Data transmission method, communication processing method, device, and communication processing program

A communication processing method in a device connected to a network, the method comprising:

• as steps executed when a packet addressed to another device is given, a step of generating a first encrypted packet by encrypting the packet with a first encryption key associated with the another device;
• a step of determining a device to be a transmission destination of the first encrypted packet, wherein the device to be a transmission destination is determined based on an IP address of each device;
• a step of generating a second encrypted packet by encrypting the first encrypted packet with a second encryption key associated with the determined device;
• and
• a step of transmitting the second encrypted packet to the determined device;
• and
• as steps executed when the second encrypted packet is received from another device,
• a step of decrypting the second encrypted packet into the first encrypted packet;
• a step of determining whether or not the decrypted first encrypted packet is addressed to the device;
• a step of determining still another device to be a transmission destination of the first encrypted packet, generating a second encrypted packet with a second encryption key associated with the determined device, and transmitting the generated second encrypted packet if the decrypted first encrypted packet is not addressed to the device in the determination regarding whether or not the decrypted first encrypted packet is addressed to the device;
• a step of further decrypting the first encrypted packet if the decrypted first encrypted packet is addressed to the device;
• a step of acquiring a private key and a public key;
• a step of determining an IP address of the device based on a hash value calculated from the public key according to a hash function;
• and
• a step of transmitting the public key to another device.

A device, comprising:

• a network interface for connecting to a network;
• and
• a control unit connected to the network interface,
• wherein the control unit includes:
• a first encryption/decryption unit capable of executing a process for encrypting a packet into a first encrypted packet using a first encryption key associated with another device and a process for decrypting the first encrypted packet;
• a second encryption/decryption unit capable of executing a process for encrypting the first encrypted packet into a second encrypted packet using a second encryption key associated with a device to be a transmission destination of the first encrypted packet and a process for decrypting the second encrypted packet, wherein the device to be a transmission destination is determined based on an IP address of the device;
• a transmission management unit that transmits the second encrypted packet, which is generated by encrypting a packet addressed to another device in the first encryption/decryption unit and the second encryption/decryption unit, to a device as a transmission destination, and
• the transmission management unit determines whether or not a first encrypted packet generated by decrypting a second encrypted packet received from another device in the second encryption/decryption unit is addressed to the device, transmits a second encrypted packet generated by encrypting the first encrypted packet in the second encryption/decryption unit to still another device if the generated first encrypted packet is not addressed to the device, and further decrypts the first encrypted packet in the first encryption/decryption unit and outputs the decrypted first encrypted packet if the generated first encrypted packet is addressed to the device;
• wherein the transmission management unit is operable to:
• acquire a private key and a public key,
• determine an IP address of the device based on a hash value calculated from the public key according to a hash function, and
• transmit the public key to another device.