Patent ID: 8607069

Claim:
A data processing apparatus comprising an attachable/detachable non-volatile recording medium and a host for receiving/transmitting encrypted contents data from/to the attachable/detachable non-volatile recording medium, wherein the attachable/detachable non-volatile recording medium comprises: an interface for receiving from the host contents data encrypted with a first key by first encrypting means at the host, and the first key encrypted with a second key; decrypting means for decrypting the encrypted first key with the second key; second encrypting means for re-encrypting the decrypted first key with a third key, the third key stored in the attachable/detachable non-volatile recording medium; storage means for storing, in the attachable/detachable non-volatile recording medium, the first key re-encrypted with the third key and the contents data encrypted with the first key; receiving means for receiving, from the storage means, the first key re-encrypted with the third key; and decrypting means for decrypting, with the third key, the first key re-encrypted with the third key, and wherein the host comprises: encrypting means for re-encrypting the decrypted first key with a fourth key that is different from the third key; and storing means for storing the contents data encrypted with the first key and the first key re-encrypted with the fourth key.