Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Yoji Kumazaki

Motoji Ohmori

Tetsuya Inoue

Shigeru Yamada

Yuichi Futa

Masao Nonaka

Hiroki Murakami

Takatoshi Ono

A content distribution system distributes contents. The content distribution system includes a key issuing center, a server, eight output apparatuses, and a communication path that connects them to each other. The key issuing center and each of the output apparatuses are previously given an individual key shared between them. For example, the key issuing center shares individual key IKa with an output apparatus, individual key IKb with an output apparatus, and individual key IKh with an output apparatus.

Content distribution server, key assignment method, content output apparatus, and key issuing center

A key management apparatus which can be used to encrypt/decrypt content data in a content playback device includes a storing unit for storing a secret key, a key information decrypting unit for decrypting encrypted key information and an updating unit operable to update the secret key with an algorithm stored therein, when the decrypted key information is key-updating information. Seed information can be received for use with the algorithm to provide a new secret key, and preliminary trigger information can be used to poll a group of appliances to request key information to determine any duplication of appliances.

Content playback apparatus method and program and key management apparatus and system

Growing community of inventors

Aichi, Japan

Yoji Kumazaki