COMMUNICATION DEVICE, COMMUNICATION METHOD, COMMUNICATION SYSTEM, AND COMPUTER PROGRAM

摘要

An objective of the present invention is to avoid illicit distribution of content while allowing authentication and key exchange procedures over an external network. A measurement to obtain an RTT to a receiving apparatus (130) is carried out with a relay apparatus (120) which is between a WAN (140) and a home network (150) and connects these two networks. By making it a condition for distribution of content from a transmission apparatus (110) that the RTT value be less than or equal to a threshold, it is possible to implement a usage environment for using content within the home network (150) which is equivalent to a system which uses current DLNA and DTCP-IP protocols.