JP5837625B2 - Communication system and communication method - Google Patents

Description

  The present invention includes two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to a communication device on the other side, and decrypt the received encrypted data into transmission target data. The present invention relates to a communication system.

  The communication system as described above is used in a situation where it is necessary to conceal transmission target data transmitted between two communication apparatuses from a third party. Various encryption techniques have been proposed and used to conceal transmission target data, but it is difficult to completely prevent the decryption of the encryption.

In general, the communication performed by encrypting the transmission target data is performed by cutting the transmission target data by a predetermined number of bits in the sender-side transmission / reception device, encrypting each of the cut data, and sending it to the communication device on the other side, This is performed by the procedure of decrypting the data received by the receiving side transmitting / receiving device.
At this time, the transmission / reception device on the sender side and the transmission / reception device on the receiver side perform encryption or decryption processing in a fixed unit such as 8 bits or 16 bits.
Therefore, when such a unit is known to the outside, the algorithm used for encryption is decrypted, and as a result, the content of communication is likely to be decrypted.
In addition, since the existing device performs encryption or decryption in a standardized unit such as 8 bits or 16 bits, the transmission / reception device encrypts or decrypts in the same unit as such a standardized unit. In this case, the algorithm used for encryption can be easily deciphered.

  The present invention includes two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to a communication device on the other side, and decrypt the received encrypted data into transmission target data. An object of the present invention is to improve the communication system so as to reduce the possibility of decryption of communication by a third party.

  In order to solve this problem, the present inventor proposes a first invention and a second invention described below.

The communication system according to the first invention encrypts the transmission target data that is plaintext and sends it as encrypted data to the communication device on the other side, and also decrypts the received encrypted data into transmission target data. A first communication device and a second communication device, which are communication devices, are included.
Both the first communication device and the second communication device in this communication system cut the transmission target data into a plurality of transmission target cut data for each predetermined number of bits, and encrypt the encrypted data. Cutting means that cuts into the plurality of encrypted cut data by cutting the same number of bits as the data that was cut when the data was encrypted, the transmission target cut data, the first communication device and the second communication device Encrypted by the same algorithm as the encrypted data to be encrypted data, and the encrypted cut data is decrypted by the algorithm used when encrypting the encrypted cut data to be the transmission target cut data Decryption means, connection means for connecting the decrypted transmission target disconnection data to the transmission target data, and transmitting / receiving the encrypted data Receiving means, and a.
In the communication system, the disconnection unit disconnects the transmission target data so that at least one of the transmission target disconnection data has a bit number different from that of the other transmission target disconnection data.
In this communication system, when the transmission target data is generated by cutting the transmission target data, at least one of the transmission target disconnect data has a different bit number from the other transmission target disconnect data. Unless a third party knows in what units the encrypted data is encrypted, even if it can know the algorithm used for encryption, the encrypted data Cannot be decrypted. In this communication system, since at least one of the transmission target cut data and the encrypted cut data can have a different bit number from the other transmission target cut data or the encrypted cut data, the decryption of the cipher is attempted. Sometimes, processing in a unit different from the general data processing unit of 8 bits or 16 bits is required for at least one cut data to be transmitted or encrypted cut data. It will be difficult.
Therefore, the encrypted communication in this communication system is difficult to be decrypted by a third party.

The communication system in the first invention can be as follows.
This communication system is composed of two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to the communication device on the other side, and decrypt the received encrypted data into transmission target data. A first communication device and a second communication device are included.
The first communication device and the second communication device both cut the transmission target data into a plurality of transmission target disconnection data for each predetermined number of bits, and convert the encrypted data into the encrypted data. Cutting means that cuts into the plurality of encrypted cut data by the same number of bits that were cut when the data was encrypted, and sequentially generates common data common to the first communication device and the second communication device The common data generating means for encrypting the transmission target disconnection data by an algorithm common to the first communication apparatus and the second communication apparatus generated based on the common data received from the common data generating means; It is set as encrypted data, and the encrypted cut data is decrypted by the algorithm used when encrypting the encrypted cut data to be transmitted. An encryption / decryption unit that converts to disconnected data, a connection unit that connects the decrypted transmission target disconnection data to the transmission target data, and a transmission / reception unit that transmits and receives the encrypted data. The common data generating means generates the common data when the encryption / decryption means receives the transmission target cut data or the encrypted cut data.
Further, the cutting means of this communication system cuts the transmission target data so that at least one of the transmission target cutting data has a different bit number from that of other transmission target cutting data.
In this communication system, since the algorithm is updated at a timing at which the first communication device and the second communication device can perform encryption and decryption using the same algorithm, there is a possibility that the encryption is decrypted. Will be lower.

  Both the first communication device and the second communication device according to the first aspect of the present invention include dummy data that is not related to the transmission target data in the transmission target disconnection data except for the data with the largest number of bits. Thus, a mixing unit may be provided that matches the number of bits of all the transmission target cut data with the number of bits of the transmission target cut data having the largest number of bits. In this way, the number of bits of the transmission target cut data or the encrypted cut data, which are the units of encryption or decryption in the first communication device or the second communication device, all match, so the encryption / decryption processing is performed. It becomes easy to do. On the other hand, since the third party does not know which data is the original transmission target cut data or encrypted cut data, and which data is the dummy data, the possibility of the decryption remains low.

The communication system according to the second invention encrypts the transmission target data in plain text and sends it as encrypted data to the communication device on the other side, and decrypts the received encrypted data into transmission target data. A first communication device and a second communication device, which are communication devices, are included.
Both the first communication device and the second communication device according to this communication system cut the transmission target data into a plurality of transmission target cut data by a predetermined number of bits, and encrypt the encrypted data. A cutting means for cutting into the plurality of encrypted cut data by cutting the same number of bits as the data cut when the data is encrypted, and sending the cut data to be transmitted by the first communication device and the second communication device. The encrypted data is encrypted by a common algorithm to be encrypted data, and the encrypted cut data is decrypted by the algorithm used when encrypting the encrypted cut data to be cut data to be transmitted. Encryption / decryption means configured to perform the encryption or the decryption for each reference number of reference bits, the decrypted transmission target switch Connecting means for connecting the data to the transmission target data, and a transmitting and receiving means for transmitting and receiving the encrypted data.
And the cutting means in this communication system cuts the transmission target data into a bit number shorter than the reference bit number, and the first communication device and the second communication device are both The transmission target disconnection data includes a mixing unit that includes dummy data that is not related to the transmission target data to match the transmission target disconnection data with the reference bit number.
The cutting means in this communication system cuts the transmission target data into a bit number shorter than the reference bit number. The reference bit number is, for example, 8 bits or 16 bits, which is the same as a general data processing unit. be able to. In this way, when decryption is attempted, at least one transmission target cut data or encrypted cut data is processed in a processing unit different from a general data processing unit of 8 bits or 16 bits. Therefore, it becomes difficult to perform analysis on a general computer. In addition, the first communication device and the second communication device included in the communication system include the dummy data that is not related to the transmission target data in the transmission target disconnection data, thereby determining the transmission target disconnection data as the reference Mixing means for matching the number of bits is provided. Therefore, the first communication device and the second communication device included in this communication system can perform encryption / decryption processing in units of processing performed by a general computer as a result. , You don't have to change it. On the other hand, since the third party does not know which data is the original transmission target cut data or encrypted cut data, and which data is the dummy data, the possibility of the decryption remains low.

The communication system in the second invention can be as follows.
In the communication system according to the second aspect of the invention, the transmission target data, which is plaintext, is encrypted and sent to the communication apparatus on the other side as encrypted data, and the received encrypted data is decrypted to be transmission target data. A first communication device and a second communication device which are communication devices are included.
The first communication device and the second communication device both cut the transmission target data into a plurality of transmission target disconnection data for each predetermined number of bits, and convert the encrypted data into the encrypted data. Cutting means that cuts into the plurality of encrypted cut data by the same number of bits that were cut when the data was encrypted, and sequentially generates common data common to the first communication device and the second communication device A common data generating means for encrypting the transmission target cut data by an algorithm common to the first communication apparatus and the second communication apparatus generated based on the common data received from the common data generating means And the encrypted cut data is decrypted by the algorithm used when encrypting the encrypted cut data, The encryption / decryption means for performing encryption or decryption for each reference number of reference bits, and connecting the decrypted transmission target disconnection data Connecting means for transmitting data, and transmitting / receiving means for transmitting / receiving the encrypted data, and the common data generating means is configured such that the encryption / decryption means transmits the transmission target disconnected data or the encrypted disconnection. The common data is generated when the data is received.
The disconnect means of the communication system is configured to disconnect the transmission target data into a bit number shorter than the reference bit number, and both the first communication device and the second communication device transmit the transmission data. Mixing means for matching the number of bits of the cut data to be transmitted with the reference bit number by including dummy data that is not related to the data to be transmitted in the target cut data.
Since this communication system is designed to update the algorithm used for encryption and decryption at a timing such that encryption and decryption can be performed using the same algorithm in the first communication device and the second communication device, The possibility of decryption of the code is lower.

If the cutting means cuts the transmission target data shorter than the reference bit number, the cutting unit may cut the data to be transmitted to a certain number of bits, or to cut to a different number of bits. It may be. The former is easier to process, but the latter is less likely to be decrypted.
When the cutting unit cuts the transmission target data into a certain number of bits shorter than the reference bit number, the mixing unit includes the dummy data at a specific position of the transmission target data. Alternatively, the dummy data may be included in a predetermined position that is different for each piece of transmission target data. The former is easier to process, but the latter is less likely to be decrypted.

The following contents are common to the first invention and the second invention.
The common data generation means may generate a pseudo random number as the common data. Of course, the common data generating means may generate other data.
The common data generation means is configured to generate an algorithm used for encryption and decryption at a timing at which encryption and decryption can be generated at a timing at which the first communication device and the second communication device can use the same algorithm. It is only necessary to generate common data. For example, the common data generation means may generate the common data every time the transmission target data is encrypted or the encrypted data is decrypted. The common data generation means may generate the common data every time the transmission target cut data is encrypted or the encrypted cut data is decrypted.
The mixing unit may determine the predetermined position including the dummy data based on the common data. When dummy data is included at different positions of the transmission target disconnect data (including the case where the number of bits of the transmission target disconnect data at the time when the transmission target data is disconnected is different from the number of bits of the other transmission target disconnect data) )), The first communication device and the second communication device perform decryption of the received encrypted cut data unless the transmission side communication device knows where the dummy data is included in the cut data to be transmitted. I can't. If the mixing means determines the predetermined position to include the dummy data based on the common data, the position of the dummy data thus included in the transmission target cut data is determined as the receiver. The communication device on the side can know the data it has (this data is common to the first communication device and the second communication device). Also, in this case, since there is no information exchange between the first communication device and the second communication device regarding where the dummy data is included in the transmission target disconnect data, a third party can communicate with this communication device. It is almost impossible to break the encryption in the system.
When cutting at least one of the transmission target cut data so as to have a bit number different from that of the other transmission target cut data, the cutting means generates at least one of the transmission target cut data based on the common data. You may make it cut | disconnect so that it may become a bit number different from other transmission object cutting | disconnection data. If at least one of the transmission target cut data has a bit number different from that of the other transmission target data, the sender side communication device does not know the bit number of the transmission target cut data and decodes it. Cannot be made. If the disconnection means is configured to disconnect the transmission target data based on the common data, the receiver side communication device has the bit number at which the transmission target data is disconnected. Data (this data is common to the first communication device and the second communication device). In this case, since there is no exchange of information about where the transmission target data is disconnected between the first communication device and the second communication device, a third party breaks the encryption in this communication system. Is almost impossible.

The first invention can also be realized by the following method.
An example of the method is two communication apparatuses that can encrypt transmission target data in plain text and send it as encrypted data to the communication apparatus on the other side, and decrypt the received encrypted data into transmission target data A method executed in a communication system including a first communication device and a second communication device.
In this method, one of the first communication device and the second communication device cuts the transmission target data into a plurality of transmission target disconnection data by cutting the transmission target data every predetermined number of bits. Is encrypted by a predetermined algorithm to be encrypted data, the encrypted data is transmitted to the other of the first communication device and the second communication device, the first communication device and the second communication device. A process of cutting the received encrypted data into a plurality of pieces of encrypted cut data by cutting the encrypted data into pieces of the same number of bits that were cut when the encrypted data was encrypted, The process of decrypting the data by the algorithm used when encrypting the encrypted cut data into the transmission target cut data, connecting the decrypted transmission target cut data The process of the serial transmission target data includes.
In this method, the first communication device and the second communication device disconnect the transmission target data so that at least one of the transmission target disconnection data has a bit number different from that of other transmission target disconnection data. To do.
Another example of the method is to encrypt the transmission target data in plain text and send it as encrypted data to the communication device on the other side, and to decrypt the received encrypted data into transmission target data. It is the method performed by the communication system containing the 1st communication apparatus and 2nd communication apparatus which are communication apparatuses.
In this method, one of the first communication device and the second communication device cuts the transmission target data into a plurality of transmission target disconnection data by cutting the transmission target data every predetermined number of bits. Is encrypted by a predetermined algorithm to be encrypted data, the encrypted data is transmitted to the other of the first communication device and the second communication device, the first communication device and the second communication device. The other is a process of cutting the received encrypted data into a plurality of encrypted cut data by cutting the same encrypted data every bit number that was cut when the encrypted data was encrypted, the encrypted cut data Is decrypted by the algorithm used when encrypting the encrypted cut data to make the cut data to be transmitted, and the decrypted transmission target cut data is connected before The first communication device and the second communication device generate the common data when receiving the transmission target disconnection data or the encrypted disconnection data. In addition, the encryption or decryption is performed for each reference bit number serving as a reference, and the one of the first communication device and the second communication device uses the transmission target data as a bit number shorter than the reference bit number. In addition, the transmission target disconnect data includes dummy data that is not related to the transmission target data, so that the number of bits of the transmission target disconnect data matches the reference bit number.

The second invention can also be realized by the following method.
An example of the second invention is two communications that can encrypt transmission target data that is plaintext and send it as encrypted data to the communication device on the other side, and decrypt the received encrypted data into transmission target data. A method executed in a communication system including a first communication device and a second communication device which are devices.
In this method, one of the first communication device and the second communication device cuts the transmission target data into a plurality of transmission target disconnection data by cutting the transmission target data every predetermined number of bits. A process of sequentially generating, a process of encrypting the transmission target disconnection data by an algorithm generated based on the common data, and converting the encrypted data into encrypted data; the other of the first communication apparatus and the second communication apparatus Transmitting the encrypted data received by the other of the first communication device and the second communication device to the same number of bits that was disconnected when the encrypted data was encrypted. A plurality of encrypted cut data, a step of sequentially generating common data common to the one of the first communication device and the second communication device, A process of decrypting data into transmission target disconnect data by decrypting the encrypted cut data generated based on the generated common data into an algorithm to be transmitted; Connecting the data to the data to be transmitted.
In addition, the first communication device and the second communication device in this method generate the common data when the transmission target disconnection data or the encrypted disconnection data is accepted, and the transmission target data, At least one of the transmission target cut data is cut to have a bit number different from that of the other transmission target cut data.
Another example of this method is to encrypt the transmission target data in plain text and send it to the communication apparatus on the other side as encrypted data, and at the same time decrypt the received encrypted data into transmission target data. The method is executed in a communication system including a first communication device and a second communication device which are communication devices.
In this method, one of the first communication device and the second communication device cuts the transmission target data into a plurality of transmission target disconnection data by cutting the transmission target data every predetermined number of bits. A step of sequentially generating, a step of encrypting the transmission target cut data by an algorithm generated based on the common data to obtain encrypted data, the encrypted data being transferred to the other of the first communication device and the second communication device A process of transmitting, the process of transmitting the encrypted data to the other of the first communication apparatus and the second communication apparatus, the encrypted data received by the other of the first communication apparatus and the second communication apparatus, A process of cutting the encrypted data into a plurality of encrypted cut data by the same number of bits that were cut when the encrypted data was encrypted, the first communication device and the second communication device A process for sequentially generating common data common to the one, the algorithm used when encrypting the encrypted cut data generated based on the generated common data The process includes the steps of decrypting the data into transmission target disconnection data and connecting the decrypted transmission target disconnection data into the transmission target data.
In addition, the first communication device and the second communication device in this method generate the common data when the transmission target disconnection data or the encrypted disconnection data is accepted, and the encryption or decryption For each reference bit number serving as a reference, and the one of the first communication device and the second communication device cuts the transmission target data into a bit number shorter than the reference bit number, and By including dummy data not related to the transmission target data in the disconnection data, the number of bits of the transmission target disconnection data is matched with the reference bit number.

The figure which shows the whole structure of the communication system of embodiment. The figure which shows the hardware constitutions of the 1st communication apparatus and the 2nd communication apparatus which are included in the communication system shown in FIG. The block diagram which shows the structure of the communication apparatus of the 1st communication apparatus and the 2nd communication apparatus which are included in the communication system shown in FIG. The flowchart which shows the flow of the process performed with the communication system shown in FIG. The flowchart which shows the flow of the process of the encryption performed with the 1st communication apparatus of the communication system shown in FIG. The flowchart which shows the flow of the process of a decoding performed with the 2nd communication apparatus of the communication system shown in FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

The communication system according to this embodiment is schematically configured as shown in FIG. The communication system includes a first communication device 11 and a second communication device 12 that are connected to each other via a network 13. The first communication device 11 and the second communication device 12 perform encrypted communication with each other.
The network 13 connecting the first communication device 11 and the second communication device 12 is, for example, the Internet. However, instead of this, the network 13 may be configured by other means, for example, an intranet or a dedicated line.

  The configurations of the first communication device 11 and the second communication device 12 will be described. Since the first communication device 11 and the second communication device 12 have the same configuration in this embodiment, only the configuration of the first communication device 11 will be described as a representative.

The hardware configuration of the first communication device 11 is shown in FIG.
In this embodiment, the first communication device 11 includes a central processing unit (CPU) 21, a read only memory (ROM) 22, a hard disk drive (HDD) 23, a random access memory (RAM) 24, an input device 25, a display device. 26, a communication device 27, and a bus 28. The CPU 21, ROM 22, HDD 23, RAM 24, input device 25, display device 26, and communication device 27 can exchange data via a bus 28.
The ROM 22 or the HDD 23 may include a predetermined program and predetermined data (this may include data to be transmitted). In the present embodiment, this is the case. Includes data necessary for executing the above program). The CPU 21 controls the entire first communication device 11 and executes processing to be described later based on programs and data stored in the ROM 22 or the HDD 23. The RAM 24 is used as a working storage area when the CPU 21 performs processing.
The input device 25 includes a keyboard and a mouse, and is used for inputting commands and data. The display device 26 includes an LCD (liquid crystal display), a CRT (cathode ray tube), and the like, and is used to display commands, input data, processing status to be described later, and the like.
The communication device 27 executes communication with the second communication device 12 via the network 13. The communication device 27 of the second communication device 12 performs communication with the first communication device 11 via the network 13.

Next, the configuration of the communication device 27 will be described. FIG. 3 shows a block configuration diagram of the communication device 27.
The communication device 27 includes an interface unit 31, a preprocessing unit 32, an encryption / decryption unit 33, a common data generation unit 34, an algorithm generation unit 35, a key generation unit 36, a communication unit 37, and a connection unit 38. The

The interface unit 31 exchanges data between the bus 28 and the encryption / decryption unit 33. The interface unit 31 also has a function of sending data from the bus 28 to the common data generation unit 34 and sending data from the connection unit 38 to the bus 28.
The preprocessing unit 32 cuts transmission target data or encrypted data received from the bus 28 via the interface unit 31 every predetermined number of bits to generate transmission target cut data or encrypted cut data, It has a function of sending this to the encryption / decryption unit 33. How to cut the transmission target data or the encrypted data will be described later. In this embodiment, the preprocessing unit 32 has a function of including dummy data, which is data unrelated to the transmission target data, in the transmission target data by a method described later.
The encryption / decryption unit 33 receives the transmission target cut data or the encrypted cut data from the preprocessing unit 32, encrypts the transmission target cut data when received, and receives the encrypted cut data. Has a function of decoding it. Note that the encryption / decryption unit 33 in this embodiment has a fixed number of reference bits, which is a processing unit when performing encryption and decryption processing. The reference bit number in this embodiment is 8 bits, although not limited thereto. Details of the encryption and decryption processing will be described later.
The common data generation unit 34 sequentially generates common data that is data common to the first communication device 11 and the second communication device 12. In this embodiment, the common data generation unit 34 in the first communication device 11 and the second communication device 12 sequentially generates common data so that common data in the same order is the same. Further, the common data in this embodiment is a pseudo-random number although it is not necessarily so. The generated common data is sent to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36.
The algorithm generation unit 35 generates an algorithm based on the common data received from the common data generation unit 34. This algorithm is used when the encryption / decryption unit 33 performs encryption processing and decryption processing.
The key generation unit 36 generates a key based on the common data received from the common data generation unit 34. The key is used when the encryption / decryption unit 33 performs encryption processing and decryption processing.
The communication unit 37 exchanges data with the network 13. The encrypted cut data generated by encrypting the transmission target cut data by the encryption / decryption unit 33 is connected by the connection unit 38 and sent to the communication device on the other side via the communication unit 37. Become. In addition, the communication unit 37 receives encrypted data from the counterpart communication device. This encrypted data is sent from the communication unit 37 to the preprocessing unit 32.
The connection unit 38 has a function of connecting the transmission target cut data generated by decrypting the encrypted cut data by the encryption / decryption unit 33 in the original order to make a batch of transmission target data. ing. This transmission target data is sent to the interface unit 31 and is sent to the HDD 23 or the CPU 21 via the bus 28 as necessary. The connection unit 38 also has a function of connecting encrypted cut data generated by encrypting the transmission target cut data by the encryption / decryption unit 33 to form a set of encrypted data. . This encrypted data is sent to the communication unit 37, and is sent from the communication unit 37 to the communication device on the other side. Note that the connection unit 38 may not have a function of connecting encrypted cut data generated by encrypting the transmission target cut data by the encryption / decryption unit 33. In this case, the encrypted cut data is sequentially sent to the counterpart communication device in the order of encryption. When the connection unit 38 is such, the encrypted cut data can be directly sent to the communication unit 37 without passing through the connection unit 38.

Next, the flow of processing performed in this communication system will be described.
If it demonstrates roughly using FIG. 4, the flow of the process performed with this communication system is as follows.
First, the first communication device 11 encrypts transmission target data to generate encrypted data (S110). Next, the first communication device 11 sends the encrypted data to the second communication device 12 (S120). Next, the second communication device 12 that has received the encrypted data decrypts the encrypted data and returns it to the transmission target data (S130).
Thus, in the following description, encrypted data is sent from the first communication device 11 to the second communication device 12, but the encrypted data is sent from the second communication device 12 to the first communication device 11 as described above. It will be obvious that the content of the process does not change even when the reverse process is performed.

  First, the process of S110 described above in which the first communication device 11 encrypts transmission target data to generate encrypted data will be described in detail with reference to FIG.

  First, transmission target data is read. The transmission target data may be any data that needs to be transmitted from the first communication device 11 to the second communication device 12. In this embodiment, it is assumed that the transmission target data is recorded in the HDD 23. For example, when a command indicating that transmission target data can be sent from the input device 25 to the second communication device 12 is input, the CPU 21 reads the transmission target data from the HDD 23 and temporarily records it in the RAM 24, for example. This transmission target data is sent from the RAM 24 to the preprocessing unit 32 via the bus 28 and the interface unit 31 in the communication device 27 (S1101).

In the preprocessing unit 32, the transmission target data is cut for each predetermined number of bits to be transmission target cut data (S1102). The preprocessing unit 32 includes dummy data in the transmission target disconnection data as necessary.
Although there may be one method for generating the transmission target disconnect data from the transmission target data, in this embodiment, the transmission target disconnect data is generated from the transmission target data by any of the following three methods. It has become.
A) The transmission target data is cut into a certain number of bits shorter than the reference bit number to be transmission target cut data, and all of the transmission target cut data whose bit number is shorter than the reference bit number When dummy data is included in a certain position B) The transmission target data is cut into a certain number of bits shorter than the reference bit number to be the transmission target cut data, and all of them are the number of bits more than the reference bit number. In the case where dummy data is included in each different position of the transmission target cut data that has been shortened, C) the transmission target data is cut into the number of bits equal to or shorter than the reference bit number to be the transmission target cut data, When dummy data is included in each of the transmission target cut data having a bit number shorter than the reference bit number

  Which of the three methods described above is used to generate transmission target disconnect data from transmission target data is determined by the common data generated by the common data generation unit 34.

Therefore, how the common data generation unit 34 generates common data will be described first.
When the interface unit 31 receives transmission target data from the bus 28, the common data generation unit 34 receives the information from the interface unit 31.
In response to this, the common data generation unit 34 starts generating common data. In this embodiment, the common data generation unit 34 generates common data every time transmission target data is received by the interface unit 31. Although not limited to this, the common data in this embodiment is a matrix (X) of 8 rows and 8 columns.

The common data generation unit 34 does not necessarily have to be so, but in this embodiment, the common data is continuously generated as a non-linear transition.
In order to continuously generate the common data so as to make a non-linear transition, for example, (1) the process of generating the common data includes the calculation of the power of the past common data, and (2) the process of generating the common data. A method of including multiplication of two or more common data in the past or combining (1) and (2) is conceivable.

In this embodiment, the common data generation unit 34 has a 01st solution (X ₀₁ ) and a 02nd solution (X ₀₂ ) as predetermined initial matrices (for example, the 01st solution and the 02nd solution). The solution is recorded in a predetermined memory).
The common data generation unit 34 substitutes this initial matrix into the solution generation algorithm, and generates the first solution (X ₁ ) as follows.
First solution (X ₁ ) = X ₀₂ X ₀₁ + α (α = 8 × 8 matrix)
This is the first common data generated.
Next, when the interface unit 31 receives the transmission target data from the bus 28, the common data generation unit 34 generates the second solution (X ₂ ) as follows.
Second solution (X ₂ ) = X ₁ X ₀₂ + α
Similarly, each time the interface unit 31 receives data to be transmitted from the bus 28, the common data generation unit 34 generates the third solution, the fourth solution,..., The Nth solution as follows.
Third solution (X ₃ ) = X ₂ X ₁ + α
Fourth solution (X ₄ ) = X ₃ X ₂ + α
:
Nth solution (X _N ) = X _N−1 X _N−2 + α
The solution (that is, common data) generated in this way is sent to the preprocessing unit 32 and the algorithm generation unit 35 and is held by the common data generation unit 34. In this embodiment, in order to generate the Nth solution ( _XN ), the N-1th solution ( _XN-1 ) and the N-2th solution ( _XN-2 ) are generated immediately before that. Two other solutions are used. Therefore, the common data generation unit 34 must hold the last two solutions generated in the past in order to generate a new solution (or if no other person holds these two solutions). Must not). Conversely, solutions older than the last two solutions generated in the past are not used in the future to generate new solutions. Therefore, in this embodiment, the two previous solutions are always held in the common data generation unit 34. However, the newest solution is the third most recent solution so far. The solution that was the solution is deleted from a predetermined memory or the like in which the solution is recorded.
It should be noted that the solution generated in this way is chaotic with a non-linear transition and becomes a pseudo-random number.

In order to cause a nonlinear transition, the Nth solution (X _N ) = X _N−1 X _N−2 + α described above is obtained when the Nth solution is obtained.
In addition to using the following formula, it is conceivable to use the following formula.
For example,
(A) Nth solution (X _N ) = (X _N−1 ) ^P
(B) Nth solution (X _N ) = (X _N-1 ) ^P (X _N-2 ) ^Q (X _N-3 ) ^R (X _N-4 ) ^S
(C) Nth solution (X _N ) = (X _N−1 ) ^P + (X _N−2 ) ^Q
Etc.
P, Q, R, and S are predetermined constants. Further, the common data generation unit 34 has two initial matrices when using the formula (a) or (c) and four initial matrices when using the formula (b).
Moreover, although α mentioned above was a constant, it can also be used as specific changing environment information. This environmental information is information that occurs naturally one after another and can be obtained in common at distant locations. For example, information that is determined based on weather in a specific region, is broadcast at a specific time. Information determined based on the contents of a television broadcast of a certain TV station, information determined by the result of a specific sport, and the like.
If the above-mentioned α is created one after another from such environmental information and common information is generated, the confidentiality of communication can be further enhanced.
Of course, it is possible to add α (this may be generated from the environment information) to the right side of the mathematical expressions (a) to (c).

As described above, the preprocessing unit 32 that has received the common data (that is, the above-described solution) determines whether to generate the transmission target disconnection data according to any of the above-described methods A), B), and C). decide. In this embodiment, although not limited to this, the sum of the numbers constituting the 8-by-8 matrix that is the common data is divided by 3, and when the remainder is 0, the method of A) When the remainder is 1, the transmission target disconnection data is generated by the method B), and when the remainder is 2, the transmission target disconnection data is generated by the method C).
In the case of generating the transmission target cut data by the method A), the preprocessing unit 32 sequentially transmits the transmission target data received from the interface unit 31 from the top to a certain number of bits shorter than the reference bit number (this implementation). In the embodiment, the transmission target cut data is generated by cutting at 7 bits). In addition, the preprocessing unit 32 embeds dummy data at a certain position of the transmission target cut data. Note that the position in the transmission target cut data in which the dummy data is embedded may change or may be fixed. In the latter case, the position where the dummy data is embedded can be, for example, the beginning or end of the transmission target cut data, or a predetermined intermediate position such as the second bit or the third bit. This dummy data may be any data as long as it is unrelated to the transmission target data. For example, a process of always embedding data of 0, embedding data of 1, or embedding data of 1 and 0 alternately is conceivable. As yet another example, it is possible to determine what dummy data is to be embedded based on the common data. For example, the sum of the numbers that make up an 8-by-8 matrix that is common data is divided by 9, and when the remainder is 0, 0, 0, 0, 0. When 1 is set, 1 is inserted every other 0, 1, 0, 1 ... When the remainder is 2, 1 is inserted every other 0, 0, 1, 0, 0, 1 ... Similarly, when the remainder is 3, every 1 is inserted every 3; when the remainder is 4, every 1 is inserted, and when the remainder is 9, every 1 is inserted.
When the transmission target cut data is generated by the method B), the preprocessing unit 32 cuts the transmission target data into a certain number of bits shorter than the reference bit number (for example, 7 bits) and transmits the data. In addition to the target cut data, dummy data is included in different positions of the transmission target cut data, all of which are shorter than the reference bit number. In this case, the position where the dummy data is embedded may be fixed, or the first bit, the second bit, the third bit,..., The eighth bit, the first bit, the second bit,. It may change regularly, such as moving in order with eyes, or may change randomly. When the position where the dummy data is embedded changes randomly, for example, the position where the dummy data is embedded may be determined based on the common data.
As a method of determining the reference bit number in which dummy data is embedded by using the common data, for example, the sum of the numbers constituting the 8-by-8 matrix that is the common data is divided by 8, and the remainder is 0. When the transmission target cut data is alternately embedded, dummy data is alternately embedded at the beginning and end. When the remainder is 1, transmission target cut data with dummy data embedded at the beginning and dummy data is embedded at the end. If there is a remainder of 2, the transmission target cutting data with dummy data embedded at the beginning and the transmission target cutting data with dummy data embedded at the end are three. If the remainder is 7, send target cut data with dummy data embedded at the beginning and send target with dummy data embedded at the end Sectional data is set to be eight every, that it is possible to perform the process. It is also possible to move the position further without fixing the position where the dummy data is embedded, such as the beginning and the end.
When the transmission target cut data is generated by the method C), the transmission target data is cut to the number of bits equal to or shorter than the reference bit number. This cutting can be performed by cutting the transmission target data into a random length shorter than 8 bits. For example, the sum of the numbers constituting the 8-by-8 matrix, which is common data, is added. When the remainder is 0, when the remainder is 0, the beginning part of the transmission target data is cut at 8 bits, and when the remainder is 1, the beginning part of the transmission target data at that point is cut by 1 bit, When the remainder is 2, the leading part of the transmission target data at that point is cut by 2 bits, and when the remainder is 7, the leading part of the transmission target data at that point is cut by 7 bits. Can do. In addition, the preprocessing unit 32 embeds dummy data in each of the transmission target cut data having a bit number shorter than the reference bit number among the transmission target cut data generated thereby. In this case, the dummy data embedding position may be a specific position such as a head or tail, or may be a predetermined position that is specified by common data, for example.
In any case, the transmission target cut data generated in this way is sent to the encryption / decryption unit 33 in a stream in the order of generation.

In parallel with the generation of the transmission target cut data, the algorithm generation unit 35 generates an algorithm used when encrypting the transmission target cut data.
The algorithm generation unit 35 generates an algorithm based on the common data.
In this embodiment, the algorithm generation unit 35 generates an algorithm as follows.
The algorithm in this embodiment is as follows: “When the transmission target cut data that is 8-bit data is a matrix Y of 1 row and 8 columns, the matrix X of 8 rows and 8 columns that is common data is raised to the power a, The matrix obtained by multiplying the matrix rotated by n × 90 ° around Y by Y ”is defined.
Here, a may be a predetermined constant, but in this embodiment, a is a number that changes based on the common data. That is, the algorithm in this embodiment changes based on common data. For example, a is the remainder when the number obtained by adding all the numbers of matrix elements included in the common data which is a matrix of 8 rows and 8 columns is divided by 5 (however, when the remainder is 0) a = 1)).
Further, the above-mentioned n is a predetermined number determined by the key. If the key is a fixed number, n is fixed, but the key changes based on the common data as described below. That is, in this embodiment, this n also changes based on the common data.
However, the algorithm can be determined as another one.
In this embodiment, the algorithm generator 35 generates an algorithm each time it receives common data from the common data generator 34, and sends it to the encryption / decryption unit 33.

In parallel with the generation of the transmission target disconnection data, the key generation unit 36 generates a key used when encrypting the transmission target disconnection data.
The key generation unit 36 generates a key based on the common data.
In this embodiment, the key generation unit 36 generates a key as follows.
The key in this embodiment is a number obtained by adding all the numbers that are the elements of the matrix included in the common data that is a matrix of 8 rows and 8 columns. Thus, the key changes based on the common data in this embodiment.
Note that the key can be determined as another one.
In this embodiment, the key generation unit 36 generates a key each time it receives common data from the common data generation unit 34 and sends it to the encryption / decryption unit 33.

The encryption / decryption unit 33 encrypts the transmission target cut data received from the preprocessing unit 32 based on the algorithm received from the algorithm generation unit 35 and the key received from the key generation unit 36 (S1103).
As described above, when the transmission target cut data that is 8-bit data is set to a matrix Y of 1 row and 8 columns, the algorithm is to raise the matrix X of 8 rows and 8 columns that is common data to the power a, It is a rule that is obtained by multiplying a matrix rotated clockwise by n × 90 ° by Y ”, and the key n is a number as described above.
For example, when a is 3 and n is 6, 8 obtained by rotating an 8 × 8 matrix obtained by raising X to the third power clockwise by 6 × 90 ° = 540 °. Encryption is performed by multiplying the matrix of 8 rows by the cutting data to be transmitted.
Data generated in this way is encrypted cut data.

  The encrypted disconnection data is sent to the connection unit 38. The connection unit 38 connects the encrypted cut data together to generate encrypted data (S1104). The arrangement order of the encrypted cut data at this time corresponds to the arrangement order of the original transmission target cut data.

  As described above, first, the process of S110 in which the first communication device 11 encrypts the transmission target data and generates the encrypted data ends.

  The encrypted data is sent to the communication unit 37 and sent to the second communication device 12 via the network 13.

In the second communication device 12 that has received the encrypted data, the process of S130 for decrypting the encrypted data and returning it to the transmission target data is executed.
Hereinafter, this decoding process will be described in detail.

The encrypted data sent to the second communication device 12 is received by the communication unit 37 of the second communication device 12 (S1201).
The communication unit 37 sends this encrypted data to the preprocessing unit 32.

The preprocessing unit 32 cuts the received encrypted data every predetermined number of bits to generate encrypted cut data (S1202).
When the encrypted data is cut to generate the encrypted cut data, the preprocessing unit 32 performs a process reverse to that performed by the connection unit 38 of the first communication device 11. That is, the encrypted data is cut every 8 bits from the head and divided into a plurality of encrypted cut data.

Next, the encrypted cut data is sent to the encryption / decryption unit 33, where it is decrypted and set as transmission target cut data (S1203).
Decryption is executed as a process reverse to that performed by the encryption / decryption unit 33 in the first communication device 11. Therefore, the second communication device 12 requires an algorithm and a key that are necessary when the first communication device 11 performs encryption.

The algorithm and key used for decryption are generated in the second communication device 12. The mechanism will be explained.
Information that the communication unit 37 of the second communication device 12 has received the encrypted data is sent from the communication unit 37 to the common data generation unit 34. The common data generation unit 34 generates common data every time this information is received, triggered by the reception of this information.
The common data generation performed by the common data generation unit 34 of the second communication device 12 is performed through the same process as that performed by the common data generation unit 34 of the first communication device 11. The common data generation unit 34 of the second communication device 12 has the same initial matrix and the solution generation algorithm as the common data generation unit 34 of the first communication device 11 has. Accordingly, the common data generated by the second communication device 12 is the same as the common data generated by the first communication device 11 if the same generation order is compared.
The generated common data is sent from the common data generation unit 34 to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36.
The algorithm generation unit 35 generates an algorithm every time the common data is received based on the received common data. The process of generating the algorithm by the algorithm generation unit 35 of the second communication device 12 is the same as the process of generating the algorithm by the algorithm generation unit 35 of the first communication device 11. The generated algorithm is sent from the algorithm generation unit 35 to the encryption / decryption unit 33.
Each time the key generation unit 36 receives the common data, the key generation unit 36 generates a key based on the received common data. The process of generating the key by the key generation unit 36 of the second communication device 12 is the same as the process of generating the key by the key generation unit 36 of the first communication device 11. The generated key is sent from the key generation unit 36 to the encryption / decryption unit 33.
By the way, in this communication system, every time the first communication device 11 performs encryption, new common data is generated in the first communication device 11 and every time the second communication device 12 performs decryption, the second communication is performed. New common data is generated in the device 12. Further, as described above, the common data generated by the second communication device 12 is the same as the common data generated by the first communication device 11 if the same generation order is compared. . Therefore, the common data generated when the transmission target data that is the first communication device 11 is encrypted, and the algorithm and the key generated based on the common data all use the common data and the common data. When decrypting the encrypted data generated using the algorithm and key generated in this way, the common data generated by the second communication device 12 and the algorithm and key generated based on the common data are used. Always match. This situation is the same when the second communication device 12 performs encryption and the first communication device 11 performs decryption.

  In the encryption / decryption unit 33, as described above, the decryption process is performed using the algorithm received from the algorithm generation unit 35. More specifically, the encryption / decryption unit 33 uses the algorithm received from the algorithm generation unit 35 (“common data when the transmission target cut data, which is 8-bit data, is a matrix Y of 1 row × 8 columns”). Based on the definition of “the encryption cut data is obtained by multiplying a matrix X rotated by n × 90 ° clockwise by Y to a power of a certain matrix X of 8 rows and 8 columns”. The algorithm for performing the decryption process (when the encrypted cut data is viewed as a matrix Z of 1 row and 8 columns, the matrix X of 8 rows and 8 columns, which is common data, is raised to the power a and then clockwise. The inverse matrix of the matrix rotated by n × 90 ° is multiplied by Y to generate a definition that is “transmission data to be transmitted”, and an operation according to the above definition is performed using a key. Thus, the decryption process is performed. In this way, the encryption / decryption unit 33 sequentially decrypts the encrypted cut data supplied in a stream form from the preprocessing unit 32, and generates transmission target cut data.

Next, the encryption / decryption unit 33 removes dummy data from the transmission target cut data as necessary (S1204). As described above, the common data generated by the common data generation unit 34 is sent to the preprocessing unit 32. This common data is used when the pre-processing unit 32 of the first communication device 11 determines how the dummy data is embedded in the transmission target cut data. That is, the common data that the pre-processing unit 32 of the second communication device 12 has at that time has been decrypted (or decrypted) by the encryption / decryption unit 33 of the second communication device 12. Or how to embed dummy data in encrypted cut data (more precisely, the cut data to be transmitted before the encrypted cut data is encrypted) Is.
The preprocessing unit 32 sends information about where the dummy data is embedded in the transmission target cut data decrypted by the encryption / decryption unit 33 to the encryption / decryption unit 33.
Using this, the encryption / decryption unit 33 removes the dummy data from the transmission target cut data.

The transmission target disconnection data generated in this way is sent to the connection unit 38. The connection unit 38 collectively connects the received transmission target disconnection data and returns the transmission target data to the original state before being encrypted by the first communication device 11 (S1205).
In this way, the process of S130 in which the second communication device 12 decrypts the encrypted data and returns it to the transmission target data ends.

  The generated transmission target data is sent from the connection unit 38 to the interface unit 31, sent to, for example, the HDD 23 via the bus 28, and stored therein.

≪Modification≫
In the communication system described above, the common data generation unit 34 generates common data every time the interface unit 31 receives transmission target data and every time the communication unit 37 receives encrypted data. It was. In this case, all the transmission target cut data generated from one transmission target data is encrypted by the same algorithm.
Instead of this, the common data generation unit 34 whenever the encryption / decryption unit 33 accepts the transmission target cut data, and every time the encryption / decryption unit 33 accepts the encrypted cut data, The common data may be generated. In this case, encryption is performed with a different algorithm and key for each transmission target disconnect data generated from one transmission target data.

In such a modification, when encryption is performed, common data, an algorithm, and a key are generated as follows.
First, a case where encryption is performed will be described.
When the interface unit 31 receives the transmission target data, information to that effect is sent from the interface unit 31 to the common data generation unit 34. The common data generation unit 34 that has received this generates common data in the same manner as in the above-described embodiment. The common data is sent to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36. The pre-processing unit 32 that has received the common data disconnects the transmission target data and starts generating the transmission target disconnection data as in the above-described embodiment. On the other hand, the algorithm generation unit 35 generates an algorithm based on the received common data, and sends the generated algorithm to the encryption / decryption unit 33. The key generation unit 36 generates a key based on the received common data, and sends the generated key to the encryption / decryption unit 33.
The encryption / decryption unit 33 encrypts the received transmission target cut data with the received algorithm and key, and generates first encrypted cut data.
Next, the common data generation unit 34 generates common data before the second transmission target cut data is sent from the preprocessing unit 32 to the encryption / decryption unit 33, and the common data generation unit 34 generates the common data with the algorithm generation unit 35 and the key generation. Send to part 36. The algorithm generation unit 35 receives this and generates an algorithm different from that used to generate the first encrypted cut data, and sends it to the encryption / decryption unit 33. Similarly, the key generation unit 36 generates a key different from the first key and sends it to the encryption / decryption unit 33. The encryption / decryption unit 33 generates the second encrypted cut data using the second transmission target cut data using the algorithm and the key.
By repeating this, different encryption is performed on each piece of transmission target cut data.
In this modification, the second and subsequent common data is sent only to the algorithm generation unit 35 and the key generation unit 36. However, the second and subsequent common data is also sent to the preprocessing unit 32. You can also In this case, it is possible to change the method for generating the transmission target cut data for each transmission target cut data.
Next, a case where decoding is performed will be described.
When the communication unit 37 receives the encrypted data, information to that effect is sent from the communication unit 37 to the common data generation unit 34. The common data generation unit 34 that has received this generates common data in the same manner as in the above-described embodiment. The common data is sent to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36. The pre-processing unit 32 that has received the common data generates information on how the transmission target cut data has been generated in the same manner as in the above-described embodiment, and transmits this to the encryption / decryption unit 33. And send. On the other hand, the algorithm generation unit 35 generates an algorithm based on the received common data, and sends the generated algorithm to the encryption / decryption unit 33. The key generation unit 36 generates a key based on the received common data, and sends the generated key to the encryption / decryption unit 33. This algorithm and key are respectively equal to the algorithm and key used when encrypting the transmission target cut data. Also, the preprocessing unit 32 sends the encrypted cut data generated by cutting the encrypted data to the encryption / decryption unit 33 as in the case of the above-described embodiment.
The encryption / decryption unit 33 decrypts the received encrypted cut data with the decryption algorithm generated using the received algorithm, and generates the first transmission target cut data. In addition, the encryption / decryption unit 33 removes the dummy data from the generated transmission target disconnection data based on the above-described information on how the received transmission target disconnection data is generated.
Next, the common data generation unit 34 generates the next common data before the second transmission target cut data is sent from the preprocessing unit 32 to the encryption / decryption unit 33, and the generated common data is sent to the algorithm generation unit 35. send. The algorithm generation unit 35 receives this, generates an algorithm different from that used to generate the first transmission target cut data, and sends this to the encryption / decryption unit 33. This algorithm is the same as the algorithm used when encrypting the transmission target cut data. The key generation unit 36 generates a key different from that used to receive the common data and generate the first transmission target cut data, and sends this to the encryption / decryption unit 33. This key is the same as the key used when encrypting the transmission target cut data.
The encryption / decryption unit 33 decrypts the second encrypted cut data using this algorithm and key, and generates the second transmission target cut data. Further, dummy data is removed in the same manner as described above.
This process is repeated, and each encrypted cut data is decrypted with a different algorithm and key to generate transmission target cut data one after another.
In addition, when performing encryption, if the method of generating the transmission target cut data is changed for each transmission target cut data by sending the second and subsequent common data to the preprocessing unit 32, the decryption is performed. Also in the case of performing, the second and subsequent common data is also sent to the preprocessing unit 32. As a result, the preprocessing unit 32 generates information about how the transmission target cut data is generated for each of the encrypted cut data. The above information about how the transmission target cut data generated in this way is generated is encrypted / decrypted every time the encrypted cut data is decrypted by the encryption / decryption unit 33. Sent to the conversion unit 33. Using this information, the encryption / decryption unit 33 reliably removes the dummy data embedded in each of the transmission target cut data by different methods.

DESCRIPTION OF SYMBOLS 11 1st communication apparatus 12 2nd communication apparatus 13 Network 31 Interface part 32 Preprocessing part 33 Encryption / decryption part 34 Common data generation part 35 Algorithm generation part 36 Key generation part 37 Communication part 38 Connection part

Claims (5)

A first communication device that is two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to the communication device on the other side, and decrypt the received encrypted data into transmission target data And a second communication device,
Both the first communication device and the second communication device are
The transmission target data is cut into a plurality of transmission target cut data for each desired number of bits, and the encrypted data is cut into the same number of bits that were cut when the encrypted data was encrypted. Cutting means for cutting into a plurality of encrypted cut data,
The transmission target cut data is encrypted by using an algorithm common to the first communication device and the second communication device to be encrypted data, and the encrypted cut data is encrypted with the encrypted cut data. Encryption / decryption means for decrypting the data to be transmitted by the algorithm used sometimes,
Connection means for connecting the decrypted transmission target disconnection data to the transmission target data,
Transmitting / receiving means for transmitting / receiving the encrypted data;
A communication system comprising:
The cutting means cuts the transmission target data so that at least one of the transmission target cutting data that is not the last transmission target cutting data has a different bit number from other transmission target cutting data. With
Both the first communication device and the second communication device are
By including dummy data irrelevant to the transmission target data except for the one with the largest number of bits among the transmission target disconnection data before encryption, the number of bits of all the transmission target disconnection data can be reduced. A mixing means for matching the number of bits of the cut data to be transmitted with the largest number of bits,
Removing means for removing the dummy data from the decrypted data to be transmitted that includes the dummy data;
With
Communications system. A first communication device that is two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to the communication device on the other side, and decrypt the received encrypted data into transmission target data And a second communication device,
Both the first communication device and the second communication device are
The transmission target data is cut into a plurality of transmission target cut data for each desired number of bits, and the encrypted data is cut into the same number of bits that were cut when the encrypted data was encrypted. Cutting means for cutting into a plurality of encrypted cut data,
Common data generating means for sequentially generating common data common to the first communication device and the second communication device;
The transmission target disconnect data is encrypted by using an algorithm common to the first communication device and the second communication device generated based on the common data received from the common data generating means, and is used as encrypted data. Encryption / decryption means for decrypting the encrypted cut data according to the algorithm used when encrypting the encrypted cut data into the cut data to be transmitted;
Connection means for connecting the decrypted transmission target disconnection data to the transmission target data,
Transmitting / receiving means for transmitting / receiving the encrypted data;
With
The common data generation means is configured to generate the common data when the encryption / decryption means receives the transmission target cut data or the encrypted cut data.
A communication system,
The cutting means cuts the transmission target data so that at least one of the transmission target cutting data that is not the last transmission target cutting data has a different bit number from other transmission target cutting data. With
Both the first communication device and the second communication device are
By including dummy data irrelevant to the transmission target data except for the one with the largest number of bits among the transmission target disconnection data before encryption, the number of bits of all the transmission target disconnection data can be reduced. A mixing means for matching the number of bits of the cut data to be transmitted with the largest number of bits,
Removing means for removing the dummy data from the decrypted data to be transmitted that includes the dummy data;
With
Communications system. A first communication device that is two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to the communication device on the other side, and decrypt the received encrypted data into transmission target data And a method executed in a communication system including a second communication device,
One of the first communication device and the second communication device is
A step of cutting the transmission target data into a plurality of transmission target cut data by cutting the transmission target data for each desired number of bits;
A process of encrypting the transmission target disconnection data by a predetermined algorithm to obtain encrypted data;
Transmitting the encrypted data to the other of the first communication device and the second communication device;
The other of the first communication device and the second communication device is
The process of cutting the encrypted data received by the cutting means into a plurality of pieces of encrypted cut data by cutting every same number of bits cut when the encrypted data is encrypted,
Decrypting the encrypted cut data according to the algorithm used when encrypting the encrypted cut data into the cut data to be transmitted,
Connecting the decrypted transmission target disconnection data to the transmission target data;
As well as
The one of the first communication device and the second communication device is:
The cutting means configured to cut the transmission target data so that at least one of the transmission target cutting data is not necessarily the last transmission target cutting data and has a different bit number from other transmission target cutting data. By cutting the transmission target data, so that at least one of the transmission target cutting data that is not the last transmission target cutting data has a different number of bits from the other transmission target cutting data,
By including dummy data irrelevant to the transmission target data except for the one with the largest number of bits among the transmission target disconnection data before encryption, the number of bits of all the transmission target disconnection data can be reduced. Match the number of bits of cutting data to be transmitted with the most number of bits,
The other of the first communication device and the second communication device is:
The dummy data is removed from the decrypted data to be transmitted that includes the dummy data,
Communication method. A first communication device that is two communication devices that can encrypt transmission target data in plain text and send it as encrypted data to the communication device on the other side, and decrypt the received encrypted data into transmission target data And a method executed in a communication system including a second communication device,
One of the first communication device and the second communication device is
A step of cutting the transmission target data into a plurality of transmission target cut data by cutting the transmission target data for each desired number of bits;
A process of sequentially generating desired common data,
A process of encrypting the transmission target disconnection data by an algorithm generated based on the common data to obtain encrypted data;
Transmitting the encrypted data to the other of the first communication device and the second communication device;
The other of the first communication device and the second communication device is
The process of cutting the encrypted data received by the cutting means into a plurality of pieces of encrypted cut data by cutting every same number of bits cut when the encrypted data is encrypted,
Sequentially generating common data common to the one of the first communication device and the second communication device;
Decrypting the encrypted cut data according to the algorithm used when encrypting the encrypted cut data generated based on the generated common data to make the cut data to be transmitted;
Connecting the decrypted transmission target disconnection data to the transmission target data;
As well as
The first communication device and the second communication device are:
While generating the common data triggered by receiving the transmission target cut data or the encrypted cut data,
The one of the first communication device and the second communication device is:
The cutting means configured to cut the transmission target data so that at least one of the transmission target cutting data is not necessarily the last transmission target cutting data and has a different bit number from other transmission target cutting data. By cutting the transmission target data, so that at least one of the transmission target cutting data that is not the last transmission target cutting data has a different number of bits from the other transmission target cutting data,
By including dummy data irrelevant to the transmission target data except for the one with the largest number of bits among the transmission target disconnection data before encryption, the number of bits of all the transmission target disconnection data can be reduced. Match the number of bits of cutting data to be transmitted with the most number of bits,
The other of the first communication device and the second communication device is:
The dummy data is removed from the decrypted data to be transmitted that includes the dummy data,
Communication method.   A communication device included in the communication system according to claim 1 or 2.

Images