KEY CONTROL SYSTEM FOR MULTICAST DISTRIBUTION

摘要

PROBLEM TO BE SOLVED: To realize easy control of keys (encryption/decryption keys) in a network system wherein encrypted data are distributed by multicast. SOLUTION: A key control server 31 holds a set of encryption and decryption keys and an key ID for uniquely identifying the keys for key control. Each of contents servers 11-1n receives a set of the encryption key and its key ID from the key control server 31 and sends a multicast packet having data encrypted with the encryption key and the key ID to clients 21-2m. Each of clients 21-2m receives the multicast packet from the contents servers 11-1n, acquires the decryption key corresponding to the key ID contained in the multicast packet from the key control server 31, and decrypts the encrypted data contained in the multicast packet with the decryption key. COPYRIGHT: (C)2004,JPO