JPS62140530A - Multiplexing device with enciphering function - Google Patents

Abstract

PURPOSE:To prevent a key from being deciphered by a tapper, by providing an enciphering function part for enciphering a bit excluding a frame synchronizing bit and a housekeeping bit in a multiplexing signal on a high speed highway, and outputting the excluded bit without enciphering it. CONSTITUTION:A high speed highway signal 11 is enciphered by an enciphering device 4. However, in such a case, by a control pulse 61 outputted from a frame synchronizing bit and housekeeping bit control pulse generator 6, the encipherment of a frame synchronizing bit and a housekeeping bit is stopped. As for an output of the enciphering device 4, only main information is enciphered, and by making this cipher pass through a frame synchronizing bit and housekeeping bit inserting device 5 which is controlled by a control pulse 62 outputted from the control pulse generator 6, the frame synchronizing bit and the housekeeping bit are put to this cipher, and it is sent out as a final output 51 to a transmission line. A receiving part executes an entirely reverse operation, and the same plain sentence as plain sentence main information which is sent out is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multiplexing device that multiplexes a plurality of low-speed lines connected to various terminals and hosts and places them on at least one time slot on a highway. In particular, the present invention relates to a multiplexing device equipped with an encryption function.

[Conventional technology]

Conventionally, when realizing a multiplexing device with an encryption function.

This has been done with a configuration of multiplexer + encoder.

A conventional configuration is shown in FIGS. 2 and 3. In the case of FIG. 2, multiple low-speed lines 101, 102. ....

The encoder 4 is connected to the high-speed highway side of a multiplexing device having a multiplexer l for multiplexing 103.
In the case shown in the figure, encoders 301, 302 . ....

303 is connected.

[Problem that the invention seeks to solve]

In the case of FIG. 2, frame synchronization bits and keeping pits other than the main information data are also encrypted. Generally, when encrypted, the number of error bits on the transmission path tends to increase during decoding. therefore,
Pit for frame synchronization.

Considering the intended use of the housekeeping pit, this is not very desirable. Also a bit for frame synchronization.

Since the housekeeping bit is a fixed pattern, encrypting the fixed pattern and sending it to the transmission path is essentially a known plain text for eavesdroppers.
This facilitates key analogy using ttack and weakens the confidentiality strength.

In the case of FIG. 3, the number of encoders 301 .
302. ..., 303 is required, which is not economical.

[Means for solving problems]

It is an object of the present invention to eliminate the above-mentioned drawbacks and to realize a substantial k
It is an object of the present invention to provide an economical multiplexing device with an encryption function that is equipped with a means for preventing a key from being easily decrypted due to a known plain text attack.

That is, the multiplexing device with encryption function according to the present invention uses frame synchronization bits on high-speed highways.

Signals other than main information such as housekeeping bits are not encrypted and remain as plain text, and main information is encrypted and sent to the transmission path. On the receiving side, the frame synchronization bits and housekeeping bits, which are plain text, are left as they are, and only the main information is decrypted according to the decryption key.

According to the present invention, there is provided a line allocation function unit that allocates a plurality of low-speed lines to arbitrary or fixed time slot positions on one high-speed highway, and a line allocation function unit that allocates a plurality of low-speed lines to arbitrary or fixed time slot positions on one high-speed highway; A multiplexing device comprising a multiplexing unit that multiplexes signals and places the multiplexed signal on the high-speed highway, wherein a frame synchronization bit and a housekeeping bit are included in the multiplexed signal on the high-speed highway. There is obtained a multiplexing device with an encryption function, characterized in that it has an encryption function section which encrypts the pits excluding the frame synchronization bits and the housekeeping bits, and outputs the frame synchronization bits and the housekeeping bits as they are without encryption.

Hereinafter, [Effects of the Invention] According to the present invention, even when signals on a high-speed highway flow to a transmission path, frame synchronization bits and housekeeping bits are not encrypted.

Virtually known plain text from eavesdroppers
It can be protected against t attack. Furthermore, since the frame synchronization bits and housekeeping bits are not encrypted, the number of error pulses on the transmission path does not spread. Furthermore, since the encryption function section is provided on the high-speed highway side of the multiplexing section, the number of encryption function sections is smaller than when an encryption function section is provided for each line on the low-speed line side of the multiplexing section. It's convenient and economical.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a multiplexing device according to an embodiment of the present invention. 101 to 103 are low-speed line signals.

1 is a multiplexing section. The low-speed line signals 101 to 103 are
The multiplexer 1 converts the signal into a high-speed highway signal 11.

The high-speed highway signal 11 is encrypted by an encoder 4. However, at this time, the encryption of the frame synchronization bits and housekeeping bits is stopped by the control pulse 61 output from the frame synchronization bit and housekeeping pit control pulse generator 6. Only the main information of the output card 7 of the encoder 4 is encrypted, and this code is
The frame synchronization bits and housekeeping bits are added by passing the frame synchronization bits and housekeeping bits controlled by the control noculus 62 outputted from the control pulse generator 6 and the housekeeping pit inserter 5, and the final It is sent out to the transmission line as output 51. That is, 4.5.6 of FIG. 1 encrypts the pits of the multiplexed signal on the high-speed highway excluding the frame synchronization bits and housekeeping bits, and encrypts the pits excluding the frame synchronization bits and the housekeeping bits. constitutes an encryption function unit 100 that outputs the data as is without encrypting it.

The receiving section performs the exact opposite operation and decrypts the encrypted signal excluding the frame pits and housekeeping bits, thereby obtaining the same plaintext as the sent plaintext main information.

As explained above, in this embodiment, only the main information is encrypted and the frame synchronization bits and housekeeping bits are encrypted by only slightly changing the frame synchronization bits and housekeeping bit control pulse generator without adding any new functions. Keeping bits can be sent in plain text. Therefore, there is virtually no known plain information by the eavesdropper.
Prevents key decoding by text attack and does not reduce confidentiality. Also.

As mentioned above, since it is possible to suppress the spread of the number of error pulses in the frame synchronization bits and housekeeping bits, it is possible to prevent network management from becoming difficult due to the addition of the encryption function. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of conventional multiplexing devices with encryption functions. 101-103...Low-speed line signal, l...Multiplexer 11...Plaintext high-speed highway signal, 4...Encryptor,
5... Frame bit and housekeeping bit inserter, 6... Frame bit and housekeeping bit control) 4 pulse generator, 100... Encryption function unit. Agent (7783) To patent attorney Hiroyasu Ikeda: j: J...
' Ha1, , , ,,,. 1 ゛・＂゛ l ′:-ノ前の１２】 scream m-" Fig. 1 Encryptor] - Fig. 2 Fig. 3, -100 Encryption function section

Claims (1)

[Claims] 1. A line allocation function unit that allocates a plurality of low-speed lines to arbitrary or fixed time slot positions on at least one high-speed highway, and multiplexes the signals of the plurality of low-speed lines according to information of the line allocation function unit; A multiplexing device including a multiplexing unit for placing a multiplexed signal on the high-speed highway, the bits of the multiplexed signal on the high-speed highway excluding frame synchronization bits and housekeeping bits being encrypted. 1. A multiplexing device with an encryption function, comprising an encryption function section that outputs the frame synchronization bit and the housekeeping bit as they are without encryption.