for exclusively ORing the code data output from the key input means and the encryption data output from the encryption code generating means, respectively; MFC generating means for generating and outputting a DTMF signal based on code data output from the logical operation means; Encrypted data storage means for storing the encrypted data non-volatile; And control means for inputting and controlling the encrypted data stored in said encrypted data storage means to an encryption code generating means, and supplying a clock signal to the encryption code generating means. The method of claim 1, And further comprising DTMF detecting means for detecting DTMF signals transmitted and received via trunk lines, wherein said control means sends a clock signal to said encryption code generating means whenever DTMF signal transmission is detected by said DTMF detecting means. Security device for a communication system, characterized in that the supply. And a terminal configured to output a DTMF signal corresponding to the keypad when the keypad is operated, and a claim value for providing a predetermined service to a user using personal identification information inputted from the terminal. In The assertion value is a DTMF receiving means for inputting a DTMF signal input through a trunk line and outputting code data corresponding thereto; An encryption code generating means configured to generate and output an encryption code based on the input encryption data, and to change the encryption code for each clock signal input; Logic operation means for exclusively ORing the code data output from the DTMF receiving means and the encryption data output from the encryption code generating means, respectively; Data output means for inputting code data output from the logical operation means into a main device, Encrypted data storage means for non-volatile storage of encrypted data for each subscriber; And control means for reading out encrypted data corresponding to the subscriber connected to the main device from the encrypted data storage means, inputting the encrypted code to the encryption code generating means, and supplying a clock signal to the encryption code generating means. Security device for a communication system. The method of claim 3, wherein And further comprising DTMF detecting means for detecting DTMF signals transmitted and received via trunk lines, wherein said control means sends a clock signal to said encryption code generating means whenever DTMF signal reception is detected by said DTMF detecting means. Security device for a communication system, characterized in that the supply. And a terminal configured to output a DTMF signal corresponding to the keypad when the keypad is operated, and a claim value for providing a predetermined service to a user using personal identification information inputted from the terminal. In The terminal comprises a key input means for outputting code data corresponding to an operation of the keypad, and a first generation of generating and outputting an encryption code based on the input encryption data and changing and outputting the encryption code every time the clock signal is input. A first logical operation means for outputting an exclusively OR of the encryption code generating means, the code data output from the key input means and the encryption data output from the first encryption code generating means, and output from the first logical operation means. MFC generating means for generating and outputting a DTMF signal based on code data, a unique number storing means for storing the unique number of the device and non-volatile storage of the encrypted data, and storing in the first encrypted data storing means Input control of the encrypted data to the first encryption code generating means, and the first encryption code Comprising: a first control means for supplying a clock signal to the play means, The claim value is a DTMF receiving means for inputting a DTMF signal input through the trunk line and outputting code data corresponding thereto, and generating and outputting an encryption code based on the input encryption data, and changing the encryption code every time the clock signal is input. Second logic operation means for outputting the second encryption code generating means, the code data output from the DTMF receiving means and the encryption data output from the second encryption code generating means, respectively, exclusively and outputting the second logic code; Data output means for inputting code data outputted from the calculation means into the main system, subscriber information storage means for non-volatile storage of unique numbers and encrypted data for each subscriber, and subscribers connected to the communication device for the main device. Encrypting the encrypted data to the second encrypted data storing means. The security device for a communication system, characterized in that configured to include a second control means for reading the second password inputted to the control code generating means and supplying a clock signal to the second password code generating means. The method of claim 5, The communication terminal further comprises a selection switch for transmitting a unique number of the device to the main device, and DTMF generating means for converting the data output from the first control means into DTMF signals and coupling them to the trunk line, And said first control means outputs a unique number stored in said unique number storage means to said DTMF generating means when said selection switch is selected. A first connection port coupled to the communication terminal, A second connection port coupled to the trunk line, Coupling means for electrically coupling the first and second connection ports to each other under a control of a control means; DTMF receiving means for receiving a DTMF signal input through the first connection port and outputting code data corresponding thereto; An encryption code generating means configured to generate and output an encryption code based on the input encryption data, and to change the encryption code for each clock signal input; Logic operation means for exclusively ORing the code data output from the DTMF receiving means and the encryption data output from the encryption code generating means, respectively; MFC generating means for generating a DTMF signal based on the code data output from the logic operation means and outputting the same through the second connection port; Encrypted data storage means for storing the encrypted data non-volatile; And control means for inputting and controlling the encrypted data stored in said encrypted data storage means to an encryption code generating means, and supplying a clock signal to the encryption code generating means. The method of claim 7, wherein It further comprises a selection switch for transmitting the unique number of the device to the main device and DTMF generating means for converting the data output from the control means into DTMF signal to couple to the trunk line, And said control means outputs said unique number stored in said unique number storage means to said DTMF generating means when said selection switch is selected.