Patent ID: 8132024

Claim:
A recording apparatus for recording an encrypted content onto a recording medium storing first media key data and a first encrypted content, the first media key data including a plurality of first encrypted media keys each generated by encrypting one first media key using a corresponding device key of a plurality of first device keys, the first encrypted content being generated by encrypting a content using a first media key, the recording apparatus comprising: a device key storing unit storing a device key assigned to the recording apparatus; a storing unit storing second media key data including a plurality of second encrypted media keys each generated by encrypting one second media key using a corresponding device key of a plurality of second device keys; a comparing unit operable to compare the first media key data stored in the recording medium with the second media key data stored in the storing unit, so as to judge which of the first media key data and the second media key data is newer; a content decrypting unit operable to, when the comparing unit judges that the second media key data is newer than the first media key data and when the first encrypted content has been stored in the recording medium, obtain the one first media key from the first media key data using a corresponding device key of the plurality of first device keys, and decrypt the first encrypted content stored in the recording medium using the obtained one first media key, so as to generate a content; a content encrypting unit operable to, when the comparing unit judges that the second media key data is newer than the first media key data, and continuously after the content decrypting unit generates the content, obtain the one second media key from the second media key data using a corresponding device key of the plurality of second device keys, and encrypt the content generated by the content decrypting unit using the obtained one second media key, so as to generate a second encrypted content; and a deleting and writing unit operable to delete the first media key data and the first encrypted content from the recording medium, and write the second media key data and the second encrypted content generated by the content encrypting unit to the recording medium, wherein one media key data is stored in the recording medium and two or more pieces of media key data are not stored in the recording medium.