KEY MANAGEMENT DEVICE FOR PROTECTING COPYRIGHT, RECORDING MEDIUM, REPRODUCTION DEVICE, RECORDING DEVICE, KEY MANAGEMENT METHOD, REPRODUCTION METHOD, KEY MANAGEMENT PROGRAM, AND COMPUTER READABLE RECORDING MEDIUM WITH KEY MANAGEMENT PROGRAM RECORDED

摘要

PROBLEM TO BE SOLVED: To provide a key management device capable of managing a key assigned to a reproduction device.;SOLUTION: The key groups of keys arranged in each node in a tree structure having N layers on different paths following those keys from the Nth layer to the uppermost layer are respectively assigned to different reproduction devices. In receiving the notification of the key group of one reproduction device, a key selecting part 115 defines the respective keys of the key group as an invalid key, and selects a key in the further lower layer of the invalid key which is assigned to another reproduction device, and which is not defined as the invalid key on another path as a selection key. A contents enciphering part 114 generates data by enciphering the contents with a contents key. A cipher text generating part 117 generates a cipher text by enciphering the contents key with the selected selection key. A selection key list generating part 118 generates the list of the selection keys used for the generation of the cipher text. A recording part 119 records the data and the cipher text and the list in a recording medium.;COPYRIGHT: (C)2002,JPO