JP2526954Y2 - Secret telephone device - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a secure telephone device with an improved telephone eavesdropping prevention function. The present invention relates to a confidential telephone device made possible.

[Problems to be solved by conventional technology and device]

2. Description of the Related Art Hitherto, a so-called secret telephone device for encrypting and transmitting a voice signal in a telephone call has been proposed by the present applicant or the like, and a part thereof has been put to practical use.

However, the conventional secret telephone device has a problem that if a third party intervenes in the telephone line using the same decryption method secret telephone device, it becomes possible to eavesdrop on the secret conversation between the parties. Was.

On the other hand, there has been proposed a secret telephone apparatus in which an encryption key negotiated by a caller is input and set in a secret telephone apparatus, and voice is encrypted using the encryption key. If the encryption key can be easily decrypted and the decrypted encryption key is input and set to a secret telephone device of the same decryption method, there is a problem that the voice is easily restored and decrypted.

Accordingly, an object of the present invention is to provide a confidential telephone device that cannot be eavesdropped even if a third party uses a third-party confidential telephone device using the same decryption method in view of the above-described problems. is there.

[Means for solving the problem]

The present invention relates to a secret telephone device for interleaving a voice from a telephone, encrypting and transmitting voice from a telephone, decoding an encrypted voice input from the telephone line, restoring the voice, and performing a secret talk. Confidential start operation means for setting the start of a call; self-secure key generation means for randomly generating a confidential key in accordance with a confidential call start operation by the confidential start operation means; Transmitting / receiving means for receiving a key; secret code generating means for generating a secret code according to a preset code method from the self-secret key and the received first secret key; and a secret code generated by the secret code generating means. Encryption / decryption means for encrypting / decoding voice according to an encryption / decryption pattern corresponding to Provides, because the third party privacy code can not be created even if eavesdropping the third both privacy key scrambler telephone device if privacy call party using by same decryption scheme will be impossible eavesdropping. In other words, the confidential code requires a confidential key that is automatically generated at random in conjunction with the pressing of the confidential start button inside the confidential telephone device. Therefore, it is impossible to restore the voice encrypted by the secret code. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Embodiment) FIG. 1 is a block diagram showing a configuration of an embodiment of a secret telephone device according to the present invention, FIG. 2 is a block diagram showing a more detailed configuration of the secret telephone device and a state connected to a telephone line,
FIG. 3 is a flowchart illustrating the operation of the secret telephone apparatus.

Referring to FIG. 1, a secret telephone device 2 according to an embodiment of the present invention includes a voice encryption / decryption unit 22, a control unit 24, a transmission / reception unit.
28, a line switching unit 31, 32, an operation unit 291 and a display unit 292, etc., and are connected to each other as shown in FIG.

Next, the function of each unit will be described with reference to FIG.

First, the secret telephone device according to the present invention is provided as an integral or integral part of the telephone for talking, and the secret telephone in the case of the embodiment attached to each of the two telephones 1, 5 for talking via a line. The device is illustrated in FIG.
In FIG. 2, the secret telephone device 2 according to the present invention is provided so as to be insertable and connectable to the telephone 1 connected to the telephone line 3, and is further connected to the partner telephone 5 via the telephone line 3 and further through the switching center 6. It is provided so as to be connectable to another connectable secret telephone device 2a. The secret telephone device 2 has a first bandpass filter (BPF) 21, which is connected to the telephone 1 via a relay 31 forming a line switching unit 31 and inputs from the telephone 1. Unnecessary frequency components other than audio are cut out of the signal, and the required frequency (for example,
Pass only 300Hz to 3,100Hz).

The voice encryption / decryption unit 22 connected to the first bandpass filter 21 encrypts or decrypts a signal that has passed through the first bandpass filter 21 and another second bandpass filter 23. The second band-pass filter 23 is provided between the signal encrypted by the voice encryption / decryption unit 22 and the voice signal received through the telephone line 3.
It is provided as filter means for cutting unnecessary frequency components.

Further, the secret telephone apparatus 2 includes a control unit (CP) formed by a well-known arithmetic processing element for performing various control operations described later.
U) 24, R storing a control program of the control unit 24, etc.
OM25, RAM 26 for storing a secret key, an interface (SIO) 27 including a well-known signal input / output element for transmitting the secret key in a serial manner via a MODEM 28, MODEM 28 for communication control of transmission and reception of the secret key, and an input / output interface 29, an operation unit 291 configured with input means such as operation switches, operation buttons, etc., for setting the start of a confidential call, a display unit 292 configured with an LED element, which lights up and displays when a confidential call is started, a relay A driver 30 for transmitting a drive signal to the relays 31 and 32 in response to a signal from the control unit 24; a driver 30 driven by a drive signal from the driver 30; Relay 3 that switches the connection with 1, that is, switches the line
1, 32, clock generator 33 that generates clock pulses
And so on.

The secret telephone device 2b in FIG.
, And is provided so as to be connectable to another telephone 5 for talking with the telephone 1 described above. Therefore, the same components as those of the above-mentioned secret telephone apparatus 2 in the respective components of the secret telephone apparatus 2 are indicated by adding the suffix “a” to the reference numbers in the apparatus 2.

Next, the operation when the secret telephone device 2, 2a of this embodiment is used will be described with reference to the flowchart of FIG.

Here, how the talker A uses the telephone 1 and the talker B uses the telephone 5 to make a secret call will be described how to use the secret telephone devices 2 and 2a.

Now, in the secret telephone device 2 on the side of the caller A, the telephone 1 and the telephone line 3 are connected via terminals 34 and 35. The telephone B and the telephone line 3 are connected to the confidential telephone device 2a via the terminals 34a and 35a on the caller B side as well as the A side.

Talker A and Talker B first have their respective telephones 1 and 5
Performs a normal call operation by telephone.

At this time, the relays 31 and 32 of the secret telephone device 2 and the relays 31a and 32a of the secret telephone device 2a are in the off (open) state (the state shown in FIG. 2). The telephone is directly connected to the telephone 5 via the telephone, and a call can be made after a normal call (step).

Next, in order to avoid a confidential call during the call between the two telephones 1 and 5, that is, to avoid eavesdropping by another third party, the caller A and the caller B use the operating means 291 of the respective confidential telephone devices 2 and 2a. Is pressed (step). The control unit 24 of the confidential telephone device 2 on the side of the caller A activates the confidential telephone device 2 in accordance with the pressing of the confidential start button (step), and generates a random number by a random number generation program stored in the ROM 25 in advance (step). For example, a secret key X consisting of five digits is generated. The secret story key X is stored in the RAM 26 as a storage unit, and the SIO 27 and the MODEM 2
It is sent to the telephone line 3 via 8 (step).

Similarly, the control unit 24a of the secret telephone device 2a of the caller B side
Generates a random number similarly, and generates a secret key Y consisting of, for example, five digits (step) when the secret start button of the operation unit 291a is pressed (step). The secret key Y is stored in the RAM 26a,
It is sent to the telephone line 3 via O27a and MODEM28a (step). At this time, the transmission timings of the secret keys X and Y of the two may be about the same time.

The secret key Y sent from the secret telephone device 2a is the telephone line 3
(Step).
When the secret telephone 2 receives the secret key Y of the other party via the MODEM 28, the control unit 24 stores the secret key Y stored in the RAM 26 using the secret key X stored in the RAM 26 and the received secret key Y. According to the program, the confidential keys X and Y are alternately arranged and mixed (for example, 10 digits), both ends are cut (for example, 8 digits), compressed by dividing by a predetermined value (for example, 300,000), and compressed. (For example, a divided integer value) is created (step).

The privacy telephone device 2a receives the other party's privacy key X transmitted from the privacy telephone device 2 via the telephone line 3. The confidential telephone device 2a receives the other-party confidential key X via the MODEM 28a (step), and the control unit 24a similarly calculates the confidential key Y and the received confidential key X stored in the RAM 26a.
The secret code Z is obtained in the same manner as described above (step).

Here, since the confidential telephone device 2 and the confidential telephone device 2a have the same confidential code generation program, the confidential key X and the confidential key Y can generate the same confidential code Z.

At the same time, the control unit 24 of the secret telephone device 2 activates the driver 30 and turns on (closes) the relays 31 and 32 of the line switching unit. That is, when the relays 31 and 32 are turned on, the voice signal input from the telephone 1 and the telephone line 3 is transmitted to the secret telephone 2
Is input to the band pass filter 21 or 23 (step). On the other hand, the secret telephone device 2a of the caller B side
Similarly, the control unit 24a of the secret telephone device 2a activates the driver 30a and turns on (closes) the relays 31a and 32a.
(Step). That is, when the relays 31a and 32a are turned on, the voice signal input from the telephone 5 and the telephone line 3 is converted to the band pass filter 21a or 23a of the private telephone device.
Will be entered.

Also, the LED 292 and the display unit of the secret telephone devices 2 and 2a
Reference numeral 292a turns on when the confidential start button is pressed on its own operation unit 291 or 291a and a confidential key is received from the other party, indicating that the confidential telephone device 2 or 2a is in the confidential talking state.

Next, when the confidential code Z is set in the voice encryption / decryption units 22 and 22a, encryption / decryption of voice, that is, confidential communication is performed using the confidential code Z. The confidential communication method performed in the voice encryption / decryption unit 22 or 22a is executed by appropriately using a known frequency conversion method, time axis compression method, or the like.

For example, in the case of the frequency division replacement method, for example, the frequency of an audio signal of 300 to 3,100 Hz that has passed through the band-pass filters 21 and 23 is divided into five frequency bands, and each divided frequency band is replaced according to a set pattern. Then, the audio signal is encrypted by synthesizing them. The conversion pattern has about 300 valid combinations in the case of five divisions, and corresponds to a secret code.

The encryption / decryption unit 22 encrypts the voice signal input from the telephone 1 via the BPF 21 according to the frequency conversion pattern corresponding to the secret code Z, and sends it to the telephone line 3 via the BPF 23. Then, the encrypted voice signal transmitted to the caller B through the telephone line 3 is input to the encryption / decryption unit 22a via the band pass filter 23a of the secret telephone device 2a. The encryption / decryption unit 22a is also set with the secret code Z, and the conversion pattern of the frequency according to the code Z, that is, the same conversion pattern as that of the secret telephone device 2 on the side of the caller A (decryption is performed by encryption). The conversion is performed by performing the reverse conversion of the pattern.

Therefore, the received encrypted voice signal is converted into the original voice signal and transmitted to the telephone 5 via the BPF 21a, and the telephone B can hear the voice of the telephone A on the telephone 5 (step).

Similarly, the voice of the caller B is transmitted from the telephone 5 to the secret telephone device.
2a, the encrypted data is transmitted to the secret telephone 2 on the side of the caller A via the telephone line 3, and is decrypted by the secret telephone 2 and transmitted to the telephone 1. Can be heard (step).

When the secret conversation ends and the telephone is hooked on, the secret telephone apparatus clears the secret code Z and returns to the initial state.

Therefore, when the next confidential call is performed, another confidential key X ', Y' is generated, and a new confidential code Z 'is similarly created, and encrypted and decrypted with a different conversion pattern. Is performed.

In the present embodiment, the secret telephone device 2 is configured to be interposed between the telephone 1 and the telephone line 3. However, the present invention is not limited to this. You may.

The start of the confidential talk may be determined by pressing one of the confidential talk start buttons, and the confidential telephone device of the other party may automatically respond to the reception of the confidential key by pressing the button of the other party. Further, a secret talk end button may be provided, and the secret talk call may be ended by pressing this button.

[Effect of the invention]

According to the secret telephone device according to the present invention, a secret key X communicated on a line by a third party using the same secret telephone device,
Even if an attempt is made to use Y, the confidential key X or Y is automatically generated at random inside the apparatus, so that the same confidential key X and Y cannot be input from outside.
Therefore, the secret code Z cannot be created, and eavesdropping can be prevented. Thus, the secrecy of the secret telephone can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a secret telephone device according to the present invention, FIG. 2 is a block diagram showing a more detailed configuration of the secret telephone device and a state connected to a telephone line, and FIG. 9 is a flowchart for explaining the operation of the secret telephone apparatus. 1, 5 telephone, 2, 2a secret telephone device, 22 voice encryption / decryption unit, 24 control unit, 28 transmission / reception unit, 31, 32 line switching unit, 291 operation unit, 292 display unit .

Claims (2)

(57) [Scope of request for utility model registration] 1. A secret telephone device for interleaving a voice from a telephone, transmitting an encrypted voice from a telephone line, decoding an encrypted voice input from the telephone line, restoring the voice, and performing a secret voice call. A secrecy start operation means for setting the start of a secrecy call; a self-secure key generation means for randomly generating a secrecy key in accordance with the start operation of the secrecy call by the secrecy start operation means; Transmitting and receiving means for receiving a confidential key, confidential code generating means for generating a confidential code from the self-confidential key and the received confidential key, and a confidential code generated by the confidential code generating means Voice encryption / decryption means for encrypting / decrypting voice according to an encryption / decryption pattern corresponding to Confidential telephone device that. 2. The secret telephone device according to claim 1, wherein the secret telephone device is integrally formed in a body of the telephone.