JPH01189246A - Communication data enciphering adapter equipment and communication data deciphering adapter equipment and system for enciphering/deciphering communication data using them - Google Patents

Abstract

PURPOSE:To improve the confidentiality of a data communication by mounting a communication data enciphering adapter equipment between a data transmitter and a communication line without giving any change to the data transmitter. CONSTITUTION:A communication data enciphering adapter equipment 2 is provided between a data transmitter 1 and a communication line 3, and it has means as follows in addition to a line switching means 21. A line condition detecting means 22 detects a call from the data transmitter 1. A control code monitoring means 23 monitors a communication control code sent from the data transmitter 1. A scrambling means 25 executes a prescribed coding to communication data sent from the data transmitter 1 after the communication control code is detected by the control code monitoring means 23. A driving control means 24 cooperates with respective means. Namely, the communication data from the data transmitter 1 are coded, and they are outputted through the line switching means 21 to the communication line 3. As a result, even when a mistransmission is executed, privacy cannot be released.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a communication data encryption adapter device and communication device applied to a data communication system in which a data transmitting device and a data receiving device are connected via a communication line. Data decryption adapter devices, communication data encryption and
Regarding decoding methods.

[Prior art and problems to be solved by the invention]

For example, a data transmitting device such as a facsimile device can easily communicate data with a destination facsimile device via a telephone line.

However, if the destination telephone number is entered incorrectly due to an erroneous operation or malfunction in facsimile communication, information will be sent to the wrong destination. In this case, a problem is encountered in which highly confidential information is reported to a third party. Additionally, there is a risk that communication information may be intercepted along the telephone line system. Erroneous transmission of confidential information due to erroneous operations, etc., and eavesdropping due to the use of public communication lines such as telephone lines, occur not only in facsimile communications but also in PC communications and other communications.

Furthermore, not only when public communication lines are used, but also in communication systems using LAN, when specific parties send confidential information to each other by facsimile, the problem of confidential information being leaked to a third party due to erroneous transmission can occur. ing.

That is, there are problems of erroneous transmission in an n-to-n communication system and eavesdropping due to the use of public lines. Regarding the former, since human operations are involved, no effective electrical circuit measures have been taken. Regarding the latter, encryption/decryption methods have been attempted, but they are generally methods that are intended for communication between specific parties, and are similar to those used in facsimile communications.
No attempt has been made to apply it to a n-to-n communication system.

The present invention is applicable to local networks such as general public lines or LANs.
Regardless of the communication system that uses AM4, it is an encryption/decryption method that maintains relative confidentiality, can be easily applied to new or existing systems, is easy to use, and is inexpensive. is intended to provide.

Another object of the present invention is to provide an encryption adapter device and a decryption adapter device that can be applied to such encryption/decryption methods.

[Means for Solving the Problems and Effects] In order to achieve the above object, the present invention provides a communication data encryption method that can be coupled between a data transmitting device 1 and a communication line 3, as shown in FIG. An adapter device 2 is provided.

The communication data encryption adapter device 2 includes a line switching means 21 for switching the line between the data transmitting apparatus and the communication line, a line state detecting means 22 for detecting a call from the data transmitting apparatus, and a line state detecting means 22 for detecting a call from the data transmitting apparatus. Control code monitor means 2 for monitoring communication control codes sent from the transmitting device
3, scrambling means 25 for performing predetermined encryption on communication data sent from the data transmitting device after the control code monitoring means detects the communication control code; drive control means 24 for outputting encrypted communication data from the communication line to the communication line via the line switching means. As a result, encrypted communication is possible without making any changes to the data transmitting device, simply by attaching the communication data encryption adapter device between the data transmitting device 1 and the communication line 3. As a result, even if there is an erroneous transmission, the confidentiality will not be broken.

The present invention also provides a communication data decoding adapter device 4 which can be coupled between the communication line 3 and the data receiving device as shown in FIG. This communication data decryption adapter device 4 corresponds to the data encryption adapter device 2 described above.

The communication data decoding adapter device 4 includes a line switching means 41 for switching the line between the communication line and the data receiving device, and a line state detection means 42 for detecting a call input via the communication line. , a control code monitor means 43 for monitoring a communication control code input via the communication line; and after the control code monitor means detects the communication control code, decrypting the encrypted data input via the communication line. It comprises a descrambling means 45, and a drive control means 44 that cooperates with each of the above means, inputs the received signal, and outputs decoded data to the data receiving device via the line switching means. . As a result, communication line 3 can be connected without making any changes to the data receiving device.
By simply attaching a communication data decoding adapter device between the communication data decoding device 5 and the data receiving device 5, decoded data can be applied to the data receiving device.

Furthermore, as shown in FIG. 1, the present invention provides a communication data encryption/decryption method that includes the above-mentioned communication data encryption adapter device 2 and communication data decryption adapter device 4 to perform encryption and decryption. do.

In such a communication data encryption/decryption method, decryption of communication data is valid only on the called side, which is equipped with a communication data decryption adapter device that is compatible with the communication data encryption adapter device provided on the calling side. It becomes possible to do this. Therefore, even if there is an erroneous transmission, since the communication data decoding adapter device is not provided at the erroneous transmission destination, effective decoding will not be performed and confidentiality will not be compromised. Furthermore, since the data on the communication line is encrypted, confidentiality is maintained.

In the communication data encryption/decryption method, communication data encryption adapter device 2, communication data decryption adapter device 4
does not necessarily have to be removable. In other words, it may be installed all the time. However, it is desirable that not only encryption but also normal data transmission and reception be possible for data transmission and reception. For this reason, the line switching means 21 of the communication data encryption adapter device 2 is provided with a switch for bypassing the function depending on whether or not to perform encrypted communication. On the side, a changeover switch can be added in the line switching means 41 so that the drive control means 44 identifies the destination and activates this function only in the case of data communication from the destination for encrypted communication. .

In data communications, data transmission and reception functions are often used together, such as in facsimile machines. Therefore, if a fishing boat is provided with a data transmitting/receiving device 7.8 via a communication line 3 as shown in FIG. A data decoding adapter device 4 can be provided.

〔Example〕

An embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 3 shows a circuit diagram of an encryption/decryption device applied when transmitting and receiving data via a telephone line 3a using facsimile machines 1a and 5a as a data transmitting device and a data receiving device, respectively.

On the calling side, an encryption adapter (or facsimile scramble adapter: PSA) 2a is provided between the facsimile device 1a and the telephone line 3a. A decoding adapter (or facsimile descrambling adapter: FDA
) 4a is provided. These FSA 2 a and FDA 4 a are connected to the existing facsimile communication system as well.

It is configured so that it can be easily attached to TOI; TI2 and TO2. Moreover, it is constructed so that it can be easily removed once it has been installed.

In the illustrated embodiment, in order to simplify the explanation, one-to-one
Although the case of communication will be exemplified, it goes without saying that n-to-n communication is generally possible via a public line. In addition, even in the case of one-to-one communication, two-way communication is generally performed, so
In many cases, an encryption adapter and a decryption adapter are installed between each facsimile machine and the telephone line, but in the illustrated example, the explanation will be made separately for the calling side and the called side. do.

The encryption adapter (FSA) 2a has relay switches 211, 212, 214 and a capacitor 213 as the line switching means 21, and these relay switches 211゜2
Relays RL3.12 and 214 are driven via driver circuits 237, which will be described later. RL2. This is an RLI relay contact. The capacitor 213 cuts the direct current flowing into the line, and its details will be described later.

The FSA 2 a includes a bell detection circuit 221, an off-footer detection circuit 222, and a CPU 234, which will be described later, as the line state detection means 22. Furthermore, the PSA 2 a includes a carrier detection circuit 231, an asynchronous communication module (USART) as a control code monitor means 23, a drive control means 24, and a scrambling (encryption) means 25.
232, I10 interface 233, CPU 2
34, tlsART 235, I10 interface 237, isolation transformer 30.2 wire/4vA conversion circuit 26, MODEM 27, MODEM 29.4v
It has an A/2-wire conversion circuit 28 and an isolation transformer 31.

Details of FSA 2 a will be described later in connection with its operation.

The decoding adapter (FDA) 4a is a descrambler (
The configuration is similar to that of the FSA 2a, except that decoding is performed using a decoding means. Descrambling is done by CPU
434.

The circuit diagrams in FIGS. 3 to 6 are basically the same, but the circuit diagrams in each mode of line status monitor, control code monitor 1, data communication, and control code monitor 2 are more specific. represents the difference in the status of the input signal in the line switching means 21.41.

The encryption/decryption process will be described below.

FIG. 3 shows the circuit state in mode 1, ie, the "line state monitor" mode. A relay switch 214 on the encryption adapter PSA Z a side connects the telephone line 3a and the facsimile machine 1a, and a relay switch 414 on the FDA A a side connects the telephone line 3a and the facsimile machine 5a. On the other hand, relay switch 2 on the FSA Z a side
12 disconnects the MODEM 27 system line (route) from the calling side line, and switches the relay switch 412 on the FDAda side.
Also MODII! The M47 line is disconnected from the called line. Naturally, the relay switch 214 opens EM29 system, and the relay switch 414 opens MO
DEM 49 line has been disconnected from the above line. However, the line status detection means 22 on the FSA Z a side,
The line state detection means 42 on the FDA Aa side is connected to the above line and is configured to be able to constantly monitor the above line state.

The contact states of the relay switches shown by solid lines in FIG. 3 indicate the initial state when FSA 2 a and FDA 4 a are connected, and relays RLI to RL3. R.L.
This corresponds to the case where 4 to RL6 are deenergized in the initial state.

The operation of the line status monitor in FIG. 3 will be described with reference to the operation flowcharts of FIG. 7 on the calling side and FIG. 8 on the called side.

Step 01.02 (SOI, SO277) When the calling party picks up the receiver (goes off-hook) to call the destination, the line loops and the voltage becomes Ov. This is detected by the off-hook dial pulse detection circuit 222 in the encryption adapter (FSA) 2a and input to the CPU 234 via the I10 interface 233.

Then, FSA 2 a is set to the ninth position for a certain period of time after the off-footer.
The off-hook dial pulse detection circuit 2 determines whether a dial pulse occurs within tl in Figure (a), for example, 13 seconds.
22 and input to the CPU 234 via the I10 interface 233. FIG. 9 (al shows the dialing timing diagram of the calling side. If a certain period of time t
If no dial pulse occurs within 1, step 0
Return to 1.

The above is F3A2 for the call originating from the facsimile machine 1a.
This is the action of a.

21.22 (S21 S22, 8') On the called side, in response to the above call processing step Of, 02, the ring detection circuit 421 of the decoding adapter (PDA) 4a detects the call from the facsimile machine 1a. Detect a sound (bell) (
S21). After detecting the ring tone, for a certain period of time, for example, FIG.
), the off-footer dial pulse detection circuit 422 checks whether off-footer detection has continued for 1 second or more corresponding to t2 (S22). If the off-footer detection does not continue for 1 second or more, the process returns to the ring tone detection process again.

FIG. 9 (bl) shows the timing diagram of the called side.

Step 03 (SO3), Susopu 23 (S23
) When the occurrence of dial pulse is detected, FSA 2 a
cpυ234 drives relay RL2 via I10 interface 236 and driver circuit 237, and closes relay switch 212 (SO3).

The called party also issues F if off-footer detection continues for 1 second or more.
DA4a CPU 434 is I10 interface 4
36. Drive relay RL5 via driver circuit 437 to close relay switch 412 (S23).

The above circuit state is illustrated in FIG. The illustrated state is called the "control code monitor I" mode. This control code monitor mode monitors control codes between facsimile machines. On the calling side FSA 2a, the control code of the facsimile machine 1a is connected to the capacitor 213, relay switch 212, 211, 2-wire/4-wire conversion circuit 26, MO
DEM 27, carrier detection circuit 231, USART
232, the signal is converted, and the CPU 2
34. The capacitor 213 cuts the inflow of direct current into the line, maintains the current in the line, and prevents the telephone receiver of the calling side facsimile machine 1a from not being able to hear the ringing tone.

For example, the control code of the facsimile machine 1a is C.
The CPU 234 monitors the FR (transmission permission) code (SO3).

The above-mentioned control code monitor also uses the transformer 50, 2-wire/4-wire conversion circuit 46, MODEM
4. ? , carrier detection circuit 431, USART 432
This is performed by the CPU 434 via the CPU 434 (S23).

Step 04, 05 SO4SO5, Step 24
25 (S24, 525) In the case shown in FIG. 4, whether the above control code is received within a certain period of time, for example, 8 seconds after the relay RL2 is driven in the calling side FSA 2a and the relay switch 212 is closed. Check whether or not (SO4). If it is not received, the CPU 234 turns off the relay RL2, opens the relay switch 212 (broken line in the figure), and returns to step 02 again (SO5).

The called side FDA 4a also drives the relay RL5 and checks whether the control code is received within 8 seconds after the relay switch 412 is closed (S24). If not, the CPU 434 turns off the relay RL5 and opens the relay switch 412 (dashed line shown), step 2.
1 and performs dialing detection again (S25).

During the above operation period, the above-mentioned FS^2a and FDA4a are communicated between facsimile machines via the telephone line 3a.
The same control processing as before is performed independently of the above.

If the control code is properly received, the device shifts to data communication mode. Encryption and decryption in the data communication mode will be described below with reference to FIG.

SO6 SO6, SU-” 6 S26 Calling party F
CPU 234 in SA2a drives relays RLI and RL3 via I10 interface 236 and driver circuit 237, and switches relay switch 214゜2.
11 is brought into the state shown by the solid line in FIG. 5 (SO6). That is, while the direct line between the facsimile machine 1a and the telephone line 3a is cut off, the relay switch 211, the transformer 30, the 2-wire/4-wire conversion circuit 26, the MODEM 27,
Carrier detection circuit 231, USART 232, CPU
234, USART 235, MODEM29. A line constituting the scrambling means 25 formed by the 4-wire/2-wire conversion circuit 28, the transformer 31, and the relay switch 214 is established.

Also on the called side, the CPU 434 in FDA Aa connects relay RL4. RL6 is driven to bring the relay switches 414 and 411 into the state shown by the solid line in FIG. 5 (S26). As a result, the direct line between the telephone line 3a and the facsimile machine 5a is cut off, while the relay switch 411, the transformer 50, the 2-wire/4-wire conversion circuit 46
, MODEM47, carrier detection circuit 431, USAR
T 432, CPU 434, USART 435, M
A line forming the scrambling means 45 formed by the ODEM 49.4 &jl/2-wire conversion circuit 48, the transformer 51, and the relay switch 414 is established.

Soup 070B (SO7, SO8, Soup 2728
(S27.328) The calling side FSA 2 a receives the transmission data from the facsimile machine f 1 a via the MODIliM 27, and encrypts (scrambles) it in the CPU 234.
The encrypted data is transmitted to the communication line 3a via the MODEM 29 (SO7, 5O8). As for encryption, the 10th
As shown in the figure, if the transmitted data is 8 bits, the upper 4
Various methods can be used, such as exchanging the bits or rotating the bit by one bit to the left four times as shown in FIG.

On the calling side FDA 4a, the CPU 434 receives the encrypted transmission data input via the communication line 3a via the MODEM 47, decodes (descrambles) the received data, and sends the encrypted transmission data to the facsimile machine 1a. The same data as that outputted from is sent to facsimile machine W5a via MODEM 49 and relay switch 414 (S27, 328). Descrambling is performed by performing the opposite operation to the scrambling shown in FIG. 10 or FIG. 11.

In the facsimile device 5a, the facsimile device 1
The transmitted data from a is restored.

The above encryption/decryption is continuously performed for one page of facsimile paper.

Steps 09-11 (SO9-511), Susobu 29
~31 (529~531) In facsimile communication, after sending one page of data, it takes 75±2 until the next control code is sent.
There is a carrier of 0ms. The carrier is detected by the carrier detection circuit 231 in the calling side FSA 2a and by the carrier detection circuit 431 in the called side FD^4a. The carrier detection is carried out by the CPU 234, 43
4, and CPUs 234 and 434 each receive 1
Detects that data communication for one page has ended (SO
9, 529).

■When it is detected that data communication for a page has ended,
The calling side CPU 234 turns off the relay RLI and sets the relay switch 214 to the state shown by the solid line in FIG. 6 (SIO
). Similarly, the called side CPU 234 turns off the relay RL4 and sets the relay switch 414 to the state shown by the solid line in FIG. 6 (S30). The line state shown in FIG. 6 is that the line formed by the facsimile machine 1a-telephone diagram 'h'A3a-facsimile machine 5a is established, and on the calling side, the facsimile machine W1a-MODEM
27 (Typical example) - A line for the CPU 234, on the called side, a telephone line 3a - MODEM 47 (Typical example) - A line for the CPU 434 is established. The latter F
The line within SA2a and the line within FDA d a again make it possible to monitor control codes between facsimile machines.

In such a control code monitor state, the calling FSA
cp port 234 in 2a and C in called side FD^4a
Both PII 434 are multi-page signals (MPS).
code) is received or a disconnection command signal (DCN code) is received (Sll, 531).

If the MPS code is received, data communication for the next page continues, so the process returns to step 06 on the calling side and step 26 on the called side.

When S12 (S12) receives the S32 disconnection command signal, it disconnects the line as described below.
As shown in the figure, the device is returned to its initial state so that it can respond to the next call.

On the calling side, CPIJ 234 turns off relays RL2 and RL3. As a result, the line forming the scrambling means 25 and the control code monitoring means 23 is disconnected from the line between the facsimile machine 1a and the telephone line 3a. However, the line state detection means 22 and the drive control means 24 are operable.

Also on the called side, CPU 434 turns off relays RL5 and RL6. As a result, the line forming the descrambling means 45 and the control code monitoring means 43 is disconnected from the line between the telephone line 3a and the facsimile machine. However, the line state detection means 42 and the drive control means 44 are operable.

As described above, the line formed by the communication line 3a and the facsimile apparatus 5a is disconnected from the facsimile machine la as shown in FIG. Only if it is bypassed. Therefore, before that,
It operates in parallel with the encryption adapter 2a and the decryption adapter 4a. That is, the transmission and reception of control codes is the same as in the prior art. Furthermore, even if the data is encrypted by the scrambling means 25 and decrypted by the descrambling means 45 during data communication, the facsimile apparatuses la and 5a themselves are not affected by these encryptions and decryptions. Therefore, the encryption adapter 2a and the decryption adapter 4a can be easily applied not only to newly installed communication systems but also to existing communication systems.

During data communication, since encrypted data is transmitted over the telephone line 3a, the transmitted data is highly confidential.

As mentioned above, no changes were made to the protocol itself. Therefore, the encryption adapter and decryption adapter of the present invention can be easily applied to various other communication systems.

For example, the present invention can be easily applied to personal computer communication by simply changing the above-mentioned characteristics of facsimile communication, such as the detection of the end of one-page data communication and the presence or absence of multi-page signal reception.

In the embodiments described above, an encryption adapter and a decryption adapter are provided on the calling side and the called side, and encrypted communication is normally performed. Therefore, even if the confidential information is mistakenly sent to a facsimile machine that is not equipped with the above-mentioned decoding adapter, the confidential information will not be restored normally.

That is, if it is desired to communicate confidential information, the above-mentioned encryption adapter and decryption adapter may be provided between the facsimile machines.

It is also possible to attach the encryption adapter and the decryption adapter only when it is desired to perform confidential information communication, and otherwise perform normal facsimile communication. To do this, as shown in FIG.
~ When the encryption adapter 2a is connected to the socket of the TOI, it opens as shown by the solid line in the figure, and when the encryption adapter 2a is removed, the facsimile device 1a and the telephone line 3 are opened as shown by the broken line in the figure.
A well-known socket switch 11 can be provided, configured for direct connection with a. A similar socket switch 12 can also be provided on the called side.

It goes without saying that the encryption adapter and the decryption adapter can be built into the facsimile machine. If built-in, the modems 27 and 29 for the encryption adapter and the modems 47 and 49 for the decryption adapter can be shared with the modems in each facsimile machine, and can be deleted.

On the other hand, unlike FIG. 12, as shown in FIG. 13, a mode switch 13 and a power supply 14 are provided, and encrypted communication is performed when the mode switch 13 is manually turned on while the encryption adapter 2a is connected. , when the mode switch 13 is manually turned off, communication can be performed. In this case, there is no need to attach or detach the encryption adapter, and it is sufficient to simply turn the mode switch 13 on and off. Similarly, a mode switch 15 and a power source 16 can be provided on the called side.

When performing bidirectional communication in facsimile communication, personal computer communication, etc., as shown in FIG.
．． An encryption adapter device and a decryption adapter device can be provided on each side of 8 as required.

The present invention can be applied to various data communication systems other than one-to-one data communication systems.

[Effects of the Invention] As described above, the encryption adapter device and decryption adapter device of the present invention have a relatively simple circuit configuration, and do not require any changes to the protocol itself.
No changes are made to communication lines or data transmitting/receiving equipment. Furthermore, no deterioration in transmission quality occurs. Therefore, the encryption adapter device and decryption adapter device of the present invention can be easily applied to various data communication systems, regardless of whether they are new or existing communication systems.

By applying the encryption adapter device and decryption adapter device of the present invention, encrypted data communication becomes easily possible, and the confidentiality of data communication is improved.

Furthermore, even if data is sent by mistake to a destination where a decoding adapter device is not installed, the transmitted data will not be effectively reproduced, so the risk of release of confidentiality due to mistaken data transmission is avoided.

[Brief explanation of the drawing]

1 and 2 are principle block diagrams of the communication data encryption/decryption method of the present invention, and the encryption adapter device and decryption adapter device applied thereto. The circuit diagrams of the encryption/decryption method according to the embodiment of the invention, FIGS. 7 and 8 are the encryption/decryption system diagrams in FIGS.
Decryption operation flowchart, Figures 9(a) and 9(b) are timing diagrams in Figures 3 to 6, Figures 10 and 11 are diagrams showing encryption in the embodiment of the present invention, Figure 12 and FIG. 13 is a circuit diagram showing another embodiment of the present invention. (Explanation of symbols) 1... Data transmission device, 2... Encryption adapter device, 3... Communication line, 4... Decryption adapter device, 5... Data receiving device, 7.8. ...Data transmission/reception device, 21.. Line switching means, 22.. Line status detection means, 23.. Control code monitoring means, 24.. Drive control means, 25.. Scrambling means, 41.. - Line switching means, 42... Line status detection means, 43... Control code monitoring means, 44... Drive control means, 45... Descrambling means.

Claims (1)

[Claims] 1. Line switching means configured to be coupled between a data transmitting device (1) and a communication line (3), and switching a line between the data transmitting device and the communication line. (21), a line state detection means (22) for detecting a call from the data transmitting device, a control code monitoring means (23) for monitoring a communication control code sent from the data transmitting device, and a control code monitoring means (23) for monitoring a communication control code sent from the data transmitting device; scrambling means (25) for performing predetermined encryption on communication data sent from the data transmission device after the code monitor means detects a communication control code; A communication data encryption adapter device comprising: drive control means (24) for outputting encrypted data to the communication line via the line switching means. 2. a line switching means (41) configured to be coupled between the communication line (3) and the data receiving apparatus (5), and for switching the line between the communication line and the data receiving apparatus; A line state detection means (42) for detecting a call input via a communication line; a control code monitor means (43) for monitoring a communication control code input via the communication line; and a control code monitor for monitoring a communication control code input via the communication line. a descrambling means (45) for decoding the encrypted data input via the communication line after detecting the communication control code by the means; Drive control means (44) for outputting data to the data receiving device via the line switching means
A communication data decoding adapter device comprising: 3. In a data communication system having a data transmitting device and a data receiving device connected via a communication line (3), provided between the data transmitting device and the communication line,
a line switching means (21) for switching a line between the data transmitting device and the communication line; a line state detecting means (22) for detecting a call originating from the data transmitting device; Control code monitoring means (23) for monitoring a communication control code sent from the data transmitting device after a call is detected; and scrambling means (25) for performing predetermined encryption on the communication data sent from the data transmitting device. and a drive control means (24) that cooperates with each of the means and outputs encrypted communication data from the data transmission device to the communication line via the line switching means.
) and a communication data encryption adapter device (2).
), provided between the communication line and the data receiving device,
a line switching means (41) for switching a line between the communication line and the data receiving device; a line state detection means (42) for detecting a call input via the communication line; a control code monitor means (43) for monitoring a communication control code inputted through the communication line; and a descrambling means for decoding the encrypted data inputted through the communication line after the control code monitoring means detects the communication control code. (45), and a drive control means (44) that cooperates with each of the means, inputs the received signal, and outputs the decoded data to the data receiving device via the line switching means.
) and a communication data decoding adapter device (4).
), the communication data from the data transmitting device is encrypted and transmitted, and the encrypted communication data is decrypted and applied to the data receiving device. method. 4. The communication data encryption adapter device (2) is configured to be detachably installed between the data transmission device and the communication line, and only when the communication data encryption adapter device is installed. 4. The communication data encryption/decryption method according to claim 3, characterized in that the communication data is encrypted. 5. The communication data decoding adapter device (4) is configured to be detachably installed between the communication line and the data receiving device, and only when the communication data decoding adapter device (4) is installed. Claim 3, characterized in that the device is configured such that received communication data is decoded.
or the communication data encryption/decryption method described in 4.