Patent ID: 8356169

Claim:
An encryption communication method in which an application in a node apparatus communicates with another node apparatus in a network, the method comprising: determining, by a processor, on a basis of a domain name contained in one of a name resolution query transmitted from the application to resolve an IP address of said other node apparatus and a name resolution response as a response to the name resolution query, whether said other node apparatus is an encryption communication target node; registering, in a first encryption communication path setting table, a correspondence between the IP address of said other node apparatus and a loopback address that is not used in any other communication session when said other node apparatus is the encryption communication target node; replacing the IP address of said other node apparatus contained in the name resolution response with the loopback address in the correspondence and transmit the name resolution response to the application; transmitting by the application a data packet in which the loopback address serving as an IP address for closed communication in a self node is set as a destination address; and; receiving, by a communication encryption module operating as an independent process, the data packet having the loopback address set as the destination address and transmitted from the application, read out a communication partner IP address corresponding to the loopback address set as the destination address of the data packet from the first encryption communication path setting table that holds a plurality of correspondences between the communication partner IP address and the loopback address, rewrite the destination address of the data packet to the readout communication partner IP address, and encrypt and transmit the data packet.