Hitachi, Ltd.

Shuichi Tago

Hiroshi Yoshiura

Shigeki Hirasawa

Isao Echizen

Masataka Okayama

Kousuke Anzai

Hiromi Ukai

A method for using digital contents is provided. In the method, a request is made to a provider apparatus for a certificate containing a first provider ID embedded therein by a certification authority, and the certificate is received from the provider apparatus. A decision is made by using the certificate as to whether or not the provider is authorized by the certification authority. A request is made to the provider apparatus for a digital content having a second provider ID embedded therein by a contents guarantee authority when the provider is authorized by the certification authority, and the digital content is received from the provider. The first provider ID is read from the certificate, the digital content is correlated with the second provider ID, and the digital content is stored in a storage medium. The second provider ID is detected from the digital content in response to a request to use the digital content. The first provider ID is compared with the second provider ID when the second provider ID is detected. The digital content is used when the first provider ID and the second provider ID match. The use of the digital content is restricted when the first provider ID and the second provider ID do no match.

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Abiko, Japan

Shuichi Tago