Patent ID: 7523303
Filing Date: 2009-04-21
Classification: G06F,G06Q

Abstract:
1. A digital work distribution system for distributing digital works over a network to a user computer, comprising: first and second computers connected to each other via a network and connected to a user computer via the network, said first computer configured for setting conditions for plural usages of the work data to be distributed, encrypting said work data with a predetermined encryption key, generating different ticket encryption keys and corresponding ticket decryption keys, each of said ticket encryption keys and the corresponding one of said ticket decryption keys being associated with a corresponding one of conditions for one usage among the set conditions for the plural usages, encrypting a predetermined decryption key corresponding to said predetermined encryption key, by using each of said ticket encryption keys generated each in association with the conditions for one of the plural usages, and encapsulating said work data and said predetermined decryption key encrypted using each of said ticket encryption keys generated each in association with the conditions for one of the plural usages, and generating a capsular work which contains said work data and said predetermined decryption key; and said second computer storing the conditions for the plural usages which have been set by said first computer and said ticket decryption keys corresponding to said ticket encryption keys generated each in association with the conditions for one of the plural usages and used to encrypt said predetermined decryption key, encrypting, in reply to an external request for use of said work data received over the network from a user computer, a ticket decryption key which is associated with the conditions for one usage corresponding to the request among the stored ticket decryption keys, and distributing the encrypted ticket decryption key to a requester at the user computer who has made the request for use of said work data.