Patent ID: 8219643

Claim:
A server/client hardware system, comprising: a server configured to store content; and a client machine including a processor configured to receive and store copied content from the content stored in the server, wherein the client machine includes a storage unit configured to store a content-ID and use-expiration date information indicating a date in which content can no longer be used, corresponding to the copied content received from the server, the server generates a content-ID list including content-IDs corresponding to content for which use-expiration-date updating is permitted from among the copied content stored in the client machine, for transmission to the client machine, the client machine selectively updates the use-expiration date of the copied content stored in the client machine and the client machine automatically invalidates the copied content stored in the client machine based on the content-ID list received from the server, the server performs confirmation processing when the client machine is in a private-use range, and executes transmission of the content-ID list to the client machine when the server receives confirmation that the client machine is in the private-use range, the server stores a moving time variable Tv indicating a time when moving of the stored content from the server to another device or storage medium is executed, executes comparison between the moving time variable Tv and a content expiration date variable Tr indicating when the use of the copied content expires, and if the moving time variable Tv is before the content expiration date variable Tr of the copied content executed at a previous time, the server performs permission processing of a new use-expiration date setting for the copied content stored in the client machine without transmitting the content-ID list to the client machine, the confirmation processing executed by the server of the client machine in a private-use range is performed as round-trip-time (RTT) check processing, and for the RTT check processing, the server transmits a packet to the client machine and measures a time period for the packet to return to the server, the server determines that the server and the client machine are in the private-use range when the time period is within a predetermined threshold, and the server only permits the client to update the use-expiration date of the copied content when the server and the client machine are in the private use range.