| 摘要 |
PROBLEM TO BE SOLVED: To provide a system for tracing the use of digital contents on a user device. SOLUTION: A content site distributes digital contents via a computer- readable medium to a user. The content site relates an unique content identifier with the related contents. An electronic store connected with a network sells a license for reproducing the digital content data to the user. The license includes the unique item identifier for uniquely identifying at least one item in the transaction. Then, a content, player which receives the content data given the license from the network, is used for the reproduction of the content data given the license. The content player prepares a purchase identifier, based on the mathematical combination of the content identifier, the transaction identifier, and the item identifier. |
