JPS58178646A - System for preventing wiretapping - Google Patents

Abstract

PURPOSE:To prevent a wiretapping fundamentally by converting a signal at the transmitting side and sending the converted signal to the exchange side on the basis of a fixed rule of a calling signal recognized mutually by speaker in respective telephone set. CONSTITUTION:A voice signal is separated into transmitting and receiving signals by HYB, the transmitting signal is converted from analog to digital signal by a COD and the digital signal is successively stored in a transmission memory M-S. The specification of writing addresses uses the output of the counter as it is and is constituted to increase the address No. one by one. On the other hand, the reading address of the transmitting memory M-S is designated by the specification of a jumper part JMP-S set up by a transmission mode A specified by SUBA. Transmitting signal read out from the transmission memory M-S in the order of address corresponding to the transmission mode A is converted into 65Kb/s by an INT and the converted signal is sent to the exchange side. The transmitted signal is received by an SUBB and reversely converted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing telephone eavesdropping.

Telephone wiretapping has become a major social problem.

With current telephones, as shown in Figure 1, when subscriber A and subscriber B are talking, subscriber C connects to subscriber A's telephone line.
By simply connecting, the content of subscriber A's calls can be easily eavesdropped, and subscriber A cannot detect whether or not there is eavesdropping, and it is difficult to prevent this from happening.

An object of the present invention is to provide a method that prevents eavesdropping in order to solve the above-mentioned problems.

The call signals within the telephones of the callers are converted according to certain rules recognized by the callers, and the signals on the transmitting side are converted and sent to the exchange. On the other hand, on the receiving side,
Inside the telephone, this call signal is converted into a normal signal by performing a conversion that is the opposite of the previous conversion law. Because of this, the signal from the telephone-to-father converter becomes meaningless when viewed by a third party who does not know the conversion law.

Even if the call is eavesdropped, the content of the call will be unreadable.

An embodiment of the present invention will be explained with reference to FIG.

In FIG. 2, 5UBA and 5UBB represent telephones of the subscriber, and EX represents a converter. EYB is a hybrid that separates analog signals into upstream and downstream analog signals, COD and DEC are A/D, respectively.
Coder and decoder for D/A conversion, M-5 is a memo I) for storing transmitted signals, M-R is a memory for storing received signals, INT is for connecting a 64kb/z digital signal line and a digital telephone. The HP-S has a jumper section that specifies the read address of M-5 according to the settings of the telephone user, and the IMF-R has a jumper section that specifies the write address of M-R according to the settings of the telephone user. show.

Next, this operation will be explained.

When SUB A and SUB B are talking, if there is a risk of eavesdropping, SUB A and SUB B will communicate 1. - Instruct each other about IK transmission mode. This is SUB A and SUB from K
B sets its reception mode based on the mutually instructed transmission mode. In this example, SUB A is sent%-)”A
5UBB indicates transmission mode B, which causes SUB
A sets reception mode B, and SUB B sets reception mode A.

Next, the relationship between transmission mode Δ and reception mode B will be explained.

Transmission memo of SUB A in a certain order of addresses +) M
-5K* Read out the input transmission data according to the read address order specified in transmission mode A, and send it to the receiving memo IJ M of the other subscriber SUB H via the exchange.
-When writing to H.

Reception memo +) Reception memo of SUB H so that when the received data is read out in the same address order as written in the transmission memory M-5K of SUB A during transmission from H-R, it will be the same as the original transmission content. Specifies the order of write addresses for IJ &-R. This is defined as reception mode A setting. This transmission mode interferes with the encryption between SUB A and SUB 8 and cannot be identified by a sixth party.

Next, the operation within the 5UBA telephone after the mode is specified will be explained. The audio signal is separated into transmission and reception by HYH, and the transmission signal is divided by t'OD.4. converted and the digital signal is sent (Memo +) M - S K
II will be written next. This write address instruction uses the output of the counter as is, and the address number is increased one by one.

On the other hand, the read address instruction for sending memory M-5 is S.
This is done according to instructions from jumper section MP-5, which is set according to transmission mode A specified by UBA.

(Detailed explanation of this address specification is given in Figure 5.) Address corresponding to transmission mode AK JIAK Transmission memo IJ
The transmission signal read from M-S is converted into 64 kb/I by IN"f and sent to the exchange side.

Next, the reception operation when SUB B receives a signal transmitted from VC5UBA via the exchange will be explained.

The received signal is taken in by the NT and stored in the reception memory M-1.
1, but the write address for is 5UBB
The jumper section set by the reception mode AK set by /
This is done according to instructions from MP-R.

As mentioned above, reception mode A is set to reverse the read address order of the memory converted by transmission mode A and restore it to the original read request.
When reading out the reception memo IJM-R of H in a fixed order, the contents are read out in the same way as if they were written in the transmission memory M-S of SUB A in a fixed order at the time of transmission.

Next, the received data read out from the receiving memory MR is DE
SUB B can be connected via audio signal via C and BYB.

Although the detailed description of the present invention has been given regarding transmission from SUB A, the same applies to transmission from SUB B.

Next, a method of addressing the transmission memory M-5 will be explained with reference to FIGS. 5 and 4.

In FIG. 6, RAM is random access memory,
CN T is a counter that counts the clock CLK, IMF
indicates a jumper section, and jumpers are used to appropriately change the counter output lines so that they are in the order of the memory read addresses corresponding to the "transmission mode" K.

cLX indicates a clock signal, and clock C'L is the fourth
As shown in the figure, E/LK separates write mode, read mode and operation mode.

5EL indicates a selector that selects one of the outputs of the counter CNT and the jumper IMF using the clock cLX and specifies the address of the memory RAM.

Next, the operation will be explained. Counter t'NT is clocked by clock CL1. When the selector SEL is in write mode, the address of the memory RAM is the counter CN.
It is specified by the output of T and is incremented by +1.

Next, when the selector SEL is in the read mode, the output of the counter C'7vT is designated by the jumper JMP so as to correspond to the "transmission mode". As a result, writing to the memory is performed in a fixed order of addresses, and reading from the memory is performed in the order of addresses specified in the "transmission mode".

As mentioned above, in order to prevent eavesdropping, subscribers mutually specify the transmission mode and convert the transmitted signal according to a certain conversion law, thereby converting the communication into a signal that has no meaning for a third party outside the telephone. On the receiving side, the telephone performs a conversion that is the opposite of the transmission conversion law, so even if a third party were to eavesdrop on a call, they would be monitoring an unreadable signal that has no meaning, and in effect It is impossible to eavesdrop.

Therefore, the present invention can fundamentally prevent telephone eavesdropping, which is a major social problem, and is a useful tool.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing eavesdropping, FIG. 2 is a circuit diagram of an embodiment of the present invention, FIG. 5 is an explanatory diagram explaining the memory address designation operation of FIG. 2, and FIG. It is a clock signal explanatory diagram. A, B...Telephone subscribers. C... Wiretapping subscriber. EX...exchange machine. 1 figure X

Claims (1)

[Claims] 1. In a telephone equipped with a coder that separates analog signals in both directions into reception and transmission analog signals, and further performs analog-digital conversion, and a decoder that performs digital-to-analog conversion, a memory that stores the transmitted signal digitized by the coder; and a memory for storing the received signal received from the exchange, and an addressing circuit for specifying the memory address according to instructions from the telephone user, and the reading address of the transmitting memory is set to the transmitting address. A wiretapping prevention circuit characterized in that a write address of the receiving memory is performed from a memory addressing circuit and a receiving memory addressing circuit.