JPH03169137A - Cryptographic system for on-line system - Google Patents

Abstract

PURPOSE:To enhance the security of cryptography against interception of a specific channel in a digital communication line by decomposing a transmission text over plural channels ciphered in time series, sending the result and combining the texts into a reception text after the reception. CONSTITUTION:In the case of data communication through a digital communication line, since an input information string is communicated through channels in time division, the string is divided into plural information strings. That is, an input information string 'abcd' is divided into 4 information strings 'a', 'b', 'c', 'd'. In the Figure a prescribed period is divided into 4 channels and the divided information strings 'a', 'b', 'c', 'd' are sent through the channels 1, 1, 1, 1 over the 4 periods, and in the case of reception, the information strings of channel numbers 1, 3, 2, 3 are extracted to combine the input information string of 'abcd'. Since the channel number used for the communication is not specific to each period, the channel number is used as time series cryptographic information in the communication system. Thus, intercept of a text is prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a security technology between an online system using a communication line and a transmitting station and a receiving station, and in particular to guaranteeing the cryptographic strength of messages during information communication. Concerning encryption methods for online systems.

[Conventional technology]

In today's society, many services that use digital communication are used, including touch-tone telephone services such as airline seat reservations, facsimile services, and online banking. These digital communications are increasingly handling data that is important not only to individuals and companies, but also to society as a whole, as data communication accuracy and communication capacity increase. For this reason, it has become necessary to establish technology that can handle wiretapping of communication data. Conventionally, when communicating data using a digital communication line, information is transmitted by time-sharing a single line over multiple channels, but in order to use a specific channel as a single line, communication data is It was common to communicate periodically. That is, in order to communicate the input information string "abcd" shown in Fig. 2, a, "b", ゛'C
It was common practice to decompose the information into ``,'' and ``d'' information, and to communicate the information sequence using channels with the same number that are time-divided for each cycle, as shown in Figure 3. [Problem to be solved by the invention] In the above-mentioned conventional method of using digital communication lines, one channel corresponds to one line, so messages are communicated periodically, and it is difficult to identify the channel. [Means for Solving the Problems] The present invention provides a system for transmitting and receiving messages using communication lines. In the station and the slave station that is the receiving side station, a message disassembly means for inputting the message in the main station and disassembling it into a digital information string, and a channel selection for transmitting the information string handed over from the message disassembly means are set in advance. transmission channel selection means based on the time-series encrypted information set in the slave station; It has channel selection means for selecting a channel and extracting an information string, and message synthesis means for synthesizing the digital information string delivered by the receiving channel selection means into a message and outputting the message. [Example] Next, The present invention will be explained with reference to the drawings. Fig. 1 is a conceptual diagram of an embodiment of the present invention. The main station 2 is
a message disassembly means 21 that takes in the message 1 and decomposes it into a plurality of digital information strings; a time-series encrypted information storage means 23 that stores preset time-series encrypted information;
a transmission channel selection means 22 connected to the message decomposition means 21 and selecting a transmission channel based on the time-series encrypted information;
The transmitting means 24 is connected to a transmission channel selection means 22 and a digital communication line 3 and transmits an information string via the digital communication line 3 from a channel designated by the transmission channel selection means 22. The slave station 4 is connected to the digital communication line 3 and has receiving means 4 for receiving the information string from the master station 2.
1, a time-series decoding storage means 43 for storing time-series decoding information set in advance, and a receiving channel connected to the receiving means 41 and selecting a receiving channel based on the time-series decoding information. It is composed of a selection means 42 and a message composition means 44 connected to the reception channel selection means 42 and for synthesizing the message 5 from a plurality of digital information strings. FIGS. 2, 3, and 4 are conceptual diagrams explaining communication line operations using digital communication lines. It shows the concept of communication operation. As shown in FIG. 2, when communicating data over a digital communication line, an input information stream is time-divided and divided into multiple information instances for communication over a channel. Second
In the figure, the input information string "abcd" is converted to a"ubn.
+i ” II d l1 C The information is divided into four information streams.As shown in Figure 3, in the conventional digital communication operation, the information is time-divided into multiple channels within the subscription period, and For reception, the divided information strings of a specific channel were sequentially retrieved and the input information string was combined.In Figure 3, a fixed period is divided into four channels. , and transmits the decomposed information strings of "a,""b","c" and "d" through the channels of ■■■■ over the four period periods, and receives the information string of channel number ■■■■ An example is shown in which the input information string of "abcd" is extracted and synthesized. In this way, in the conventional method, the channel number used for communication is specified for each cycle.
It can be said to be a communication method using channel numbers as time-series unencrypted information. As shown in FIG. 4, in the digital communication system according to the present embodiment, information is time-divided into multiple channels within a fixed period, and the divided information strings are transmitted through channels spanning multiple channel numbers. The input information was synthesized by sequentially extracting the divided information sequences of the channel used for transmission. In Figure 4, a fixed period is divided into 4 channels,
During these four periods, the divided C information strings of ``a'', ``b'', ``, and d'' are transmitted through the channels of An example is shown in which an information string is extracted and an input information string of "'abcd" is synthesized. In this way, in the method of this embodiment, the channel number used for communication is not specified for each cycle, so it can be said that the method is a communication method in which the channel number is used as time-series encrypted information. Next, the operation of this embodiment will be explained with reference to FIG. Transmitting means 24 and receiving means 4 via digital communication line 3
1, the master station 2 transmits a communication start instruction (process 2-1>, and the slave station 4 accepts the communication start instruction (process 2-1).
Processing 4-1). The main station takes out the transmitted message "abcd" (process 2-2), and uses the message disassembly means 21 to disassemble the message into multiple information strings "a" followed by "b", ", and 'd" (process C 2-3), the transmission channel selection means 22 selects a channel to be transmitted in correspondence with the information string decomposed based on the time-series encrypted information retrieved from the time-series encrypted information storage means (process 2- 4) The information string is passed through the transmitting means 24, and is encrypted and transmitted to the slave station across multiple channels (Process 2-5>. The above process 2-4.2-5 is transmitted to the entire information string "
Repeat "b" and "d" following "a" until they are completed (process 2-6). Transmission channel selection means 22 based on decoding information
Select a reception channel synchronized with (process 4-2). The receiving means 41 receives the selected receiving channel. Receive the information string decomposed according to the channel (Process 4-3>, above-mentioned Process 4)
-2. 4-3 as the previous information string “a” followed by “b”, “ ′
゛, "d" Repeat until C is completed (process 4-4). The message synthesizing means 44 synthesizes the received message "abcd" from all the received information strings (process 4-5), and the slave station 4 synthesizes the received message "abcd".
c d” (process 4-6). The master station 2 sends a communication end instruction (process 2-7), and the slave station 4 accepts the communication end instruction (process 4-7). The operation of each means in the example will be explained.

FIG. 6 is a flowchart showing the operation of the message disassembly means of this embodiment. The message decomposition means 21 extracts a message of a certain size (process 21-1), decomposes the message into a digital information string (process 21-2), and delivers the digital information string to the transmission channel selection means 22 (process 21-3). Repeat steps 21-1 to 21-3. FIG. 7 is a flowchart showing the operation of the transmission channel selection means of this embodiment. The transmission channel selection means 22 waits for the information string to be delivered from the message disassembly means 21 (processing 22-1).
．． When the information string is handed over from the message decomposition means 21, time-series encrypted information is retrieved from the time-series encrypted information storage means 23 (process 22-2), and a transmission channel is selected based on the time-series encrypted information. , (processing 22-3), instructing the transmission means 24 of the selected channel (processing 24-4), and delivering the transmission digital information string to the transmission means 24 (processing 22-5).
Processes 22-2 to 22-5 are repeated until the transmission digital information string is completed (process 22-6). Repeat processes 22-1 to 22-6. FIG. 8 is a flowchart showing the operation of the transmitting means of this embodiment. The transmitting means 24 determines whether the input is an instruction to start communication (process 24-2), and if communication has started, transmits a communication start (process 24-1); otherwise, determines whether the input is an instruction to end communication. (Process 24-3),
If it is an instruction to terminate communication, the communication is terminated (process 24-4), otherwise it is determined whether the input is a channel instruction or not (process 24-5), and if the channel is supported, the transmission channel is changed (process 24-6). ), otherwise it transmits the information string (process 24-7>, Fig. 9 is a flow chart showing the operation of the receiving means of this embodiment. The receiving means 4l determines whether the input is an instruction to start communication. It is determined (processing 41-1), and if communication is to be started, the reception channel selection means 42 is instructed to start reception (processing 41-2).
If not, it is determined whether the input is an instruction to end communication (process 41-3), and if communication has ended, it instructs the receiving channel selection means 42 to end the reception (process 41-4). 10 is a flowchart showing the reception channel selection means of this embodiment. The reception channel selection means 42 receives the reception start instruction from the reception means 41. Wait (process 42-1).Next, if there is a reception end instruction from the receiving means 41, the process ends; if not, it is determined that there is a delivery information string (process 42).
-2>, When there is a delivery information sequence, a process 42 for extracting time-series decoding information from the time-series decoding information storage means 43 -
3>, select a reception channel based on the time-series decoding information (process 42-4), extract a digital information string from the reception channel (process 42-5), and send the information string to the message synthesis means 44. Hand over (processing 42-6). Processing 42-
2 to 42-6 are repeated until receiving an instruction to end reception.

FIG. 11 is a flowchart showing the operation of the message synthesis means of this embodiment. The message combining means 44 receives the message from the receiving channel selection means 42 (processing 44-1), and synthesizes the digital information string into a message (processing 44-2). Output message 5 (process 44-3). [Effects of the Invention] As explained above, the present invention is capable of improving digital communication by disassembling and transmitting a transmitted message across multiple channels encrypted in time series, and combining it with a received message after receiving it. This has the effect of increasing the encryption strength against eavesdropping on specific channels on the line.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
The figure is a conceptual diagram explaining the division and composition operation of information strings.
FIG. 3 is a conceptual diagram explaining the communication operation of the conventional method.
FIG. 4 is a conceptual diagram explaining the communication operation of this embodiment method. FIG. 5 is a flowchart of the present invention, FIG. 6 is a flowchart showing the operation of the message disassembly means, and FIG.
8 is a flowchart showing the operation of the transmitting means, FIG. 9 is a flowchart showing the operation of the receiving means, and FIG. 10 is a flowchart showing the operation of the transmitting means. FIG. 11 is a flowchart showing the operation of the means, and FIG. 11 is a flowchart showing the operation of the telegraphic admonition means. 1...Transmission message, 2...Main station which is a transmitting side station, 21...Message disassembly means for disassembling the message into a digital information string, 22... - Transmission channel selection means for selecting a channel for transmission, 23...
... preset time-series encrypted information storage means, 24 ... transmission means, 3 ... digital communication circuit, 4 ... slave station which is one receiving side station, 41
. . . Receiving means, 42 . . . Receiving channel selection means for selecting a channel for reception, 43 . . .
・Preset time-series decoding information storage means, 44... Telegram synthesis means for synthesizing a digital information string into a message, 5... Received message.

Claims (1)

[Claims] In an online system that transmits and receives messages using a communication circuit, in a main station that is a sending station and a slave station that is a receiving station, a message in the main station is input and decomposed into a digital information string. a transmission channel selection means for selecting a channel for transmitting the information string handed over by the message disassembly means based on preset time-series encrypted information; and digital communication within the slave station. receiving channel selection means for selecting a receiving channel based on time-series decoding information set from a message received via a line and extracting an information string; An encryption method for an online system, comprising a message synthesizing means for synthesizing a digital information string received from the means into a message and outputting the message.