JPH05336076A - Secrecy telephone set and secrecy method - Google Patents

Abstract

PURPOSE:To protect privacy by decoding the digital signal obtained by deciphering to obtain a voice signal of telephone and making secret of the signal in a network. CONSTITUTION:When a handset 8 of a telephone set is hooked off, a call signal is transmitted to an originating station 11; and when a dial signal is transmitted from the telephone set, the originating station 11 transmits it to a relay exchange 12. The exchange 12 sends the dial number to a pertinent private branch exchange 13, and a terminating station 13 sends the call signal to a terminal equipment 9 for privacy. This equipment 9 is provided with a means which sends the voice input of telephone to the exchange 13 to obtain the secrecy output and a means which obtains the secrecy input to obtain the voice output of telephone. When a cipher key is set to the terminal equipment 9 to switch normal speaking to secrecy speaking and synchronism is settled between equipments 9, secrecy speaking between handsets 8 is possible. Thus, the signal is made secret of in the network to protect privacy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secret talk device and a secret talk method suitable for protecting privacy by making a call between telephone terminals in a network including a telephone and a switch secret.

[0002]

2. Description of the Related Art A known example closest to the present invention is JP-A-62-62.
It is a secret story between the subscriber terminal and the exchange described in Japanese Patent No. 239633. In this prior art, a plurality of voice digital signal encryption and decryption patterns are set in a switchboard, one of the voice digital signal encryption and decryption patterns is assigned to each subscriber terminal, and voice digital signals are multiplexed. It is intended for confidential communication between the subscriber terminal and the exchange, which is advantageous in that the voice digital signal encryption and decryption device on the exchange side can be shared by performing encryption and decryption according to a pattern later.

[0003]

SUMMARY OF THE INVENTION The above-mentioned prior art aims at secret communication between subscriber terminals in the same private branch exchange, and aims to be economical by sharing a voice digital signal encryption and decryption device on the exchange side. It is an advantage. Therefore, the patent does not describe any apparatus and method for connecting the private branch exchanges with a transit exchange to keep the call confidential. Further, in the past, since no secret talk was made on the trunk line, it was possible to eavesdrop on that part. An object of the present invention is to provide a confidential talk device and a confidential talk method capable of protecting a privacy by making a call from a subscriber terminal confidential within a network composed of a private branch exchange and a relay exchange so as to prevent eavesdropping.

[0004]

A secret telling device of the present invention for achieving the above object is, for example, as shown in FIG. 1, provided in a telephone terminal with the secret telling device built in or outside the telephone. Further, the confidential talk device is provided with means for obtaining a secret talk output to be sent to the exchange side by receiving a voice input of the telephone, and means for obtaining a secret voice input from the exchange side to obtain a voice output of the telephone. The means for obtaining the confidential input to be sent to the exchange side by obtaining the voice input of the telephone is the voice encoding means 1 for voice-compressing and digitizing the voice input signal to a frequency at which digital transmission is possible, and the digitalized signal for encryption. Encrypting means 2 for processing, and modulating means 3 for converting the encrypted digital signal into a modulated signal of a modem to obtain a confidential modem signal output.
The means for obtaining the secret voice input from the exchange side and obtaining the voice output of the telephone are the demodulation means 6 for obtaining the secret voice modem signal input from the exchange side, demodulating the demodulated modem modem signal input and converting it into a digital signal. It is supposed to be provided with an encryption / decryption means 5 for decrypting the encryption of the signal and an audio decryption means 4 for decrypting the decrypted digital signal to obtain the voice output of the telephone.

Further, the secret talking method of the present invention for achieving the above object is characterized in that, as shown in FIG. 2, for example, a secret talking between telephone terminals having a secret talking device is carried out by the following procedure. (1) As the procedure from calling to enabling plain-speaking call,
Procedure for connecting lines between terminals by normal calling and sending dial signals (Fig. 2 (a)) (2) As a procedure for transition from plain talk to secret talk, set the encryption key of the secret talk device in the plain talk state. Switch to confidential communication, perform training to synchronize encryption between terminals, after establishing synchronization, switch to confidential communication and enter the confidential communication (Fig. 2
(B)) (3) In the procedures of (1) and (2) above, the exchange does not perform processing related to confidential talk. In this case, there are various methods for compressing voice and encrypting voice. There is no particular restriction on the method. The present invention provides a configuration of a confidential communication device and a confidential communication method for protecting the privacy of telephone calls between telephone terminals, and does not specify individual element technologies.

[0006]

In the present invention, the confidential device is built in the telephone,
Alternatively, it is externally provided in the telephone terminal, and the voice of the telephone is converted into a digital signal by lowering it to a frequency passing through the speech path by a voice compression device in the voice encoding means. The encryption circuit as an encryption means is designed to be confidential so that wiretapping cannot be performed between the communication line and the exchange. The modulation means by the modem circuit converts the digital signal into an analog signal and passes it through the inside of the exchange in order to transmit the digital signal through the communication line.
Also, in the exchange, as a normal exchange / connection operation, it is identified whether the call is a dropped call or a relay call, and the dropped call is sent to the corresponding subscriber circuit without any processing in the case of a relay call. Connect to the exchange at the latter stage. The signal from the exchange is converted into a digital signal through the demodulation means of the modem circuit, and decrypted by the encryption circuit by the encryption / decryption means to remove the secret. In the voice decoding means, the voice decompression circuit restores the voice to make the call. As described above, in the confidential communication device of the present invention, the confidential communication signal is encrypted in the telephone terminal, and the encrypted communication signal is connected to the telephone terminal of the other party through the conventional ordinary private branch exchange or relay exchange, and then the ordinary communication is performed. Since it is returned to the voice signal, it becomes impossible to eavesdrop in the network such as the communication path outside the telephone terminal and the communication line, and the privacy is completely protected. Further, as shown in the secret-speaking method of the present invention, the exchange does not perform the process related to the secret-speak, but the switching from the plain-speak to the secret-speak is performed only by the switching operation in the telephone terminal. Therefore, according to the present invention, it is possible to use the conventional exchange as it is, and it becomes possible to economically secure the conversation.

[0007]

1 is a block diagram of an embodiment of a secret talking device of the present invention. Reference numeral 1 is a voice encoder for compressing and digitizing voice signals input from a transmitter of a telephone up to a speed through a communication path. Reference numeral 2 is a device section that encrypts a voice digital signal compressed by 1 to provide confidentiality. Three
Is a modulator / demodulator for converting the two digital signals into analog signals for passing through the communication line and the exchange.
Reference numeral 6 is a device section for converting a modem signal output from the exchange side into a digital signal. Reference numeral 5 is a circuit for decoding the digital signal encrypted on the line 2. Reference numeral 4 is a circuit for returning the digitized voice signal to voice. As described above, this device uses a circuit for converting the signal transmitted from the telephone transmitter of the telephone into voice compression, encryption, and modem signal transmission to the exchange side and the signal input from the exchange side to decrypt the voice and It has a circuit configuration for returning.

FIG. 2 shows an embodiment of the secret talking method of the present invention.
2 shows the exchange of signals when a telephone call is actually made using this device. 2 (a) is a call to a plain call, (b)
Shows how to move from a plain story to a secret story. 8 in FIG.
Indicates a telephone handset. Reference numeral 9 denotes a confidential terminal device provided in the telephone terminal separately from the telephone, and 10 corresponds to the confidential device described in FIG. Reference numeral 11 is a private branch exchange of the calling station, 12 is a relay exchange for relaying the call, and 13 is a private branch exchange for receiving the call. An example of a confidential telephone device incorporated in the telephone is shown in FIG. Next, a procedure from a call to a plain call will be described with reference to FIG. In FIG. 2A, by raising the handset 8 of the telephone, the calling signal is transmitted to the transmitting station 11. When the telephone transmits the dial signal to the transmitting station 11, the transmitting station 11 transmits the dial number to the transit exchange 12. The repeater exchange 12 sends the dial number to the corresponding private branch exchange 13,
Sends a call signal to the confidential terminal device 9. When the handset 8 is lifted and responded to, the response signal is
It is transmitted via the receiving station 13, the relay station 12, and the transmitting station 11. In this state, a plain call is possible. The transition from the plain story to the secret story will be described with reference to FIG. When the encryption key is set to the terminal device 9 in the plain talk state and the terminal device 9 is switched to the confidential talk, the training for synchronizing the ciphers is performed between the terminal devices 9, and when the synchronization is established, the terminal device 9 is switched to the confidential talk, and the handset 8 switches the confidential talk. You can talk. In this case, the repeater exchange 12 transmits data to the private branch exchange 13 in the subsequent stage without performing any processing on the input voice signal.

[0009]

As described above, according to the present invention, it is possible to make voice confidential to protect the privacy of a call. Further, since the conventional exchange can be used as it is for the confidentialization of the present invention, it can be economically confidentialized.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a secret talking device of the present invention.

2A and 2B show a connection procedure in an embodiment of a secret talking method of the present invention, in which FIG. 2A shows a procedure from a call to plain call, and FIG. 2B shows a procedure from plain talk to secret talk.

FIG. 3 is an embodiment of a secret phone device according to the present invention, in which the secret phone device is incorporated in a telephone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Voice encoding circuit 2 ... Encryption circuit 3 ... Modem modulation circuit 4 ... Voice decoding circuit 5 ... Cryptography / decoding circuit 6 ... Modem demodulation circuit 9 ... Secret terminal device 10 ... Secret device

Claims (2)

[Claims] 1. A confidential communication device for confidentializing a telephone call of a network including a telephone and an exchange for connecting a telephone call to the telephone, wherein the confidential communication device is provided inside or outside the telephone and provided in a telephone terminal. And, the confidential talk device comprises means for obtaining a secret talk output to be sent to the exchange side by receiving a voice input of the telephone, and means for obtaining a secret voice input from the exchange side to obtain a voice output of the telephone. Means for obtaining a confidential output to be sent to the exchange side is a voice encoding means for voice-compressing and digitizing a voice input signal to a frequency at which digital transmission is possible, and an encryption means for encrypting the digitized signal. , Means for converting the encrypted digital signal into a modulated signal of a modem to obtain a secret-talking modem signal output, and obtaining a secret-talk input from the exchange side to obtain a voice output of a telephone, Demodulation means for obtaining a secret modem signal input from the exchange side, demodulating it, and converting it into a digital signal, encryption / decryption means for decoding the encryption of the digital signal, and decoding the decoded digital signal for the telephone A secret talking device comprising a voice decoding means for obtaining a voice output. 2. A secret talking method for performing a secret talking between telephone terminals having a secret talking device according to the following procedure. (1) As the procedure from calling to enabling plain-speaking call,
Procedure for connecting lines between terminals by normal calling and sending dial signals (2) As a procedure to shift from plain talk to secret talk, set the encryption key of the secret talk device in plain talk and switch to secret talk. In order to synchronize the ciphers, train to switch to the confidential talk after establishing the synchronization, and then enter the confidential call (3) In the steps (1) and (2) above, the exchange performs processing related to the confidential talk. Absent