Encrypted communication device and method for performing encrypted communication while reducing traffic in communication system

Abstract

An encrypted communication device includes: a pattern generation unit configured to judge whether or not a security association including as matching data a data portion whose data pattern matches between data in a packet targeted for processing and data in a sample packet is to be generated; a key information exchange unit configured to transmit to an opposite device a key information exchange packet including the matching data and key data when the pattern generation unit judges that the security association is to be generated, and receives from the opposite device a key information exchange packet including a security association identifier of the security association, thereby establishing the security association with the opposite device; and a key information unit configured to store the matching data, the key data, and the security association identifier of the security association established by the key information exchange unit.