COMMUNICATION APPARATUS

摘要

The conventional data transmitting/receiving system has problems that a verification process time cannot be precisely measured because it is added to a transmission time and then measured; there is a need to provide a separate authentication process required for a transmission time measurement process; and that an unnecessary key exchange process is executed. A transmitting apparatus (a) shares authentication information with a request source that requests a transmission of content data, (b) transmits to the request source a measurement request generated by using the authentication information, (c) receives, as a response to the measurement request, from the request source a measurement response generated by using the authentication information shared by the request source, (d) measures, as a round-trip delay time, a time from the transmission of the measurement request until the reception of the measurement response, (e) transmits, before the transmission of the measurement request, to the request source a measurement preparation request for requesting a preparation required for generating the measurement response, and (f) determines, after the measurement of the round-trip delay time, that the request source is an appropriate apparatus as a destination of transmitting the content data if the round-trip delay time is equal to or less than a reference value so that the correctness of the measurement response is verified and if the correctness of the measurement request is verified at the request source.