CONTENTS TRANSMITTING DEVICE, CONTENTS RECEIVING DEVICE AND CONTENTS TRANSMITTING METHOD, PARTICULARLY FOR PROTECTING COPYRIGHT OF CONTENTS TRANSMITTED AND RECEIVED THROUGH A NETWORK

摘要

PURPOSE: A contents transmitting device, a contents receiving device and a contents transmitting method are provided to prevent receiving and illegal copying of contents by a device other than an authenticated contents receiving device and also prevent transmission of contents beyond a wide area network. CONSTITUTION: Network communication processing circuit(103,203) transmit/receive data through a network. A transmission contents generator supplies contents to be transmitted to a contents receiving circuit(201) connected through the network to a network communication unit. Authentication units(104,204) receive an authentication request from the contents receiving circuit(201), determines whether to authenticate it, and issues an authentication request with respect to the contents receiving circuit(201). A coding unit(102) generates key information and codes contents to be transmitted to the contents receiving circuit(201). Timer units(108,208) measure time taken for receiving reception ACK from the contents receiving circuit(201) after an authentication request is transmitted to the contents receiving circuit(201) or after the contents receiving circuit(201) transmits a response to the authentication request. If a measurement result in the timer units(108,208) exceeds a certain value, contents is not transmitted to the contents receiving circuit(201).