Patent ID: 7874014

Claim:
A content distribution server arranged to be connectable via a telecommunication circuit to a user terminal device, comprising: a distribution-content storing section which stores a distribution content file subject to distribution, the distribution content file being composed of: content data; and a regulatory program for enforcing a regulation reproducing the content data, the regulatory program including a first key required for the regulation; a key storing section for storing a second key which forms a pair with the first key; a key generating section for generating, when receiving terminal identification information transmitted from the user terminal device, based on the received terminal identification information and the second key stored in the key storing section, a third key including these pieces of information; and a transmitting controller for transmitting, in response to a request from the user terminal device, to the user terminal device the distribution content file stored in the distribution-content storing section, and transmitting to the user terminal device the third key generated by the key generating section, wherein the regulatory program is configured to: when the distribution content file is opened on the user terminal device at least for a first time, firstly execute the regulatory program, and thereafter, reproduce the content data; and to perform a process in which on the user terminal device, the terminal identification information based on unique information of the user terminal device is generated and is transmitted to the content distribution server, a process in which the third key transmitted from the content distribution server is received, information corresponding to the second key and the terminal identification information are each recognized from the received third key, whether the recognized second key is a key which forms a pair with the first key in the regulatory program is confirmed, and whether the recognized terminal identification information agrees with the generated terminal identification information is confirmed, and a process in which when the recognized second key is the key which forms a pair with the first key and the recognized terminal identification information agrees with the generated terminal identification information, the content data are reproduced.