Abstract: The present invention relates to a content distribution server or the like, capable of more surely preventing an unauthorized use of a content. Content distribution servers 2 and 3 are arranged to be connectable via a telecommunication circuit to a user terminal device, and include: a distribution-content storing section 14 for storing a distribution content file composed of: content data; and a regulatory program including a first key for regulating reproducing the content data; a key storing section 15 for storing a second key which forms a pair with the first key; a key generating section 34 for generating, when receiving the terminal identification information transmitted from the user terminal device, a third key including the received terminal identification information and information of the second key; and transmitting controllers 16 and 34 for transmitting the third key to the user terminal device.

Abstract: The present invention relates to a content distribution server or the like, capable of more surely preventing an unauthorized use of a content. Content distribution servers 2 and 3 are arranged to be connectable via a telecommunication circuit to a user terminal device, and include: a distribution-content storing section 14 for storing a distribution content file composed of: content data; and a regulatory program including a first key for regulating reproducing the content data; a key storing section 15 for storing a second key which forms a pair with the first key; a key generating section 34 for generating, when receiving the terminal identification information transmitted from the user terminal device, a third key including the received terminal identification information and information of the second key; and transmitting controllers 16 and 34 for transmitting the third key to the user terminal device.