A recording apparatus for recording a second 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, wherein the plurality of first encrypted media keys each corresponds to one of a plurality of devices, including the recording apparatus and reproduction apparatuses, and each are generated by encrypting one first media key using a device key of a corresponding one of the plurality of devices for each device being unrevoked and are generated by encrypting predetermined detection information using the device key of a corresponding one of the plurality of devices for each device being revoked, the first encrypted content being generated by encrypting a content using the one first media key, the revoked and unrevoked devices being reproduction apparatuses, the recording apparatus comprising: a device key storing unit for storing the device key unique to the recording apparatus; and a media key data storing unit for storing second media key data including a plurality of second encrypted media keys, wherein the plurality of second encrypted media keys each corresponds to one of the plurality of devices including the recording apparatus, and each are generated by encrypting one second media key using the device key of a corresponding one of the plurality of devices for each device being unrevoked and are generated by encrypting predetermined detection information using the device key of a corresponding one of the plurality of devices for each device being revoked; and wherein the recording apparatus is operable to: compare the first media key data stored in the recording medium with the second media key data stored in the media key data storing unit, so as to judge which of the first media key data and the second media key data is of a newer version; and when the second media key data is judged to be of the newer version than the first media key data: decrypt the first encrypted content stored in the recording medium, so as to generate a decrypted content; re-encrypt the decrypted content based on the one second media key, so as to generate a re-encrypted content; delete the first encrypted content from the recording medium; and write the re-encrypted content onto the recording medium. a device key storing unit for storing the device key unique to the recording apparatus; and a media key data storing unit for storing second media key data including a plurality of second encrypted media keys, wherein the plurality of second encrypted media keys each corresponds to one of the plurality of devices including the recording apparatus, and each are generated by encrypting one second media key using the device key of a corresponding one of the plurality of devices for each device being unrevoked and are generated by encrypting predetermined detection information using the device key of a corresponding one of the plurality of devices for each device being revoked; and wherein the recording apparatus is operable to: compare the first media key data stored in the recording medium with the second media key data stored in the media key data storing unit, so as to judge which of the first media key data and the second media key data is of a newer version; and when the second media key data is judged to be of the newer version than the first media key data: decrypt the first encrypted content stored in the recording medium, so as to generate a decrypted content; re-encrypt the decrypted content based on the one second media key, so as to generate a re-encrypted content; delete the first encrypted content from the recording medium; and write the re-encrypted content onto the recording medium. compare the first media key data stored in the recording medium with the second media key data stored in the media key data storing unit, so as to judge which of the first media key data and the second media key data is of a newer version; and when the second media key data is judged to be of the newer version than the first media key data: decrypt the first encrypted content stored in the recording medium, so as to generate a decrypted content; re-encrypt the decrypted content based on the one second media key, so as to generate a re-encrypted content; delete the first encrypted content from the recording medium; and write the re-encrypted content onto the recording medium. decrypt the first encrypted content stored in the recording medium, so as to generate a decrypted content; re-encrypt the decrypted content based on the one second media key, so as to generate a re-encrypted content; delete the first encrypted content from the recording medium; and write the re-encrypted content onto the recording medium.