JPH0535679A - Data communication system - Google Patents

Abstract

PURPOSE:To improve to hold the secrecy by changing hourly the password, and renewing freely a data converting table in the storing media of a host computer only by a terminal user. CONSTITUTION:To password data, time data messages are added and the password is converted by the converting character data corresponding to the time data for at least one hour. In this case, a means to renew freely the renewal of the converting character data stored in the data base of a host computer 2 by a terminal 3 side user is provided. Then, the decoding for the password is not fixed as conventionally, but changed as the time passes, and the user of the terminal 3 can re-write the converting character used as the time passes. Thus, the secrecy of the information for the unfair user can be held.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a data communication system,
In particular, the present invention relates to a data communication system in which a password is converted every hour to keep information confidential and data is exchanged between a host computer and a terminal.

[0002]

2. Description of the Related Art Conventionally, this type of data communication system is shown in FIG.
As shown in FIG. 2, data is transmitted and received between the host computer 2 having the database 1 and the terminals 3 and 4 via a telephone line. The database 1 stores a password table for each user of the terminal. There is. Therefore, when the password is input from the terminal, the password is encrypted, and the host computer 2 collates the password, so that the user who inputs the password from the terminal can obtain the access right. Here, the encryption for the password was fixed.

[0003]

The above-mentioned conventional fixed password conversion data communication method has a drawback that an unauthorized user can easily decipher the password and the confidentiality of information is significantly impaired.

An object of the present invention is that the encryption for a password is not fixed as in the past and can be changed over time, and the terminal user can change the conversion character used over time. By being rewritable, information is kept confidential to unauthorized users.

[0005]

According to the data communication method of the present invention, a host computer and a plurality of terminals are connected by a telephone line, and an individual user of the terminal inputs a password to a database of the host computer. In a data communication system in which a password table provided is used for decryption and communication is performed, a message of time data is added to the password data, and the password is converted at least every one hour using converted character data corresponding to the time data.

[0006]

The present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are explanatory diagrams of a data format and a code of time data according to an embodiment of the present invention, FIG. 2 is a flowchart showing an operation on the terminal side of the present embodiment, and FIG. 3 is on a host computer side. FIG. 4 is a flowchart showing the operation, and FIG. 4 is a flowchart for converting the characters of the password on the terminal side of the present embodiment. First, in the data format of FIG. 1A, time data is newly added to a password and a message for each user. Therefore, the password is changed every hour to increase the confidentiality of the data. FIG. 1B shows an example of the format of time data, which is 24 hours per hour from 1 o'clock.
Assuming that the code up to the hour contains conversion characters in the conversion method as shown in the table, first, the time information is 1H (Hou
At the time of r), the lower 5 bits of the ASCII code (41H) of A is added to each character of the encrypted password data to convert the data. At that time, one character is 8 bits, and the same data conversion is performed on the lower 5 bits for each character. Similarly, the code shown in the table of FIG. 1 (b) is changed by changing the time. It then sends the data to the host computer.

Next, a flow chart of password exchange on the terminal side will be described with reference to FIG. The user of the terminal logs in (S1), and since the time information is added to the message B from the host computer, the time information is first added to the password to be sent and sent together. Then, the encrypted password data sent is stored in the buffer (S2 to S4). This time, the time information added to the password is read from the buffer (S
5). And because the conversion method is decided every time,
The encrypted password data sent is converted (S6 to S11). And the converted password C
Is transmitted to the host computer (S12). The conversion character used in the conversion method can be converted by the user of the terminal as described later.

Next, a flowchart of the operation on the host computer side will be described with reference to FIG. First, the host computer requests the password from the terminal (SIA),
Since the data converted from the encrypted password data is sent from the terminal side, the sent data is input to the buffer (S3A). Then, the time information added to the data is read (S4A). Conversion based on the time information is performed to decrypt the converted data into the original password (S5A to S10A). Then, the host computer verifies the password (S11).
A). For example, when the time information is 1H (Hour), in order to decrypt the data converted on the terminal side into the password based on the original data, the data 1 The ASCII code of A (4
Convert the data by subtracting the lower 5 bits of 1H).
At that time, one character is 8 bits, and the same data conversion is performed to the lower 5 bits for each character. Similarly, FIG. 1 (b)
The conversion is performed by changing the code shown in the table in accordance with time. In this way, the data of the encrypted password is decrypted to the original state, so that the host computer can verify the password. Then, the access right can be given to the user of the terminal (S13 in FIG. 2).

Next, a flow chart for updating the password conversion character on the terminal side will be described with reference to FIG. When the terminal user updates the conversion character used in the conversion method, the data conversion table containing the conversion character is read from the database of the host computer (S2).
1). Then, the data in the data conversion table is updated (S23). Since the same updated data conversion table exists in the file on the terminal side, the data conversion table containing the conversion characters on the terminal side is updated (S2).
4). In addition, in the character string of the password, 1 character 8
The lower 5 bits of each character, which is a bit, is converted by performing predetermined calculation (addition / subtraction) on the lower 5 bits of the converted character with respect to time. The conversion character used at the time of data conversion can be converted by the terminal user, and the confidentiality of information is further improved.

[0010]

As described above, according to the present invention, the password is changed every moment, and only the user of the terminal can freely update the data conversion table in the storage medium of the host computer. This has the effect of making it difficult for the terminal user to use the host computer and ensuring confidentiality.

[Brief description of drawings]

FIG. 1 is a data format diagram (a) and an explanatory diagram (b) showing a code of time data according to an embodiment of the present invention.
Is.

FIG. 2 is a flowchart on the terminal side of the present embodiment.

FIG. 3 is a flowchart of the host computer side of the present embodiment.

FIG. 4 is a flowchart of conversion character update on the terminal side of the present embodiment.

FIG. 5 is a configuration diagram of a general data communication system.

[Explanation of symbols]

1 Database 2 Host Computers 3, 4 Terminals S1 to S13 Steps S1A to S11A of Terminal Side Flowchart Steps S21 to S24 of Host Computer Side Flowchart Steps of Flowchart for Updating Converted Characters on Terminal Side

Claims (2)

[Claims] 1. A host computer and a plurality of terminals are connected by a telephone line, an individual user of the terminal inputs a password, and a password table provided in a database of the host computer decrypts the password for communication. In the data communication method, a message of time data is added to the password data, and the password is converted at least every one hour by conversion character data corresponding to the time data. 2. The data communication system according to claim 1, further comprising means for freely updating the conversion character data stored in the database of the host computer by the terminal side user.