COMMUNICATION APPARATUS, KEY SERVER, MANAGEMENT SERVER, COMMUNICATION SERVER, COMMUNICATION METHOD, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a distribution technique capable of suppressing unauthorized description of an encrypted content distributed in a content distribution system. SOLUTION: A leecher 50A receives a Torrent File from a sales server 54; obtains node information by accessing a tracker 51, based on the Torrent File; receives decrypted pieces by accessing at least one of seeders 52A, 52B, 52C and a leecher 50B, based on the obtained node information; obtains all encrypted pieces corresponding to the pieces; and receives a key ring containing decryption keys that are respectively used for decrypting the encrypted pieces from the key server 53. COPYRIGHT: (C)2009,JPO&INPIT