JPS5961329A - Cryptic communicating system - Google Patents

Abstract

PURPOSE:To attain cryptic communication with high transmission quality, by providing a detour circuit giving a detour to a signal from one cryptic line to the other cryptic line without passing through each voice analysis synthesizer in an exchange station. CONSTITUTION:In connecting a subscriber 11A to a subscriber 11B, the subscriber 11A is connected to the subscriber 11B through normal lines 21A, 21A', an analog exchanger 13 and normal lines 21B, 21B'. When a subscriber desires the cryptic communication, a cryptic command signal is outputted from the subscriber, a detector DET of each line detects the command signal, which controls a switch to change over the line to the cryptic position. In this case, the voice from the subscriber 11A is converted into a digital signal at a voice analysis synthesizer V, encrypted at a digital encryptor P and transmitted to an exchange station through an MODEM M. The signal is detoured at a digital repeater 31 via the MODEM M and the device P in the exchange station as the digital signal, transmitted to the subscriber 11B through the device P and the MODEM M, and the signal is reproduced through the MODEM M and the devices P, V.

Description

[Detailed description of the invention] (]) Technical fields from The present invention relates to a secure communication system.

(2) Background of the technology General audio and other signals are the same! The signal is transmitted from one subscriber to another via a switching center as a baseband signal or as a signal modulated by PCM or the like. Since this transmission is performed through a carrier circuit, there is a possibility that it may be subject to so-called eavesdropping. For this reason, for example, signals such as audio that belong to trade secrets are subjected to secrecy processing, and then
transmitted from one subscriber to another subscriber. The other subscriber cancels the ciphering process and then reproduces the original voice or other signal. The present invention refers to such a secure i+71 communication system.

(3) Prior Art and Summary Figure 1 is a block diagram showing an example of a general communication system. In this figure, 11A and IIB are remote subscribers;
11C is a central subscriber, which is connected to an analog exchange (for example, a 2W (wire) analog exchange) 1 via the transmitting end station equipment 12A and 12A' and 12B and 12B'.
Connect to 3. The central subscriber 11C is connected directly to the analog exchange 13 in the case shown.

By the way, the carrier end station devices 12A and 12A' and 12B and 12B' are connected through transmission lines 14A and 14B, respectively. In this case, there is a risk that information, such as audio signals, between subscribers may be intercepted. For this reason, information that requires secrecy is treated confidentially and transferred to the transport line 14A.
, 14 B. Note that 15 in the figure indicates the area of one switching center.

Generally, analog carrier lines are often used as the carrier lines 14A and 11B, and analog concealment processing must be performed to avoid this. Of course,
This analog concealment process is usually technically complex, so
The cost of concealment processing is quite high. Therefore, the current situation is that the transmission cost of information that needs to be kept confidential is high and its usage is low.

Therefore, the present applicant generally proposes a digital concealment device 1.1.
Noting that a low-cost and high-performance device has been realized, we attempted to perform 11 secrets using this digital concealment device. Configuration 1 shows a 16-secure communication system.In this figure, 1111 minutes shown by each set of M, P, and V or V, P, and M is the main +915 minutes of the attempt, and Mk
t modem, Pl [digital concealment device, ■ is a voice analysis and synthesis device. The modem MFi analog signal is converted to a digital signal (7) 51:, and the j1 digital signal β is converted to an analog signal. Device P performs 8@ processing on the digitizer) L signal. The device V analyzes the analog signal and converts it into a digital signal (No. 8), or returns the decrypted digital signal to an analog signal via the device P.

21A, 21A', 21B and 21B' are normal optical line parts, but v-P-M (or ~1-P-V
) has been slightly resemblance added to work with the set. That is, the changeover switch 22A.

22 r+ , 23 A 123 B , 22A'
, 22B', 23A'.

23B' is newly provided. These changeover switches are switched from 1 to 1 by a detector indicated by 1') ET in the figure. +
(Upper contact or lower (to Ql contact). Note that the changeover switches marked 22 and 23 are interlocked with each other).

What is noteworthy about the configuration of the above trial is that the system as a whole still constitutes an analog network. In other words, it is possible to use an inexpensive and high-performance digital concealment device P without destroying the analog network structure. Therefore, the transmission cost of information to be kept confidential is reduced.

The operation is as follows. First, when connecting from subscriber 11A to subscriber 11B, 1) subscriber 11A goes off-hook and the other subscriber 1, I
C'r dial. Detector 1) ET detects this off-hook and first changes the t#Il exchange switch 22A (2
3A) to the upper contact. Set it on a tsusuri Heihishin decoy. This can also be done automatically using (■) described below. At this time, the changeover switch, switch 23A'.

228' are both connected to the upper point 41j, and there is no instruction (to be described later), always connect the optical line 21A' side.

(2) 2W analog AC t'? machine] 31-. i. Complete the above dialing process to connect to the destination subscriber 11c. In particular, the conventional analog system was established.

(2) When the subscriber 11A desires to receive a confidential a-mail, the subscriber 11A selects the confidential line side, that is, the V-P-M set. For example, by pressing the 4rsj button on a button telephone, the detector DgT is activated, and each 1γ point of the changeover switches 22A and 23A is connected to the lower side. Also, the signal of the nabutton is 4'', ;:no transmission ffl:N 14 A, and the detector 1) on the 8' side of the plano-concave line 21 is set to a value of 1.
Lower each contact of selector switches 23A' and 22A' ([
11, that is, the secure line fP'J (Qll). Thus, a secure line is established.

■ The confidential voice analog signal from the subscriber 11A is converted into a digital signal by the voice synthesis and analysis device V, and then
The signal is applied to the digital concealment device P and subjected to concealment processing. Furthermore, the signal is converted into a confidential analog signal by a modem M in order to be transferred to a telecommunications analog communication network.

G) Thus, the confidential analog signal carried on the general transmission line 14A enters the modem M through the lower contact of the changeover switch 23A' and converts the confidential analog signal into a digital signal. Furthermore, the secrecy is canceled in the device P, and the tart signal is returned to the normal analog signal in the next stage device (2). Note that M, P, and V each include two processing systems Fc, and in the case where the signal is transferred from V − + p → M and when the signal is transferred from M − + P → V, respectively. Different processing systems.

As described above, the analog signal reaches the exchange 13 and further reaches the other subscriber 11C.

G) Conceal as much as possible lPj, Ur! ? It should be finished in between. This is to minimize the chance that the 114 code will be decoded by a third party. For this reason, t・11
¥ call f: When ending, press 1fll, for example -7
° Push the button on the screen, activate the detector DET at the button corresponding to the ≠ button, and set the changeover switches 22A, 23A and 22A', 23A' to the upper shield, that is, the normal flat concave position. Return to IN fl!I+.

Next, subscriber 11. Connecting from A to subscriber 11B 1!
In case A, (1γ) As in (1) above, the destination subscriber 11B is dialed and the half-line side is selected.This can also be done automatically using the GY command described later.

(2)' Same as above 11■ (/C1 subscriber 11■3
7) Establish a regular analog line.

(3)' Similarly to the above ■, changeover switches 22A, 23A, 23A', 22A', 22 in No. 11)J
B', 23]'3'.

23 B, 22.11 (B strains are each D
F: Connect each contact (controlled by T) to the lower side to establish a secret line) 7'.

(4)′ Move 111i similar to (4) and ■ above:
Subscriber who reached analog exchange 13 at i] 1, A
Analogue from (U is folded 9 times here, f; JI
V → P → M → 1 from the bottom 1 point of P switch 2211'
411 → [511 conversion switch 23B lower side, 1 loaf point → M
-) P - + V to subscriber 11B.

■' Same as ■ above (:; β, for example, press the hrx button to remove 117r from secrecy and end the call.

Now let's talk about the problem that we are trying to solve. In FIG. 2, it has been assumed that, for example, when a secret call is made between subscribers 11A and 11B, the transmission quality deteriorates compared to the case of the X1 line.

The deterioration of this transmission product due to its age is a problem.

(4) Purpose of the Invention In view of the above-mentioned problems, the present invention provides a method for concealing Akane transmission quality,
The purpose is to provide a system that can perform ft.

(5) Is it Ming's 17'? In order to achieve the above object, the present invention provides the transmission product 'ji
``Atsunai's deterioration of voice analysis and synthesis device V 2 link seed''
The reason is that the signal is transmitted through two lines ('ζ arrival').
1, cross 1λ:゛(Inside station 15, l, -, from the hidden line of power to the other J, 14 Hirokawa, each voice part i synthesis recommended V 1j 1 without a formula, The '11f' feature is to provide a detour to detour the signal.

(6) Embodiment of the Invention Figure 3 shows an example of the invention based on the present invention. Basically the same reference number I) k number and rainbow (,
Shown with No. 1. Therefore, ;31 in this figure is the circuit 31 which is a detour for the subscriber to pass through.
The signal is detoured as indicated by the arrows FJJQ in FIG. When the + button is pressed, the digital trunk exchange connects the subscriber 11A to the subscriber 11B on the secret line side through the detour 31. In this case, the device P located at the top 1 of the arrow Q is Once the secrecy is removed, the signal device on the detour 31 is concealed again using human power 17 and the device P located below the arrow Q.

In this way, the number of passes through the speech analysis and synthesis device V, which is not the cause of characteristic deterioration, is reduced from 2 links in the case of Fig. 2 to 1 link, and no significant characteristic deterioration occurs in the signal.

The disadvantage of the digital relay exchange shown in FIG. 3 is that it is expensive and requires a large number of control trees.The following embodiment is suitable for eliminating these disadvantages. No. 4191
FIG. 2 is a configuration diagram not showing a second embodiment based on the present invention. The detour 41 shown in this figure is composed of a 4W (wire) analog trunk exchange and therefore does not have the above-mentioned drawbacks. However, a modem M' as an interface must be provided at the input/output section. /r11 is the modem M' on the analog exchange 13 side.
&Yo is necessary when making a secret call with the central subscriber 11C.

(7) Effects of the Invention As explained above, according to the present invention, even though it is an analog-based telecommunications network, it is possible to carry out confidential communication using an inexpensive and high-performance digital concealment device, and also to secure the confidentiality. NJ function suppresses deterioration of transmission quality in communication.

[Brief explanation of drawings]

Figure 2111 is a block diagram showing an example of a general communication system + Figure 2 is a block diagram showing a secure communication system attempted by the present applicant, and Figure 3 is a block diagram showing a first embodiment based on the present invention. 4 are configuration diagrams showing a second embodiment based on the present invention. 11A, 11B, 11C...Subscriber, 13...Analog exchange, 14A, 14B...4? Mr. N, 15
... Y switching area, 21 A, 21 A', 71
R, 21B'... Plano-concave line system, 22AI23A, 2
3A'122A'122B, 23B', 22B'
, 23B...t;71 Jl'! Switch, M...
Mob Mu, P...'Izikuru Hidden Device N-1■...
F6 Voice analysis/synthesizer F, 2.31, 41...Detour, Δ/τ...Interface modem 'I'jr rF 1.1 digits Fujitsu Ltd.! ! '41'r Patent attorney Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Uchida Patent attorney Akira Yamaguchi Figure 1 □-45-- Figure 2

Claims (1)

[Scope of Claims] 1. A switching center including a plurality of subscribers, an analog switch connecting at least two of the multiple subscribers, and a switching center connecting these subscribers via the analog switch. A communication system comprising a carrier line connecting between the subscribers, wherein the subscriber (4) is parallel to the existing flat line constituting the carrier line. The system is equipped with a secret line consisting of a modem and a voice analysis/synthesizer connected in series with a digital concealment device in the middle, and a changeover switch for selectively selecting between the modem and the voice analysis/synthesizing device. In addition, in the switching center, the analog switch also has a front; i
+-! The modem is equipped with a secret line and a 1-71 conversion switch similar to a secret line and a 1-71 conversion switch, and the modem converts an input analog signal into a digital signal, or converts an input digital signal into an analog signal. The di-notal concealment device performs J"6 concealment processing on the input F(digital signal) or cancels the concealment, and the speech analysis and synthesis device converts the input analog signal into a digital signal, or converts the deciphered 7' digital signal from the digital security device into an analog signal; 1. A secret communication system characterized by the following: 1. A detour is provided to bypass the analog signal without passing it through the voice analysis/synthesis device. 2. The detour is from the opportunity of Dinotal's middle phase! exchange ↑ Naru! 1″
〒11' [Secret 1 communication system set forth in Claim 1. :3 Detour is 4w (wire) analog relay exchange tA%
It is equipped with a modem as an input/output interface! 1″￥koma:Claim ff:'ll Shin α11
11th tj+V Concealment 11 Pursuit Systemdem.