Patent ID: 8393005
Filing Date: 2013-03-05
Classification: G06F,G11B

Abstract:
1. A recording apparatus for recording content to a recording medium, comprising: a receiver that receives content in a first format and a first format content key, the first format content key being obtained by encrypting a content key using a first key encryption key, the content key being used to encrypt the content; a first key writer that writes the received first format content key into the recording medium; a first format content writer that writes the received first format content into an unprotected area of the recording medium; a key converter that converts the first format content key to a second format content key without changing the key value of the content key; a content converter that converts the first format content to content in a second format; a second key writer that writes the second format content key into the recording medium; and a second content writer that writes the second format content into the unprotected area of the recording medium; wherein the key converter comprises: a content key decryptor that reads the first format content key from the recording medium and decrypts the first format content key, using the first key encryption key; and a content key encryptor that encrypts the decrypted first format content key, using a second key encryption key to obtain the second format content key, the second key encryption key being different from the first key encryption key, wherein the unprotected area can be accessed freely by the recording apparatus, regardless of whether the recording apparatus succeeds in performing mutual authentication with the recording medium, wherein: the recording medium further comprises: a system area from which data can only be read; a reserved area that cannot be externally accessed; and a protected area that can only be accessed when mutual authentication is performed successfully, wherein the system area stores key encryption key retrieval information that is used for performing mutual authentication, the reserved area stores the second key encryption key and a third key encryption key, the unprotected area stores the first format content key, and the protected area stores the first key encryption key encrypted with the third key encryption key; and wherein: the recording apparatus further comprises: a key encryption key calculator that calculates the second and third key encryption keys, using the key encryption key retrieval information stored in the system area of the recording medium; a mutual authenticator that performs first mutual authentication and second mutual authentication with the recording medium, respectively using the calculated second and third key encryption keys; and a key encryption key decryptor that reads the encrypted first key encryption key, when the mutual authenticator succeeds in performing the second mutual authentication using the third encryption key, and decrypts the read encrypted first key encryption key with the third key encryption key; wherein the content key decryptor reads the first format content key from the unprotected area, and decrypts the first format content key, using the decrypted first key encryption key; and the second content key writer stores the second format content key to the protected area if the mutual authenticator succeeds in performing the second mutual authentication using the third key encryption key.