Communication system, first communication device, second communication device, and communication method

Abstract

Provided is technology for safely and easily sharing shared data between two communication devices that perform encrypted communication.　A first communication device encrypts shared data with a first solution and a unique first key to obtain first encrypted data (S503), and transmits this data to a second communication device (S504). The second communication device receives the first encrypted data (S601), decrypts this data with the first solution, encrypts this data with a second solution and a unique second key to obtain second first encrypted data (S602), and transmits this data to the first communication device (S603). The first communication device receives the second first encrypted data (S505), decrypts this data with the first key, encrypts this data with a third solution to obtain second encrypted data (S506), and transmits this data to the second communication device (S507). The second communication device receives the second encrypted data (S604), decrypts this data with the third solution and the second key, and returns this data to the shared data (S605).

Claims

1. A communication system comprising a first communication device, which is one of two communication devices that communicate with each other, and a second communication device, which is the other communication device, wherein the first communication device comprises a first encryption unit that performs a transformation for encryption that satisfies the commutative and associative laws, a first decryption unit that performs the reverse transformation of the encryption performed by the first encryption unit, a first solution generation unit that can continuously generate solutions that are always the same when generated under the same conditions based on an initial solution, and a first communication unit that communicates with the second communication device via a predetermined network, wherein the second communication device comprises a second encryption unit that performs a transformation for encryption that satisfies the commutative and associative laws in the same way as the first encryption unit, a second decryption unit that performs the reverse transformation of the encryption performed by the second encryption unit, a second solution generation unit that can continuously generate the same solutions as the first solution generation unit using the same initial solution used by the first solution generation unit, and a second communication unit that communicates with the first communication device via the network, The first communication device takes plaintext data, which is data to be shared with the second communication device, and uses a first key, which is a key unique to the first communication device and kept secret from the outside, and a first solution, which is the first solution generated by the first solution generation unit, to perform an encryption transformation in the first encryption unit to obtain first encrypted data, and transmits the first encrypted data to the second communication device via the network from the first communication unit. The second communication device, upon receiving the first encrypted data from the first communication device, performs an inverse transformation of the encryption transformation performed by the first encryption unit using the same first solution generated by the first solution generation unit in the second decryption unit, and uses a second key, which is a key unique to the second communication device and kept secret from the outside, and a second solution, which is the second solution generated by the second solution generation unit, to perform an encryption transformation in the second encryption unit to obtain second first encrypted data, and transmits the second first encrypted data to the first communication device via the network from the second communication unit.When the first communication device receives the second first encrypted data from the second communication device at the first communication unit, the first decryption unit performs the reverse transformation of the encryption transformation performed by the second encryption unit using the same second solution generated by the first solution generation unit, and also performs the reverse transformation of the encryption transformation performed by the first encryption unit using the first key at the first encryption unit, and the first encryption unit performs the encryption transformation using the third solution, which is the third solution generated by the first solution generation unit, to obtain the second encrypted data, and the first communication unit transmits the second encrypted data to the second communication device via the network. A communication system in which, when the second communication device receives the second encrypted data from the first communication device at the second communication unit, the second decryption unit performs the reverse transformation of the encryption transformation performed by the first encryption unit using the third solution, using the same third solution generated by the first solution generation unit and generated by the second solution generation unit, and also performs the reverse transformation of the encryption transformation performed by the second encryption unit using the second key, thereby converting the second encrypted data into the shared data.

2. A communication system comprising a first communication device, which is one of two communication devices that communicate with each other, and a second communication device, which is the other communication device, wherein the first communication device comprises a first encryption unit that performs a transformation for encryption that satisfies the commutative and associative laws, a first decryption unit that performs the reverse transformation of the encryption performed by the first encryption unit, a first solution generation unit that can continuously generate solutions that are always the same when generated under the same conditions based on an initial solution, a coupling unit that combines data, and a first communication unit that communicates with the second communication device via a predetermined network, wherein the second communication device comprises a second encryption unit that performs a transformation for encryption that satisfies the commutative and associative laws in the same way as the first encryption unit, a second decryption unit that performs the reverse transformation of the encryption performed by the second encryption unit, a second solution generation unit that can continuously generate the same solutions as the first solution generation unit using the same initial solution used by the first solution generation unit, a second splitting unit that splits data, and a second communication unit that communicates with the first communication device via the network, The first communication device takes the shared data, which is plaintext data to be shared with the second communication device, and uses the first key, which is unique to the first communication device and secret from the outside, and the first solution, which is the first solution generated by the first solution generation unit, to perform an encryption transformation in the first encryption unit to obtain first encrypted data. The first communication unit then transmits the first encrypted data to the second communication device via the network.When the second communication device receives the first encrypted data from the first communication device in the second communication unit, the second decryption unit performs the reverse transformation of the encryption transformation performed in the first encryption unit using the same first solution generated in the second solution generation unit on the first encrypted data, and the second encryption unit performs the encryption transformation using a second key which is unique to the second communication device and is kept secret from the outside, and further divides the data obtained by the encryption transformation performed in the second encryption unit using the second key into two parts in the second division unit, and The second encryption unit performs an encryption transformation on one of the divided data using the second solution generated by the second solution generation unit to obtain data A, which is part of the second first encrypted data, and the second encryption unit performs an encryption transformation on the other of the divided data using the third solution generated by the second solution generation unit to obtain data B, which is the remainder of the second first encrypted data, and the second communication unit transmits the data A and the data B, which constitute the second first encrypted data, to the first communication device via the network.When the first communication device receives the A data and B data, which constitute the second first encrypted data, from the second communication device, the first decryption unit performs the reverse transformation of the encryption transformation performed in the second encryption unit using the same second solution generated in the second solution generation unit and the first solution generation unit, on the A data, and also performs the reverse transformation of the encryption transformation performed in the first encryption unit using the first key, and on the B data, the first decryption unit uses the same third solution generated in the second solution generation unit and the first solution generation unit. The second encryption unit performs the reverse transformation of the encryption transformation performed using the third solution, and the first encryption unit performs the reverse transformation of the encryption transformation performed using the first key, and the data obtained based on the A data and the data obtained based on the B data are combined in the joining unit, and the first encryption unit performs an encryption transformation on the combined data using the fourth solution, which is the fourth solution generated in the first solution generation unit, to obtain the second encrypted data, and the first communication unit transmits the second encrypted data to the second communication device via the network, and the second communication device, upon receiving the second encrypted data from the first communication device in the second communication unit, performs the reverse transformation of the encryption transformation performed using the fourth solution in the first encryption unit using the same fourth solution generated in the second solution generation unit, and performs the reverse transformation of the encryption transformation performed using the second key in the second encryption unit using the second key, thereby obtaining the second encrypted data as the shared data.

3. The communication system according to claim 1 or 2, wherein the network is one of the following: the Internet, a telecommunications carrier line, a global IP-assigned IP-VPN, a private network, Short Message Service (SMS), or Multimedia Message Service (MMS).

4. The communication system according to claim 1 or 2, wherein the first encryption unit, the first decryption unit, the second encryption unit, and the second decryption unit are each configured to perform an exclusive OR operation.

5. The communication system according to claim 1 or 2, wherein the first communication device and the second communication device are configured to automatically and continuously perform the following processes: the first communication device encrypts the shared data into the first encrypted data, and the second communication device decrypts the second encrypted data into the shared data.

6. The communication system according to claim 1 or 2, wherein the first communication device is configured to change the first key at a predetermined timing.

7. The communication system according to claim 1 or 2, wherein the second communication device is configured to change the second key at a predetermined timing.

8. A first communication device included in the communication system described in any one of claims 1 to 7.

9. A second communication device included in the communication system described in any one of claims 1 to 7.

10. A communication method executed by a communication system comprising a first communication device, which is one of two communication devices that communicate with each other, and a second communication device, which is the other communication device, wherein the first communication device includes a first encryption unit that performs a transformation for encryption that satisfies the commutative and associative laws, a first decryption unit that performs the reverse transformation of the encryption performed by the first encryption unit, a first solution generation unit that can continuously generate solutions that are always the same when generated under the same conditions based on an initial solution, and a first communication unit that communicates with the second communication device via a predetermined network, wherein the second communication device includes a second encryption unit that performs a transformation for encryption that satisfies the commutative and associative laws in the same way as the first encryption unit, a second decryption unit that performs the reverse transformation of the encryption performed by the second encryption unit, a second solution generation unit that can continuously generate the same solutions as the first solution generation unit using the same initial solution used by the first solution generation unit, and a second communication unit that communicates with the first communication device via the network, The first communication device takes the shared data, which is plaintext data to be shared with the second communication device, and uses a first key, which is unique to the first communication device and secret from the outside, and the first solution, which is the first solution generated by the first solution generation unit, to perform an encryption transformation in the first encryption unit to obtain first encrypted data, and the first communication unit transmits the first encrypted data to the second communication device via the network in a first process, When the second communication device receives the first encrypted data from the first communication device at the second communication unit, the second decryption unit performs the reverse transformation of the encryption transformation performed by the first encryption unit using the same first solution generated by the second solution generation unit on the first encrypted data, and the second encryption unit performs the encryption transformation using the second key, which is unique to the second communication device and secret from the outside, and the second solution, which is the second solution generated by the second solution generation unit, to obtain second first encrypted data, and the second communication unit transmits the second first encrypted data to the first communication device via the network.When the first communication device receives the second first encrypted data from the second communication device in the first communication unit, the first decryption unit performs the reverse transformation of the encryption transformation performed in the second encryption unit using the same second solution generated in the first solution generation unit, and also performs the reverse transformation of the encryption transformation performed in the first encryption unit using the first key using the first key, and the first encryption unit performs the encryption transformation using the third solution, which is the third solution generated in the first solution generation unit, to obtain the second encrypted data, and the first communication unit transmits the second encrypted data to the second communication device via the network, A communication method comprising: a fourth step in which, when the second communication device receives the second encrypted data from the first communication device at the second communication unit, the second decryption unit performs the reverse transformation of the encryption transformation performed in the first encryption unit using the third solution, using the same third solution generated in the second solution generation unit and generated in the first solution generation unit, and also performs the reverse transformation of the encryption transformation performed in the second encryption unit using the second key, thereby converting the second encrypted data into the shared data.

11. A communication method executed by a communication system comprising a first communication device, which is one of two communication devices communicating with each other, and a second communication device, which is the other communication device, wherein the first communication device includes a first encryption unit that performs an encryption transformation satisfying the commutative and associative laws, a first decryption unit that performs the reverse transformation of the encryption performed by the first encryption unit, a first solution generation unit that can continuously generate solutions that are always the same when generated under the same conditions based on an initial solution, a coupling unit that combines data, and a first communication unit that communicates with the second communication device via a predetermined network, wherein the second communication device includes a second encryption unit that performs an encryption transformation satisfying the commutative and associative laws in the same way as the first encryption unit, a second decryption unit that performs the reverse transformation of the encryption performed by the second encryption unit, a second solution generation unit that can continuously generate the same solutions as the first solution generation unit using the same initial solution used by the first solution generation unit, a second splitting unit that splits data, and a second communication unit that communicates with the first communication device via the network, The first communication device takes the shared data, which is plaintext data to be shared with the second communication device, and uses a first key, which is unique to the first communication device and secret from the outside, and the first solution, which is the first solution generated by the first solution generation unit, to perform an encryption transformation in the first encryption unit to obtain first encrypted data, and the first communication unit transmits the first encrypted data to the second communication device via the network in a first process,When the second communication device receives the first encrypted data from the first communication device in the second communication unit, the second decryption unit performs the reverse transformation of the encryption transformation performed in the first encryption unit using the same first solution generated in the second solution generation unit, and the second encryption unit performs the encryption transformation using a second key which is unique to the second communication device and is kept secret from the outside, and the second division unit divides the data obtained by the encryption transformation performed in the second encryption unit using the second key into two parts. The second process involves the second encryption unit performing an encryption transformation on one of the divided data using the second solution, which is the second solution generated by the second solution generation unit, to obtain data A, which is part of the second first encrypted data; the second encryption unit performing an encryption transformation on the other of the divided data using the third solution, which is the third solution generated by the second solution generation unit, to obtain data B, which is the remainder of the second first encrypted data; and the second communication unit transmitting the data A and the data B, which constitute the second first encrypted data, to the first communication device via the network.When the first communication device receives the A data and B data, which constitute the second first encrypted data in the first communication unit, the first decryption unit performs the reverse transformation of the encryption transformation performed in the second encryption unit using the same second solution generated in the first solution generation unit and the second solution generation unit on the A data, and also performs the reverse transformation of the encryption transformation performed in the first encryption unit using the first key and the first decryption unit using the first key on the B data, and the first decryption unit performs the same third solution generated in the first solution generation unit and the second solution generation unit and the first solution generation unit The second encryption unit performs the reverse transformation of the encryption transformation performed using the third solution, and the first encryption unit performs the reverse transformation of the encryption transformation performed using the first key, the data obtained based on the A data and the data obtained based on the B data are combined in the combination unit, and the first encryption unit performs an encryption transformation on the combined data using the fourth solution, which is the fourth solution generated in the first solution generation unit, to obtain the second encrypted data, and the third process involves the first communication unit transmitting the second encrypted data to the second communication device via the network, A communication method comprising: a fourth step in which, when the second communication device receives the second encrypted data from the first communication device at the second communication unit, the second decryption unit performs the reverse transformation of the encryption transformation performed in the first encryption unit using the fourth solution, using the same fourth solution generated in the second solution generation unit and generated in the first solution generation unit, and also performs the reverse transformation of the encryption transformation performed in the second encryption unit using the second key, thereby converting the second encrypted data into shared data.

12. The communication method according to claim 10 or 11, wherein the first communication device and the second communication device automatically perform the first to fourth processes in succession.

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