JP3078962B2 - Message compression / encryption method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data compression / encryption technique in data communication, and more particularly to a case where at least one of terminal devices connected by a communication line is a simple terminal device having relatively small processing capacity. The present invention relates to a message compression / encryption method.

[0002]

2. Description of the Related Art In recent years, systems for performing data communication by connecting a center to a home via a communication line, such as a home voting system for public sports and online shopping, have become widespread. In such a system, the weight of the communication process is high due to the nature of the service, but in consideration of the financial burden of the subscriber and the convenience of the operation, the processing capacity of the message data structure and the terminal device that performs the process are: Usually, it is set to the minimum necessary place.

For example, the message data structure includes, for each transmission frame, a start delimiter (STX), a text portion, an end delimiter (ETX), a checksum for detecting a transmission error, and an end flag (CR) indicating the end of the transmission frame. The text portion is composed of identification data, amount data, voting data, or product data, etc., in a combination of JIS8 code (8 bit 1 code) numbers and spaces. Also, a terminal device for processing message data having such a structure is a simple terminal device of about 8 bits, so inexpensive family computers and multifunctional telephones are used.

[0004]

As described above, the data communication system targeting the home is basically based on the communication and processing of electronic data with a simple configuration. Bank balance information, etc.)
It is necessary to ensure sufficient security in order to prevent a third party from analyzing the message. In addition, it is desired that the communication time be reduced as much as possible in order to reduce the call charge, improve the operational feeling, and suppress the communication error rate.

[0005] The above request can be satisfied by using a well-known excellent message compression / encryption technology. However, such a message compression / encryption technology is premised on a computer device having a high processing capability and a data processing device. It involves complicated processing such as replacement and mapping. For this reason, a sufficient processing speed cannot be obtained with a simple terminal device of about 8 bits, and it has hardly been used conventionally. Also, even if it is used, it is unique to each terminal device, that is, it is processed in hardware,
There was no one that could be used in common for all terminal devices.

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and an object of the present invention is to provide a general-purpose data compression / compression system which can process even a simple terminal device having a low processing capability in a data communication system of this kind. An object of the present invention is to provide an encryption method.

[0007]

Means and operation for solving the problems] To achieve the above object message compression and encryption method of the present invention, the conversion in the transmitting-side communication terminal apparatus, the heat transmission sentence code corresponding to 4 bits per byte and two combined binding the corresponding code transmission message Nitsu have to obtain a compressed code of 1 byte, 1 byte to determine the exclusive logical sum of the compression codes and a predetermined encryption key for each bit to generate a transmission code, at the receiving side, the exclusive OR of the transmission code and the encryption key is determined for each bit to restore the compressed code, the reconstructed compressed code two said corresponding After the code is decomposed into codes, the corresponding code is inversely converted into the corresponding transmission message . In this case, the transmitting side
If the transmitted message is an odd number, 4 bits not subject to the inverse conversion
And the total size of the corresponding code
Is not a natural number times the code length of the encryption key,
The pseudo code is replenished until it becomes several times .

In the above-mentioned message compression / encryption method,
Compression and encryption of transmitted messages should be performed once.
Can also be. That is, the two transmission messages and the transmission
Compression / encryption information indicating the correspondence with the code for each user
Recorded on an IC card issued to the company. The user
When sending text, search the compressed / encrypted information
Code, and when the transmission code is received, the compression / encryption
The transmission information is inversely converted by searching the conversion information.

In the above method, it is also possible that the transmitting side transmits the encryption key together with the transmission code, and the receiving side restores the compressed code based on the encryption key. According to this configuration, the compressed code can be reliably restored on the receiving side even if the encryption key is changed each time transmission is performed, and the security measures are thorough.

[0010]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a main part of a message transmission system for realizing a message compression / encryption method according to the present invention. The center host computer 1 and a terminal device 4 provided at home are shown.
Are connected via the communication line 3. The host computer 1 and the terminal device 2 are respectively provided with communication control units 11 and 21 serving as interfaces with the communication line 3, message processing units 12 and 22 for generating and decompressing a compressed code, and transmitting and receiving a compressed code and an encryption key or a decryption key. Exclusive OR (hereinafter XO)
R), and control units 14 and 24 for controlling the above units.

Hereinafter, a description will be given of a case where the text part of the message is composed of a combination of numbers "0" to "9" of the JIS 8 code and a space, and this text part is transmitted from the terminal device 2 to the host computer 1.

The number "0" in the JIS8 code is a binary code (hereinafter referred to as a BIN code) "0011000".
0 ”and the number“ 5 ”are represented by“ 00110101 ”.
In transmitting a message, the terminal device 2 first sets the JI
The message processing unit 12 converts the S8 code into a 4-bit corresponding code.

FIG. 2 is a correspondence table showing the conversion procedure.
Basically, one JIS8 code is associated with each of the lower 4 bits of the data structure, ignoring the upper 4 common bits. However, a specific combination is associated with “space” and “end symbol” described later. In the illustrated example, 2
"101" in each "space" as an extension of the base number
“1011” corresponds to “0” and “end signal”.
Next, a 4-bit corresponding code is set as two sets in the message processing unit 22 to generate an 8-bit (1 byte) compressed code. Then, an XOR is determined for each bit to generate an encrypted transmission code. Since the XOR has the fastest response among the logic determination means, a sufficient processing speed can be obtained even with a processing capacity of about an 8-bit family computer. This transmission code is sent to the communication control unit 21, where it is arranged in a predetermined transmission frame and sent out to the communication line 3.

The upper part of FIG. 3 schematically shows the processing on the terminal device 2 side. A two-digit number (JIS8 code) consisting of two bytes is compressed into one byte, and the two-digit number is used as an encryption key. It shows a state where the transmission code is converted into a transmission code having a message structure that can be understood only by a party by XOR and transmitted.
Note that this transmission code can be represented by a HEX code (hexadecimal code, the same applies hereinafter).
(D2) and (C3) show this HEX code.
On the other hand, on the host computer 1 side, as shown in the lower part of FIG. That is, the transmission code is extracted from the transmission frame received from the communication control unit 11, the corresponding compressed code is compared with the one-byte decryption key by the logic circuit 13, and XOR is performed for each bit.
The decryption key used here is the same as the encryption key used on the terminal device 2 side.

The message processing device 12 extracts two 4-bit corresponding codes from the compressed code for each byte decoded by the above procedure. Then, each 4-bit corresponding code is decompressed into an 8-bit BIN code by reversing the corresponding relationship in FIG. The decompressed BIN code is the same as the original JIS8 code in the terminal device 2.

In this manner, the transmission message is compressed, and XOR
Thus, the communication time can be reduced while the processing capability of the terminal device 2 is reduced, and the rate of occurrence of transmission errors can be reduced by about 50%.

The above description is an example of compressing and encrypting 2 bytes into 1 byte, and is applicable to an even-length transmission message. However, due to the nature of telegrams, there are some that have odd lengths. Therefore, in this case, on the transmitting side, after the last byte of the corresponding code, the above-mentioned "end symbol" (pseudo code)
To perform compression and encryption. On the receiving side, the compressed code is decompressed in the same manner as in the normal case (in the case of an even-length message), but the "end symbol" is not decompressed.

FIGS. 4A and 4B are explanatory diagrams of the data structure before and after compression in this embodiment. FIG. 4A shows an example in which the transmission message has an even length, and FIG. 4B shows an example in which the transmission message has an odd length. In each figure, the upper part shows the structure of a 4-bit corresponding code (JIS8 code), and the lower part shows the structure of a compressed code. As is clear from these figures, even if the transmission message has an odd length, the same processing as in the case of the even length can be performed by adding a 4-bit “end signal”.

Next, the correspondence between the data structure of the transmission message and the structure of the actual transmission code will be described in detail.

FIG. 5 is a correspondence table of compression codes with respect to the data structure of a transmission message, and shows a correspondence between a 2-byte JIS8 code (for example, "00") and a 1-byte compression code. The transmission code is a HEX code ("C2
h ") and the BIN code (" 11000010 "). In this figure (table), the underlined portion is" space ", and the one-digit JIS8 code means that the message is of odd length. ing.

FIG. 6 shows that the encryption key is "11000010".
9 is a matrix table showing a correspondence relationship between a data structure of a transmission message after compression and a HEX code when (= “C2h”). In FIG. 6, the row element is the first digit (including “space”) of the JIS8 code converted into 4 bits, that is, the upper 4 bits of the data structure, and the column element is the same as JIS8 code.
The second digit of the code (including "space" and "terminator"),
That is, it corresponds to the lower 4 bits of the data structure. In the present embodiment, two-digit numbers using “0” to “9”, “space” and “end symbol” are expressed, so that “B” to “F” are used as row elements and “column” elements are used as columns. "C" to "F" are unused. In this type of data communication, the start delimiter (STX) of a transmission frame is "0" in HEX code.
In general, the end delimiter (ETX) is also “03” and the end flag (CR) is also “0D”. In this embodiment, the encryption key "00h" to "0F" are not used.

FIG. 7 is a correspondence table between the received transmission code and the data structure of the actual transmission message, and has a reverse relationship to the correspondence table of FIG. FIG. 8 is a matrix table showing the correspondence between the transmission code structure and the HEX codes representing the data structure of the actual transmission message. In FIG. 8, the row elements correspond to the upper 4 bits of the transmission code, and the column elements correspond to the lower 4 bits of the transmission code.

As is clear from FIGS. 5 to 8, according to the present embodiment, the compression and encryption of the transmission message is extremely simple and reliable, and the decryption and decompression are performed in exactly the reverse manner. It can be easily realized. Therefore, a sufficient processing speed can be obtained even with a simple terminal device such as a general-purpose family computer.

In this embodiment, an example is described in which a one-byte encryption key is used, but this encryption key may be two or more bytes. However, also in this case, in order to avoid confusion with the above-described transmission frame delimiter or the like, the upper 4 bits of each byte are not set to “0” in the HEX code. Further, for example, when a 2-byte encryption key is used, a 4-byte transmission message is compressed to 2 bytes, so that the message length may not be a natural number multiple of 4 bytes. FIG. 9 is an explanatory diagram of the data structure before and after compression when the encryption key is “92ABh”, and shows an example in which the number of corresponding codes (JIS8 codes) in the upper row is not a multiple of the compression code in the lower row. . In this case, as shown in the figure, the above problem can be solved by adding the above-mentioned three “end symbols” and adjusting the number of corresponding codes.

Although the present embodiment has been described with respect to an example of a 2-to-1 message compression ratio, an n-byte transmission message is converted into m-bit corresponding codes for each byte, and a plurality of these corresponding codes are combined. If a new compressed code for each byte is obtained, a compression ratio of n to j (nm / 8) is possible.

Further, as an application of this embodiment, the encryption key can be dynamically changed in each communication. That is,
After the transmission code is generated using an encryption key arbitrarily determined on the transmission side, the encryption key is arranged at an arbitrary position on the transmission frame and sent to the communication line 3 together with the transmission code.
The receiving side decrypts the transmission code to the original compressed code using the encryption key. By doing so, the security of the transmission message can be further enhanced.

Further, if there is enough memory, the matrix tables shown in FIGS. 6 and 8 are provided in the host computer 1 and the terminal device 2 as compression / encryption information, and a table search is performed at the time of transmission / reception of a message. May be realized. In this case, there is an effect that compression and encryption can be realized by one process. In addition, the terminal device 2 is provided with a card reading device, and the above-mentioned compressed / encrypted information is recorded on an IC card or the like issued for each user, and the same processing is performed by expanding this information into a table when transmitting / receiving a message. You may do it. With such a configuration, the security of the transmission message can be further enhanced.

[0028]

As described in detail above, according to the message compression / encryption method of the present invention, after a transmission message is compressed to n: j (nm · 8) according to a predetermined correspondence relationship, a predetermined Since the XOR with the encryption key is determined bit by bit and encryption is performed, the processing procedure is simple and reliable.
Quick processing of R and the characteristics of assembler and C language, etc., where bit operation is easier than other languages, can be effectively used, and sufficient processing speed can be achieved even with a simple terminal device such as a general-purpose family computer. The effect is obtained. Therefore, security of transmission messages, reduction of call charges,
It is possible to improve the operation time and suppress the communication error rate.

According to the present invention, when the number of corresponding codes to be transmitted is not a natural number multiple of the code length of the encryption key, the predetermined pseudo code is supplemented, so that the compression / encryption process is unified irrespective of the message length. effective.

Further, since the transmitting side transmits the encryption key together with the transmission code, and the receiving side restores the compression code based on the encryption key, the encryption key can be arbitrarily determined for each communication. This has the effect of increasing the security of the message.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a system for realizing a message compression / encryption method according to the present invention.

FIG. 2 is a correspondence table showing a procedure for converting an 8-bit JIS8 code into 4-bit.

FIG. 3 shows a message compression / encryption / decryption /
It is a descriptive processing explanatory drawing.

FIGS. 4A and 4B are explanatory diagrams of a data structure before and after compression in the present embodiment, wherein FIG. 4A shows an example in which a transmission message has an even length, and FIG. 4B shows an example in which a transmission message has an odd length.

FIG. 5 is a correspondence table of a compression code to a data structure of a transmission message according to the embodiment;

FIG. 6 is a matrix table showing a correspondence between a data structure of the transmission message and a HEX code.

FIG. 7 is a correspondence table between a transmission code and a data structure of an actual transmission message according to the embodiment.

FIG. 8 is a matrix table showing a correspondence between the structure of the transmission code and a HEX code representing a data structure of an actual transmission message.

FIG. 9 is an explanatory diagram of a data structure before and after compression according to another embodiment of the present invention, showing an example in which the number of corresponding codes in the upper row is not a multiple of the compression code in the lower row.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 2 Terminal device 3 Communication line 11, 21 Communication control part 12, 22 Message processing part 13, 23 Logic circuit 14, 24 Control part

Claims (3)

(57) [Claims] 1. A compression and encryption method of message that is transmitted and received between communication terminal apparatuses, the transmitting side, the heat transmission statement converts each byte of the 4-bit code corresponding to the two transmission telegram one had to the obtained compression codes 1 byte engaged forming a corresponding code, to generate a transmission code of 1 byte to determine the exclusive logical sum of the compression codes and a predetermined encryption key for each bit On the receiving side , the exclusive OR of the transmission code and the encryption key is determined bit by bit to decompress the compressed code, and after decomposing the decompressed compressed code into two corresponding codes, A step of inversely converting the corresponding code into the corresponding transmission message, wherein the transmitting side performs the inverse conversion when the number of transmission messages is odd.
Add a 4-bit pseudo code that is not targeted
The total size of the code is a natural number times the code length of the encryption key
If not, add the pseudo code until it becomes a natural number multiple.
A message compression / encryption method characterized by being satisfied . 2. The message compression / encryption method according to claim 1, wherein a correspondence between the two transmission messages and the transmission code is displayed.
IC card issued for each user with compression / encryption information
In the case where the user sends a message,
Searches the encrypted information to generate a transmission code, and
Search and transmit the compressed / encrypted information when receiving
A message compression / encryption method characterized by inversely transforming a message. 3. The method of claim 1 Symbol placement message compression and encryption method, transmitting the encryption key together with the transmission code from the transmitting side,
A message compression / encryption method, wherein the compression code is decompressed on the receiving side based on the encryption key.