Method and apparatus for decrypting contents information

摘要

A first-key signal representative of a first key is generated from first-key base information being a base of the first key. Contents information is encrypted into encryption-resultant contents information in response to the first-key signal. A second-key signal representative of a second key is generated from second-key base information being a base of the second key. The first-key base information is encrypted into encryption-resultant first-key base information in response to the second-key signal. Second-key-related information is generated from the second-key base information and additional information according to a predetermined function. The encryption-resultant contents information, the encryption-resultant first-key base information, and the second-key-related information are transmitted or recorded.