CONTENTS REPRODUCTION DEVICE

摘要

PROBLEM TO BE SOLVED: To enable the same user to reproduce contents to be once downloaded even if the constitution of hardware and software is changed. SOLUTION: A constitution storage means 101 stores pre-change constitution information outputted from a constitution detector 405. A ciphering key storage means 103 stores a second ciphering key characteristic to a contents reproduction device generated by a ciphering key generator 102 based on post-change constitution information. A mutual authentication device 408 authenticates the contents and pre-change constitution information to authenticate the second ciphering key and the post-change constitution information.