JPH02177742A - Communication privacy system - Google Patents

Abstract

PURPOSE:To prevent the content of a message from being deducted or interpreted depending on the length of the message by constituting the system such that privacy processing is applied to a transfer block in which the data length of communication content is short together with information representing the data length of the communication content and a dummy data for expanding the data length. CONSTITUTION:A transfer block 13 including destination information DAI and a communication content CNT is subject to privacy processing to attain the communication between communication equipments 11, 12. The transfer block 13 whose data length of the communication content CNT is short is subject to privacy processing together with the information DLI representing the data length of the communication content and a dummy data DMY for expanding the data length. For example, when the communication content CNT is a message with a short data length such as a command, the information DLI representing the data length of the communication content CNT and the dummy data DMY to expand apparently the data length are added to the communication content CNT, privacy processing such as scrambling is applied and the result is sent to a transmission line. Then the dummy data DMY is deleted based on the data length information DLI to obtain the communication content CNT at the receiver side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a communication concealment method in a communication system that performs communication between communication devices by encrypting transfer blocks containing destination information and communication contents such as packets and messages.

Infer the message content based on the length of the message.

The purpose is to prevent it from being decrypted.

Mi1 for a transfer block whose communication content has a short data length
It is configured to perform concealment processing including information indicating the data length of the contents of one communication and dummy data for data length extension.

(Industrial Application Field) The present invention relates to a communication concealment method in a communication system in which communication is performed between communication devices by encrypting a transfer block containing destination information and communication contents such as a packet or a message.

For example, in a communication network such as a LAN, a destination address and a source address are added to a message and sent to the network, and each communication device communicates with each other by identifying and receiving messages addressed to itself based on the destination address. There is. In such a communication system, all communication devices can receive messages, so if there is a malicious recipient, he or she can receive the message and steal the contents even if it is addressed to someone else. be.

Especially in recent years, the number of nodes that make up the 9 communication networks has increased,
Installation locations are becoming wider, and many people are now sharing the network, such as a LAN in a tenant building. Therefore, there is an increasing need to keep communication contents secret using passwords, scrambles, etc.
A more robust communication secrecy method is needed.

[Conventional technology]

The mainstream of conventional communication networks is one that uses synchronous time-division multiplexing transmission lines, and in such networks, an eavesdropper can recognize in which part of the multiplexed signal the message he or she wants to steal is located. Even when communication devices are not communicating with each other,
Since some signals are present due to multiplexing, it is considered that it is sufficient to conceal the contents of the communication.

Regarding message communication where reception is controlled by address, some communication devices, such as host computers, can perform confidentiality processing at the application level; Not known.

C Problems to be Solved by the Invention In conventional communication systems, the contents of messages other than control fields such as addresses are limited.

It is possible to protect the information using conventional secrecy methods such as passwords and scrambling. However, for example, a short message is likely to be a command, and it is easy to infiltrate the message content based on the message length, so secrecy cannot be said to be sufficient, and a stronger secrecy method is desired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a communication secrecy system that can prevent the contents of a message from being guessed or decoded based on the length of the message.

[Means to solve the problem]

FIG. 1 is a diagram illustrating the principle of the present invention.

The communication concealment method according to the present invention is a communication concealment method in a communication system that performs communication between communication devices 11 and 12 by encrypting a transfer block 13 containing destination information DA and communication content CNT, and is a communication concealment method for one communication content. Information IIDLI indicating the data length of the communication content for the transfer block 13 with a short data length of CNT and dummy data DM for data length expansion
The configuration is such that concealment processing is performed including Y.

[Effect]

For example, when the communication content CNT is a message with a short data length such as a command, information DLI indicating the data length of the communication content CNT and dummy data DMY for apparently extending the data length are added to the communication content CNT. , and then undergoes ciphering processing such as scrambling and sends them out to the transmission path. As a result, the length of the transfer block becomes apparently longer, making it difficult to infer from the block length information that the block has command-7.

On the other hand, on the receiving side, the communication content CNT can be obtained by deleting the dummy data DMY based on the data length information DLI.

〔Example〕

The present invention will be described in detail below based on two drawings.

FIG. 2 shows a block configuration of a communication device using a communication security method as an embodiment of the present invention. In Figure 2,
The transmission side circuit is the transmission processing section 2. Transmission concealment section 3. The receiving side circuit includes a transmitting section 4, etc., and a receiving section 5. Confidential receiving section 6. It is configured to include a reception processing section 7 and the like. These transmitting side circuits and receiving side circuits are connected to the data processing section 1 and the network 8, respectively.

This message length formant is shown in FIG. 3. As shown in the figure, the message includes the destination address DA, source address SA, etc. as a header (control information) HD, and the communication content (content) that is the main object of the communication. The CNT includes data DT, data length DL of the data DT, and the like.

The data processing section 1 is a circuit that processes transmitted and received data, and is composed of an ant, a microprocessor, and the like.

The transmission processing section 2 receives data from the data processing section 1 and assembles it into a message to be transmitted to the network 8. The formant of this message is shown in FIG.

As shown in the figure, a header (control information 1) HD includes a destination address DA, a source address SA, etc., and data DT as a communication content (content) CNT, which is the main object of one communication.
It includes the data length DL of the data DT, etc.

The transmission concealment section 3 receives a message from the transmission processing section 2 and performs a concealment process, which will be described later, on the communication content CNT in the message. The transmitting section 4 receives the encrypted message from the transmitting encrypting section 3, adds an error control code, etc., and sends it to the network 8.

The receiving unit 5 receives a message in which its own station is designated as the destination address from among the messages on the network 8, performs error control, etc., and sends the communication content CNT that has been anonymized together with the header HD of the control information to the confidential receiver 6. give it to

Concealed reception B6 converts one communication content CNT into normal data by performing the reverse operation of the operation performed in the transmission concealment unit 3, and receives data of the length specified by the data length DL in the communication content CNT. The DT is passed to the reception processing section 7. The reception processing section 7 disassembles the received message and passes it to the data processing section 1.

A detailed configuration example of the transmission concealment section 3 is shown in FIG. Fourth
In the figure, 32 is a transmission control information memory in which the header HD in the message received from the transmission processing unit 2 is written;
33 is a data memory in which the communication content CNT in the message is written; 34 is a security processing section that reads out the contents of the data memory 33 and performs security processing such as scrambling;
is a separation circuit that controls the write timing of the transmission control information memory 32 and the data memory 33 and the drive timing of the privacy processing section 34 based on information passed from the transmission control information memory 32.

Reference numeral 35 denotes a transmission data memory into which a certain length of encrypted data encrypted by the encrypting unit 34 is written.

36 is a data selector that controls the read timing of the transmission control information memory 32 and the transmission data memory 35 in accordance with the drive from the privacy processing section 34.

37 is an AND gate 37 which assembles the read data from the transmission control information memory 32 and the transmission data memory 35 into a message and sends it to the transmitter 4.

A detailed configuration example of the secure receiving section 6 is shown in FIG. Fifth
In the figure, 62 is a reception control information memory in which the header HD in the message received by the receiving unit 5 is written, and 63 is a reception data memory in which the part of the message after the communication content CTN that has been subjected to the concealment processing is corrupted. Reference numeral 61 denotes a separation circuit that controls write timing of the reception control information memory 62 and the reception data memory 63 based on information passed from the reception section 5.

Reference numeral 64 denotes a decryption processing unit that decrypts the concealed data read out from the received data memory 63, and 65 represents a decryption processing unit 6.
A data memory 966 into which the communication content CNT decoded in step 4 is written is a data selector which controls the read timing of the reception control information memory 62 and data memory 65 according to a drive signal from the decoding processing section 64; and an AND gate that assembles a message using the data read from the data memory 65 and passes it to the reception processing section 7.

The operation of the above-described embodiment device will now be explained.

To explain the transmission operation of τF, the data processing unit 1 generates various information regarding the message to be transmitted and passes it to the transmission processing unit 2. The transmission processing unit 2 converts this information into a message in the format shown in FIG. Assemble to. This message is further passed on to the transmission secret section 3.

The transmission concealment unit 3 receives the header H in the received message.
Confidential processing is performed on the CN7 portion of the communication content excluding the D portion. At this time, if the message length is not the maximum message length, dummy data DMY is added to make the message length the maximum, and then the encryption process is performed.Hereinafter, the processing in the transmission encryption unit 3 will be explained.

When a message is input from the transmission processing section 2.

The separation circuit 31 controls the sending of a write clock to each circuit 32 and 33 so that the header HD in the message is written into the transmission control information memory 32 and the communication content CNT is written into the data memory 33. This control is performed by the transmission processing unit 2 when the message format is known.
This can be done by counting the clocks from the beginning of the message received from and knowing the separation timing of the header HD and communication content CNT. In addition, if the message format is not constant, the header H is sent from the transmission processing unit 2.
The separation timing may be known by receiving a signal instructing the switching position between D and the communication content CNT.6 By above, the header HD information is written in the transmission control information memory 32, and the communication content is written in the data memory 33. Content CNT is written.

When the message reception is completed, the one-separation circuit 31 sends a drive signal to the security processing section 34. In response to this, the concealment processing section 34 is driven and reads all the stored contents from the data memory 33. The data length that can be written in the data memory 33 is set to the maximum data length of the data DT. Therefore, if the data length of the data DT such as a command is shorter than the maximum data length, the data length of the data DT is set to the maximum data length of the data DT. For the missing portion exceeding , the contents written last time will be read out as dummy data DMY.

The ciphering processing unit 34 performs ciphering processing such as scrambling on the read data, that is, the content CNT and dummy data DMY added thereto, if any, and writes the processed data into the transmission data memory 35. . Therefore, the data length written in the transmission data memory 35 is the maximum data length. Concealment processing unit 34
When the concealment process is completed, it sends a drive signal to the data selector 36.

In response to this drive signal, the data selector 36 first sends a read clock to the transmission control information memory 32 and reads out the header HD, which is the stored content.

Then, a read clock is sent to the transmission data memory 35 to read out the concealed processing result data, and these data are passed to the transmission section 4 via the AND gate 37.

The transmitting section 4 transmits the encrypted message passed from the transmitting encrypting section 3 to the network 8 .

Next, the reception operation will be explained. When the receiving section 5 receives a message addressed to itself from the network 8, it passes it to the confidential receiving section 6. The encrypted receiving unit 6 converts the encrypted part into normal data by performing an operation opposite to that performed in the [y anonymizing process], and receives the data content of the length specified by the data length DL. This operation of passing the data to the processing unit 7 will be explained below.

When the separation circuit 61 receives a received message from the receiving section 5, it counts clocks from the beginning of the message to measure the timing, separates the header HD from the content CNT, stores the header HD in the reception control information memory 62, and stores the content CNT. A write clock is sent to both circuits 62 and 63 so that they are respectively written into the received data memory 63.

When the reception of the message is completed, the 2-separation circuit 61 sends a drive signal to the decoding processing section 64 to start the decoding processing of the decoding processing section 64. When the decoding processing unit 64 is activated, it reads out all write items from the received data memory 63, performs decoding processing, and obtains the data length DL, data DT, etc. as the decoding results.

This is written into the data memory 65.

When the decoding processing unit 64 completes the decoding process, it sends a drive signal to the data selector 66. This allows data selector 6
6 is driven. Then, first, the data length DL is read from the data memory 65 and stored. Next, the header HD information is read from the reception control information memory 62 and passed to the reception processing section 7 via the AND gate 67. Next, data of the length specified by the data length DL (that is, data DT) is read from the data memory 65 and passed to the reception processing section 7 via the AND gate 6.7, whereby the data is read from the data memory 65. The data is

Only the data DT portion excluding the dummy data DMY is included. The reception processing section 7 processes information in the same manner as in the prior art.

As a result of the above operations, the length of messages transmitted and received on the network 8, including messages such as commands, becomes a constant length, and therefore it is no longer possible to infer that the message is a command from the message length.

[Effects of the Invention] According to the present invention, it becomes possible to prevent the contents of a message from being guessed and decoded based on the length of the message, and it becomes possible to perform stronger communication secrecy.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention. FIG.
This is a block diagram showing the system. FIG. 3 is a diagram showing a message formant. FIG. 4 is a block diagram illustrating an example of the configuration of the transmission concealment unit in the embodiment system, and FIG. 5 is a block diagram illustrating an example configuration of the concealment receiving unit in the embodiment system. In fig. 1-Data processing section 2--Transmission processing section 3--Transmission concealment section 4-Transmission section 5--Reception section 6--Secret reception section 7--Reception processing section 8--Network 31.61-.- Separation circuit 32 -- Transmission control information memory 33.65 -- Data memory 34 -- Concealment processing section 35 -- Transmission data memory 36.66 -- Data selector 37.67 -- AND gate 62 -- Reception control information Memory 63 - Received data memory 64 - Decoding processing unit

Claims (1)

[Claims] A communication concealment method in a communication system that performs communication between communication devices (11, 12) by encrypting a transfer block (13) containing destination information and communication content, comprising: data of communication content; A communication concealment method configured to perform concealment processing on a short transfer block (13) including information indicating the data length of the communication content and dummy data for data length extension.