Patent ID: 7644265

Claim:
A content transmitting device comprising: network communication process means for transmitting and receiving data via a network; send-content generating means for supplying said network communication process means with a content to be transmitted to a content receiving device connected via said network; authenticating means for receiving an authentication request from said content receiving device and authenticating said authentication request; encrypting means for generating key information by key information generated based on information obtained by performing an authentication process by said authenticating means, and carrying out an encryption process of a content to be transmitted to said content receiving device, by using said key information; timer means for measuring a time from transmission of information to said content receiving device until arrival of acknowledgement of receipt from said content receiving device, wherein when the time is larger than a predetermined value, said authenticating means decides that the authentication of said content receiving device is a failure, so that the transmittable range of the content is restricted to within a location or house in which said content transmitting device is placed to prohibit the transmission of the content to an outside of said location or said house, listening and viewing of the content is restricted, and copying and transmitting of the content is limited to personal use; wherein if said authenticating means decides that said authentication request was transmitted and received via a number of external devices in said network, where the number being more than or equal to a predetermined value, said authentication request is not accepted.