JPH06326767A - Wiretapping preventing method for cordless telephone set and cordless telephone set applied with the same method - Google Patents

Abstract

PURPOSE:To obtain the wiretapping preventing method for the cordless telephone set and the cordless telephone set applied with the method. CONSTITUTION:The cordless telephone set consists of a fixed unit 11 which is connected to a telephone line and a slave unit 6 which performs radio transmission to and reception from the fixed unit 11. In addition to circuits 5 and 7 for radio transmission and reception, the slave unit 6 and fixed unit 11 have ciphering and deciphering circuits 4 and 8 for multi-mode cipher which cipher and send out a speech signal to the transmitting and receiving circuits 5 and 7 and decipher the ciphered signal received by the transmitting and receiving circuits and mode setting circuits 3 and 9 which selectively set a mode of cipher to be used according to a user's indication.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone, and more particularly to a method of preventing wiretapping and a cordless telephone to which the method is applied.

[0002]

2. Description of the Related Art Conventionally, cordless telephones of this type are
There is a cordless telephone of Japanese Examined Patent Publication No. 3-44146. In this cordless telephone, the voice signal input to the transmission side input terminal of the slave is compressed by the compression circuit, and then the transmission noise signal from the transmission noise generation circuit is added to the voice signal by the addition circuit. At this time, if the transmission noise signal is sufficiently larger than the voice signal, this output signal becomes a confidential signal. The secret noise signal is transmitted by the adaptive echo canceller with reference to the reference noise signal of the reference noise generator circuit having the same function as the transmission noise generator circuit, and then transmitted by the decompression circuit. It is decompressed and received.

[0003]

The above-mentioned conventional cordless telephone communicates by adding noise within a predetermined range to radio transmission / reception, and the noise is removed by the echo canceller at the receiving side to receive the call. There is a drawback that it is difficult to secure the peculiarity of the type of noise due to fluctuations in the output of the unit, and highly stable wiretapping prevention cannot be expected.

An object of the present invention is to provide a stable wiretapping prevention method which is less affected by output fluctuations and the like, and a cordless telephone to which the method is applied.

[0005]

The wiretapping prevention method for a cordless telephone according to the present invention is directed to a cordless telephone which is composed of a fixed machine connected to a telephone line and at least one child machine and is wirelessly connected to each other. In the wiretapping prevention method,
Wireless communication between a fixed device and a slave device is performed by encrypted communication.

[0006] A cordless telephone to which the wiretapping prevention method of the present invention is applied is a cordless telephone which comprises a fixed machine connected to a telephone line and at least one slave, and is wirelessly connected to each other. The fixed device and the child device have wireless communication means for performing encrypted communication with each other.

The present invention also includes a cordless telephone in which the wireless communication means has a plurality of selectable encryption communication modes.

Further, the wireless communication means executes encryption / decryption processing in a circuit capable of arbitrarily setting an encryption mode for each of the fixed device and the slave device and a mode instructed in accordance with an instruction from the mode setting circuit. The present invention also includes a cordless telephone having an encryption / decryption circuit that enables

The cordless telephone of the present invention may further include an answering machine function.

[0010]

Since the wireless transmission / reception between the fixed device and the slave unit is transmission / reception of a signal encrypted by a code different from the code used in the nearby cordless telephone, the call is not eavesdropped.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a cordless telephone to which the wiretapping prevention method for a cordless telephone according to the present invention is applied.

This cordless telephone comprises a stationary unit 11 connected to a telephone line and a slave unit 6, and the slave unit 6
Is a handset circuit 1 for mutually converting voice and voice signals.
And a call control circuit 2 for detecting the on-hook and off-hook of the handset and controlling the setting of the call circuit, a mode setting circuit 3 for setting the encryption / decryption mode arbitrarily designated by the user, and a mode setting circuit. 3 has an encryption / decryption circuit 4 for executing encryption / decryption processing in a mode designated according to the instruction of No. 3, and a transmission / reception circuit 5 for transmitting / receiving an encrypted voice signal to / from the fixed device 11.

The fixed machine 11 receives a call from a telephone line,
Call control circuit 10 for controlling the setting of a designated circuit such as a call circuit
A mode setting circuit 9 for setting an encryption mode arbitrarily specified by the user, and an encryption / decryption circuit 8 for executing encryption / decryption processing in a mode specified according to an instruction from the mode setting circuit 9. It has a transmission / reception circuit 7 for transmitting / receiving an encrypted audio signal to / from the slave unit 6.

Next, the operation of this embodiment will be described.

After the user is connected to the other party through the telephone line via the stationary device 11 and starts a call, the voice is converted into a voice signal by the handset circuit 1 and is encrypted / decrypted via the call control circuit 2. It is input to the digitization circuit 4.

The encryption / decryption circuit 4 executes the encryption process of the mode preset by the mode setting circuit 3.

The encrypted voice signal is transmitted from the transmitting / receiving circuit 5.

The transmitted encrypted voice signal is sent to the stationary device 11
It is received by the transmission / reception circuit 7 and input to the encryption / decryption circuit 8.

The encryption / decryption circuit 8 executes the decryption processing in the mode set in advance by the mode setting circuit to be the same as the slave unit 6. The decoded voice signal is the call control circuit 1
From 0 to the other party via the telephone line.

A voice signal from the other party of the call is received by the call control circuit 10 of the fixed machine 11 via the telephone line and is encrypted by the encryption / decryption circuit 8 into a cipher in a preset mode. Is transmitted from the transmission / reception circuit 7. This encrypted voice signal is transmitted / received by the transmitter / receiver circuit 5 of the child device 6.
Is received by the encryption / decryption circuit 4 to be a voice signal, which is received via the handset circuit 1.

When the fixed telephone 11 is provided with an answering machine function, the received voice signal is stored in the automatic response storage circuit by the call control circuit 10, and in the case of reproduction, the call control circuit 10 is operated by the user. A voice signal is sent from the answering machine memory reading circuit 21 of the answering machine 20.
The voice signal is encrypted via the encryption / decryption circuit 8, received by the handset 6 via the transmission / reception circuit 7, and thereafter listened to in the same manner as a general call.

[0023]

As described above, according to the present invention, since the signal wirelessly transmitted and received is the encrypted voice signal, there is an effect that the wiretapping can be prevented, and moreover, various kinds of encryption modes are provided, A further effect can be expected by allowing arbitrary selection.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a cordless telephone of the present invention.

FIG. 2 is a connection diagram in which the cordless telephone shown in FIG. 1 is provided with an answering machine function.

[Explanation of symbols]

 1 handset circuit 2 call control circuit 3 mode setting circuit 4 encryption / decryption circuit 5 transmission / reception circuit 6 handset 7 transmission / reception circuit 8 encryption / decryption circuit 9 mode setting circuit 10 call control circuit 11 fixed machine 20 answering machine 21 answering machine Phone memory read circuit

Claims (5)

[Claims] 1. A method for preventing eavesdropping of a cordless telephone, which comprises a stationary device connected to a telephone line and at least one slave device and is wirelessly connected to each other, wherein wireless communication between the stationary device and the slave device is performed. A method for preventing eavesdropping of a cordless telephone, which uses encrypted communication. 2. In a cordless telephone, which comprises a fixed machine connected to a telephone line and at least one slave machine and is wirelessly connected to each other, the fixed machine and the slave machine perform encrypted communication with each other. A cordless telephone having a wireless communication means. 3. The cordless telephone according to claim 2, wherein the wireless communication means has a plurality of selectable modes of encryption communication. 4. The wireless communication means executes encryption / decryption processing in a circuit capable of arbitrarily setting an encryption mode for each of a stationary device and a slave device and a mode instructed in accordance with an instruction from the mode setting circuit. The cordless telephone according to claim 2 or 3, further comprising an encryption / decryption circuit for performing. 5. A telephone answering machine having an answering machine function.
The cordless telephone set forth in any one of paragraphs.