JPS603242A - Ciphering communication system - Google Patents

Abstract

PURPOSE:To improve the degree of confidentiality of cipher and to attain ease of management of a key by preserving the number of keys for ciphering the same as the number of frames and designating a key depending on the frame number used for communication. CONSTITUTION:A communication controller 4 detects a signal burst at a communication control section 7, a synchronizing detection section 8 detects an idle frame and identifies the frame number of the idle frame. A key management section 9 extracts the key of the frame number and transmits it to a ciphering/ decoding circuit 10. A transmitted message from a terminal processor 5 is formed into a ciphered message at the ciphering/decoding circuit 10 by using the key. Further, this ciphered message is inserted in the idle frame while being added with an own station identification number, an opposite station identification number and a control code, and the result is transmitted to a communication line CC.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] When performing multiplex communication using ciphertext, the present invention manages multiple ciphers for each frame order when creating ciphertext. The present invention relates to an encrypted communication method that can maintain confidentiality using a small number of ciphertexts even when data is communicated with other devices.

[Conventional technology and problems]

In data communications, messages are encrypted to maintain confidentiality in order to prevent the contents of the communications from being stolen. For example, when such an encryption method is applied to multiplex communication of data between one host and a large number of terminals, one cipher is used for the entire network.

There is a method that uses a cipher prepared for each terminal in the communication between the host and the terminal. However, the former method uses only one key for encryption and decryption as a network, so it is easily decrypted and therefore has low encryption strength. Therefore, when the system changes, such as when the number of partner terminals increases, it is necessary to create keys accordingly, and it is not easy to change the system. only have to manage the keys,
Therefore, there is a drawback that key management is not easy.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned drawbacks by determining a key for encryption/decryption for each frame, thereby increasing encryption strength and providing an encrypted communication method that facilitates key management. That's true.

[Structure of the invention]

In order to achieve this objective, the encrypted communication method of the present invention:
A data communication cryptographic device applied to a multi-transmission communication network system includes a cryptographic key management unit that holds a plurality of cryptographic keys to be used for each frame rank of nine messages and extracts cryptographic keys according to the frame rank, and a cryptographic key management unit used for transmission. a synchronization detection unit that detects the empty frame order and the frame order in which the received text is located, and an encryption/decryption unit that encrypts the transmitted text and decrypts the received text using the encryption key required according to these frame orders. is set up, and when transmitting, it detects an empty frame and extracts a key according to the frame order to encrypt the transmitted text, and when receiving, it extracts a key according to the frame order of the received text and decrypts the received text. It is characterized by the following.

[Embodiments of the invention]

Before describing the present invention in detail based on one embodiment.

The outline will be explained with reference to FIG.

In the case of multiplex communication, as shown in Figure 31 (a), the signal burst unit (BU) has a synchronization control code SY
C is located and then multiple frames FO.

Fl...Fn are located. In the present invention, keys to be used when encrypting messages in frames FO, Fl, . . . , Fn are determined for each number of frames FO to Fn. Therefore, when an empty frame is detected during transmission, the key to be used is specified based on the frame number of the empty frame. Furthermore, when the own station identification number DA in Fig. 3(b) is decoded and a message addressed to the own station is received, the encryption key is determined by the frame number.

This encryption key can be used to decrypt the received text. With this configuration, even if there are a large number of receiving terminal devices, the number of encryption keys is limited by the number of frames, so even if more terminal devices are added, the number of keys will not increase.Next, the present invention Based on an example of FIG. 1 and FIG. 2,
This will be explained with reference to FIG.

FIG. 1 is a system configuration diagram using the cryptographic communication system of the present invention, and FIG. 2 is a detailed diagram of the communication control device and cryptographic device.

In the figure, 1 is a host processing device/device, and 2 is a communication control device.

3 is an encryption device, and 4.4-0...4-N is a communication control device.

5.5-0...5-N is a terminal processing device, 6.6-0...
... 6-N is an encryption device, 7 is a communication control unit, and 8 is a synchronization detection unit.

9 is a key management section, and 10 is an encryption/decryption circuit.

First, a communication control device and an encryption device having a characteristic configuration according to the present invention are a master station M and a terminal station S.

...Since they all have the same configuration in SN, the second
This will be explained using figures.

The communication control device 4 includes a communication control section 7. A synchronization detection section 8 is provided. The communication control unit 7 is connected to the master station M or the slave station SO~
It performs various controls for sending data from the 8N to the communication line or receiving data from the communication line, and synchronization is detected by receiving the multi-frame signal parse (BU) when it is transmitted. This is what is sent to section 8.

When this signal parse) BU is transmitted, the synchronization detecting section 8 synchronizes from the synchronization control code 5YCr2 at the head thereof, and then reads the frames constituting this and recognizes the frame number.

The encryption device 6 stores keys necessary for creating and decoding codes for at least the same number of frames, and uses these keys to encrypt transmitted texts and decrypt received texts. It has a key management unit 9 that holds keys, and an encryption/decryption circuit 10 that creates and decrypts ciphertext.

The operation of the present invention will be explained below.

(1) When transmitting ciphertext For example, when transmitting data from slave station SO to SN, communication control device 4-0 of slave station SO transmits data from master station M to each slave station 8O-8N. The communication control section 7 detects the signal burst, and the synchronization detection section 8 detects the empty frame, for example, frame F1. As a result, the frame number of the empty frame is identified as 1, and the key management unit 9
extracts the key of frame number 1 and sends it to the encryption/decryption circuit 10. Then, using this key, the transmission text transmitted from the terminal processing device 5-0 is sent to the encryption/decryption circuit JO.
Create a ciphertext at Then, as shown in FIG. 3 (b), this ciphertext is added with the own station identification number DA, the destination station identification number SA, and the control code C to complete the frame.

It is inserted into an empty frame and sent to the communication line CC.

(2) This signal is once caught by the master station M, and then the master station M parses the multi-frame signal (BU) and sends it out to each slave station. At this time, slave station 8N
searches the partner station identification number SA of each frame in the synchronization detection section 8, and when the slave station SN is written therein, detects the frame number, and extracts the key from the key management section 9 based on this, Based on this, the transmitted text is deciphered and decrypted in the encryption/decryption circuit 1o, and data processing is performed on the own terminal processing device 5-N based on this. [Effects of the Invention] In the present invention, the encryption device We have the same number of keys for encryption or decryption as the number of frames, and the key is determined by the frame number used for 9 communications, so a different key is used for each 9 individual communications, that is, each frame, to ensure secure encryption. In addition, since keys are not managed for each party, it is possible to easily deal with changes in the system, such as the addition or reduction of terminal devices or changes in keys.

[Brief explanation of the drawing]

Fig. 1 is a system diagram using the encrypted communication method of the present invention, Fig. 2 is a detailed diagram of the communication control device and dark device, and Fig. 3
The figure shows the structure of the message. In the figure, 1 is a host processing device, 2 is a communication control unit 3 is an encryption device, and 4.4-0...4-N are communication control units 5.5-0.
...5-N is a terminal processing device, 6.6-0...6-N is an encryption device, 7 is a communication control section, 8 is a synchronization section, 9 is a key management section, and 10 is an encryption/decryption circuit. . Patent applicant Fujitsu Ltd. Representative Patent Attorney Akira Yamatani Eiichi [21

Claims (1)

[Claims] In a data communication cryptographic device applied to a multiplex communication network system, there is a cryptographic key management unit that holds multiple cryptographic keys to be used and extracts cryptographic keys according to the frame rank (2) for each frame order of nine messages, and a cryptographic key management unit that extracts cryptographic keys according to the frame rank (2). A synchronization detection unit that detects the empty frame order to be used and the frame order in which the received text is located, and an encryption/decryption unit that encrypts the transmitted text and decrypts the received text using the encryption key required according to these frame orders. - When transmitting, it detects an empty frame and extracts a key according to the frame order to encrypt the transmitted text, and when receiving, it extracts a key according to the frame order of the received text and decrypts the received text. An encrypted communication method characterized by: