Network adapter and communication device

A communication device comprising:

• a network adapter including a network connection unit which is connected to a network, transmitting and receiving packet data, a bus connection unit which is connected to a bus, transmitting and receiving data and control information to a host device, an encryption/decryption processing unit executing an encryption/decryption application which encrypts contents or decrypts the encrypted contents and a network control unit executing software including respective hierarchies of a socket interface, a protocol stack and a device driver;
• and
• a host device including a device connection unit connected to the network adapter through the bus and a host control unit executing software including respective hierarchies of the socket interface, the protocol stack and the device driver, and
• wherein the encryption/decryption application performs communication with the network connection unit or the bus connection unit through the socket interface, and
• wherein the network control unit and the host control unit control transmission and reception of data and control information between the bus connection unit and the device connection unit by using a network device driver as the device driver.