JP2020120297A - Transmission/reception system, transmission device, reception device, method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission / reception system, a transmission device, a reception device, a method and a computer program using a highly practical encryption technique which can be used for communication by a computer and which can be said to be undecipherable or close to it. A first communication device 11 encrypts data to be processed and transmits the data to a second communication device 12. The data to be transmitted is data about text and is in plain text. The first communication device 11 cuts the transmission target data to a length equal to or shorter than the bit length of the code for specifying the character included in the transmission target data to generate a large number of transmission target disconnection data to generate a transmission target. Encryption is performed for each disconnected data. The encrypted disconnection data obtained by encrypting the transmission target disconnection data is transmitted from the first communication device 11 to the second communication device 12. [Selection diagram] Fig. 1

Description

The present invention relates to encrypted communication technology performed using a computer.

The origin of cryptography is said to date back to BC.
A well-known old cipher is the Caesar cipher. The Caesar cipher is a very simple substitution cipher. Cryptographic techniques require two characters, a person who encrypts plaintext to make a ciphertext (sender) and a person who receives a ciphertext and decrypts it (receiver). As you can see from common sense, the encryption is good if it cannot be seen by a third party and the person who decrypts the ciphertext can decrypt it correctly. It can be said that there is.
Suppose that the Caesar cipher is used to encrypt an English sentence consisting of only the alphabet. Here, only 26 characters are used to compose the English sentence. In Caesar encryption, the sender and the receiver make two arrangements. One of the arrangements is an arrangement that in the Caesar cipher, some characters are shifted. Another arrangement is an arrangement regarding the number of characters to shift. The former is an algorithm in cryptography and the latter is a key in cryptography. For example, assume that the original plaintext was "IBM". If it is encrypted in the above two arrangements assuming that the key is "-1" or "25", each character that constitutes the sentence "IBM" is one character before or 25 characters. It shifts backward one by one and becomes "HAL". The recipient who has received this ciphertext "HAL" uses the above-mentioned algorithm and key to perform the reverse processing on the ciphertext, which is the reverse of what the sender did at the time of encryption. .. Then, the characters forming the sentence "HAL" are shifted one character backward or 25 characters forward to become "IBM". Then, a person who does not know both the algorithm and the key cannot decipher the plaintext "IBM" from the ciphertext "HAL". Although Caesar's cipher is such a simple one, it was very successful, at least when it was in use.

In the above-mentioned Caesar cipher, there is only one type of algorithm, and from the viewpoint of the influence on the encryption process, the number of keys is at most 26 types (or 26×2=52 even if shifting in the opposite direction is considered). Type). Then, a person who attempts to illegally decrypt the ciphertext, assuming that the person who tries to illegally know the algorithm, performs the brute force using 26 kinds (or 52 kinds) of keys, and You will be able to decipher the sentence.
The history of cryptography is the history of efforts to prevent deciphering ciphertext. In such efforts, various cryptographic techniques have been proposed. Of course, since the Caesar cipher is an extremely simple cipher, its decryption is easy. However, even with a cipher using a technology that is incomparable to the currently used Caesar cipher, etc., especially when the amount of ciphertext transmitted and received between the sender and the receiver becomes large. By analyzing a huge amount of ciphertext data using a computer, it becomes possible to decipher the ciphertext in the end.

However, there are several cryptographic techniques that have proven unbreakable in the past.
Examples are the Vernam cipher and the one-time pad cipher. It is premised that some conditions are satisfied, but it is mathematically proved that if these conditions are satisfied, it is impossible to decipher.
The Burnham cipher uses a long tape having a large number of holes corresponding to plaintext and a long tape having a large number of holes corresponding to keys. The tape corresponding to the key is the same for both sender and receiver. The sender superimposes both tapes, and then punches a rule corresponding to the algorithm, for example, if a hole is formed in only one of the first tape and the second tape, The third tape is prepared according to the rule that no hole is formed in both the first tape and the second tape or in a place where neither of the two tapes has holes. This third tape corresponds to a ciphertext. This rule is also shared by the sender and the recipient.
The third tape is sent from the sender to the recipient. The receiver who receives the third tape, superimposes the second tape it has on the third tape, and then uses the same rule as described above, that is, the third tape and the second tape. If there is a hole in only one side, make a hole in both the third tape and the second tape, or if there is no hole in both tapes. According to the rule that no hole is made, a fourth tape is prepared by making an appropriate hole in a new tape.
Then, the fourth tape returns to the first tape. That is, the receiver can return the third tape as the ciphertext to the first tape by using the second tape as the key and the algorithm shared with the sender. Thereby, encrypted communication is established.

Such a Vernam cipher is indecipherable to a third party as long as the condition that "the second tape as a key is different each time and secret to the third party" is satisfied. Is mathematically proven.
However, as the amount of ciphertext exchanged between the sender and the receiver increases, the length of the second tape increases accordingly. In other words, the Vernam cipher cannot secure its security unless there is a secret key having the same amount of information as the length of the plaintext character string to be encrypted and transmitted. Therefore, the Vernam cipher is practically difficult to use. This is the reason why the Vernam cipher is not widely used in computer encrypted communication.
An encryption technique called a one-time pad is known as an indecipherable encryption similar to the Vernam encryption. The one-time pad cipher is a key that allows a sender and a receiver to share a bundle of random numbers that can be used only once, such as a daily calendar, and can be encrypted and decrypted. Each time, the sender and the receiver use a new random number table to dispose of it. As the number of characters transmitted and received increases, the bundle of random number tables naturally becomes thicker. Therefore, the one-time pad encryption has the same practical usability as the Vernam encryption.

The reason why the Vernam cipher and the one-time pad cipher are not so popular is that, as described above, the Vernam cipher and the one-time pad cipher use the same amount of information as the plaintext before encrypting the plaintext data. This is because it is necessary for the sender and the receiver to hold a long key or a key having a large amount of data. The key is a long tape with holes at random in the case of Vernam encryption, and a random number table in the case of one-time pad encryption. For both the Vernam cipher and the one-time pad cipher, the condition that the same key can be used only once is also necessary to guarantee the integrity of the cipher.
Therefore, when using the Vernam cipher or the one-time pad cipher, how can both the sender and the receiver have such a key that can be used only once for a long time each time encrypted communication is performed? It becomes a big problem. In addition, the sharing of the key between the sender and the receiver is necessary every time the ciphertext is transmitted/received, and as the number of times of transmission/reception increases, the burden for realizing it increases more and more. It would be simple if the sender and receiver could be in physical contact, but if so, encrypted communication would not be needed. Due to such circumstances, both the Barnum cipher and the one-time pad cipher are not practical.

It is an object of the present invention to provide a highly practical encryption technique that can be used for computer communication and that can be said to be undecipherable or close to it.

In order to solve such a problem, the present inventor proposes the invention described below.
The present invention relates to a transmitting device that encrypts transmission target data that is plaintext and is plaintext and then transmits the data to the other party, and a receiving device that can decrypt the data received from the transmission device to be the transmission target data. And a transmission/reception system including.
The transmission device in this transmission/reception system cuts the transmission target data for each predetermined number of bits into a plurality of transmission target disconnection data, and the transmission target disconnection data by a predetermined algorithm and a key. An encryption unit that encrypts the encrypted cut data to obtain encrypted cut data and a transmission unit that sends the encrypted cut data to the receiving device are provided.
Further, the receiving device in this transmission/reception system includes a receiving unit that receives the encrypted cut data from the transmitting device, and the encrypted cut data that is a series of data received from the transmitting device, the encrypted cut data. A receiving device disconnecting unit that disconnects each time, and a decrypting unit that decrypts the encrypted disconnection data with the same algorithm and key as the algorithm and key used in the encrypting unit of the transmitting device to obtain disconnection data to be transmitted. And a connection unit for connecting the decrypted transmission target disconnection data to form the transmission target data.
Up to this point, the transmission/reception system of the present application is not much different from the conventional transmission/reception system. The transmission and reception of the encrypted cut data between the transmitting device and the receiving device may or may not be performed via the Internet or another network.
On the other hand, the transmission device disconnection unit in the transmission/reception system of the present application disconnects the transmission target data for each bit length that is equal to or shorter than the bit length of the code that identifies the character included in the text, and transmits the plurality of transmissions. It is designed to be target disconnection data, and when encrypting the transmission target disconnection data, the encryption unit encrypts other transmission target disconnection data for at least one of the transmission target disconnection data. When the encryption method and the encryption method to be executed at different times, the decryption unit, when decrypting the encrypted disconnection data obtained by the receiving device disconnection unit, The decryption method is changed in accordance with the encryption method being changed in the encryption unit of the transmission device.
In the transmission/reception system of the present application, the transmission target data to be encrypted and transmitted from the transmission device to the reception device is text data. The text includes letters, numbers and symbols. Spaces are included in characters. On the other hand, the text data does not include data such as moving images, images including still images, and sound. The current situation in which encrypted communication technology breaks it causes a great deal of damage when the data to be transmitted is text. The present invention focuses particularly on such cases. In the current computer technology, text is used by replacing the data of 0 and 1 with a code that enumerates data, and one code includes one character (including a number and a symbol. Unless otherwise specified, the same applies below. .) has been specified. For example, in English (including symbols, the same applies hereinafter) that is sometimes referred to as 1-byte characters, one character is specified by a code with a length of 1 Byte (8 bits), and is sometimes referred to as 2 Byte characters. As for Japanese characters, one character is specified by a code having a length of 2 bytes (16 bits).
Then, the transmission device disconnection unit of the transmission device according to the invention of the present application is configured such that the bit length of the transmission target disconnection data, which is the size of the data that the encryption unit performs the encryption process or the calculation at one time, determines the characters included in the text. The transmission target data is disconnected by making the bit length of the specified code equal to or shorter than that (obviously not 0 bit).
The transmitting device in the transmitting/receiving system of the present invention performs encryption with data that is equal to or shorter than the bit length of the code that specifies the character as one unit, and the receiving device in the transmitting/receiving system of the present invention performs the decryption process. Each time, the data that is equal to or shorter than the bit length of the code that specifies the character is obtained.
Moreover, in the transmission device in the transmission/reception system of the present invention, at least one of the processes of encrypting the disconnection data to be transmitted that is performed at least as many times as the number of characters included in the plaintext text is transmitted to another transmission target. It is executed by a method different from the process of encrypting the cut data. Of course, at least one of the processes of decrypting the encrypted cut data performed by the receiving device at least the number of characters is performed by a method different from the process of decrypting other encrypted cut data.
The above guarantees the indecisibility (at least the indecipherability) of the encryption used in the transmission/reception system in the present invention. The guarantee is obtained for the following reasons. Anyone attempting to decrypt the encrypted data, typically a malicious third party who is neither the sender nor the recipient, said how successful it was in decrypting the encrypted data. Can you recognize it? That is when the self-perceived data or character string obtained by a malicious third party attempting to decrypt the encrypted data has returned to "meaningful" data. Whether the character string is "meaningful" or "meaningless" depends on whether the character string obtained by oneself can grasp the meaning, " It will be judged by "subjectivity". If the encryption and decryption processes are performed in units that are the same as or shorter than the code that identifies the character, one unit of data obtained by the malicious third party will also identify one character. It is a thing, or even one character cannot be specified. As a result, connecting the data may result in a code corresponding to a character string. However, if at least one of the data for each unit is encrypted by a different method, the character string obtained by the malicious third party attempting to decrypt has a plurality of meanings. You may go back to the text you have. This means that a malicious third party cannot be convinced that the decoding has succeeded by the "subjective" judgment as to whether or not the character string obtained by himself can grasp the meaning.
Take the Caesar cipher as an example. For example, assume that the plaintext is "DOG". If the characters "D", "O", and "G" are encrypted with different keys (that is, encrypted by changing the encryption method), it becomes the ciphertext "HAL". To do. Then, it is assumed that a malicious third party obtains the ciphertext and attempts to decrypt it. Then, the plaintext character string obtained by the malicious third party may be “DOG”, “CAT”, “PIG”, or “EYE” or “YES”. May be. Since all of these are meaningful texts, even if a malicious third party could reach the correct plaintext “DOG”, it would not be possible to judge that it is a correct character string. As a result, the data encrypted by the present invention becomes undecipherable or at least close to it.
In addition, in the transmission device in the transmission/reception system of the present invention, at least one of the processes of encrypting the disconnection data to be transmitted, which is performed at least as many times as the number of characters included in the plain text, is transmitted to another transmission. It is executed by a method different from the process of encrypting the target cut data. The encryption process can be performed by changing at least one of a key and an algorithm as described repeatedly. The change in the encryption method and the decryption method between the transmitting device and the receiving device is synchronously changed so that the receiving device can correctly decrypt the encrypted cut data. As a result, a malicious third party does not know which encrypted cut data was encrypted by what method, and thus it becomes more and more impossible to decipher the data encrypted by the present invention. The transmission device in the transmission/reception system of the present invention executes at least one of the processes of encrypting the transmission target disconnection data by a method different from the process of encrypting other transmission target disconnection data. It is permissible that more than one of the processes for encrypting? Is performed in the same way. Therefore, even when the transmitting device and the receiving device use a plurality of common keys, more specifically, when performing encryption and decryption processing while changing different types of common keys in a synchronized state, The data amount of the common key is not necessarily required to be equal to or larger than the data amount of the transmission target data. Therefore, a small number of keys such as a common key shared by the transmitting device and the receiving device or a short key length is allowed, so that the practicability is maintained while maintaining the property of being undecipherable or close to it. Is more than the Barnum cipher or the one-time pad cipher.

The inventor of the present application also proposes, as one aspect of the present invention, a transmitting device that constitutes a transmitting/receiving system according to the present invention in combination with a receiving device. The effect of such a transmitting device is equal to the effect of the transmitting/receiving system according to the present invention.
An example is a transmitting device that encrypts data to be transmitted, which is plaintext and is plaintext, and then sends the data to the other party, and the data received from the transmitting device can be decrypted to be transmission target data. A transmission device that comprises a transmission/reception system including a reception device, in combination with the reception device.
The transmitting device cuts the transmission target data for each predetermined number of bits to form a plurality of transmission target disconnection data, and the transmission target disconnection data is encrypted and encrypted by a predetermined algorithm and key. An encryption unit for making cut data and a transmitting unit for sending the encrypted cut data to the receiving device are provided. The transmission device disconnection unit of the transmission device disconnects the transmission target data into a plurality of transmission target disconnection data by disconnecting each of the bit lengths that is equal to or shorter than the bit length of a code specifying a character included in the text. In the case of encrypting the transmission target disconnection data, the encryption unit executes at least one of the transmission target disconnection data when encrypting another transmission target disconnection data. The encryption method is different from the encryption method.
The receiving device used in combination with such a transmitting device is as follows. The receiving device receives the encrypted cut data from the transmitting device, and receives the encrypted cut data, which is a series of data received from the transmitting device, for each encrypted cut data. A device disconnection unit, a decryption unit that decrypts the encrypted disconnection data with the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain transmission target disconnection data, and is decrypted. And a connection unit that connects the transmission target disconnection data to make the transmission target data, and the decryption unit decrypts the encrypted disconnection data obtained by the reception device disconnection unit. At the time of encryption, the decryption method is changed in accordance with the encryption method being changed by the encryption unit of the transmission device.

The transmission device disconnection unit in the transmission device of the present invention may disconnect the transmission target data into a certain number of bits. On the other hand, the transmission device disconnecting unit disconnects the transmission target data so that at least one of the transmission target disconnection data other than the last one has a different number of bits from other transmission target disconnection data. I don't mind. The latter makes it more difficult for a malicious third party to detect the encryption method. In the latter case, the number of bits different from that of the other transmission target disconnection data is the transmission target disconnection data excluding the last transmission target disconnection data, that is, the last transmission target disconnection data is the transmission target data. This is because, when a plurality of pieces of transmission target disconnection data are generated by disconnection, the data may be smaller than other transmission target disconnection data simply because the amount of data is insufficient. In other words, if a large number of transmission target disconnection data other than the last transmission target disconnection data include those having different numbers of bits, "at least one of the transmission target disconnection data other than the last data is other transmission target disconnection data. The condition that "the number of bits is different from that of the cut data" is satisfied.
The transmission device includes a mixing unit that aligns the number of bits of all the transmission target cut data to a predetermined number of bits by including dummy data that is not related to the transmission target data in the transmission target cut data. Good. In this case, the receiving device may include a removing unit that removes the dummy data from the transmission target cut data obtained by the decoding unit. By including the dummy data in the transmission target disconnection data, it becomes more difficult for a malicious third party to detect the encryption method. In the dummy data, even if the transmission device cutting unit cuts the transmission target data by a certain number of bits, the transmission device cutting unit determines that at least one of the transmission target disconnection data other than the last one is Even if the transmission target data is cut so that the number of bits is different from that of the transmission target disconnection data, it can be included in the transmission target cut data. The bit length of each transmission target cut data in which the number of bits is aligned by including dummy data as necessary may be longer than the bit length of a code that specifies a character included in text.
The mixing unit may include the dummy data in a specific position of the transmission target data. The mixing unit may include the dummy data in a predetermined position that differs for each of the transmission target data. The latter makes it more difficult for a malicious third party to detect the encryption method.

As described above, the encryption unit in the transmission device performs encryption of at least one of the transmission target disconnection data when encrypting other transmission target disconnection data when encrypting the transmission target disconnection data. The encryption method is different from the encryption method. It is arbitrary how the encryption unit changes the encryption method, but the encryption unit uses, for example, at least the algorithm and the key used for encryption as the method of encrypting the transmission target disconnection data. The change may be made by changing one.
The encryption unit of the present invention, when encrypting the transmission target disconnection data, performs encryption for at least one of the transmission target disconnection data when encrypting other transmission target disconnection data, and an encryption method. Different methods of conversion are being adopted. Therefore, the encryption unit in the transmission device of the present application changes the encryption method at some timing. Although the timing of changing the encryption method can be freely determined, for example, the encryption unit changes the method of encrypting the transmission target disconnection data each time the transmission target disconnection data is encrypted. You may be allowed to do so. Of course, the number of times the transmission target disconnection data is encrypted by a predetermined number (the predetermined number is not limited to a certain number, and in the case of a certain number, for example, it can be two or three) Alternatively, the encryption unit may change the encryption method. In addition, at a certain time, if the predetermined time has elapsed since the transmission of encrypted cut data started, or if the amount of encrypted cut data transmitted exceeds a certain amount, the encryption unit will The method of encrypting the cut data may be changed.

As described above, the encryption unit in the transmission device of the present invention changes the method of encrypting the transmission target cut data at some timing. If so, the decryption unit in the receiving device, if it cannot grasp how the encryption unit encrypts the transmission target disconnection data and how the timing has changed, the decryption unit performs a process of decrypting the encrypted disconnection data. It means that we cannot do it correctly. This can be realized, for example, as follows.
For example, the transmission device includes a transmission device common data generation unit that can generate the same common data that is a pseudo-random number under the same conditions, and the encryption unit generates the transmission device common data generation unit. The encryption method may be determined based on the common data. In this case, the reception device includes a reception device common data generation unit that can generate the same common data as the transmission device common data generation unit, and the decoding unit includes the reception device common data generation unit. The decoding method may be determined based on the generated common data. The transmission device common data generation unit and the reception device common data generation unit can be, for example, equivalent to a mechanism for generating a known or known one-time password. The mechanism for generating a one-time password is based on the number of one-time passwords generated in the past, a method of matching one-time passwords generated at two distant locations (so-called event synchronization), and one-time passwords. There are two known methods for matching one-time passwords generated at two distant locations (so-called time synchronization) based on the time when a password is generated, both of which are common to transmitter data. It can be applied to the generation unit and the reception device common data generation unit.

The present inventor also proposes, as an aspect of the present invention, a receiving device that constitutes a transmitting/receiving system according to the present invention in combination with a transmitting device. The effect of the receiving device is equal to the effect of the transmitting/receiving system according to the present invention.
As an example, it is possible to encrypt data to be transmitted, which is plain text, and which is plain text, and to transmit the data to the other side, and to decrypt the data received from the transmission device to make the data to be transmitted. A receiving device that constitutes a transmission/reception system including a receiving device, in combination with the transmitting device.
The transmitting device combined with the receiving device is as follows. The transmitting device encrypts the transmission target cutting data with a predetermined algorithm and a key by cutting the transmission target data into a plurality of transmission target cutting data by cutting the transmission target data for each predetermined number of bits. The text data includes an encryption unit for converting the encrypted cut data and a transmission unit for transmitting the encrypted cut data to the reception device, and the transmission device disconnection unit includes the transmission target data in the text. The bit length of the code that specifies the character is equal to or shorter than the bit length, and is cut into a plurality of pieces of transmission target disconnection data. The encryption unit encrypts the transmission target disconnection data. In this case, at least one of the transmission target disconnection data is set to have a different encryption method from the encryption method executed when other transmission target disconnection data is encrypted. To be done.
The receiving device disconnects the encrypted disconnection data, which is a series of data received from the transmitting device, for each of the encrypted disconnection data, and the encryption disconnection data of the transmitting device. A decryption unit that decrypts with the same algorithm and key as the algorithm and key used in the encryption unit to obtain transmission target disconnection data, and a connection that connects the decrypted transmission target disconnection data to the transmission target data And a decryption unit that, when decrypting the encrypted cut data obtained by the receiving device disconnecting unit, uses a different encryption method in the encrypting unit of the transmitting device. The decoding method is changed according to the change.

The transmission device includes a mixing unit that aligns the number of bits of all the transmission target cut data to a predetermined number of bits by including dummy data that is not related to the transmission target data in the transmission target cut data. If so, the receiving device may include a removing unit that removes the dummy data from the transmission target cut data obtained by the decoding unit.
It is assumed that the transmission device is configured such that the encryption unit changes a method of encrypting the transmission target disconnection data by changing at least one of an algorithm and a key used for encryption. In this case, the decryption unit in the receiving device changes the method of decrypting the encrypted cut data obtained by the receiving device disconnecting unit by changing at least one of the algorithm and the key used for the decryption. It may be like this.
In the case where the transmission device is adapted to change the method for the encryption unit to encrypt the transmission target disconnection data each time the transmission target disconnection data is encrypted, The decrypting unit of the receiving device may change the method of decrypting the encrypted cut data obtained by the receiving device disconnecting unit each time the encrypted cut data is decrypted. Good.
The transmitter includes a transmitter common data generator capable of generating the same common data that is a pseudo-random number under the same conditions, and the encryption unit is generated by the transmitter common data generator. In the case where the encryption method is determined based on the common data, the reception device is capable of generating the same common data as the transmission device common data generation unit. The decoding section may include a data generating section, and the decoding section may determine a decoding method based on the common data generated by the receiving apparatus common data generating section.
The above four points are as described above.

The inventor of the present application also proposes, as an aspect of the present invention, a method executed by a transmitting device that constitutes a transmitting/receiving system according to the present invention in combination with a receiving device. The effect of this method is equal to that of the transmitting/receiving system according to the present invention.
An example is a transmitting device that encrypts data to be transmitted, which is plaintext and is plaintext, and then sends the data to the other party, and the data received from the transmitting device can be decrypted to be transmission target data. A method for executing the transmission/reception system including a receiving device and a transmitting device configured by combining the receiving device with the receiving device.
This method is performed by the transmitting device, wherein the transmitting device disconnection process is performed by cutting the transmission target data into a plurality of transmission target disconnection data for each predetermined number of bits, and the transmission target disconnection data using a predetermined algorithm and An encryption process of encrypting the encrypted cut data with a key to obtain encrypted cut data, and a transmission process of transmitting the encrypted cut data to the receiving device. In the transmitting device disconnecting process, the transmission target data is converted into the text. Is cut into bit data having a bit length equal to or shorter than the bit length of a code for specifying a character to be transmitted into a plurality of pieces of cut data to be transmitted, and in the encryption process, the cut data to be transmitted is encrypted. In this case, for at least one of the transmission target cut data, the encryption method executed when encrypting other transmission target cut data is made different from the encryption method.
Then, the receiving device combined with the transmitting device that executes such a method is as follows. The receiving device disconnects the encrypted cut data, which is a series received from the transmitting device, for each of the encrypted cut data, and a receiving device cutting unit that encrypts the encrypted cut data by the encryption of the transmitting device. Decoding unit that decrypts with the same algorithm and key as the algorithm and key used in the encryption process to obtain the transmission target cut data, and the connection unit that connects the decrypted transmission target cut data to the transmission target data The decryption unit changes the encryption method in the encryption process of the transmission device when decrypting the encrypted cut data obtained by the reception device disconnection unit. It is said that the decoding method is changed according to the situation.

The inventor of the present application also proposes, as an aspect of the present invention, a method executed by a receiving device which constitutes a transmitting/receiving system according to the present invention in combination with a transmitting device. The effect of this method is equal to that of the transmitting/receiving system according to the present invention.
As an example, it is possible to encrypt data to be transmitted, which is plain text, and which is plain text, and to transmit the data to the other side, and to decrypt the data received from the transmission device to make the data to be transmitted. A method of being executed by a receiving device configured by combining the transmitting and receiving system including the receiving device with the transmitting device.
The transmitting device combined with the receiving device performing this method is as follows. The transmitting device encrypts the transmission target cutting data with a predetermined algorithm and a key by cutting the transmission target data into a plurality of transmission target cutting data by cutting the transmission target data for each predetermined number of bits. The text data includes an encryption unit for converting the encrypted cut data and a transmission unit for transmitting the encrypted cut data to the reception device, and the transmission device disconnection unit includes the transmission target data in the text. The bit length of the code that specifies the character is equal to or shorter than the bit length, and is cut into a plurality of pieces of transmission target disconnection data. The encryption unit encrypts the transmission target disconnection data. In this case, at least one of the transmission target disconnection data is set to have a different encryption method from the encryption method executed when other transmission target disconnection data is encrypted. To be done.
Then, such a method includes a receiving device disconnection step, which is executed by the receiving device and disconnects the encrypted cut data, which is a series of data received from the receiving device, for each of the encrypted cut data, and the encrypted disconnection. The decryption process of decrypting the data with the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain the transmission target disconnection data and the decrypted transmission target disconnection data are connected. And a step of connecting the data to be transmitted as the transmission target data. In the decryption step, the encryption of the transmission device is performed when the encrypted disconnection data obtained in the reception device disconnection step is decrypted. The decryption method is changed to match the encryption method used by the department.

The inventor of the present application also proposes, as one aspect of the present invention, a computer program for causing a predetermined, for example, general-purpose computer to function as a transmitting device that constitutes a transmitting/receiving system according to the present invention in combination with a receiving device. The effect of such a computer program is that a general-purpose computer can be made to function as the transmitting device of the present invention, in addition to the effect of the transmitting/receiving system of the present invention.
An example is a transmitting device that encrypts data to be transmitted, which is plaintext and is plaintext, and then sends the data to the other party, and the data received from the transmitting device can be decrypted to be transmission target data. And a receiving device, which is a computer program for causing a predetermined computer to function as a transmitting device configured by combining the transmitting and receiving system with the receiving device.
This computer program causes the computer to cut the transmission target data into a plurality of transmission target disconnection data by cutting the transmission target data for each predetermined number of bits, and the transmission target disconnection data by a predetermined algorithm and a key. It is for performing an encryption process of encrypting the encrypted cut data and a transmitting process of transmitting the encrypted cut data to the receiving device, and in the transmitting device disconnecting process, the transmission target data Is cut into a plurality of pieces of transmission target cut data for each bit length that is equal to or shorter than the bit length of a code that identifies a character included in the text, and in the encryption process, the transmission target cut data is included. When encrypting, the encryption method for at least one of the transmission target disconnection data and the encryption method executed when encrypting the other transmission target disconnection data is made different.
The receiving device combined with the transmitting device generated by the computer program is as follows. The receiving device disconnects the encrypted disconnection data, which is a series of data received from the transmitting device, for each of the encrypted disconnection data, and the encryption disconnection data of the transmitting device. A decryption unit that decrypts with the same algorithm and key as the algorithm and key used in the encryption process to obtain transmission target disconnection data, and the decrypted transmission target disconnection data is connected to form the transmission target data. And a decryption unit that, when decrypting the encrypted cut data obtained by the receiving device disconnecting unit, uses the encryption method in the encryption process of the transmitting device. It is said that the decoding method is made different in accordance with the different method.

The inventor of the present application also proposes, as one aspect of the present invention, a computer program for causing a predetermined, for example, general-purpose computer to function as a receiving device that constitutes the transmitting/receiving system according to the present invention in combination with the transmitting device. The effect of such a computer program is that a general-purpose computer can be made to function as the receiving device of the present invention, in addition to the effect of the transmitting/receiving system of the present invention.
As an example, it is possible to encrypt data to be transmitted, which is plain text, and which is plain text, and to transmit the data to the other side, and to decrypt the data received from the transmission device to make the data to be transmitted. It is a computer program for causing a predetermined computer to function as a receiving device configured by combining a transmitting/receiving system including the receiving device with the transmitting device.
The transmitting device combined with the receiving device generated by this computer program is as follows. The transmitting device encrypts the transmission target cutting data with a predetermined algorithm and a key by cutting the transmission target data into a plurality of transmission target cutting data by cutting the transmission target data for each predetermined number of bits. The text data includes an encryption unit for converting the encrypted cut data and a transmission unit for transmitting the encrypted cut data to the reception device, and the transmission device disconnection unit includes the transmission target data in the text. The bit length of the code that specifies the character is equal to or shorter than the bit length, and is cut into a plurality of pieces of transmission target disconnection data. The encryption unit encrypts the transmission target disconnection data. In this case, at least one of the transmission target disconnection data is set to have a different encryption method from the encryption method executed when other transmission target disconnection data is encrypted. To be done.
Then, the computer program causes the computer to send the encrypted cutting data, which is a series of data received from the transmitting device, to the receiving device cutting process of cutting the encrypted cutting data for each of the encrypted cutting data, and the encrypted cutting data. , A decryption process of decrypting with the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain transmission target disconnection data, and connecting the decrypted transmission target disconnection data And a connection process for making the data to be transmitted, and in the decryption process, when decrypting the encrypted disconnection data obtained in the reception device disconnection process, The decryption method is changed in accordance with the different encryption method in the encryption unit.

The figure which shows the whole structure of the communication system of embodiment. FIG. 3 is a perspective view showing appearances of a first communication device and a second communication device included in the communication system shown in FIG. 1. The figure which shows the hardware constitutions of the 1st communication apparatus and the 2nd communication apparatus contained in the communication system shown in FIG. FIG. 3 is a block diagram showing a configuration of communication devices of a first communication device and a second communication device included in the communication system shown in FIG. 1. 3 is a flowchart showing a flow of processing executed in the communication system shown in FIG. 3 is a flowchart showing the flow of encryption processing executed by the first communication device of the communication system shown in FIG. 1. 3 is a flowchart showing the flow of a decoding process executed by the second communication device of the communication system shown in FIG.

An embodiment of the present invention will be described below with reference to the drawings.
The communication system according to this embodiment is roughly configured as shown in FIG. The communication system includes a first communication device 11 and a second communication device 12 which 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 first communication device 11 and the second communication device 12 can communicate with each other. In this embodiment, the first communication device 11 and the second communication device 12 are realized by being connected by the network 13. The network 13 is, for example, the Internet. However, instead of this or in addition to this, the network 13 may be configured by a LAN. The communication performed by the first communication device 11 and the second communication device 12 via the network 13 may be wired or wireless.

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 first communication device 11 is a computer or includes a computer. More specifically, the first communication device 11 in this embodiment is configured by a general-purpose computer.
The first communication device 11 is a mobile phone, a smartphone, a tablet, a laptop computer, a desktop computer, or the like. All of them are required to be able to communicate via the network 13, and to be able to generate the functional blocks described below by installing the computer program described below therein and to execute the processes described below. To be On the other hand, other specifications are not particularly limited as long as they can be realized.
For example, if the first communication device 11 is a smartphone or a tablet, the first communication device 11 as a smartphone may be, for example, a product of the iPhone series manufactured and sold by Apple Japan GK, or the first communication device as a tablet. The device 11 may be, for example, an iPad series product manufactured and sold by Apple Japan GK. Hereinafter, although not limited to this, the description will proceed assuming that the first communication device 11 is a smartphone.

An example of the appearance of the first communication device 11 is shown in FIG.
The first communication device 11 includes a display device 26. The display device 26 is for displaying a still image or a moving image, and a known device or a known device can be used. The display device 26 is, for example, a liquid crystal display. The first communication device 11 also includes an input device 25. The input device 25 is for the user to make a desired input to the first communication device 11. A known or well-known input device 25 can be used. Although the input device 25 of the first communication device 11 in this embodiment is of a button type, it is not limited to this, and a ten-key pad, a keyboard, a trackball, a mouse or the like can be used. In particular, when the first communication device 11 is a notebook computer or a desktop computer, the input device 25 will be a keyboard, a mouse or the like. When the display device 26 is a touch panel, the display device 26 also has the function of the input device 25, which is the case in this embodiment.

The hardware configuration of the first communication device 11 is shown in FIG.
The hardware includes a CPU (central processing unit) 21, a ROM (read only memory) 22, an HDD 23 (hard disk drive), and a RAM (random access memory) 24, which are interconnected by a bus 28. Has been done. The display device 26 and the input device 25 are also connected to the bus 28. The data input from the input device 25 is input to the bus 28 and sent to the CPU 21. Image data may be sent from the bus 28 to the display device 26, and when the image data is received, the display device 26 displays an image based on the image data.
The CPU 21 is a computing device that performs computation. The CPU 21 executes the processing described below by executing a computer program recorded in the ROM 22 or the RAM 24, for example. The calculation performed by the CPU 21 is executed based on the input from the input device 25, for example. The above-mentioned computer program may be recorded in an HDD (hard disk drive) 23, which is an example of a large-capacity recording device. In that case, the CPU 21 executes the computer program recorded in the HDD 23, The processing described later is executed.
The computer program mentioned here includes at least a computer program for causing the first communication device 11 to function as a transmitting device and a receiving device of the present invention. This computer program may be pre-installed in the first communication device 11, or may be installed after the shipment of the first communication device 11. The installation of this computer program in the first communication device 11 may be performed via a predetermined recording medium such as a memory card or may be performed via a network such as a LAN or the Internet.
The ROM 22 stores the above-mentioned computer programs and data necessary for the CPU 21 to execute the processing described later. The computer program recorded in the ROM 22 is not limited to this, and if the first communication device 11 is a smartphone, a computer program necessary for causing the client to function as a smartphone, for example, a computer program for executing a call or an e-mail. Or data may be recorded. The first communication device 11 is also capable of browsing a home page based on the data received via the network 13, and even if a well-known web browser is installed to enable it. Good.
The RAM 24 provides a work area required for the CPU 21 to perform processing. In some cases, the above-mentioned computer program and data may be recorded.
The HDD 23 is a large capacity recording medium as described above. At least a part of the computer program and data described as being recorded in the ROM 22 may be recorded in the HDD 23. The data included in the HDD 23 may include data that can be the transmission target data, which is the case in the present embodiment.
The communication device 27 is a known or well-known means for performing communication with the second communication device 12 via the network 13. The communication device 27 of the second communication device 12 executes communication with the first communication device 11 via the network 13.

When the CPU 21 executes the computer program, the functional blocks as shown in FIG. 4 are generated inside the first communication device 11. Note that the following functional blocks may be generated by the functions of the above-mentioned computer program alone for causing the first communication device 11 to function as the transmitting device and the receiving device of the present invention. 1 It may be generated in cooperation with an OS or other computer program installed in the communication device 11.
In the first communication device 11, the interface unit 31, the preprocessing unit 32, the encryption/decryption unit 33, the common data generation unit 34, the algorithm generation unit 35, the key generation unit 36, the communication unit 37, and the connection unit 38. Composed of.

The interface section 31 has a function of sending data from the bus 28 to the preprocessing section 32 and a function of receiving data from the connection section 38 and sending it to the bus 28.
When the preprocessing unit 32 receives the data to be transmitted or the encrypted data received from the bus 28 via the interface unit 31 (hereinafter, a series of a plurality of or a plurality of encrypted cut data is referred to as “encrypted data”) Is cut for each predetermined number of bits to generate transmission target cut data or encrypted cut data, and sends this to the encryption/decryption unit 33. The transmission target data is text data and plain text data. Each character included in the transmission target data, which is text data, is described by a code that identifies each character. How to disconnect the transmission target data or encrypted data will be described later, but the transmission target disconnection data is at least for each bit length equal to or shorter than the bit length of the code identifying the character included in the text. Be disconnected. Although not limited to this, the characters included in the transmission target data in this embodiment are so-called 1-byte characters in English, and the bit length of the code specifying each character is 8 bits. Note that, although not limited to this, the pre-processing unit 32 in this embodiment may add dummy data, which is data unrelated to the transmission target data, to the transmission target data by a method described below, as necessary. Have the function of including. As described above, when the preprocessing unit 32 generates the transmission target cut data from the transmission target data, the preprocessing unit 32 sends the transmission target cut data to the encryption/decryption unit 33. Information indicating that the transmission target data is to be cut off is sent to the common data generation unit 34. Further, the pre-processing unit 32 is adapted to send the encrypted cut data from the encrypted data to the encryption/decryption unit 33, but in addition to this, for example, immediately before the encryption, Information indicating that the data is to be cut off is sent to the common data generation unit 34.
The encryption/decryption unit 33 receives the transmission target disconnection data or the encrypted disconnection data from the preprocessing unit 32, encrypts the transmission target disconnection data when it is received, and receives the encrypted disconnection data when it is received. Has the function of decrypting it. The data to be transmitted is text data and includes a plurality of characters, usually a large number of characters. Further, the transmission target cut data is obtained by cutting the transmission target data with a length equal to or shorter than the bit length of the code specifying the character. Therefore, the number of pieces of transmission-target cut data is equal to or more than the number of characters included in the transmission-target data, and therefore is plural, usually a large number. The encryption/decryption unit 33 is adapted to perform an encryption process on a plurality of, or usually a large number of pieces of transmission target disconnection data. Similarly, the encryption/decryption unit 33 is adapted to perform decryption processing on a plurality of or usually a large number of encrypted cut data. The details of the encryption and decryption processing will be described later, but in the case of performing encryption and decryption, the encryption/decryption unit 33 uses the algorithm supplied from the algorithm generation unit 35 as described below. The key supplied from the key generation unit 36 as described later is used. Although not limited to this, in this embodiment, the algorithm and the key are processed each time the encryption/decryption unit 33 performs the encryption process or the encryption/decryption unit 33 performs the decryption process. Then, it is supplied to the encryption/decryption unit 33. Although not limited to this, the encryption/decryption unit 33 in this embodiment has a fixed processing unit when performing encryption and decryption processing. Usually, this processing unit is determined depending on the hardware configuration of the first communication device 11, for example, the specifications of the CPU 21. The above-mentioned processing unit in this embodiment is, but not limited to, 8 bits. The length of data to be encrypted at one time, or the unit of processing (hereinafter referred to as "reference bit number") is the length of the code that fixes the characters included in the transmission target data (this implementation 8 bits in the form) or longer than that.
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 is configured to generate common data sequentially so that common data in the same order becomes the same. This means that in this embodiment, a so-called event synchronization technique is used to generate common data that is common to the first communication device 11 and the second communication device 12. The so-called time synchronization may be used as the method for generating the common data. Also, the common data in this embodiment is a pseudo-random number, although this is not necessarily the case. The generated common data is sent to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36. Although not limited to this, in this embodiment, the common data is generated each time the encryption/decryption unit 33 performs encryption processing or decryption processing. As described above, the common data generation unit 34 includes the transmission target data or the encrypted data immediately before the disconnection every time the transmission target data is disconnected or the encrypted data is disconnected from the preprocessing unit 32. Information is sent that indicates that the encrypted data will be cut. Each time the information is received, the common data generation unit 34 generates common data and sends it to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36.
The algorithm generation unit 35 is for generating 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 algorithm generation unit 35 is configured to generate an algorithm each time the common data is received, and sends the generated algorithm to the encryption/decryption unit 33 each time it is generated.
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 key generation unit 36 generates a key each time the common data is received, and sends the generated key to the encryption/decryption unit 33 each time it is generated.
The communication unit 37 exchanges data with the network 13 via the communication device 27. The encrypted cut data generated by encrypting the transmission target cut data in the encryption/decryption unit 33 is connected by the connection unit 38, and is connected via the communication unit 37, the communication device 27, and the network 13 to the other side. Will be sent to the communication device. The communication unit 37 also receives encrypted data from the communication device on the other side. 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 disconnection data generated by decrypting the encrypted disconnection data by the encryption/decryption unit 33 in the original order to form a single transmission target data. ing. The data to be transmitted is transmitted to the interface unit 31 and is transmitted via the bus 28 to the HDD 23 or the CPU 21 as required. The connection unit 38 also has a function of connecting the encrypted cut data generated by encrypting the cut data to be transmitted by the encryption/decryption unit 33 into a single piece 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 partner side. The connection unit 38 may not have a function of connecting the encrypted cut data generated by encrypting the transmission target cut data in the encryption/decryption unit 33. In this case, the encrypted cut data is sequentially sent to the communication device on the partner side in the order of encryption. If the connection unit 38 is such, the encrypted disconnection data can be sent directly 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.
A brief description will be given with reference to FIG. 5, and the flow of processing performed in 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, the 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 remains the same even when the process reverse to the case is performed.

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

First, the transmission target data is read. The transmission target data may be any data as long as the data 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 having the content to send the transmission target data to the second communication device 12 is input from the input device 25, the CPU 21 reads the transmission target data from the HDD 23 and temporarily records the data in the RAM 24, for example. This data to be transmitted 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 pre-processing unit 32, the transmission target data is cut for each predetermined number of bits, more specifically, for each bit length that is equal to or shorter than the bit length of the code that identifies the character included in the text of the transmission target data. And is set as transmission target disconnection data (S1102). The pre-processing unit 32 includes dummy data in the transmission target disconnection data as needed.
Although there may be one method of generating the transmission target cut data from the transmission target data, in this embodiment, the transmission target cut data is generated from the transmission target data by any of the following four methods. It has become.
A) The data to be transmitted is cut at a fixed number of bits shorter than the bit length of the code specifying the character to make the cut data of the transmission target, and all of them have a bit number shorter than the bit length of the code specifying the character. When including the dummy data in each fixed position of the transmission target cut data, and aligning the length of all the transmission target cut data to the reference bit number B) The bit length of the code that identifies the character of the transmission target data The cut data is cut with a fixed number of bits that is shorter than the above to make the cut data to be sent, and all of them have a bit number shorter than the bit length of the code that identifies the character. When including dummy data in the position and aligning the length of all transmission target cut data with the reference bit number C) Cut the transmission target data with the same bit length as the bit length of the code specifying the character or with a bit number shorter than that. As the target cut data for transmission, and includes dummy data in each of the target cut data whose number of bits is shorter than the bit length of the code that identifies the character, and sets the length of all target cut data as the reference number of bits. When aligning D) When the transmission target data is cut by the same number of bits as the bit length of the code for specifying the character (in this embodiment, this number of bits is equal to the reference number of bits) to be the transmission target cut data (in this case) Does not need to use dummy data.)

Which of the above-described four methods is used to generate the transmission target cut data from the transmission target data is not limited to this, but in this embodiment, it is determined by the common data generated by the common data generation unit 34. It has become so.
However, which of the four methods may be adopted may be pre-arranged between the first communication device 11 and the second communication device 12, and for example, only one of the above-mentioned four methods is used. It may be always used.

The preprocessing unit 32 disconnects the transmission target data. Each time the preprocessing unit 32 disconnects the transmission target data, immediately before the disconnection, the preprocessing unit 32 sends information indicating that the transmission target data will be disconnected, to the common data generation unit 34. Every time the information is received, the common data generation unit 34 generates the common data.
How the common data generation unit 34 generates common data will be described.
Although not limited to this, the common data in this embodiment is an 8×8 matrix (X).
The reason why the common data is a matrix of 8 rows and 8 columns in this embodiment is that the number of reference bits is 8. For example, if the reference bit number is 32 bits, the common data may be a matrix of 32 rows and 32 columns, and if the reference bit number is 64 bits, the common data may be a matrix of 64 rows and 64 columns. ..

The common data generation unit 34 does not necessarily have to do 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, in the process of (1) generation of the common data, the calculation of the exponentiation of the past common data and (2) the process of generation of the common data are performed. , A method of including multiplication of two or more pieces of common data in the past, or a combination of (1) and (2) can be considered.

In this embodiment, the common data generation unit 34 has, as an initial matrix, a 01th solution (X ₀₁ ) and a 02nd solution (X ₀₂ ) as predetermined ones (for example, the 01st solution and the 02nd solution). The solution is recorded in the RAM 24).
The common data generation unit 34 substitutes this initial matrix into the solution generation algorithm to generate the first solution (X ₁ ) as follows.
First solution (X ₁ )=X ₀₂ X ₀₁ +α (α=8×8 matrix)
This is the common data that is initially 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, every time the interface unit 31 receives the transmission target data from the bus 28, the common data generation unit 34 generates the third solution, the fourth solution,... 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 in 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, in short, generated immediately before that. Two solutions are used. Therefore, the common data generation unit 34 must hold the two most recent solutions generated in the past when generating a new solution (or if somebody else does not hold these two solutions). Not). Conversely, a solution older than the two most recently generated solutions will not be used in the future to generate a new solution. Therefore, in this embodiment, the common two data are always held in the past two solutions. However, the new solution is generated to become the third most recent solution. The solution that was the solution is to be deleted from a predetermined memory in which the solution was recorded.
The solution generated in this way is chaotic with a non-linear transition, and is a pseudo random number.

In order to cause a non-linear transition, the above-mentioned Nth solution ( _XN )= _{XN- 1XN-2} +[alpha] when obtaining the Nth solution.
In addition to using the equation, it is possible to use the following equation.
For example,
(A) Nth solution (X _N )=(X _N−1 ) ^P
(B) Nth solution ( _XN )=( _XN-1 ) ^P ( _XN-2 ) ^Q ( _XN-3 ) ^R ( _XN-4 ) ^S.
(C) Nth solution ( _XN )=( _XN-1 ) ^P +( _XN-2 ) ^Q
And so on.
Note that P, Q, R, and S are predetermined constants. In addition, the common data generation unit 34 has two initial matrices when the formula (a) or (c) is used and four initial matrices when the formula (b) is used.
Further, although α described above is a constant, this can also be used as specific changing environment information. This environmental information is information that occurs naturally one after another over time, and is information that can be commonly obtained even in distant places. Information that is determined based on the content of a television broadcast from a certain television station, information that is determined based on the results of a specific sport, and the like.
If the above α is created one after another from such environment information and common information is created, the confidentiality of communication can be further enhanced.
Of course, it is also possible to add α (this may be generated from the environment information) to the right side of the mathematical expressions (a) to (c) described above.
The common data generation unit 34 sends the generated common data to the preprocessing unit 32, the algorithm generation unit 35, and the key generation unit 36.

The preprocessing unit 32 receives the common data. In this state, the preprocessing unit 32 is about to disconnect the top data of the transmission target data at that time.
The preprocessing unit 32 that has received the common data (that is, the above-described solution) accordingly determines which of the above-mentioned A), B), C), and D) is used to generate the transmission target disconnection data. .. In this embodiment, although not limited to this, the sum of the numbers forming the matrix of 8 rows and 8 columns which is common data is divided by 4, and when the remainder is 0, the method of A) is performed. When the remainder is 1, the method B) is used, when the remainder is 2, the method C) is used, and when the remainder is 3, the method D) is used to generate the transmission target disconnection data. ..
When the transmission target cut data is generated by the method A), the pre-processing unit 32 sequentially sets the transmission target data received from the interface unit 31 from the beginning, and determines the number of bits of a code that identifies a character included in the transmission target data. The transmission target cut data is generated by cutting with a fixed number of bits (for example, 7 bits in this embodiment) shorter than this. Further, the pre-processing unit 32 arranges the lengths of all the transmission target cut data to the reference number of bits by embedding dummy data in a fixed position of the transmission target cut data. In this case, the position where the dummy data is embedded in the transmission target data is determined in advance. For example, the position may be the beginning or end of the transmission target cut data, or a predetermined intermediate position such as the second bit or the third bit. it can. This dummy data may be any data as long as it is data unrelated to the transmission target data. For example, processing such as always embedding data of 0, embedding data of 1, or embedding data of 1 and 0 alternately is conceivable. As still another example, it is possible to determine what dummy data to embed based on the above-mentioned common data. For example, the sum of the numbers forming the matrix of 8 rows and 8 columns, which is common data, is divided by 9, and when the remainder is 0, 0, 0, 0, 0... And 0 are consecutive, and the remainder is When 1, the value is 0, 1, 0, 1... Every other 1 is inserted, and when the remainder is 2, it is 0, 0, 1, 0, 0, 1... and every other 1 is inserted. Similarly, when the remainder is 3, every third, when the remainder is 4, every 4th, and so on, when the remainder is 9, 1 can be inserted every 9th.
When the transmission target cut data is generated by the method B), the preprocessing unit 32 sets the transmission target data to a certain number of bits that is shorter than the number of bits of the code that identifies the character included in the transmission target data. (For example, 7 bits) is cut and used as cut data for transmission. Further, the pre-processing unit 32 aligns the bit lengths of all the transmission target cut data by including dummy data in different positions of all the transmission target cut data. In this case, the position where the dummy data is embedded is sequentially moved to the 1st bit, 2nd bit, 3rd bit... 8th bit, 1st bit, 2nd bit... 8th bit for each transmission target cut data. It may be a regularly changing one, or a random one (or a seemingly random one). 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 the dummy data is embedded by the common data, for example, the sum of the numbers forming the matrix of 8 rows and 8 columns which is the common data is divided by 8 and the remainder is 0. In this case, every other piece of transmission target cut data is embedded with dummy data alternately at the beginning and end. When the remainder is 1, the transmission target cut data with dummy data embedded at the beginning and dummy data at the end are embedded. When there is a remainder of 2, the transmission target disconnection data in which the dummy data is embedded at the beginning and the transmission target disconnection data in which the dummy data is embedded at the end are three When the remainder is 7, every 8 pieces of transmission target cut data in which dummy data is embedded at the beginning and transmission target cut data in which dummy data is embedded at the end , Can be performed. It is also possible to move the positions further without fixing the positions where the dummy data is embedded like the beginning and the end.
In the case of generating the transmission target cut data by the method of C), the transmission target data is cut to the same bit number as or shorter than the bit number of the code specifying the character included in the transmission target data. This disconnection can be performed by cutting the transmission target data into 8 bits or a random length shorter than 8 bits. For example, the numbers forming the matrix of 8 rows and 8 columns that are common data are added. The combined sum is divided by 8, and when the remainder is 0, the beginning part of the transmission target data at that time is cut by 8 bits, and when the remainder is 1, the beginning part of the transmission target data at that time is 1 bit When the remainder is 2, the leading part of the transmission target data at that time is cut by 2 bits, and... When the remainder is 7, the leading part of the transmission target data at that time is cut by 7 bits. You can Further, the pre-processing 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 thus generated. In this case, the embedding position of the dummy data may be a specific position such as the head or the end, or may be a changing predetermined position specified by the common data, for example.
When the transmission target cut data is generated by the method D), the preprocessing unit 32 sequentially sets the transmission target data received from the interface unit 31 from the beginning, and determines the number of bits of a code that identifies a character included in the transmission target data. The transmission target cut data is generated by cutting with the same fixed number of bits (for example, 8 bits in this embodiment). Then, even if the dummy data is not used, the number of bits of all the cut data to be transmitted is equal to the reference number of bits.
What kind of transmission target cut data is generated from the transmission target data depends on the content of the common data sent from the common data generation unit 34, as described above. Regardless of which method is used, the transmission target cut data generated in this manner 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.
In this embodiment, the algorithm generation unit 35 generates an algorithm each time the common data is received from the common data generation unit 34, based on the received common data. However, the algorithm may be a fixed one that does not change, or may be selected from a plurality of prepared algorithms.
In this embodiment, the algorithm generator 35 generates an algorithm as follows.
According to the algorithm in this embodiment, when the transmission target cut data that is 8-bit data is the 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, and then the clock It is obtained by multiplying a matrix rotated by n×90° around it by Y”.
Here, a may be a predetermined constant, but in this embodiment, it is a number that changes based on common data. That is, the algorithm in this embodiment changes based on the common data. For example, a is the remainder when the number obtained by adding all the numbers of the elements of the matrix included in the common data, which is a matrix with 8 rows and 8 columns, is divided by 5 (however, when the remainder is 0, a=1)).
The above-mentioned n is a predetermined number determined by the key. If the number of keys is a fixed number, n is fixed, but as will be described below, the keys change based on common data. That is, in this embodiment, this n also changes based on the common data.
However, the algorithm can be determined as another.
In this embodiment, the algorithm generation unit 35 generates an algorithm each time the common data is received from the common data generation unit 34 and sends it to the encryption/decryption unit 33. As described above, the common data generation unit 34 generates the common data every time the preprocessing unit 32 generates the transmission target cut data from the transmission target data. Since the algorithm generation unit 35 generates the algorithm each time the common data is received, the algorithm generation unit 35 generates the algorithm every time the preprocessing unit 32 generates the transmission target cut data from the transmission target data. It will be.

In parallel with the generation of the transmission target cut data, the key generation unit 36 generates a key used when encrypting the transmission target cut data.
The key generation unit 36 generates a key based on the received common data every time the common data is received from the common data generation unit 34. However, the key generation unit 36 may always provide the same fixed key to the encryption/decryption unit 33, or the plurality of keys prepared in advance may be supplied to the encryption/decryption unit 33. The key to be provided may be selected.
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 of elements of the matrix included in the common data, which is a matrix of 8 rows and 8 columns. Therefore, the key changes in this embodiment based on the common data.
Note that the key may be determined as another key.
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. As described above, the common data generation unit 34 generates the common data every time the preprocessing unit 32 generates the transmission target cut data from the transmission target data. Since the key generation unit 36 generates the key each time the common data is received, the key generation unit 36 generates the key each time the preprocessing unit 32 generates the transmission target cut data from the transmission target data. It will be.

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, the algorithm generation unit 35 generates an algorithm each time the preprocessing unit 32 generates transmission target cut data from transmission target data, and sends the algorithm to the encryption/decryption unit 33. Similarly, the key generation unit 36 generates a key each time the preprocessing unit 32 generates transmission target cut data from transmission target data, and sends the key to the encryption/decryption unit 33. As a result, the encryption/decryption unit 33 receives a new algorithm and a new key from the algorithm generation unit 35 and the key generation unit 36 each time it receives the transmission target disconnection data, and receives the latest algorithm supplied. Using the key and the key, the transmission target disconnection data is encrypted by a different method every time.
As described above, when the transmission target disconnection data that is 8-bit data is the matrix Y of 1 row and 8 columns, as described above, after the matrix X of 8 rows and 8 columns that is common data is raised to the power a The matrix is obtained by multiplying the matrix rotated by n×90° clockwise by Y, and the key n is a number as described above.
For example, when a is 3 and n is 6, 8×8 matrix obtained by raising X to the power of 8 is obtained by rotating clockwise by 6×90°=540°. Encryption is performed by multiplying the matrix with 8 rows by the disconnection data to be transmitted.
The data generated in this way is the encrypted cut data.
In this embodiment, the encryption/decryption unit 33 repeats the process of encrypting the cut data to be transmitted into encrypted cut data. In this embodiment, the algorithm and the key used for the encryption process are generated each time the algorithm generation unit 35 and the key generation unit 36 perform the encryption process, and therefore the encryption/decryption unit 33 repeats. The encryption processing method to be performed is different every time. However, the encryption process that is repeatedly performed does not have to be different every time, and at least one of the encryption processes may be executed by a method different from that of the other encryption processes. The algorithms and keys are probabilistic, but the same can appear, but it is acceptable. If at least one of the algorithm and key used in one encryption process is different from the algorithm and key used in combination in another encryption process, the encryption method is different. As described above, in this embodiment, the algorithm and the key that change each time the encryption process is executed do not necessarily change, and the algorithm or the key can always be the same, but at least once encryption is performed. Since it is necessary to perform the method used in the encryption processing different from the method used in other encryption processing, it is not allowed to fix both the algorithm and the key.
In any case, the encryption/decryption unit 33 sends the generated encrypted cut data to the connection unit 38.

The encrypted cut data is received by the connection unit 38. The connection unit 38 connects the encrypted cut data all 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 to generate the encrypted data ends.

The encrypted data is sent to the communication unit 37, from the communication unit 37 to the communication device 27, and from the communication device 27 to the second communication device 12 via the network 13.

The second communication device 12, which has received the encrypted data, executes the process of S130 of decrypting the encrypted data and returning it to the transmission target data.
Hereinafter, the decoding process will be described in detail with reference to FIG.

The encrypted data sent to the second communication device 12 is accepted 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 pre-processing unit 32 cuts the received encrypted data for each predetermined number of bits to generate encrypted cut data (S1202).
When cutting the encrypted data to generate the encrypted cut data, the pre-processing unit 32 performs the reverse process 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 beginning 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 to be cut data to be transmitted (S1203).

Common data is required for the process of generating encrypted cut data from encrypted data.
Further, the decryption process performed by the encryption/decryption unit 33 of the second communication device 12 is performed as the reverse process to that performed by the encryption/decryption unit 33 of the first communication device 11. Therefore, the second communication device 12 requires the algorithm and the key that were required when the first communication device 11 performed the encryption. Therefore, in order for the second communication device 12 to perform the decryption, the algorithm and the key are generated before the encryption is performed in the first communication device 11, and the common data is generated prior to the generation thereof. Similarly, common data is required.
When the second communication device 12 receives the encrypted data, it is sent to the preprocessing unit 32 via the communication device 27 and the communication unit 37. Then, the preprocessing unit 32 disconnects the encrypted data. Each time the preprocessing unit 32 disconnects the transmission target data, immediately before the disconnection, the preprocessing unit 32 sends information indicating that the transmission target data will be disconnected, to the common data generation unit 34. Every time the information is received, the common data generation unit 34 generates the common data.
The method by which the common data generation unit 34 in the second communication device 12 generates the common data is the same as the method by which the common data generation unit 34 in the first communication device 11 generates the common data. Since the common data generation unit 34 of the second communication device 12 has the same initial matrix and solution generation algorithm that the common data generation unit 34 of the first communication device 11 has, the first communication device The same common data as 11 can be generated. The common data generated by the second communication device 12 is the same as the common data generated by the first communication device 11 when the data having the same generation order are compared.
Also in the second communication device 12, 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 preprocessing unit 32 of the second communication device 12 receives the common data. In this state, the preprocessing unit 32 is about to disconnect the head data of the encrypted data at that time. When receiving the common data, the pre-processing unit 32 cuts the encrypted data and generates encrypted cut data. In this case, the disconnection is executed as a disconnection with a fixed length for each reference bit number, and the processing does not depend on the content of the common data. In this respect, the processing in the first communication device 11 and the processing in the second communication device 12 are different.
On the other hand, the algorithm generator 35 generates an algorithm each time the common data is received, based on the received common data. The process of the algorithm generation unit 35 of the second communication device 12 generating an algorithm is the same as the process of the algorithm generation unit 35 of the first communication device 11 generating an algorithm. The generated algorithm is sent from the algorithm generating unit 35 to the encryption/decryption unit 33.
Every 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 in which the key generation unit 36 of the second communication device 12 generates a key is the same as the process in which the key generation unit 36 of the first communication device 11 generates a key. The generated key is sent from the key generation unit 36 to the encryption/decryption unit 33.
As in the case of the encryption process of the first communication device 11, when the decryption process is executed by the second communication device 12, the encryption/decryption unit 33 of the second communication device 12 is Each time the encrypted cut data is received, a new algorithm and a key are supplied from the algorithm generation unit 35 and the key generation unit 36. The encryption/decryption unit 33 uses the latest received algorithm and key to decrypt the encrypted cut data and returns the encrypted cut data to the cut data to be transmitted.
By the way, in this communication system, the first communication device 11 performs the encryption process and the second communication device 12 performs the decryption process a plurality of times, usually a large number of times, and the encryption and the decryption are performed. The number of times it is done is consistent. In this communication system, new common data is generated in the first communication device 11 each time the first communication device 11 performs the encryption process, and new common data is generated in the second communication device 12 each time the common data is decrypted. The new common data is generated in the second communication 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 encrypting the disconnection data to be transmitted, which is the first communication device 11, and the algorithm and the key generated based on the common data are all the common data and the common data. When decrypting the encrypted cut data generated using the algorithm and the key generated using the common data generated by the second communication device 12, the algorithm generated based on the common data, and Always matches the key. Note that this circumstance is the same when the second communication device 12 performs the encryption and the first communication device 11 performs the decryption.

In the encryption/decryption unit 33, as described above, the decryption process is performed using the algorithm accepted from the algorithm generation unit 35. More specifically, the encryption/decryption unit 33 uses the common data when the algorithm received from the algorithm generation unit 35 It is the encrypted cut data that is obtained by multiplying a matrix X of 8 rows and 8 columns by the power a and then multiplying the matrix rotated by n×90° clockwise by Y”. Then, an algorithm for performing the decryption process (when the encrypted cut data is regarded as a 1-row 8-column matrix Z, the 8-row 8-column matrix X that is common data is raised to the power a, The inverse matrix of the matrix rotated by n×90° is multiplied by Y to obtain the disconnection data to be transmitted.”), and the operation according to the above definition is performed using the key. By doing so, decryption processing is performed. In this way, the encryption/decryption unit 33 sequentially decrypts the encrypted cut data supplied from the pre-processing unit 32 in a stream to generate the transmission target cut data.

Next, the encryption/decryption unit 33 removes dummy data from the transmission target disconnection data as necessary (S1204). As described above, the common data generated by the common data generator 34 is sent to the preprocessor 32. This common data is used when the preprocessing 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 by the encryption/decryption unit 33 of the second communication device 12 (or is decrypted). Or, about to decrypt it), shows how the dummy data was embedded in the encrypted cut data (more accurately, the cut data to be transmitted before the encrypted cut data was encrypted). It is a thing.
The pre-processing unit 32 sends to the encryption/decryption unit 33 information about where the dummy data is embedded in the transmission target cut data decrypted by the encryption/decryption unit 33.
By using this, the encryption/decryption unit 33 removes the dummy data from the transmission target disconnection data. If the cut data to be transmitted does not include dummy data, this process except for dummy data is omitted.

The transmission target disconnection data thus generated is sent to the connection unit 38. The connection unit 38 connects the received transmission target disconnection data all together, and restores the transmission target data in 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 transmitted from the connection unit 38 to the interface unit 31, is transmitted to the HDD 23 via the bus 28, and is stored therein.

11 first communication device 12 second communication device 13 network 31 interface unit 32 preprocessing unit 33 encryption/decryption unit 34 common data generation unit 35 algorithm generation unit 36 key generation unit 37 communication unit 38 connection unit

Claims (19)

It includes a transmission device that encrypts transmission target data that is data about text and is plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device into the transmission target data. A transmission/reception system,
The transmitter is
A transmission device disconnecting unit that disconnects the transmission target data for each predetermined number of bits to form a plurality of transmission target disconnection data,
An encryption unit that encrypts the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitter for transmitting the encrypted disconnection data to the receiver,
Is equipped with
The receiving device,
A receiver for receiving the encrypted disconnection data from the transmitter,
A receiver disconnecting unit that disconnects the encrypted cut data, which is a series of data received from the transmitter, for each of the encrypted cut data,
A decryption unit that decrypts the encrypted cut data with the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain cut data to be transmitted.
A connection unit that connects the decrypted transmission target disconnection data to the transmission target data,
Is equipped with
The transmission device disconnecting unit disconnects the transmission target data into a plurality of transmission target disconnection data for each bit length equal to or shorter than a bit length of a code specifying a character included in the text. Has become
The encryption unit, when encrypting the transmission target disconnection data, performs an encryption method for encrypting at least one of the transmission target disconnection data when encrypting another transmission target disconnection data; It is designed to differ in the method of conversion,
The decryption unit decrypts the encrypted cut data obtained by the receiving device disconnecting unit according to the fact that the encrypting unit of the transmitting device uses a different encryption method. Different methods,
Transmission and reception system. It includes a transmission device that encrypts transmission target data that is data about a text and is a plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device to be the transmission target data. A transmitting device comprising a transmitting/receiving system in combination with the receiving device,
A transmission device disconnecting unit that disconnects the transmission target data for each predetermined number of bits to form a plurality of transmission target disconnection data,
An encryption unit that encrypts the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitter for transmitting the encrypted disconnection data to the receiver,
Is equipped with
The transmission device disconnecting unit disconnects the transmission target data into a plurality of transmission target disconnection data for each bit length equal to or shorter than a bit length of a code specifying a character included in the text. Has become
The encryption unit, when encrypting the transmission target disconnection data, performs an encryption method for encrypting at least one of the transmission target disconnection data when encrypting another transmission target disconnection data; It is designed to differ in the method of conversion,
The receiving device,
A receiver for receiving the encrypted disconnection data from the transmitter,
A receiver disconnecting unit that disconnects the encrypted cut data, which is a series of data received from the transmitter, for each of the encrypted cut data,
A decryption unit that decrypts the encrypted cut data with the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain cut data to be transmitted.
A connection unit that connects the decrypted transmission target disconnection data to the transmission target data,
Is equipped with
The decryption unit decrypts the encrypted cut data obtained by the receiving device disconnecting unit according to the fact that the encrypting unit of the transmitting device uses a different encryption method. Different methods,
Supposed to
Transmitter. The transmitter disconnection unit is configured to disconnect the transmission target data into a certain number of bits.
The transmission device according to claim 2. The transmission device disconnecting unit disconnects the transmission target data so that at least one of the transmission target disconnection data other than the last one has a different number of bits from other transmission target disconnection data,
The transmission device according to claim 2. The transmission target disconnection data includes dummy data that is not related to the transmission target data, and includes a mixing unit that aligns the number of bits of all the transmission target disconnection data to a predetermined number of bits,
The receiving device includes a removing unit that removes the dummy data from the transmission target cut data obtained by the decoding unit,
The transmission device according to claim 2. The mixing unit is configured to include the dummy data in a specific position of the transmission target data,
The transmission device according to claim 5. The mixing unit is configured to include the dummy data in a predetermined position that differs for each of the transmission target data,
The transmission device according to claim 5. The encryption unit is configured to change the method for encrypting the transmission target disconnection data by changing at least one of an algorithm and a key used for encryption.
The transmission device according to claim 2. The encryption unit is configured to change the method of encrypting the transmission target disconnection data each time the transmission target disconnection data is encrypted.
The transmission device according to claim 2. Equipped with a transmitter common data generator that can generate the same common data that is a pseudo-random number under the same conditions,
The encryption unit is configured to determine an encryption method based on the common data generated by the transmission device common data generation unit,
The reception device includes a reception device common data generation unit capable of generating the same common data as the transmission device common data generation unit,
The decoding unit is adapted to determine a decoding method based on the common data generated by the reception device common data generation unit.
The transmission device according to claim 8 or 9. It includes a transmission device that encrypts transmission target data that is data about text and is plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device to be the transmission target data. A receiving device comprising a transmitting/receiving system in combination with the transmitting device,
The transmitter is
A transmission device disconnecting unit that disconnects the transmission target data for each predetermined number of bits to form a plurality of transmission target disconnection data,
An encryption unit that encrypts the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitter for transmitting the encrypted disconnection data to the receiver,
Is equipped with
The transmission device disconnecting unit disconnects the transmission target data into a plurality of transmission target disconnection data for each bit length equal to or shorter than a bit length of a code specifying a character included in the text. Has become
The encryption unit, when encrypting the transmission target disconnection data, performs an encryption method for encrypting at least one of the transmission target disconnection data when encrypting another transmission target disconnection data; It is designed to use different methods,
As well as being
A receiver disconnecting unit that disconnects the encrypted cut data, which is a series of data received from the transmitter, for each of the encrypted cut data,
A decryption unit that decrypts the encrypted cut data with the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain cut data to be transmitted.
A connection unit that connects the decrypted transmission target disconnection data to the transmission target data,
Is equipped with
The decryption unit decrypts the encrypted cut data obtained by the receiving device disconnecting unit according to the fact that the encrypting unit of the transmitting device uses a different encryption method. Different methods,
Receiver. The transmission device includes a mixing unit that aligns the number of bits of all the transmission target cut data to a predetermined number of bits by including dummy data that is not related to the transmission target data in the transmission target cut data. Is said to be
A removing unit for removing the dummy data from the transmission target cut data obtained by the decoding unit,
The receiving device according to claim 11. In the transmission device, the encryption unit is configured to change the method of encrypting the transmission target disconnection data by changing at least one of an algorithm and a key used for encryption. Along with
The decryption unit is configured to change the method for decrypting the encrypted cut data obtained by the receiving device disconnection unit by changing at least one of an algorithm and a key used for decryption,
The receiving device according to claim 11. The transmission device is configured such that the encryption unit changes the method of encrypting the transmission target disconnection data each time the transmission target disconnection data is encrypted, and
The decryption unit is configured to change the method of decrypting the encrypted disconnection data obtained by the receiving device disconnection unit, each time the encrypted disconnection data is decrypted.
The receiving device according to claim 11. The transmission device includes a transmission device common data generation unit capable of generating the same common data that is a pseudo-random number under the same conditions, and the encryption unit is generated by the transmission device common data generation unit. It is supposed to decide the encryption method based on common data, and it is assumed that,
A receiver common data generator capable of generating the same common data as the transmitter common data generator,
The decoding unit is adapted to determine a decoding method based on the common data generated by the reception device common data generation unit.
The receiving device according to claim 11. It includes a transmission device that encrypts transmission target data that is data about text and is plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device into the transmission target data. A transmitting/receiving system, which is a method executed by a transmitting device configured by a combination with the receiving device, comprising:
Executed by the transmitter,
A step of disconnecting the transmitting device by cutting the transmission target data for each predetermined number of bits into a plurality of transmission target disconnection data,
An encryption process of encrypting the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitting step of transmitting the encrypted cut data to the receiving device,
Including
In the transmitting device disconnection process, the transmission target data is cut into a plurality of transmission target disconnection data by cutting for each bit length equal to or shorter than the bit length of a code specifying a character included in the text,
In the encryption process, when encrypting the transmission target disconnection data, an encryption method to be executed when encrypting another transmission target disconnection data for at least one of the transmission target disconnection data, and an encryption method. Different ways of
The receiving device,
A receiver disconnecting unit that disconnects the encrypted cut data, which is a series of data received from the transmitter, for each of the encrypted cut data,
A decryption unit that decrypts the encrypted cut data with the same algorithm and key as the algorithm and key used in the encryption process of the transmission device to obtain cut data to be transmitted.
A connection unit that connects the decrypted transmission target disconnection data to the transmission target data,
Is equipped with
The decryption unit decrypts the encrypted cut data obtained by the receiving device disconnecting unit in accordance with a different encryption method in the encryption process of the transmitting device. Different methods,
Supposed to
Method. It includes a transmission device that encrypts transmission target data that is data about text and is plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device into the transmission target data. A transmitting/receiving system, which is a method executed by a receiving device configured by a combination with the transmitting device,
The transmitter is
A transmission device disconnecting unit that disconnects the transmission target data for each predetermined number of bits to form a plurality of transmission target disconnection data,
An encryption unit that encrypts the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitter for transmitting the encrypted disconnection data to the receiver,
Is equipped with
The transmission device disconnecting unit disconnects the transmission target data into a plurality of transmission target disconnection data for each bit length equal to or shorter than a bit length of a code specifying a character included in the text. Has become
The encryption unit, when encrypting the transmission target disconnection data, performs an encryption method for encrypting at least one of the transmission target disconnection data when encrypting another transmission target disconnection data; It is designed to use different methods,
As well as being
Executed by the receiving device,
A receiving device disconnection step of disconnecting the encrypted disconnection data, which is a series of data received from the transmitting device, for each of the encrypted disconnection data,
A decryption step of decrypting the encrypted cut data by the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain transmission target cut data;
A connection process of connecting the decrypted transmission target disconnection data to the transmission target data,
Contains
In the decryption process, when decrypting the encrypted cut data obtained in the receiving device disconnection process, the decryption process is performed in accordance with a different encryption method in the encryption unit of the transmission device. Different way of
Method. It includes a transmission device that encrypts transmission target data that is data about text and is plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device into the transmission target data. A transmission/reception system, which is a computer program for causing a predetermined computer to function as a transmission device configured by a combination with the reception device,
On the computer,
A step of disconnecting the transmitting device by cutting the transmission target data for each predetermined number of bits into a plurality of transmission target disconnection data,
An encryption process of encrypting the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitting step of transmitting the encrypted cut data to the receiving device,
To run
In the transmitting device disconnection process, the transmission target data is cut into a plurality of transmission target disconnection data by cutting for each bit length equal to or shorter than the bit length of a code specifying a character included in the text,
In the encryption process, when encrypting the transmission target disconnection data, an encryption method to be executed when encrypting another transmission target disconnection data for at least one of the transmission target disconnection data, and an encryption method. Different ways of
The receiving device,
A receiver disconnecting unit that disconnects the encrypted cut data, which is a series of data received from the transmitter, for each of the encrypted cut data,
A decryption unit that decrypts the encrypted cut data with the same algorithm and key as the algorithm and key used in the encryption process of the transmission device to obtain cut data to be transmitted.
A connection unit that connects the decrypted transmission target disconnection data to the transmission target data,
Is equipped with
The decryption unit decrypts the encrypted cut data obtained by the receiving device disconnecting unit in accordance with a different encryption method in the encryption process of the transmitting device. Different methods,
Supposed to
Computer program. It includes a transmission device that encrypts transmission target data that is data about text and is plaintext and then sends the data to the other party, and a reception device that can decrypt the data received from the transmission device into the transmission target data. A transmission/reception system, which is a computer program for causing a predetermined computer to function as a reception device configured by a combination with the transmission device,
The transmitter is
A transmission device disconnecting unit that disconnects the transmission target data for each predetermined number of bits to form a plurality of transmission target disconnection data,
An encryption unit that encrypts the transmission target disconnection data with a predetermined algorithm and a key to obtain encrypted disconnection data,
A transmitter for transmitting the encrypted disconnection data to the receiver,
Is equipped with
The transmission device disconnecting unit disconnects the transmission target data into a plurality of transmission target disconnection data for each bit length equal to or shorter than a bit length of a code specifying a character included in the text. Has become
The encryption unit, when encrypting the transmission target disconnection data, performs an encryption method for encrypting at least one of the transmission target disconnection data when encrypting another transmission target disconnection data; It is designed to use different methods,
As well as being
On the computer,
A receiving device disconnection step of disconnecting the encrypted disconnection data, which is a series of data received from the transmitting device, for each of the encrypted disconnection data,
A decryption step of decrypting the encrypted cut data by the same algorithm and key as the algorithm and key used in the encryption unit of the transmission device to obtain transmission target cut data;
A connection process of connecting the decrypted transmission target disconnection data to the transmission target data,
To run
In the decryption process, when decrypting the encrypted cut data obtained in the receiving device disconnection process, the decryption process is performed in accordance with a different encryption method in the encryption unit of the transmission device. Different way of
Computer program.

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